Traditional Posters : Diffusion & Perfusion - Neuro
Click on to view the abstract pdf and click on to view the pdf of the poster viewable in the poster hall.

Monday May 9th
Exhibition Hall  14:00 - 16:00

2035.   Effects of Contrast Agent Accumulation on Background Correction of Phase-Based Arterial Input Functions  
Anders Garpebring1, Ronnie Wirestam2, and Mikael Karlsson1
1Radiation Sciences, Umeĺ University, Umeĺ, Sweden, 2Medical Radiation Physics, Lund University, Lund, Sweden

Phase sensitive MRI has shown great potential for quantification of the Arterial Input Function (AIF). Phase based AIFs are sensitive to motion and B0 drift, and a background phase curve is thus normally subtracted from the AIF phase. However, this procedure can be complicated by accumulation of contrast agent (CA) in the background tissue region. The purpose of this study was to assess the importance of CA in the background ROI and to develop a method to compensate for this effect. The results showed that CA in the background was a significant problem and that the developed compensation was beneficial.

2036.   Comparison between MRI Blood-to-Brain Transfer Rate Constants from Individual MRI and Population Averaged Quantitative Autoradiographic Arterial Input Functions 
Kishor Karki1, Ramesh Paudyal1, Tavarekere N. Nagaraja2, James R. Ewing1,3, Joseph D. Fenstermacher2, and Robert A. Knight1,3
1Department of Neurology, Henry Ford Hospital, Detroit, Michigan, United States, 2Department of Anesthesiology, Henry Ford Hospital, Detroit, Michigan, 3Department of Physics, Oakland University, Rochester, Michigan, United States

The present study investigates the possibility of using an average arterial input function (AIF) obtained from direct blood sampling experiments to estimate blood–brain barrier (BBB) permeability or blood-to-brain transfer constant (Ktrans) of Gd-DTPA for a step-down infusion (SDI) procedure instead of using the individual MRI derived AIF. Enhanced spatial resolution of areas with BBB opening was generally observed with the SDI technique. The Ktrans values from both types of AIF’s agreed closely and were highly correlated, suggesting that an averaged AIF for a given contrast agent obtained from a standard technique can be used to assess vascular permeability.

2037.   Dispersion correction in DCE-MRI microvascular parameters using a recirculating bolus AIF model 
Ross A Little1, Marietta Scott2, Anita Banerji1, Yvonne Watson1, Josephine Naish1, and Geoff JM Parker1
1Imaging Sciences & Biomedical Engineering, University of Manchester, Manchester, United Kingdom, 2AstraZeneca, Cheshire, United Kingdom

An arterial input function (AIF) model is presented that allows the effects of AIF dispersion to be characterised. This facilitates modelling of dispersion between the measurement point of an AIF and the tissue voxel of interest, providing an improved fit and a measure of AIF dispersion across the tissue. Simulations and application to clinical data show the applicability of the dispersed AIF method within the DCE-MRI analysis pipeline. They show that not accommodating dispersal leads to errors on the tissue microvascular parameters.

2038.   Optimizing perfusion imaging of brain tumors: Validation of venous output function used as a surrogate AIF 
Claire Foottit1, Greg O. Cron1, Jean Francois Mercier1, Viviane Thanh-Van Nguyen2, Ian Cameron1, Mark E Schweitzer1, John Sinclair1, John Woulfe1, Matthew J Hogan3, and Thanh B Nguyen1
1The Ottawa Hospital, Ottawa, Ontario, Canada, 2University of Montreal, 3Neuroradiology, The University of Ottawa, Ottawa, Ontario, Canada

In DCE-MRI studies of human brain tumors, a suitable artery for the arterial input function (AIF) is often not available or is insufficiently large. The venous output function (VOF) in the superior sagittal sinus is often used as a surrogate AIF. However, to our knowledge no DCE-MRI study has ever validated this practice for high-temporal-resolution data. In this work, we acquired phase-derived AIFs and VOFs simultaneously during DCE-MRI studies, with the hypothesis that tumor tracer kinetic parameters would be equivalent using either vascular function. The data support the use of a VOF in place of the AIF.

2039.   Intra-operative perfusion imaging of brain tumors using dynamic contrast enhanced MRI: A comparison with dynamic susceptibility contrast MRI 
Shy-Chyi Chin1, Yeng-Peng Liao2, Ya-Ting Chuang1, and Ho-Ling Liu2,3
1Department of medical imaging and intervention, Chang-Gung Medical Center, Guei-Shan, Tao-Yuan, Taiwan, 2Chang Gung University, Department of Medical Imaging and Radiological Sciences, Guei-Shan, Tao-Yuan, Taiwan, 3Department of Medical Imaging and Intervention, Chang-Gung Medical Center

A new trend is to utilize MRI intra-operatively to assess the sufficiency of brain tumor resection, not just for better navigation. Both dynamic contrast-enhanced (DCE) and dynamic susceptibility-contrast (DSC) techniques are applied to patients after surgical resection. Our study, distinct from previous works biased toward DSC-MRI, has concluded that (1) no discrepancy between the normalized VP from DCE-MRI and normalized CBV from DSC-MRI and (2) Ktrans map from DCE-MRI seemingly more precise in denoting the permeability and extent of impaired brain-blood-barrier than K2 map from DSC-MRI.

2040.   In Vivo correlation between non-model-based parameters and model-based Ktrans in brain tumors 
Chih-Feng Chen1, Lin-Wei Hsu2, and Ho-Lin Liu2
1Department of Radiology, Chang Gung Memorial Hospital, Chiayi, Taiwan, Taiwan, 2Department of Medical Imaging and Radiological Sciences Institute of Medical Physics and Imaging Sci, Chang Gung University, Taoyuan, Taiwan, Taiwan

The most common estimated parameters in DCE-MRI are Ktrans and Ve. The process of Ktrans estimation is not easy. but the IAUC is more feasible. In this study, we aim to further investigate the application of mIAUCktrans in clinical and find the correlation between mIAUCktrans and Ktrans. With the correlation coefficients of 0.95, mIAUCktrans was more correlated with Ktrans. Since the high correlation between Ktrans and mIAUCktrans was demonstrated in this study, it reveals that mIAUCktrans could be an alternative for physiological condition evaluation in DCE-MRI.

2041.   Dynamic Contrast Enhanced and Diffusion Weighted MRI from Primary Tumors and Metastatic Cervical Lymph Nodes in Squamous Cell Carcinomas of the Head and Neck 
Sanjeev Chawla1, Sungheon Kim1,2, Larry Dougherty1, Sumei Wang1, Laurie A Loevner1, Harry Quon3, and Harish Poptani1
1Radiology, University of Pennsylvania, Philadelphia, PA, United States, 2Radiology, New York University, New York, NY, United States, 3Radiation Oncology, University of Pennsylvania, Philadelphia, PA, United States

Twenty-eight patients with squamous cell carcinomas of head and neck underwent DCE- MRI with a radial acquisition and dynamic K-space weighted image reconstruction contrast technique and diffusion weighted imaging. Motion correction algorithms were applied to further reduce motion artifacts. Strong positive correlations in Ktrans (r=0.684, p<0.001) and ADC (r=0.407, p=0.031) from primary tumors and metastatic nodes were observed. These findings indicate that both lesions have similar physiological characteristics. Good quality Ktrans and ADC maps from primary tumors, located in regions prone to physiological motion, is feasible and may help in assessing these tumors for therapeutic response using these imaging markers.

2042.   Value of Semi-Quantitative Analysis of Dynamic Contrast-enhanced MRI for Diagnosing Staging of Nasopharyngeal Carcinoma, and Comparison with PET-CT 
Bingsheng Huang1, Pek Lan Khong1, Chung-sing Wong1, Dora Lai Wan Kwong2, and Queenie Chan3
1The University of Hong Kong, Hong Kong Island, Hong Kong SAR, Hong Kong, 2Clinical Oncology, The University of Hong Kong, 3Philips Healthcare

Dynamic Contrast-enhanced MRI (DCE-MRI) is useful for estimating the tumor malignancy because the contrast enhancement pattern reflects the perfusion and permeability of the tumor as well as the tumor angiogenesis. In this study we investigated the relationship between semi-quantitative contrast enhancement parameters in dynamic DCE-MRI and the diagnosing staging of nasopharyngeal carcinoma, and the correlation between these parameters and PET-CT scanning. Our results showed that some parameters from semi-quantitative analysis of DCE-MRI significantly correlate with the T stages of NPC tumors, but not with PET-CT parameter.

2043.   MR Renography: Coherence Investigation between Thin Slab and Whole Kidney Scans 
Bin Chen1, Yi Dang1, Xue Dong Yang2, Jing Fang1,3, Xiaoying Wang1,2, and Jue Zhang1,3
1Academy for Advanced Interdisciplinary Studies, Peking University, BEIJING, BEIJING, China, People's Republic of, 2Radiology, Peking University First Hospital, BEIJING, BEIJING, China, People's Republic of, 3College of Engineering, Peking University, BEIJING, BEIJING, China, People's Republic of

MR Renography was widely used to provide renal functional information in recent studies. However, conventional 3-D whole kidney scan takes more than ten minutes to obtain MRR curves in diffuse renal disease. The purpose in this study was to investigate a higher temporal resolution scan protocol to reflect renal functional information. The center thin slab scan employed, instead of the whole kidney scan protocol, was proved feasible for reflecting whole kidney perfusion information, and it also significantly improved the temporal resolution of MRR.

2044.   Three-Dimensional Myocardial Perfusion MRI with an Undersampled 3D Hybrid Radial Sequence 
Liyong Chen1,2, Ganesh Adluru1, Matthias C. Schabel1, Christopher J. McGann3, and Edward V.R. DiBella1,2
1Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, Utah, United States, 2Department of Bioengineering, University of Utah, Salt Lake City, Utah, United States, 3Division of Cardiology & Radiology, University of Utah, Salt Lake City, Utah, United States

3D hybrid radial pulse sequence was applied dynamic contrast enhanced myocardial perfusion MR imaging.

2045.   First-Pass Myocardial Perfusion Imaging with Sparse (k,t)-Space Sampling 
Anthony Glenn Christodoulou1, Cornelius Brinegar1, Bo Zhao1, Justin P Haldar1, Haosen Zhang2, Yi-Jen L Wu2, T. Kevin Hitchens2, Chien Ho2, and Zhi-Pei Liang1
1Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States, 2Pittsburgh NMR Center for Biomedical Research, Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, United States

Myocardial perfusion imaging is an important and challenging application of cardiovascular MRI. This work demonstrates that sparse sampling of (k,t)-space with the joint use of partial and spatial-spectral sparsity constraints can significantly improve the spatiotemporal resolution of first-pass myocardial perfusion imaging experiments. Experimental results in rats show a 390 μm in-plane spatial resolution and 15 ms temporal resolution, representing an equivalent acceleration factor of 51.

2046.   3D-liver quantitative perfusion mapping using EGEE grid with MR-DCE imaging and MS-325 blood pool contrast agent 
Benjamin Leporq1, Sorina Camarasu1, Frank Pilleul1,2, and Olivier Beuf1
1CREATIS, CNRS UMR 5220, Inserm U1044, INSA-Lyon, Université Lyon 1, Villeurbanne, France, 2Département d'imagerie digestive, CHU Edouard Herriot, Hospices Civils de Lyon, Lyon, France

Liver fibrosis is an important cause of mortality and morbidity in patients with chronic liver diseases and can lead to cirrhosis which the complications involve 15,000 deaths per year in France. An early detection and a clinical follow-up of liver fibrosis are still needed. The histology after liver biopsy is the gold standard but has inherent risk, interobserver variability and sampling errors. It has been demonstrated that liver perfusion imaging has the potential to detect and assess vascular modifications associated with liver fibrosis. However, these methods are only ROI-based and regional variations often met in diffuses liver diseases couldn’t be observed. This work presents a post-processing method using EGI (European Grid Initiative) for parallel processing to allow 3D liver parametric mapping with a reasonable processing time. Acquisition is founded on MR-DCE imaging technique after injection of the MS-325 blood pool agent.

2047.   Accessing Changes of Functional Dynamic Magnetic Resonance Imaging in Locally Advanced Breast Cancer Patients undergo Neoadjuvant Chemotherapy 
Si-Wa Chan1, Yi-Jui Liu2,3, Dah-Cherng Yeh4, Jeon-Hor Chen5, Fang-Yi Lee6, Huei-Jen Hsueh4, Kuo-Fang Shao3, and Hsiao-Wei Peng1
1Department of Radiology, Taichung Veterans General Hospital, Taichung, Taiwan, Taiwan, 2Department of Automatic Control Engineering, Feng-Chia University, Taichung, Taiwan, Taiwan,3Master's Program in Biomedical Informatics and Biomedical Engineering, Feng-Chia University, Taichung, Taiwan, Taiwan, 4Division of General Surgery, Taichung Veterans General Hospital, Taichung, Taiwan, Taiwan, 5Center for Functional Onco Imaging, University of California, Irvine, CA, United States, 6Department of Physicain, Taichung Veterans General Hospital, Taichung, Taiwan, Taiwan

Dynamic contrast-enhanced MR (DCE-MRI) is able to distinguish malignancy from benign tissue by recognizing the differences in contrast enhancement that originates from their differences in microcirculation. DCE-MRI also evaluates some of the functional images, such as tissue perfusion and permeability of tumor vessels. Therefore, this ability can be used as a functional image to monitor the pathophysiological responsiveness to treatment. In this work, two-compartment model proposed by Buckley et al. was applied in DCE-MRI to monitor the sequential chemotherapy response of patient with LABC. We aim to find the perfusion parameters which are sensitive to chemotherapy response.

2048.   Evaluation of ve in a Rat Glioma Model with DCE-MRI and Quantitative SPECT 
Jack T Skinner1,2, Mary E Loveless1,2, Todd E Peterson2,3, Thomas E Yankeelov2,3, and Mark D Does1,2
1Biomedical Engineering, Vanderbilt University, Nashville, TN, United States, 2Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States, 3Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, United States

DCE-MRI characterizes tissue in terms of physical properties, such as the extracellular/extravascular volume fraction (ve), by indirectly measuring the kinetics of a contrast agent into and out of the interstitial space. The fitted model parameters, including ve, are potentially biased by confounding water dynamics, which are not accounted for in the model. In contrast to MRI, radiotracer imaging with SPECT is insensitive to water dynamics. Estimates of ve were obtained using DCE-MRI and dual-isotope SPECT imaging in a rat glioma model and the results showed a large and consistent overestimation by DCE-MRI.

2049.   Quantitative perfusion measurement of liver metastasis using DCE-MRI: Comparing a 3D-Flash vs. a IR-trueFISP protocol within a clinical phase II study 
Martin Büchert1, and Klaus Mross2
1MRDAC Magnetic Resonance Development and Application Center, University Medical Center Freiburg, Freiburg, Germany, 2Klinik für Tumorbiologie

For assessing treatment response to cancer therapeutics dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) is a valuable tool. For DCE-MRI a 3D-Flash and an IR-TrueFISP protocol providing different spatial and temporal resolution were investigated in phantom and 12 tumor patients. Data of both methods were in good agreement with each other. IR-TrueFISP data showed a much lower variability compared to 3D-Flash results, leading to a three times higher average fit error in the model fit of the later. It was shown that the IR-TrueFISP protocol with its high temporal resolution and good accuracy is a suitable DCE-MRI acquisition method.

2050.   Patlak Model Selection Using Dynamic Contrast Enhanced T1-weighted MR Measurement of Vascular Permeability 
Abbas Babajani-Feremi1, Rajan Jain1,2, Jayant Narang1, Ali Syed Arbab1, Kourosh Jafari-Khouzani1, Mohammad-Reza Nazem-Zadeh3, and Hamid Soltanian-Zadeh1,4
1Department of Radiology, Henry Ford Hospital, Detroit, Michigan, United States, 2Department of Neurosurgery, Henry Ford Hospital, Detroit, Michigan, United States, 3Department of Neurology, Henry Ford Hospital, Detroit, Michigan, United States, 4CIPCE, Electrical and Computer Engineering Department, University of Tehran, Tehran, Tehran, Iran

We propose a method to find the best Patlak model that appropriately represents vascular permeability of tumor using dynamic contrast-enhanced T1-weighted magnetic resonance perfusion (DCET1MRP). Three Patlak models were developed . Model 1 estimates only vascular plasma volume (VP). Model 2 estimates VP and influx transfer constant (Ki). Model 3 estimates VP, Ki, and reverse transfer constant (Kb). Using least-square method, three models were fitted to dynamic data. F-statistic was used for model comparison. Based on analysis of 31 patients with brain tumors, we conclude that that F-statistic can be used to choose appropriate model for tumor and non-tumor regions.

2051.   Early time point perfusion imaging: Estimating tissue transit time directly from the data time course 
Kenneth K Kwong1, Ona Wu1, Suk-tak Chan1, Koen Nelissen1, and David A Chesler1
1Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, United States

In MR perfusion analysis, the tissue mean transit time τ is normally estimated indirectly by using the ratio of regional cerebral blood volume (rCBV) and regional cerebral blood flow (rCBF). We propose two different methods to estimate τ directly using signals from the tissue contrast agent bolus concentration time course.

2052.   Quantitative assessment of blood-brain-barrier permeability by Patlak plots after intraperitoneally administrated gadolinium-DOTA 
Dana Suciu Poole1, Johannes Rolf Sikkema2, Arnoldus M van den Maagdenberg3, and Louise van der Weerd2,4
1Radiology, Leiden University Medical Centre, Leiden, Netherlands, 2Radiology, Leiden University Medical Centre, Netherlands, 3Human Genetics, Leiden University Medical Centre, Netherlands,4Anatomy and Embriology, Leiden University Medical Centre, Netherlands

Dynamic contrast-enhanced magnetic resonance imaging typically uses intravenous administration of a contrast agent. In mice, however, repeated intravenous injections often cause scarring, and insertion of permanent canulae in the tail or femoral vein require an invasive procedure and are prone to infection and damage by grooming. In this study, we have developed an alternative longitudinal DCE-MRI protocol at 9.4T using intraperitoneal administration of gadolinium-DOTA. We show that Patlak plots can be calculated following intraperitoneal administration of contrast agent on mice with unilateral blood-brain barrier impairment.

2053.   A modified Generalized Tracer Kinetic model for Perfusion Parameters in DCE- MRI for High Grade Intracranial mass Lesions 
Ram Kishore Singh Rathore1, PRATIVA sahoo2, rishi awashti3, rakesh k gupta4, SANJAY verma5, and divya Rathore5
1Mathematics and Statistics, IIT Kanpur, KANPUR, U.P., India, 2Mathematics and Statistics, IIT Kanpur, KANPUR, India, 3SGPGI, 4SGPGI, LUCKNOW, 5IIT Kanpur

A modified generalized tracer kinetic model incorporating a strong leakage compartment, presenting as a local sink to BBB, is proposed. The new model as such automatically takes care of the cerebral blood volume correction and avoids choosing a neighboring feeding artery. The additional term in the model in the absence of the leakage compartment would give insignificant values to the corresponding rate constant and therefore does not cause any significant change in the parameters in such cases. The results, however, show that such compartments occur in the case of high grade gliomas, as compared with the low grade ones.

2054.   Feasibility of Dynamic Contrast Enhanced MRI in Oral Cavity Cancer: A Comparison between Reference Region Model, General Kinetic Model and Pathological Grading 
Shy-Chyi Chin1, Yeng-Peng Liao2, Ya-Ting Chuang1, and Ho-Ling Liu2
1Department of medical imaging and intervention, Chang-Gung Medical Center, Guei-Shan, Tao-Yuan, Taiwan, 2Chang Gung University, Department of Medical Imaging and Radiological Sciences, Guei-Shan, Tao-Yuan, Taiwan

We concluded that the ideal application of the dynamic contrast-enhanced MRI (DCE-MRI) technique can be achieved in the clinical oncology even in patients with suboptimal scanning condition like oral cavity malignancy with inevitable head motion and image distortion. Most of the imaging distortion can be overcome by using the alternate DCE-MRI method, that is, reference region model (RRM) to substitute with the conventional general kinetic model (GKM). On the other hand, DCE-MRI derived parameters are not correlative to pathological grading, though. The more sophisticated analysis between these parameters deserves further investigation.

2055.   3D Radial Twisted Projection Imaging for DCE-MRI with Variable Flip Angles 
Philipp Krämer1, Simon Konstandin1, Melanie Heilmann1, and Lothar Rudi Schad1
1Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany

A new sequence is presented which uses the advantages of a Twisted Projection Imaging trajectory design to reduce measurement time in radial proton imaging. The SNR of this sequence is higher when compared to standard 3D radial imaging. It is shown that this sequence can be used for fast and accurate T1 measurement with a Variable Flip Angle approach. Especially in DCE-MRI this sequence has advantages for precontrast as well as dynamic measurement. It could be used where conventional radial approaches to DCE-MRI suffer from lower SNR and undersampling artifacts.

2056.   Optimizing Acquisition and Reconstruction for a Narrower Temporal Footprint in Time-Resolved 3DPR Liver Perfusion 
Ethan K. Brodsky1,2, Kevin M. Johnson2, Walter F. Block2,3, and Scott B. Reeder1,2
1Radiology, University of Wisconsin, Madison, WI, United States, 2Medical Physics, University of Wisconsin, Madison, WI, United States, 3Biomedical Engineering, University of Wisconsin, Madison, WI, United States

Detection, characterization and monitoring of hepatocellular carcinomas (HCC) in cirrhotic patients is challenging due to their variable and rapid arterial enhancement. Early efforts to supplant conventional multiphase CE-MRI with a time-resolved undersampled multi-echo 3DPR technique have shown promise, but require a wide temporal footprint to achieve adequate image quality, compromising temporal fidelity of small lesions enhancement and complicating quantitative modeling. In this work, we discuss improved k-space sampling trajectories and the incorporation of an iterative SENSE-based constrained reconstruction algorithm that lead to substantially improved temporal resolution and image quality. Consistency weighting allows for efficient use of data from multiple echo times.

2057.   Feasibility of high temporal resolution compressed sensing based DCE-MRI 
Haoyu Wang1, Da Wang1, Shanglian Bao1, and Jiani Hu2
1Beijing Key Lab of Medical Physics and Engineering, Peking University, Beijing, China, People's Republic of, 2Department of Radiology, Wayne State University, Detroit, MI, United States

The purpose of this study is to investigate the feasibility of applying CS theory to breast DCE-MRI to improve the temporal resolution while faithfully reconstructing uptake curves. In the preliminary experiment, DCE images were reconstructed using Reference Image based Compressed Sensing technique (RICS). The uptake curve reconstruction experiment shows a high correlation between uptake curves reconstructed from fully sampled data by Fourier transform and from undersampled data by RICS, indicating high similarity between them. In conclusion, our preliminary results demonstrate the feasibility of RICS for improving temporal resolution and faithfully reconstructing uptake curves of DCE-MRI.

2058.   Dynamic Contrast Enhanced MRI of the Brain at 7 T 
Lars Gerigk1, Hendrik Laue2, Lydia Schuster1, Thomas Hauser1, Ann-Kathrin Homagk3, Armin Nagel3, Marco Essig1, Heinz-Peter Schlemmer1, and Michael Bock3
1Radiology, German Cancer Research Center, Heidelberg, Baden-Württemberg, Germany, 2Institute for Medical Image Computing, Fraunhofer MEVIS, Bremen, Bremen, Germany, 3Medical Physics in Radiology, German Cancer Research Center, Heidelberg, Baden-Württemberg, Germany

Since vascularization is essential in tumors, analyzing the amount and distribution of tissue perfusion is important to understand tumor growth and to monitor therapies. At lower field strengths, DCE-MRI has been used successfully to quantify permeability and flow, but has been limited in spatial resolution. To make use of the higher signal strength, we adapted this technique to a 7 T whole body system and applied it to patients with brain tumors. Due to the high spatial resolution at 7 T, tumor heterogeneity can be visualized.

2059.   A dynamic lesion phantom for quantitative evaluation of dynamic contrast enhanced MRI 
Melanie Freed1,2, Jacco A de Zwart3, Prasanna Hariharan4, Matthew R Myers4, and Aldo Badano1
1CDRH/OSEL/DIAM, Food and Drug Administration, Silver Spring, MD, United States, 2Dept. Bioengineering, University of Maryland, College Park, MD, United States, 3Advanced MRI Section, LFMI, NINDS, National Institutes of Health, Bethesda, MD, United States, 4CDRH/OSEL/DSFM, Food and Drug Administration, Silver Spring, MD, United States

There is a need for realistic and well-characterized dynamic phantoms for dynamic contrast-enhanced MRI of the breast to aid in optimization and standardization of imaging protocols. We have developed a dynamic lesion model that mimics the border shape and washout curve behavior of benign and malignant breast lesions. Measurements of the true contrast agent concentration versus time were acquired with an x-ray system and compared with MRI measurements using different spatial and temporal resolutions.

2060.   Quantitative Perfusion and Permeability Analysis of Animal Brain Using Dual echo DCE-MRI 
Yanming Yu1, Quan Jiang2, Haoyu Wang3, Shanglian Bao3, E. Mark Haacke4, and Jiani Hu4
1Logging technique research institute, great wall drilling company, China National Petroleum Corporat, Beijing, China, People's Republic of, 2Department of Neurology, Henry Ford Health Sciences Center, Detroit, MI, United States, 3Beijing Key Lab of Medical Physics and Engineering, Peking University, Beijing, China, People's Republic of, 4Department of Radiology, Wayne State University, Detroit, MI, United States

The purpose of this project is to investigate the effect of T2* on permeability and effect of T1 on perfusion using a new pharmacokinetic model with simultaneously acquired T1 and T2* DCE-MRI data. The preliminary results demonstrate that 1) T2* has great effects on the estimation of permeability parameters; 2) T1 has great effects on the estimation of perfusion parameters; 3) both the T1 and T2* effects are much greater in tumors when compared to healthy brain tissue. In conclusion, simultaneously acquired T1- and T2*-weighted DCE-MRI data can be used to improve the estimation accuracy of permeability and perfusion parameters.

2061.   Modeling of Look-Locker Estimates of the Magnetic Resonance Imaging Estimate of Longitudinal Relaxation Rate in Tissue after Contrast Administration 
Ramesh Paudyal1, Hassan Bagher-Ebadian1, Robert A. Knight1,2, Tavarekere N Nagaraja3, Joseph D Fenstermacher3, and James R Ewing1,2
1Neurology, Henry Ford Hospital, Detroit, MI, United States, 2Physcis, Oakland University, Rochester, MI, United States, 3Anesthesiology, Henry Ford Hospital, Detroit, MI, United States

In this study, we evaluate the effects of equilibrium intercompartmental water exchange kinetics in a monoexponential estimate of tissue water protons relaxation rate R1 using an experimentally measured plasma concentration vs. time, an arterial input function (AIF), of a paramagnetic contrast agent like Gd-DTPA via a Look-Locker measurement in a three site two exchange [3S2X] model. The observable change in R1 was used in a Patlak graphical plot to asses the influence of protons of water exchange on the measured cerebrovascular parameters.

2062.   Characterizing cerebral blood volume and permeability with a undersampled multiple-echo 3D projection reconstruction sequence and a fast T1 mapping method 
Aiming Lu1, and Keith R Thulborn1
1Center for MR Research, University of Illinois, Chicago, IL, United States

DCE-MRI has been applied to characterize tissue parameters such as cerebral blood volume (CBV) and permeability. Although whole brain imaging with high temporal and spatial resolution is desired, current acquisition techniques often compromise either resolution or coverage. Meanwhile, fitting the tracer models requires a fast and robust method for mapping tissue T1s prior to contrast injection. The multiple-echo 3D projection reconstruction sequence was adopted here to image the entire brain with high temporal and spatial resolution. Fast T1 mapping was achieved by linearly fitting the signals collected at different flip angles. The propose approach were demonstrated in brain tumor patients.

2063.   T2*-correction in DCE-MRI from double echo acquisitions 
Magne Mřrk Kleppestř1,2, Oliver Marcel Geier1, Christopher Larsson1, Frederic Courivaud1, Raimo Aleksi Salo1, Petter Brandal3, Inge Andre Rasmussen1, and Atle Bjornerud1,4
1Interventional Centre, Oslo University Hospital, Oslo, Norway, 2Dept. of Physics, Univ. of Oslo, Oslo, Norway, 3Dept. of Oncology, Oslo University Hospital, Oslo, Norway, 4Dept. of Physics, Univ. of Oslo

T2*-effects in blood from a single bolus injection of gadolinium based contrast agents can be significant even when short TE heavily T1-weighted sequences are used. We investigated the effect of T2*-shortening on the measured permeability related parameters obtained from standard two-compartment modeling with vascular deconvolution by applying a double echo 3D-saturation recovery (SR) DCE sequence with a TR of 3.3 sec. Both the transfer constant (Ktrans) and plasma volume (Vp) were found to be significantly over-estimated when T2*-effects were not considered in the dose-response calculation and the error was largest for Vp

Traditional Posters : Diffusion & Perfusion - Neuro
Click on to view the abstract pdf and click on to view the pdf of the poster viewable in the poster hall.
Perfusion & Diffusion Animal Models

Tuesday May 10th
Exhibition Hall  13:30 - 15:30

2064.   Continuous Arterial Spin Labeling (CASL) of Cerebral Blood Flow of Mouse at 9.4T 
Hongxia Lei1,2, Yves Pilloud1, and Rolf Gruetter1,3
1Laboratory of Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland, 2Radiology, Univeristy of Lausanne, Lausanne, Switzerland, 3Radiology, University of Geneva, Geneva, Switzerland

In this study, we demonstrated that continuous arterial spin labeling for mapping cerebral blood flow of mouse at 9.4T was feasible. This opens possibilities of studying transgenic mouse models by means of MR techniques.

2065.   A new transcriptionally driven oncovirus with Vstat120 expression has antiangiogenic and anti-tumorigenic effects 
Ji Young Yoo1, Amy Haseley1, Anna Bratasz2, E Antonio Chiocca1, J Y Zhang2, Donna Cain1, Kimerly Powell2, and Balveen Kaur1
1Department of Neurological Surgery, OSU, Columbus, OH, United States, 2Department of Biomedical Informatics, OSU, Columbus, OH, United States

A novel oncolytic virus - 34.5ENVE enhanced by nestin and Vasculostatin expression has been described. Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) revealed that mice treated with 34.5ENVE showed distinct spatial and temporal changes in the pattern of vascular leakage. Treatment of mice bearing subcutaneous and intracranial glioma with 34.5ENVE showed a significant increase in survival rate by 100% and 75% (respectively). This virus showed anti-glioma specific and anti-angiogenic effects. These preclinical results will facilitate future clinical testing of 34.5ENVE.

2066.   Determination of optimal parameters for intra-arterial injection and blood brain barrier disruption in the mouse using MRI 
Conor P Foley1, David Rubin2, Alejandro Santillan2, Eric Aronowitz1, Walter Zink2, Y. Pierre Gobin2, and Douglas Ballon1
1Radiology, Weill Cornell Medical College, New York, NY, United States, 2Neurosurgery, Weill Cornell Medical College, New York, NY, United States

This work presents techniques that can be used to reproducibly disrupt the mouse blood brain barrier by using custom built endovascular microcatheters to intra-arterially deliver a hyper-osmolar solution of mannitol to the cerebral vasculature via the internal carotid artery. The extent of barrier disruption in different brain territories was quantified by performing dynamic contrast enhanced MRI using a 7 tesla small animal imaging system following the mannitol injection. We found that the extent of barrier disruption is not uniform across all brain territories, and that both injection volume and rate have a significant effect on the extent of disruption.

2067.   Pharmacological MRI of the retina: blood flow and BOLD uncoupling during nitroprusside infusion 
Yen-Yu Ian Shih1, Li Guang1, and Timothy Q Duong1
1Research Imaging Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States

reports demonstrated tremendous advantages of anatomical, physiological, and functional MRI for eye research. The present study, to our knowledge, is the first pharmacological MRI application of the retina. We employed continuous arterial spin labeling MRI at an 11.7T scanner to investigate the effect of nitroprusside infusion on the rat eye. Suprising positive BF with strong negative BOLD response was found in the retina during drug infusion, which may have strong implications for neurovascular coupling and hemodynamic regulation.

2068.   An automatic protocol to detect the fed and fasted brain using multivariate analysis of diffusion weighted data sets 
Ania Benítez1,2, Blanca Lizarbe1, Luis Lago-Fernández2, Pilar López-Larrubia1, Sebastian Cerdán1, and Manuel Sánchez-Montańés2
1Instituto de Investigaciones Biomédicas "Alberto Sols", Madrid, Madrid, Spain, 2Departamento de Ingeniería Informática, Escuela Politécnica Superior, Universidad Autónoma de Madrid, Madrid, Madrid, Spain

We present a model for the automatic classification of diffusion weighted images from C57 mouse brain between fed and fasted states. The method requires no preprocessing steps and provides 100% correct classifications of the eight mice of the study between the corresponding fed and fasted classes. The absence of pre-processing steps avoids the possibility to introduce information previously not present in the original image and favors an automatic unbiased interpretation. The approach outlined here may be useful in the investigation of the cerebral causes of obesity and its treatments and could extend to an automated diagnostic imaging system for food intake disorders, obesity, anorexia or bulimia.

2069.   Evolving axon degeneration in optic nerve crush mice assessed using in vivo diffusion tensor imaging 
Peng Sun1, Xu Zhang1, Qing Wang2, and Sheng-Kwei Song1
1Radiology, Washington University in St. Louis, Saint Louis, Missour, United States, 2Mechanical Engineering and Materials Science, Washington University in St. Louis

Glaucoma is an optic neuropathy originating from intraocular pressure induced optic nerve damage and the ensuing retrograde degeneration of retinal ganglion cells and the progressive loss of vision. Using a widely accepted mouse model of optic nerve crush, in vivo DTI performed at 6 hr, 3, 7, 14, and 28 days after unilateral optic nerve crush to investigate the relationship between optic nerve injury and retinal ganglion cell damage. The current results suggest that DTI may be used to identify axon injury and demyelination tracking the disease progression of glaucoma in vivo.

2070.   White matter reorganization and functional recovery following stroke in adult rat 
Chrystelle Po1, Young-Beom Kim1, Daniel Kalthoff1, Melanie Nelles1, and Mathias Hoehn1
1In-vivo-NMR Laboratory, Max-Planck-Institut for Neurological Research, Cologne, Germany

The brain seems to be, after stroke, capable of recovering functional activity by adaptation of the neuronal networks. The aim of the present study was to correlate structural cerebral reorganisation with functional recovery after transient focal ischemia in adult rat. For this purpose, high resolution Diffusion Spectrum Imaging (DSI) was applied together with BOLD fMRI. The combination of tractography and fMRI results indicated a link between the functional recovery post-stroke and the presence of white matter reorganization combined with the one of interhemispheric connection.

2071.   White matter quantification in a model of schizophrenia mice using microscopic Diffusion Tensor Imaging 
Franck Mauconduit1, Jean Christophe Deloulme1, Annie Andrieux1, and Hana Lahrech1
1Grenoble Institute of Neuroscience, INSERM U836 - UJF, La Tronche, France

STOP knockout (KO) mice have been proposed as a model of some schizophrenia-like symptoms. KO mice exhibit brain anatomical abnormalities such as whole-brain volume reduction and white matter (WM) disorder. The purpose of the study was to determine the WM alteration using Diffusion Tensor Imaging in the commissure of fornix which links hippocampus to mammillary bodies. As well as a total brain diminution, KO stop mice exhibit a global white matter reduction. FA values in the post-commissural fornix might confirm a net loss of fibres for KO mice whereas no changes are obtained in the dorsal fornix.

2072.   Longitudinal TBSS reveals progressing demyelination in the mouse model of progressive neurodegenerative disease EPM1 
Otto H H Manninen1, Teemu Laitinen2, Outi Kopra1, Olli Gröhn2, and Anna-Elina Lehesjoki1
1Folkhälsan institute of Genetics and Neuroscience Center, University of Helsinki, Helsinki, Finland, 2Department of Neurobiology, University of Eastern Finland, Kuopio, Finland

We studied white matter (WM)-changes in the neurodegenerative Unverricht-Lundborg-disease (EPM1) by performing longitudinal FA TBSS in the gene-targeted mouse model of the disease. After ex-vivo DTI, we did a TBSS comparison of FA between Cstb-/- mice and wildtypes at 2, 4 and 6 months of age. TBSS detected no significant changes at 2 months, with significant decrease in FA at 4 months at cerebellum and thalamus, that progressed into more drastic decrease at same areas at 6 months, suggesting demyelination as cause of WM-changes in EPM1.

2073.   Accelerated Mouse Spinal Cord Diffusion Measurements with SNR-Enhancing Joint Reconstruction 
Justin P. Haldar1, Joong H. Kim2, Sheng-Kwei Song2, and Zhi-Pei Liang1
1Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States, 2Radiology, Washington University in St. Louis, St. Louis, MO, United States

Diffusion imaging experiments have previously been demonstrated to accurately quantify spinal cord white matter injury and disease in various rodent models. One limitation of these experiments is that substantial signal averaging has been necessary to achieve sufficient signal-to-noise ratio (SNR). Averaging necessitates long imaging experiments, which can be stressful for imaging subjects and limits throughput. In this work, we demonstrate that an appropriate statistical denoising strategy can be used in place of averaging, leading to experiments that are 4 times faster but are still capable of quantifying spinal cord disease and injury in mouse models of multiple sclerosis and trauma.

2074.   Diffusion kurtosis abnormalities in a pre-symptomatic lower case Greek alpha-synucleinopathy mouse model. 
Rafael Delgado y Palacios1, Jelle Veraart2, Greet Vanhoutte1, Heinrich Schell3, Marleen Verhoye1, Philipp Kahle3, Jan Sijbers2, and Annemie Van der Linden1
1Bio-Imaging Lab, University of Antwerp, Antwerp, Antwerp, Belgium, 2Vision Lab, University of Antwerp, Antwerp, Belgium, 3Laboratory of Functional Neurogenetics, Hertie Institute for Clinical Brain Research, University Clinics Tübingen, Tübingen, Germany

Parkinson’s disease (PD) is a movement disorder mainly characterized by impaired motor function and the presence of abnormal lower case Greek alpha-synuclein(lower case Greek alphaSYN). To assess pre-symptomatic changes in regions involved in the motor circuit (caudate putamen and motor cortex) and cognitive function (hippocampus), we performed Diffusion Kurtosis Imaging in a pre-symptomatic human mutant lower case Greek alphaSYN overexpressing mouse model for PD. This showed diffusion and kurtosis variation in the three examined regions, which suggests that microstructural alterations precede the expression of symptoms. Although the exact nature of these changes has yet to be resolved, these findings may help to develop a non invasive marker for PD.

2075.   Recovery of Regional Cerebral Blood Flow and Brain Tissue Oxygenation by 24 Hours After Asphyxial Cardiac Arrest 
Lesley M Foley1, Mioara D Manole2,3, T Kevin Hitchens1,4, Chien Ho1,4, Henry L Alexander2, Patrick M Kochanek2,5, and Robert S Clark2,3
1Pittsburgh NMR Center for Biomedical Research, Carnegie Mellon University, Pittsburgh, PA, United States, 2Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States, 3Department of Pediatrics, Children's Hospital of Pittsburgh, Pittsburgh, PA, United States, 4Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, United States, 5Departments of Critical Care Medicine, Pediatrics and Anesthesiology, University of Pittsburgh, Pittsburgh, PA, United States

The aim of this study was to determine if CBF and PbtO2 disturbances seen immediately after pediatric asphyxial cardiac arrest (CA) persist 24 h after resuscitation. Hyperemia is still present in the thalamus whereas CBF values for all other brain regions return to sham values. Tissue oxygenation decreases to below acceptable thresholds in the cortex and thalamus when FIO2 is lowered to 0.21. Monitoring tissue O2 may be warranted to guide therapy following pediatric asphyxial CA.

2076.   Correlation Between Hyperpolarized 13C MRSI and Perfusion Data from Dynamic Susceptibility Contrast MRI 
Ilwoo Park1, Janine M Lupo1, Achuta Kadambi1, Tomoko Ozawa2, C. David James2, Daniel B Vigneron1,3, and Sarah J Nelson1,3
1Surbeck Laboratory of Advanced Imaging, Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, United States, 2Brain Tumor Research Center, Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, United States, 3Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, United States

We have demonstrated that total hyperpolarized 13C carbon can be used to estimate perfusion in a rat model of glioblastoma multiforme. Normalized total 13C-carbon correlated strongly with normalized peak height measured from dynamic susceptibility contrast MRI and may be used to estimate blood volume in tumors. In addition, a perfusion-metabolism mismatch in our data suggest that the perfusion data may provide important additional information for investigating cancer metabolism and microenvironment.

2077.   Longitudinal changes of diffusion tensor imaging in acute stages of post-mortem animal brain tissue decomposition 
Luis Concha1, Oscar Méndez2, and Fernando Barrios-Alvarez1
1Instituto de Neurobiologia, UNAM, Queretaro, Queretaro, Mexico, 2School of Biological Sciences, University of California - Irvine, Irvine, CA, United States

DTI is often used in post-mortem animal studies. Although it is recognized that tissue processing may alter diffusion characteristics, it is unclear how the normal decomposition of the brain tissue modifies DTI parameters. We performed brain DTI on a 3T scanner on three adult rabbits before death and following euthanasia for a period of 12-14 hours. Fractional anisotropy changed very little over the time studied, while mean diffusivity declined progressively over time, to an extent that cannot be explained by temperature changes alone, but rather by tissue degeneration such as vacuolization and cell autolysis.

2078.   Susceptibility Weighted Imaging (SWI) of Cerebral Physiology of Non-Human Primate during Carbogen Inhalation 
Asamoah Bosomtwi1, Swati Rane2, Quan Jiang3, and Leonard L Howell1
1Yerkes Primate Center, Emory University, Atlanta, GA, United States, 2Vanderbilt University, 3Neurology, Henry Ford Hospital

We investigated the effect of carbogen inhalation on cerebrovascular reactivity and blood oxygenation on healthy non-human primates. We demonstrate that during the inhalation of carbogen the venous architecture slightly attenuated and then recover few minutes after pure oxygen is restore. Our data demonstrate that these SWI measurements can be used to visualize modulation of CO2 during respiratory challenge cases.

2079.   Language Pathway Homologues in Chimpanzees Reconstructed Using Diffusion Tractography 
Frederick William Damen1,2, Longchuan Li1, William D Hopkins3, Todd M Preuss4, James K Rilling3,5, Govind Nair1, Xiaodong Zhang4, Susan Kramer1, and Xiaoping Hu1,2
1Biomedical Imaging Technology Center, School of Medicine, Emory University, Atlanta, GA, United States, 2Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, GA, United States, 3Division of Developmental and Cognitive Neuroscience, Yerkes National Primate Research Center, Atlanta, GA, United States, 4Division of Neuropharmacology and Neurological Diseases, Yerkes National Primate Research Center, Atlanta, GA, United States, 5Department of Anthropology, Emory University, Atlanta, GA, United States

The homologues of Broca’s and Wernicke’s areas have been identified in chimpanzees using histological methods. However, the white-matter pathways linking these two areas and their hemispheric asymmetry have not yet been extensively explored. In this study, we reconstructed the white-matter pathways connecting the inferior frontal gyrus and superior temporal gyrus in chimpanzees using probabilistic tractography. Our results support previous findings of tracts connecting these regions through the ventral external/extreme capsule, in addition to the dorsal arcuate fasciculus with a trend of rightward asymmetry. The results suggest that leftward asymmetry of the arcuate may be a distinctive human attribute.

2080.   T2* and phase contrast in marmoset brain 
Pascal Sati1, Afonso C Silva2, Maria I Gaitan1, Jillian E Wohler3, Colin Denis Shea1, Iordanis E Evangelou1, Luca Massacesi1,4, Peter van Gelderen5, Jeff H Duyn5, Steven Jacobson3, and Daniel Salo Reich1
1Translational Neuroradiology Unit, Neuroimmunology Branch, NINDS, National Institutes of Health, Bethesda, Maryland, United States, 2Cerebral Microcirculation Unit, LFMI, NINDS, National Institutes of Health, Bethesda, Maryland, United States, 3Viral Immunology Section, Neuroimmunology Branch, NINDS, National Institutes of Health, Bethesda, Maryland, United States,4Department of Neurology, University of Florence, Florence, Italy, 5Advanced MRI section, LFMI, NINDS, National Institutes of Health, Bethesda, Maryland, United States

The common marmoset (Callithrix jacchus) has a gray-to-white-matter ratio close to that of humans, making it an ideal nonhuman primate for visualizing, in vivo and noninvasively, myelinated structures. Thus, the marmoset has been increasingly studied with MRI. In this work, T2* and phase contrast were explored in marmoset brain. A striking heterogeneous pattern, potentially related to fiber orientation, was observed in posterior WM areas. The marmoset brain is therefore an interesting system in which to study the mechanisms of T2* and phase contrast.

2081.   White-Matter Tract-Based Atlas of the Chimpanzee Brain 
Longchuan Li1, Susan Kramer1, William Hopkins2, Todd Preuss2, James Rilling3, Govind Nair1, Xiaodong Zhang2, Frederick Damen4, and Xiaoping Hu4
1School of Medicine, Emory University, Atlanta, GA, United States, 2Division of Neuroscience, Yerkes National Primate Research Center, Atlanta, GA, United States, 3Division of Psychobiology, Yerkes National Primate Research Center, Atlanta, GA, United States, 4Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, United States

Although diffusion magnetic resonance imaging (MRI) and tractography have been used to generate white-matter tract based atlases of the human and macaque brain, no such atlas has been created for our closest living relative, the chimpanzee. In this study, we acquired diffusion MR data from nine chimpanzees and virtually dissected the major white-matter tracts via probabilistic tractography. We then generated an atlas of the course, location and extent of these tracts. This white-matter tract-based atlas of the chimpanzee brain will have extensive applications in comparative neurology and provide insights into primate brain evolution

2082.   Longitudinal study of the corpus callosum thickness in developing monkeys 
Chun-Xia Li1, Anthony MS Chan1,2, and Xiaodong Zhang1,2
1Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States, 2Division of Neuropharmacology and Neurologic Diseases, Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States

The thickness of Corpus callosum (CC) is of particular interest on the study of agenesis of CC and it is reported there exists positive correlation between CC thickness and intelligence. The non-human primate models have been increasingly applied for studying cognitive impairment relative disorders. In this study, 4 young rhesus monkeys were longitudinally investigated at the age of 6, 12, 18 and 24 months old respectively with MRI. 4 adult monkeys were used for comparison purpose. The data indicated that the CC thickness of the monkeys has age-dependent elevation from infancy to juvenile. There may exist fast developing period when 24 month-old during the development of monkeys.

2083.   Anatomical Connectivity of the Internal Capsule 
Kyle Taljan1,2, Cameron McIntyre1, and Ken Sakaie3
1Lerner Research Institute, Biomedical Engineering, Cleveland Clinic, Cleveland, OH, United States, 2Biomedical Engineering, Cleveland State University, Cleveland, OH, United States, 3Imaging Institute, Cleveland Clinic

In order to optimize electrode placement in deep brain stimulation it is essential to know what subcortical tracts are being stimulated. We use probabilistic tractography to segment the internal capsule (IC) of six macaques according to highest connectivity to caudate, lentiform nucleus, and thalamus. We include a statistical correction to account for distance-related tractography bias. We find that correction results in 23±6% change in IC voxel classification. There are consistent patterns of IC connectivity across the 6 subjects with the filter, as opposed to numerous IC segmentation differences across subjects without the correction.

2084.   A New Model For Characterizing the Temporal Progression of the Ischemic Penumbra in Acute Ischemic Stroke 
Warren Misik1,2, Andrew Demchuk1,3, Richard Frayne1,3, and Bijoy Menon1,4
1Seaman Family MR Research Centre, Foothills Medical Centre, Calgary, Alberta, Canada, 2Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada, 3Radiology and Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada, 4Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada

An essential element in acute stroke care is knowledge about the ischemic penumbra, tissue around the infarct core that is hypoperfused but not yet dead. Current stroke paradigms are limited in their ability to describe the temporal progression of the penumbral tissue. We propose a new model of the ischemic region based on “balloon volumes” – lesion volumes corresponding to different thresholds of Tmax. This model shows promise in predicting penumbral stability based on proximity to recruited collaterals, and shows correlation with the rate of growth of infarct as seen on diffusion tensor images.

2085.   Validation of Diffusion Weighted Imaging of cortical anisotropy by means of a histological stain for myelin 
Michiel Kleinnijenhuis1,2, Kees Jan Sikma1,3, Markus Barth2,4, Pieter Dederen1, Valerio Zerbi1,5, Benno Küsters6, Dirk Ruiter1,2, Cornelis H Slump3, and Anne-Marie van Cappellen van Walsum1,7
1Department of Anatomy, University Medical Centre St. Radboud, Nijmegen, Netherlands, 2Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, Netherlands, 3Signals and Systems, Faculty of Electrical Engineering, Mathematics and Computer Science, University of Twente, Enschede, Netherlands, 4Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen, Germany, 5Department of Radiology, University Medical Centre St. Radboud, Nijmegen, Netherlands, 6Department of Pathology, University Medical Centre St. Radboud, Nijmegen, Netherlands, 7MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, Netherlands

We report on a pilot study aimed to validate Diffusion Weighted Imaging (DWI) of cortical anisotropy by means of a histological stain for myelin (LFB)in ex vivo human brain tissue samples.

Traditional Posters : Diffusion & Perfusion - Neuro
Click on to view the abstract pdf and click on to view the pdf of the poster viewable in the poster hall.
Arterial Spin Labeling

Wednesday May 11th
Exhibition Hall  13:30 - 15:30

2086.   Parallel Transmit Vessel Selective Arterial Spin Labelling: A proof of concept simulation 
Aaron Oliver-Taylor1, Roger J Ordidge1, and David L Thomas2
1Medical Physics and Bioengineering, University College London, London, England, United Kingdom, 2Institute of Neurology, University College London, London, England, United Kingdom

Vessel Selective Arterial Spin Labelling allows assessment and quantification of vessel specific perfusion territories. We make use of Parallel Transmission in order to create 'label' and 'no label' regions to selectively label arteries within the neck. An in-silico simulation was performed to assess the specificity of the method in comparison to using a single surface coil when attempting to only label the right side arteries in the human neck. Results show that for an increasing number of coils contralateral labelling of the left side arteries is reduced whilst maintaining high labelling efficiency on the right.

2087.   Spatially Selective PCASL with Parallel Excitation 
Daehyun Yoon1, Hesamoddin Jahanian2, Douglas C Noll2, and Luis Hernandez-Garcia2
1Electrical Engineering, University of Michigan, Ann Arbor, MI, United States, 2Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States

We present a novel approach with parallel excitation for spatially selective pseudo CASL to perform vessel selective arterial spin labeling (ASL). Previously, several methods have been proposed to perform vessel selective ASL, but they are either vulnerable to motion due to acquiring multiple images or limited in selectivity. We use multiple RF transmission coils to tag only the desired vessel and to leave the other vessels untagged. Our approach provides superior spatial selectivity and high inversion efficiency, making it an efficient tool for vessel selective ASL.

2088.   Multi-vessel labeling approach for perfusion territory imaging in pseudo-continuous arterial spin labeling 
Michael Helle1, Susanne Rüfer1, Matthias van Osch2, Olav Jansen1, and David Gordon Norris3,4
1Institute for Neuroradiology, Christian-Albrechts-Universität, UK-SH, Kiel, Germany, 2C.J. Gorter Center for high field MRI, Department of Radiology, Leiden University Medical Center, Leiden, Netherlands, 3Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, Netherlands, 4Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen, Germany

Superselective pseudo-continuous arterial spin labeling has been recently introduced for perfusion territory imaging. The method offers the possibility to change the size of the labeling spot, thus to adapt to individual arteries. However, this approach requires separate measurements for individual arteries. Here, we propose a new labeling scheme for superselective ASL that utilizes an elliptical labeling spot in order to label the blood in multiple vessels simultaneously. This results in decreased scan time, less artifacts and potentially better labeling efficiency.

2089.   Mixed cerebral perfusion territories in the posterior circulation investigated using super-selective arterial spin labeling MRI 
Nolan S Hartkamp1, M Helle2, J Hendrikse1, and M J P van Osch3
1Radiology, UMC Utrecht, Utrecht, Netherlands, 2Institute of Neuroradiology, Christian-Albrechts-Universität, Kiel, Germany, 3C.J. Gorter Center, Leiden UMC, Leiden, Netherlands

A previous research group proposed there was little evidence of mixing of blood in the basilar artery as they observed separate perfusion territories for both vertebral arteries in the cerebellum and cerebrum. The proposition of blood not mixing in the basilar artery was demonstrated with regional perfusion arterial spin labeling (ASL) MR imaging. A method that depends on clustering voxels by using a cut-off value or by more advanced techniques such as k-means clustering. It may be argued these techniques do not accurately reflect mixed perfusion territories. Therefore we aim to investigate this observation with a more suitable method.

2090.   Regional Perfusion Imaging Using pTILT 
Cheng Ouyang1,2, Keith Thulborne3, and Brad P. Sutton1,2
1Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States, 2Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL, United States, 33Center for Magnetic Resonance Research, University of Illinois at Chicago, Chicago, IL, United States

A novel vessel-encoded regional perfusion imaging technique is proposed by adding in-plane gradients into the pTILT sequence to provide differentiation of phase during flow encoding at different vessels. Simulations showed the labeling efficiency as the function of offset from encoded vessels follows an analytical sinusoid equation, which is useful to improve the separation of vascular perfusion regions. In vivo studies demonstrated the ability to provide robust delineation of vascular territories in regional perfusion imaging.

2091.   Extending the Adaptive Sequential Design (ASD) Approach for Real-Time TI Optimisation in Arterial Spin Labelling 
Alexander Graeme Gardener1, Stuart Clare1, and Peter Jezzard1
1FMRIB, University of Oxford, Oxford, United Kingdom

Adaptive Sequence Design ASL optimises multi-TI timings in real-time whilst the subject is within the scanner. Previously, a voxel mask based on difference signal was used; this study uses prior-acquired and stored GM-weighted DIR images loaded into the ASL acquisition to generate perfusion-independent masks. It is shown in healthy adult subjects that both approaches give similar TI optimisation and perfusion quantification, with simple online regional segmentation showing later inflow from PCA. This technique will be of use when dealing with diseased subjects, such as stroke patients, where perfusion may be altered, for which the original approach would not be sensitive.

2092.   Adaptive averaging improves the Signal to Noise Ration in ASL experiments especially at high inflow times 
Johanna Kramme1, Johannes Gregori1, and Matthias Günther1,2
1Fraunhofer MEVIS-Institute for Medical Image Computing, Bremen, Germany, 2Faculty of Physics and Electronics, University of Bremen, Germany

A challenge in Arterial Spin Labeling experiments is low Signal to Noise Ratio (SNR) and physiological noise, especially at inflow times above 2500ms. For time series over 3000ms a high number of averages was necessary to guaranty sufficient SNR, leading to long scan times. In this work a 3D-GRASE sequence is presented which is capable of adaptive averaging, allowing to average higher TIs more often than lower ones. Due to this scan times can be halved, by increasing the SNR by at least one halve compared to standard imaging where all inflow times are imaged equal number of times.

2093.   Modeling the Effect of Flow Dispersion in Continuous Arterial Spin Labeling 
Weiying Dai1, Ajit Shankaranarayanan2, and David Alsop1
1Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States, 2Global Applied Science Laboratory, GE Healthcare, Menlo Park, CA, United States

Quantification of perfusion with arterial spin labeling (ASL) requires knowledge of the label delivery over time. Standard ASL perfusion quantification assumes simple plug flow, i.e., all labeled blood takes the same time to travel from the labeling plane to the imaging region. Simple plug flow may not well approximate the tracer delivery. Here, we show that approximating the transit time distribution with a gamma variate function produces a relatively simple analytic solution to the modified Bloch equations. Pixel-by pixel fitting to in-vivo data was used to measure transit time dispersion. Using a dispersion model provided better fits to the multiple delay data compared with the standard model. Dispersion varies with spatial locations: deep gray matter regions have less dispersion and posterior regions have more.

2094.   Improved 3D TFEPI ASL with Flip Angle Sweep 
Fernando F Paiva1, Bernd U Foerster2, Rafael G Oliveira3, Fernanda Tovar-Moll1, and Jorge Moll1
1D'Or Institute for Research and Education, Rio de Janeiro, RJ, Brazil, 2Philips Medical Systems, 3InRad-Hospital das Clinicas, Magnetic Resonance Department, Faculty of Medicine of the University of SĂŁo Paulo

Due to the intrinsic low SNR, EPI-based ASL requires several signal averages to achieve a reliable measurement. A possible approach to overcome this SNR issue is based on using single-shot 3D EPI. However, the ASL signal evolves during the data acquisition and this can result in image blurring if not taken into account. In the present study we present an optimization for a 3D gradient echo EPI acquisition scheme by exploring a modulation of the flip angle of the MR acquisition to keep the ASL contrast constant over the 3D image readout.

2095.   A New Encoding Scheme for Single-shot 3D GRASE to Double Slice Coverage 
Huan Tan1, W. Scott Hoge2, and Robert A Kraft1
1VT-WFU School of Biomedical Engineering and Sciences, Winston-Salem, NC, United States, 2Brigham and Women's Hospital and Harvard Medical School, Boston, MA, United States

Single-shot 3D GRASE is a popular acquisition technique for ASL imaging. The slice coverage is limited by T2 relaxation. Increasing the number of slices acquired aggravates through-plane blurring due to the longer acquisition window. A new 3D GRASE encoding scheme is developed which performs two kz encodes for each spin echo that doubles slice coverage without compromising image quality. The new encoding scheme is shown to achieve similar image quality as a standard 2-shot 3D GRASE for in-vivo ASL imaging.

2096.   Determining the optimal label duration of pseudo-continuous ASL at 7 Tesla 
Eidrees Ghariq1, Wouter M. Teeuwisse1, Andrew Webb1, and Matthias J.P. van Osch1
1C.J. Gorter Center for high field MRI, Radiology, Leiden University Medical Center, Leiden, Zuid-Holland, Netherlands

High field MRI holds promises for better SNR in ASL applications due to the prolonged blood T1. To fully reach this gain in SNR the label duration must be chosen optimally. In the present study we determined theoretically and experimentally the optimal label duration for pseudo-continuous ASL at 7Tesla. The optimal label duration was found in vivo to be approximately 1500ms, which is lower than the optimal theoretical value around 3000ms. This can probably be attributed to sub-optimal robustness in label efficiency, which in the end results in a shift of the optimal SNR to shorter label durations.

2097.   Optimization of pseudo continuous ASL tagging for robust inversion efficiency - A Bloch simulation and in vivo study at 3T 
David Dongsuk Shin1, Eric C Wong1, Youngkyoo Jung1, Ho-Ling Liu2, and Thomas T Liu1
1Center for Functional MRI, University of California, San Diego, La Jolla, CA, United States, 2Department of Medical Imaging and Radiological Sciences, Chang Gung University, Taiwan

Phase tracking errors in PCASL can lead to significant loss in inversion efficiency. This error can be significantly reduced by minimizing the duration of the RF-to-RF spacing of the PCASL pulse train. Based on a Bloch simulation study, we propose a set of tagging parameters that achieve a sub-millisecond RF-to-RF spacing while preserving high inversion efficiency over a wide range of flow velocities. These parameters were also chosen to be relatively insensitive to B1 and gradient imperfections. In-vivo measurements were used to compare the effectiveness of the new optimized tagging parameters with those from a previous study.

2098.   Comparison of CASL perfusion signal with and without velocity dependent labeling RF power modulation 
S. L. Talagala1, W-M Luh2, and H. Merkle3
1NMRF/NINDS, National Institutes of Health, Bethesda, MD, United States, 2FMRIF/NIMH, National Institutes of Health, Bethesda, United States, 3LFMI/NINDS, National Institutes of Health, Bethesda, MD, United States

Velocity dependent labeling RF power modulation (VDLM) has been proposed as a possible method to achieve a high labeling efficiency throughout the cardiac cycle with minimum power deposition. Here, we investigate if real-time application of VDLM could be employed to increase the CASL signal when using a neck labeling coil. Current data indicate that the perfusion signal is dependent on the particular VDLM employed. When using the same average power, 3.5/1.5W VDLM was found to yield slightly higher perfusion signal compared to constant labeling. Further studies are needed to optimize VDLM in terms of perfusion signal. However, since VDLM can be used to reduce power deposition from the labeling pulse, it should prove useful for CASL perfusion MRI at higher magnetic field strengths.

2099.   Tagging Efficiency Corrected Pseudo-Continuous Arterial Spin Labeling – A New Approach for Correction of Phase Tracking Errors 
David Dongsuk Shin1, Ho-Ling Liu2, Ajit Shankaranarayanan3, and Thomas T Liu1
1Center for Functional MRI, University of California, San Diego, La Jolla, CA, United States, 2Department of Medical Imaging and Radiological Sciences, Chang Gung University, Taiwan, 3GE Healthcare, Waukesha, Wisconsin, United States

In PCASL, accurate and reliable CBF estimates can be complicated by variations in tagging efficiency (α) caused by phase tracking errors. We present a new technique named α-corrected PCASL, which compensates for tagging efficiency variations on a per voxel basis. The key component of this technique is the accurate estimation of the phase errors and the associated tagging efficiency map. In a healthy subject, CBF estimates obtained with OptPCASL and α-corrected PCASL were similar (87.7 vs. 86.0 ml/100ml-min), while conventional PCASL estimates were lower (78.4 ml/100ml-min). For phase tracking errors < 30 degrees, CBF quantification error is less than 2.85%.

2100.   Feasibility of Arterial Spin Labeling on a 1T open bore scanner 
Dennis Franciscus Ramon Heijtel1, Matthias J P van Osch2, Matthan W A Caan1, Ed van Bavel3, and Aart J Nederveen1
1Radiology, Academic Medical Center, Amsterdam, Netherlands, 2Radiology, Leiden University Medical Center, Leiden, Netherlands, 3Biomedical Engineering & Physics, University of Amsterdam, Amsterdam, Netherlands

The purpose of this study was to implement and investigate the performance of different available ASL sequences on a 1T open bore scanner. We demonstrate that ASL on a 1 Tesla open bore scanner is possible with a reasonable resolution and within a scanning period of approximately 5-6 min.

2101.   Effect of background suppression on CBF quantitation in pseudo continuous arterial spin labeling 
David Dongsuk Shin1, Ho-Ling Liu2, Eric C Wong1, and Thomas T Liu1
1Center for Functional MRI, University of California, San Diego, La Jolla, CA, United States, 2Department of Medical Imaging and Radiological Sciences, Chang Gung University, Taiwan

Background suppression (BGS) of static tissue can be effective for reducing structural and physiological noise and improving SNR in arterial spin labeling. However, BGS leads to a reduction in quantitative CBF estimates in a manner that has not yet been accurately predicted with theory. To address this issue, CBF estimates obtained with BGS are typically compensated using an empirically determined global scaling factor. We show that the BGS scaling factor varies across subjects and exhibits a dependence on baseline CBF. As a result, the use of a global scaling factor can lead to substantial errors in quantitative CBF estimates.

2102.   Optimizing Perfusion Imaging of pTILT in the Presence of Magnetic Field Inhomogeneity 
Cheng Ouyang1,2, and Brad P. Sutton1,2
1Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States, 2Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL, United States

Pseudo-continuous transfer insensitive labeling technique (pTILT) is a novel pseudo-continuous arterial spin labeling method, which employs non-adiabatic saturation RF pulses for tagging. However, magnetic field inhomogeneities, can compromise the labeling efficacy of pTILT, which induces loss in signal-to-noise ratio and perfusion quantification errors. We propose a method to restore the signal loss by correcting the field inhomogeneity effects through the use of variable phase offsets in the tagging RF pulse pairs. Simulation and in vivo results are shown to demonstrate the effectiveness of this approach. This will provide more robust perfusion measures than the conventional pTILT technique.

2103.   Performance of capnia-derived regressors for ASL measurement of cerebral vasoreactivity to circulating gases 
Marjorie Villien1,2, Julien Bouvier3, Irčne Tropres3, Matthias J. P. van Osch4, Christoph Segebarth1,2, Jean-François Le Bas5, Alexandre Krainik1,5, and Jan Martin Warnking1,2
1Centre de Recherche Inserm, U836, Grenoble, France, 2Grenoble Institut des Neurosciences, Université Joseph Fourier, Grenoble, France, 3IFR 1, Université Joseph Fourier, Grenoble, France,4Department of Radiology, Leiden University Medical Center, Leiden, Netherlands, 5Service de Neuroradiologie, CHU Grenoble, Grenoble, France

Robust MRI methods to measure cerebral vasoreactivity in patients are increasingly sought. A challenge in such studies is to correctly model the signal during a capnic stimulus, potentially varying with subject compliance and response. This is especially critical in ASL with limited SNR, as any mismatch will further decrease sensitivity. Here we compare the performance of regressors derived from hypercapnia data collected during each scanning session for the analysis of ASL data to a standard block regressor. Capnia-derived regressors slightly but consistently outperformed block regressors, more than compensating any variability in the capnia measurement and increasing robustness to experimental variability.

2104.   Comparison of pulsed and continuous ASL for measurements of CBF changes induced by hypercapnia 
Felipe Tancredi1,2, Claudine Gauthier1,2, Cécile Madjar2, Joseph Fisher3, Danny JJ Wang4, and Richard Hoge1,2
1Université de Montréal, Montreal, Quebec, Canada, 2Centre de recherche de l'institut universitaire de gériatrie de Montréal, Montreal, Quebec, Canada, 3University of Toronto, Toronto, Ontario, Canada, 4Neurology, UCLA, Los Angeles, California, United States

Hypercapnia is known to induce a global increase in cerebral blood flow and is an important component in MRI-based techniques measuring brain’s metabolic and vascular reactivity. While ASL methods have shown promise in these applications, there has been concern about possible underestimation of flow changes during global manipulations. We sought to compare pulsed and continuous labeling methods for detection and quantification of CBF changes induced by mild hypercapnia. Our results show that, although both offer comparable sensitivity to visually evoked CBF responses, continuous labeling yields higher flow change values for a given global manipulation and at higher SNR.

2105.   Detection of exposure related cortical responses by amphetamine using PCASL and pharmacokinetic/pharmacodynamic dose modeling 
Love Erlandsson Nordin1, Tie-Qiang Li1,2, Jacob Brogren3, Niclas Sjögren3, Kristin Hannesdottir3, JiongJiong Wang4, and Per Julin3,5
1Diagnostic Medical Physics, Karolinska University Hospital, Huddinge, Stockholm, Sweden, 2Clinical Science, Intervention and Technology, Division of Medical Imaging and Technology, Karolinska Institute, Stockholm, Sweden, 3AstraZeneca R&D Neuroscience, Södertälje, Sweden, 4Neurology, UCLA, Los Angeles, CA, United States, 5Section for Brain Injury Rehabilitation, Department of Rehabilitation Medicine, Danderyd University Hospital, Karolinska Institutet, Stockholm, Sweden

The aim of this study is to quantify and model neurological response pattern measured by regional CBF changes in relation to variations in plasma concentration of d-amphetamine after a single oral dose of d-amphetamine. Results from voxel- and region of interest-based analyses of arterial spin labeling (ASL) data have been compared. The study was carried out on a 3 T MRI unit using a 32 channel head coil. 12 randomized volunteers participated, 6 d-amphetamine (20mg)/6 placebo. The results show a significant reduction of global grey matter CBF. This shows that ASL technique has sufficient sensitivity to detect statistically significant changes of cerebral perfusion following administration of d-amphetamine.

2106.   An improved 3D GRASE pCASL method for whole-brain resting-state functional connectivity 
Xiaoyun Liang1, Jacques-Donald Tournier1,2, Richard Masterton1, Alan Connelly1,2, and Fernando Calamante1,2
1Brain Research Institute, Florey Neuroscience Institutes, Heidelberg West, VIC, Australia, 2Department of Medicine, University of Melbourne, Melbourne, VIC, Australia

3D GRASE has been shown to have some advantages over EPI, and ASL has the advantage of providing a more direct measure and better localization of activation than BOLD. However, the role of 3D GRASE ASL in resting-state functional connectivity has not been investigated. In this study, an improved 3D GRASE pCASL sequence was implemented with whole-brain coverage and then resting-state functional connectivity was investigated. BOLD data were acquired for comparison. In addition to the similarity of results of our method to that of BOLD, our method shows improved coverage in high susceptibility regions, which provides a viable means for studies that especially focus on those particular regions.

2107.   Altered Resting Cerebral Blood Flow in adults following low-frequency Electronic Acupuncture as Revealed by Perfusion Functional MRI 
Ying Hao1, Yin Jiang2, Yue Zhang3, Cailian Cui2, Xiaoying Wang1,4, Jue Zhang1,3, and Jing Fang1,3
1Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, Beijing, China, People's Republic of, 2Neuroscience Research Institute, Peking University, Beijing, Beijing, China, People's Republic of, 3College of Engineering, Peking University, Beijing, Beijing, China, People's Republic of, 4Dept. of Radiology, Peking University First Hospital, Beijing, Beijing, China, People's Republic of

This study determined the effect of a relatively long period (30min) of low-frequency electroacupuncture stimulation (EAS) on resting-state CBF utilizing arterial spin labeling (ASL) technique. We observed that blood flow significantly decreased within the ipsilateral IPL and dACC, as well as the contralateral IPFC and postcentral gyrus. The observation that the acupuncture did not significantly increase CBF within any brain region is contrary to previous reports using block-designed acupuncture assessed by functional MRI.

2108.   Cerebral Blood Flow and CerebroVascular Reserve of the brain in diabetes 
Iain D Wilkinson1, Nyssa Craig1, Elaine Cachia1, Tim J B Hughes1, Dan Warren1, Solomon Tesfaye2, Petersen T Esben3, Xavier Golay4, and Dinesh Selvarajah2
1Academic Radiology, University of Sheffield, Sheffield, S Yorkshire, United Kingdom, 2Diabetes, Sheffield Teaching Hospitals, 3National University of Singapore, 4University College London

Cerebral ischemia and a reduced ability to recover from it are linked with type-2 diabetes mellitus (T2DM). This study uses QUASAR arterial spin labeling (ASL) to determine arterial cerebral blood flow (CBF) before and after a pharmacological vasodilatory challenge (acetazolamide), providing a measurement of cerebrovascular reserve (CVR) in groups of patients with T2DM and controls. Increases in gray matter CBF were seen following acetazolamide. Results suggest a subset of neurologically normal T2DM patients have limited CVR. This technique may provide clinically useful methods with which to identify such subgroups.

2109.   The Precision of ASL in Measuring Cerebrovascular Reactivity in Cardiovascular disease patients. 
U C Anazodo1,2, N Suskin3, J Wang4, J K Shoemaker5, and K St Lawrence1,2
1Lawson Health Research Institute, St Joseph’s Health Care, London, Ontario, Canada, 2Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada, 3London Health Science Cardiology Rehabilitation Program, London, Ontario, Canada, 4Department of Neurology, UCLA, Almanson-Lovelace Brain Mapping Center, Los Angeles, California, United States,5Neurovascular Research Laboratory, School of Kinesiology, University of Western Ontario, London, Ontario, Canada

Recent evidence suggests that in cardiovascular disease patients, aerobic fitness can decrease the adverse effect of the disease on cognitive function and improve cerebrovascular health. A relative marker of cerebrovascular health is the measure of the brain’s response to change in arterial CO2 tension, known as cerebrovascular reactivity. In this study, the reproducibility of arterial spin labeling in assessment of cerebrovascular reactivity in cardiovascular disease patient is investigated. Our results demonstrate that the variation between repeated measures is minimal and, as such will not compromise further intra-subject comparisons on fitness effects.

2110.   Retinal and Choroidal Blood-Flow MRI and Visual Function in Diabetic Retinopathy in Mice 
Eric R Muir1, René C Rentería2,3, and Timothy Q Duong1
1Research Imaging Institute, University of Texas Health Science Center, San Antonio, TX, United States, 2Department of Physiology, University of Texas Health Science Center, San Antonio, TX, United States, 3Center for Biomedical Neuroscience, University of Texas Health Science Center, San Antonio, TX, United States

Diabetic retinopathy (DR) is the leading cause of new blindness in working age adults. Vascular dysfunction is the most prominent feature of DR. The retina is nourished by two separate vasculatures, the retinal and choroidal vessels. Arterial spin labeling was used to image layer-specific, quantitative retinal and choroidal blood flow (RBF and ChBF) in the Akita mouse model of DR at 42x42x400 micron. RBF was significantly reduced in Akita mice, while ChBF was unchanged. Vision assessed by the optokinetic response was also worse in Akita mice. MRI provided a non-invasive method to monitor vascular changes in rodents in vivo.

2111.   Layer-Specific Retinal and Choroidal Blood-Flow MRI of Retinitis Pigmentosa in Mice 
Eric R Muir1, Bryan H De La Garza1, and Timothy Q Duong1
1Research Imaging Institute, University of Texas Health Science Center, San Antonio, TX, United States

Retinitis pigmentosa (RP), which causes photoreceptor death and blindness, affects 1.5 million people worldwide. The vasculature and blood flow (BF) of the retina is attenuated in RP. The retina is nourished by two separate vasculatures, the retinal and choroidal vessels. Arterial spin labeling was used to image layer-specific, quantitative retinal and choroidal BF in the rd10 mouse model of RP at different stages of disease at 42x42x400 microns. Retinal BF was reduced as the retina degenerated, while choroidal BF was unchanged. MRI provided a non-invasive method to monitor vascular changes in rodents in vivo.

2112.   Probing Arterial Spin Labeling MR Signal in Human Brain with T1ρ Technique 
Xiang He1, and Kyongtae Ty Bae1
1Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States

Tracking arterial spin labeled (ASL) water in the human brain provides key information on the dynamics of water exchange and brain perfusion measured by PET and MR imaging. In this study, we used the T1ρ characteristic of ASL signal to investigate the labeled water compartment structure. Our result is in agreement with PASL T2* studies and is consistent with the results from other PASL studies for flow quantification. We postulate that the discrepancy between the T1ρ PASL and T2 pCASL may be due to the difference between their techniques, and PASL technique provides more accurate information on water compartmental structure.

2113.   Quantification of arterial and microvascular cerebral blood volume using multiphase TrueFISP based ASL 
Lirong Yan1, Cheng Li2, Emily Kilroy1, Felix Werner Wehrli2, and Danny JJ Wang1
1Department of Neurology, University of California Los Angeles, Los Angeles, CA, United States, 2Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States

A new method was introduced to measure arterial and microvascular cerebral blood volume (CBV) by combining multiphase trueFISP readout with arterial spin labeling. Both simulation and experimental results demonstrated well preserved longitudinal magnetization of flowing spins, which can be treated as an intravascular contrast agent for CBV measurement. The measured arterial and microvascular cerebral blood volume (CBV) was around 1.5%.

2114.   Is cerebral microvascular flow anisotropic - preliminary evidence from multi-directional diffusion weighted perfusion MRI 
Anitha K Priya1, Lirong Yan1, and Danny JJ Wang1
1Neurology, UCLA, Los Angeles, CA, United States

Perfusion Tensor Imaging has been introduced recently to demonstrate anisotropic microvascular flow. In the present study, a multi-directional diffusion-weighted arterial spin labeling (DW-ASL) sequence was performed with a post-labeling delay of 1.2s and a b value of 50s/mm2 to derive the directional information of capillary flow. Fractional anisotropy values were relatively high throughout the brain but were significantly greater in white matter than in gray matter. The primary eigenvectors showed random patterns in the brain. The largely isotropic microvascular flow or perfusion observed in this study implies that a single ASL scan may be enough to quantify cerebral perfusion.

2115.   Comparison of spin dynamics in pseudo-continuous and velocity-selective arterial spin labeling with and without vascular crushing 
Wouter M. Teeuwisse1, Aart J. Nederveen2,3, Eidrees Ghariq1, Dennis F. Heijtel2,3, and Matthias J.P. van Osch1
1Radiology, C.J. Gorter Center for high field MRI, Leiden University Medical Center, Leiden, Netherlands, 2Radiology, Amsterdam Medical Center, Amsterdam, Netherlands, 3Spinoza Center, Amsterdam, Netherlands

Information on the dynamics of labeled spins is essential in ASL to enable absolute quantification and interpretation of the data. In this study multi-echo, multi-delay-time imaging is employed to study differences in spin dynamics of pseudo-CASL (PCASL) and velocity selective ASL (VSASL) and to study the influence of vascular crushing. It is shown that vascular crushing decreases the contribution of arterial signal in PCASL and both arterial and venous signal in VSASL. Delay times larger than 1800 ms or vascular crushing is needed to achieve sensitivity towards perfusion signal.

2116.   Removal of CSF Contamination in VSASL and QUIXOTIC using a long TE CSF Scan 
Jia Guo1, and Eric C. Wong2
1Bioengineering, University of California San Diego, La Jolla, California, United States, 2Department of Radiology and Psychiatry, University of California San Diego, La Jolla, California, United States

In Velocity Selective ASL (VSASL) and the QUIXOTIC method for measurement of venous T2, flow/diffusion weighting gradients are used to attenuate the signal of flowing spins. The flow weighting is strong enough that diffusion related attenuation in CSF, which has high diffusivity, can become significant, and the CSF signal can contaminate the desired vascular signal. We introduce here the use of a long TE image to estimate the CSF signal, and remove this contamination from VSASL and QUIXOTIC data. Results demonstrate CBF values in VSASL and T2 values in QUIXOTIC that are closer to literature values after CSF correction.

2117.   Magnetization “reset” in T2-Relaxation-Under-Spin-Tagging (TRUST) MRI 
Feng Xu1, Jinsoo Uh2, and Hanzhang Lu1
1University of Texas Southwestern Medical Center, Dallas, TX, United States, 2University of Texas Southwestern Medical Center

The T2-Relaxation-Under-Spin-Tagging (TRUST) MRI technique was developed to quantitatively estimate blood oxygenation via the measurement of pure blood R2. A limitation of the current TRUST is the long TR (=8s), as a shorter TR results in an over-estimation of R2. We applied a non-selective 90° RF pulse after the EPI acquisition, and achieved the unbiased R2 estimation in TR of 3s with the precision preserved. Furthermore, we also tested the impact of reducing the TE although previous TRUST already used a relatively short TE of 7ms. The TE of 3.6ms was found to reduce R2 estimation uncertainty by 50%.

2118.   Arterial Spin Labeling based T2 measurements of restricted blood-to-tissue water transfer in human brain 
Johannes Gregori1, Norbert Schuff2,3, and Matthias Günther1,4
1Fraunhofer MEVIS, Bremen, Bremen, Germany, 2Radiology & Biomedical Imaging, University of California San Francisco, United States, 3Center for Imaging of Neurodegenerate Diseases (CIND), VA Medical Center, San Francisco, California, United States, 4FB1, University Bremen, Bremen, Germany

A new method is presented to derive quantitative brain maps of water transfer from blood to tissue, based on non-invasive Arterial Spin Labeling (ASL) techniques using additional T2 measurements. A two-compartment perfusion model including T2 and permeability effects is derived based on the General Kinetic Model. Resulting whole-brain maps of transfer time, which is inversely proportional to capillary water permeability, are shown for healthy volunteers acquired on a 3 Tesla system.

2119.   Optimal Acquisition Strategies for Transit Time Measurement with Continuous ASL 
Weiying Dai1, Ajit Shankaranarayanan2, and David C. Alsop1
1Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States, 2Global Applied Science Laboratory, GE Healthcare, Menlo Park, CA, United States

A good estimate of arterial transit time (ATT) is required to eliminate ATT effects in perfusion measurement with ASL. Multiple delay methods for measuring ATTs can be time consuming. Both a rapid, low resolution scan at multiple labeling delays and more efficient encoding of multiple delay signals using Hadamard encoding can reduce the time penalty. We sought to determine the optimal delays and labeling durations for estimating ATT with continuous labeling using a theoretical model for signal and a Monte Carlo optimization of parameters. Simulations suggest that only two delays and labeling durations are required to estimate ATT and that Hadamard encoding can improve the measurement speed and sensitivity. A low resolution scan at two optimal delays using Hadamard encoding is demonstrated to achieve in-vivo ATT measurement efficiently.

2120.   Accordance of ASL delay time and bolus arrival times in parenchyma 
Kay Jann1, Martinus Hauf2, Frauke Kellner-Weldon2, Marwan Mohamed El-Koussy2, Claus Kiefer2, Andrea Federspiel1, and Gerhard Schroth2
1Department of Psychiatric Neurophysiology, University Hospital of Psychiatry / University of Bern, Bern, Switzerland, 2University Institute of Diagnostic and Interventional Neuroradiology, Inselspital and University of Bern, Bern, Switzerland

The time needed by labelled blood to reach the cortical capillaries (parenchyma phase) has to be accounted for in ASL, therefore a delay between labelling and readout is introduced. The duration of this delay is limited by the fast T1 relaxation-time to only a few seconds. In patients with steno-occlusive arterial disease (SOAD) above the labelling plane (intracranial stenosis) this time window might be too narrow due to prolonged arrival times to the parenchyma. We estimated to what extent arrival is delayed in patients with SOAD and from which vascular compartment the ASL signal origins at a given delay time.

2121.   The influence of voxel-wise rCBF covariates in pharmacological BOLD-fMRI studies 
Fernando O Zelaya1, Astrid Pauls2, Owen O'Daly2, Matthew Howard2, David Alsop3, and Mitul Mehta2
1Neuroimaging, Institute of Psychiatry, London, London, United Kingdom, 2Neuroimaging, Institute of Psychiatry, London, United Kingdom, 3Beth Israel Hospital, United States

Several physiological modulators have been proposed as a means of reducing the inter-subject variance of BOLD-fMRI signals in group comparisons. In this abstract, we demonstrate that rCBF maps can be used as a voxel-wise co-variate in standard statistical models that compare brain activity maps, obtained from 2 groups of subjects who execute the same cognitive task after administration of a placebo and a psycho-active substance. The rCBF maps allow us to successfully identify statistically significant, drug-dependent differences that would otherwise appear as a type 2 error (false negative) using conventional analysis models.

2122.   Combined Arterial Spin Labelling and Diffusion Weighted Imaging for Estimation of Capillary Volume Fraction and Permeability-Surface Product in the Human Brain 
Patrick William Hales1, and Chris A Clark1
1Imaging and Biophysics Unit, UCL Institute of Child Health, London, United Kingdom

We present a methodology to measure flow, capillary permeability-surface product (PS) and capillary volume fraction (vbw) in the human brain, using combined diffusion weighted imaging (DWI) and arterial spin labelling (ASL). Local values of vbw were calculated from DWI data using the intra voxel incoherent motion theory. These data were used in a two-compartment model of time-series ASL data in the same subject. Mean values in three healthy subjects were flow = 42.6 ±2.7 ml/100g/min, PS = 58.6±8.1 ml/100g/min. A slight under-estimation of PS is caused by partial volume contamination from CSF, which we aim to eliminate in future studies.

2123.   Whole brain quantification of arterial transit time and perfusion using multi-slice pseudo-continuous arterial spin labelling 
Wayne Lee1, Rafal Janik2, Bojana Stefanovic2,3, and John G Sled1,3
1Hospital for Sick Children, Toronto, Ontario, Canada, 2Sunnybrook Health Sciences Center, Canada, 3Medical Biophysics, University of Toronto, Canada

Whole brain quantitative imaging of cerebral perfusion and transit time provides a means to assess and characterize neurodegeneration. Robust estimation of perfusion and transit time by arterial spin labelling requires adequate sampling of the labelled spins in the tissue preceding the difference signal peak. However, even with rapidly acquired slices, the top third of the brain may not be sampled before the signal peak, too late for estimation of tA and having lower SNR. To address the issue of poor time-delay sampling of distal slices in traditional multi-slice acquisitions, we propose a novel slice ordering approach to multi-slice pseudo-continuous ASL. This Round Robin approach ensures that all slices are equally acquired across the same range of delays, enabling reliable model fits for a wide range of transit times throughout the brain.

2124.   The B1 field and variability in left-right brain perfusion with 3D IR-PULSAR and its implications on symmetry studies 
Neville D Gai1, and John Butman1
1Radiology & Imaging Sciences, National Institutes of Health, Bethesda, MD, United States

Brain perfusion asymmetry is thought to be associated with several cerebrovascular diseases. To a radiologist left-right asymmetry serves a critically important function as a visual cue to the presence of pathology. The ability to assess inter-hemispheric symmetry in the human brain with precision is therefore of importance. Arterial spin labeling is now of routine clinical relevance. Here we study the effect of B1 field inhomogeneity on a whole brain pulsed arterial spin labeling method and show that correcting for transmit and residual B1 inhomogeneity is essential before any inferences can be made based on CBF values particularly related to perfusion asymmetry.

2125.   Saturated label effects with multi-slice imaging in ASL 
Wayne Lee1, Rafal Janik2, Bojana Stefanovic2,3, and John G Sled1,3
1Hospital for Sick Children, Toronto, Ontario, Canada, 2Sunnybrook Health Sciences Center, Canada, 3Medical Biophysics, University of Toronto, Canada

Conventional practice for whole brain cerebral perfusion imaging using arterial spin labelling (ASL) is to acquire consecutive transverse slices from the inferior to the superior aspect of the brain. However, when consecutive slices are acquired at equivalent post-label-delay a confound associated with ascending slice order becomes evident. Labelled blood that is intravascular and transiting to a distal slice can be saturated during the imaging of proximal slices. This study demonstrates that this effect decreases label efficiency by an undetermined amount, which may lead to underestimated perfusion. This effect may be avoided by acquiring multislice data from superior-to-inferior acquisition using the Round Robin sampling approach.

2126.   Feasibility and repeatability of ASL-based phMRI after a single dose oral challenge as a tool for assessing 5-HT function 
Anne Klomp1, Matthan W Caan1, Aart J Nederveen1, and Liesbeth Reneman1
1Radiology, Academic Medical Center, Amsterdam, Netherlands

The purpose of this study was to verify feasibility and repeatability of ASL-based phMRI after an oral challenge in assessing cerebral serotonin function. Twelve subjects were scanned six times; twice before and after taking 16mg citalopram and once before and after taking placebo. Subjects were blinded to treatment and treatment order was (pseudo)randomized. Although within-session reproducibility of the ASL signal was good, effects of the citalopram challenge could not be repeated between sessions. We attribute these contradictory findings between the two citalopram sessions to the need for relatively large sample sizes due to variation in both ASL signal and serotonergic activity.

2127.   Arterial Spin Labeling in Young Adults during Alcohol Infusion 
Michael Marxen1,2, Gabriela Gan1,2, Christine Monika Zimmermann1,2, Maximilian Pilhatsch1,2, Ulrich S Zimmermann1, Matthias Guenther3,4, and Michael N Smolka1,2
1Department of Psychiatry and Psychotherapy, Technische Universität Dresden, Dresden, Germany, 2Neuroimaging Center, Technische Universität Dresden, Dresden, Germany, 3Fraunhofer MEVIS-Institute for Medical Image Computing, Bremen, Germany, 4Faculty of Physics and Electronics, Universität Bremen, Bremen, Germany

Perfusion changes (rCBF) during a 15 min. alcohol infusion up to a target alcohol concentration of 0.06 % were studied in 5 subjects using a pulsed arterial spin labelling technique with 3D GRASE readout. 5-25% changes in global gray matter perfusion were observed, which are above the level of change found with a placebo. Increases were seen in most of the brain, especially superiorly. Local decreases were also found in inferior regions such as the medial temporal lobe. The observed changes need to be accounted for in functional BOLD fMRI studies.

2128.   Comparison of CBF and CMRO2 Measurements using MRI and PET in large Nonhuman Primates (Baboons) 
Hsiao-Ying Wey1,2, Kihak Lee1, Peter T Fox1,2, and Timothy Q Duong1,2
1Research Imaging Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States, 2Radiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States

We cross validated quantitative (1) CBF at rest and during global and regional activations using pseudo-continuous arterial spin labeling MRI and 1H215O-PET, and (2) stimulus-evoked CMRO2 using calibrated fMRI and 15O2-PET on large nonhuman primates (baboons) when experimental differences were minimized in this study. Baseline CBF was higher as measured with MRI than PET, but comparable stimuli-evoked CBF and CMRO2 were found. Future studies will investigate CBF and CMRO2 measurements in stroke where CBF is compromised and to develop models to better determine CBF and CMRO2 under perturbed conditions.

2129.   Flow-weighted iVASO-DS for absolute arterial CBV quantification 
Kathrin Lorenz1, Toralf Mildner1, Andre Pampel1, and Harald E. Möller1
1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany

Inflow vascular-space-occupancy with dynamic subtraction (iVASO-DS) is a non-invasive MRI method for absolute arterial cerebral blood volume (aCBV) quantification. In the present study, mild flow-weighting (FW) gradients were added to the imaging readout. Experiments without FW gradients show a significant drop of the measured aCBV from more than 3% at TI=839ms to about 1.5% at TI=1143ms in regions which are dominated by signals from larger-scale arteries. This drop is explained by non-inverted blood reducing the iVASO-DS contrast at longer TI. It is shown that experiments with FW gradients effectively remove this source of error yielding aCBV values of about 1%.

2130.   Late Effects of Cancer Treatment on Gray Matter Perfusion Assessed by Arterial Spin Labeling MRI and its Association with Neurocognitive Function 
Adam Martin Winchell1,2, Kevin Krull3, Noah Sabin1, Jan Sedlacik1, Ruitian Song1, Ralf B Loeffler1, Melissa Hudson3, and Claudia M Hillenbrand1
1Radiological Sciences, St. Jude Children's Research Hospital, Memphis, TN, United States, 2Biomedical Engineering, University of Memphis, Memphis, TN, United States, 3Epidemiology & Cancer Control, St. Jude Children's Research Hospital, Memphis, TN, United States

The purpose of our study was to explore the association between gray matter perfusion assessed by arterial spin labeling (ASL)-MRI and neurocognitive function in long-term adult survivors of ALL.