ISMRM 23rd Annual Meeting & Exhibition • 30 May - 05 June 2015 • Toronto, Ontario, Canada

Traditional Poster Session • Perfusion
2322 -2369 Perfusion & Permeability

Wednesday 3 June 2015
Exhibition Hall 13:30 - 15:30

Absolute CBV and AIF from Global Recirculation Approach
Jeiran Jahani1, Timothy M Shepherd1, Glyn Johnson1, Valerij G Kiselev2, and Dmitry S Novikov1
1Department of Radiology, New York University School of Medicine, New York City, New York, United States, 2Department of Radiology, Medical Physics, University Medical Center Freiburg, Freiburg, Germany

Indicator dilution techniques have been at the heart of vascular disease diagnostics for decades. The current approaches consider the first pass of the contrast and cannot account for recirculation. This complicates data interpretation as the first pass and recirculation boluses overlap. For the first time, we develop a global approach to contrast circulation within the body with account for all organs and the topology of the circulation system. This framework allows us to obtain the explicit form of contrast kinetics in individual organs. It also provides us with AIF without directly measuring it, and a practical way to map the local absolute CBV without the need for the first pass extraction.

2323.   Measurement of Local Cerebral Hematocrit with MRI
Fernando Calamante1, André Ahlgren2, Matthias J.P. van Osch3, and Linda Knutsson2
1The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia, 2Department of Medical Radiation Physics, Lund University, Lund, Sweden, 3Department of Radiology, C.J. Gorter Center for high field MRI, Netherlands

The % blood-volume occupied by red-blood-cells is known as hematocrit (Hct). Whereas it is straightforward to measure Hct in large arteries (e.g. blood sample), it is very challenging to do it in microvasculature (cerebral Hct). Currently, this can only be done using invasive methods (e.g. PET, SPECT, autoradiography), but their use is very limited. Local variations in cerebral Hct have been reported in various brain abnormalities (e.g. stroke, tumours). We propose an MRI method to image cerebral Hct, which relies on combining data from two MRI measurements: one that provides Hct-weighted, and another one Hct-independent values of the same parameter.

2324.   Reconstructing the one-compartment tracer-kinetic field with diffusion and convection
Steven Sourbron1
1University of Leeds, Leeds, UK, United Kingdom

A tracer-kinetic field theory has been proposed for DCE- and DSC-MRI that may reduce error and provide new information by spatial modelling of indicator transport. In this study a 2D simulation of the simplest one-compartment field model is used to investigate whether all model parameters are uniquely identifiable. The discrete system is written as a large sparse linear inverse problem and solved iteratively using constrained gradient descent. A well-defined optimum is found but the reconstructed fields are not sufficiently accurate for a simulation of ideal conditions. It is concluded that a better reconstruction algorithm is required, or additional constraints must be imposed.

2325.   Arterial Spin Labeling Improvement by Incorporating Local Similarity with Anatomic Images
Li Zhao1, Weiying Dai1, and David Alsop1
1Radiology, Beth Israel Deaconess Medical Center & Harvard Medical School, Boston, MA, United States

Arterial spin labeling provides important perfusion information, but it suffers from intrinsically low SNR and spatial resolution. Since high quality T1 weighted images are collected in routine MRI procedures, we present a method to enhance ASL image by incorporating its local similarity with anatomic images. The proposed method was evaluated on five tumor patients and results preserved the low resolution contrast of ASL with improved CNR and spatial resolution.

2326.   On the Use of DSC-MRI for Measuring Vascular Permeability
Jack T Skinner1,2, Paul L Moots3, and C Chad Quarles1,2
1Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, United States, 2Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, United States, 3Neurology, Vanderbilt University Medical Center, Nashville, TN, United States

Leakage of contrast agent can confound DSC-MRI measurements, necessitating correction techniques. Parameters relating to contrast extravasation (K2, Ka) can be extracted from these techniques. Dual gradient-echo acquisitions also mitigate leakage effects and allow the extraction of T1-weighted data and subsequently the computation of DCE-MRI parameters Ktrans and ve. Using dual-echo DSC-MRI, these parameters were simultaneously compared. A poor voxel-wise correlation was found between K2 and Ka andKtrans, potentially attributed to competing T1 and T2* leakage effects and echo time dependence. A strong correlation was observed, however, between K2 and Ka and ve, suggesting a relationship with the extravasation space.

2327.   A Simplified Spin and Gradient Echo (SAGE) Approach for Brain Tumor Perfusion Imaging
Ashley M Stokes1 and C. Chad Quarles1
1Institute of Imaging Science, Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, United States

Contrast agent leakage in tumors can severely reduce the reliability of DSC perfusion measures due to competing T1 effects. While dual gradient-echo (GE) sequences can provide robust T1-insensitive GE hemodynamic measures, no analogous method exists for T1-insensitive spin-echo (SE) measures. Here, we propose a simplified spin- and gradient-echo (sSAGE) approach that utilizes a combined dual GE and SE sequence and an analytical solution for T1-insensitive ∆R2* and ∆R2 timecourses. As this approach only requires acquisition and storage of three echoes and does not rely upon computationally demanding non-linear fitting, it could facilitate more rapid clinical translation and adoption of SAGE-based DSC-MRI.

2328.   Cell Size Imaging
Natenael B Semmineh1, Ashley M Stokes1, John C Gore1, and C Chad Quarles1
1Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States

Recently, we demonstrated that T2* and T2 weighted contrast enhanced MRI signals, when acquired at contrast agent equilibrium, are predominantly influenced by the cellular properties of tissue. We now propose a novel imaging approach that utilizes these T2* and T2 effects to derive an estimate of mean cell size in a voxel. Using simulations, in vitro and in vivo studies we demonstrate that the ratio of ΔR2* and ΔR2 is related to cellular size and may be used to estimate mean cell size in a voxel.

2329.   Comparative Assessment of SAGE and GRE DSC Perfusion: Initial Assessment in a Stroke Cohort
Shalini A. Amukotuwa1,2, Fernando Calamante2, and Roland Bammer1
1Department of Radiology, Stanford University, Stanford, CA, United States, 2The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia

Combined spin- and gradient-echo (SAGE) dynamic susceptibility contrast (DSC) perfusion-weighted imaging (PWI) has considerable benefits over conventional single-echo spin-echo (SE) or gradient-echo (GRE) DSC PWI. However, mismatch criteria are based on GRE DSC PWI. Our aim is to investigate the comparability of the second gradient-echo of SAGE with GRE DSC PWI in patients with suspected stroke. Our findings indicate that, with matching scan parameters, the SAGE 2nd gradient-echo yields comparable results to conventional GRE DSC PWI; therefore SAGE data can be calibrated with GRE DSC data, and postprocessing algorithms optimized through previous clinical trials can be applied to SAGE.

2330.   Improving Look & Locker readout for pCASL using a variable Flip Angle sweep
Marco Castellaro1, Alessandra Bertoldo1, Denis Peruzzo2, Filippo Arrigoni2, and Matthias Van Osch3
1Department of Information Engineering, University of Padova, Padova, Italy, 2Department of Neuroimaging, Research institute IRCCS "E. Medea", Bosisio Parini, Lecco, Italy,3C.J. Gorter Center for High Field MRI, Radiology, Leiden University Medical Center, Leiden, Netherlands

Arterial spin labelling (ASL) is a technique that permits to estimate perfusion non-invasively. The readout phase of ASL sequence can follow several schemes. In particular, to sample the entire kinetic curve of the inflowing blood the use of a Look&Locker (LL) read-out has been proposed. The LL approach suffers, however, from a progressively lower Signal-to-Noise Ratio (SNR) for later post-labeling delays (PLDs) due to T1-relaxation and the fact that the label experienced multiple excitation pulses. This work presents an approach to optimize the SNR over all PLDs of a LL read-out scheme by introducing a variable flip-angle (FA) sweep.

2331.   Effect of labelling plane angulation on pCASL labelling efficiency – does it really matter?
Magdalena Sokolska1, Xavier Golay1, and David Thomas1
1UCL Institute of Neurology, London, United Kingdom

Pseudo-continuous Arterial Spin Labeling (ASL) (pCASL) is emerging as a method of choice for the non-invasive measurement of tissue perfusion in research and clinical practice. It is not clear, what the effect of imperfect angulation and mis-placement will have on the labeling efficiency and consequently, on CBF estimation. Therefore this work aims to address this question by simulation and in vivo experiment and quantitatively assess the effect of the angulation of the labeling plane on pCASL labeling efficiency.

2332.   Time-resolved Artery-selective Angiography based on Super-selective Arterial Spin Labeling
Thomas Lindner1, Ulf Jensen-Kondering1, Olav Jansen1, Matthias JP van Osch2, and Michael Helle3
1Department of Radiology and Neuroradiology, UKSH, Kiel, Germany, 2Department of Radiology, LUMC, C. J. Gorter Center for High Field MRI, Leiden, Netherlands, 3Philips Research, Hamburg, Germany

In this study, we present a method for time-resolved artery-selective non-contrast enhanced magnetic resonance angiography. The presented method is based on superselective arterial spin labeling (ASL), which allows tagging of a single artery. Time-resolved imaging is achieved by increasing the post labeling delay for each image, resulting in a temporal resolution of 100ms. To keep the acquisition time to an acceptable amount, keyhole reduced imaging is applied, where the keyhole factor as well as the flip angle were optimized using numerical simulations. This method was successfully applied in healthy volunteers, visualizing the individual flow territories of the intracranial arteries.

2333.   The many advantages of arterial spin labeling with long label duration
R. Marc Lebel1,2, Ajit Shankaranarayanan3, Eric E. Smith4, Cheryl McCreary2, Richard Frayne2, Weiying Dai5, and David C Alsop5
1GE Healthcare, Calgary, Alberta, Canada, 2Radiology, University of Calgary, Calgary, Alberta, Canada, 3GE Healthcare, Menlo Park, California, United States, 4Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada, 5Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States

Pseudo-continuous arterial spin labeling (PCASL) is a method for non-contrast perfusion imaging that tags blood flowing across a labeling plane. The labeling plane is active for only a finite period of time prior to imaging. A 1.5 s labeling time is typical. It is well known that the signal-to-noise ratio increases with longer labeling times but additional benefits exist. We describe improved temporal stability and demonstrate a reduced sensitivity to arterial transit delays with longer labeling. Overall we recommend using a label duration that is much longer than what is commonly done.

2334.   Inflow velocity density mapping using Fourier Analysis of Velocity Selective ASL images
Tianrui Luo1 and Luis Hernandez-Garcia2
1University of Michigan, Ann Arbor, Michigan, United States, 2FMRI Laboratory, University of Michigan, Ann Arbor, Michigan, United States

A method to measure Inflow Velocity Density of brain tissue based on velocity selective ASL is proposed. The method uses modified BIR-8 pulses to generate both cosine and sine velocity dependent profiles in the observed magnetization. Fourier analysis of the resulting data yields the distribution of flow velocities in the arterial blood supply to a given voxel.

2335.   Conversion of the arterial input function using accelerated dual-contrast EPIK: a multi-modality MR-PET study
Liliana Lourenco Caldeira 1, Seong Dae Yun1, Nuno André da Silva1, Christian Filss1, and N. Jon Shah1,2
1Institute of Neuroscience and Medicine (4), Forschungszentrum Juelich, Jülich, Germany, 2RWTH Aachen University, Faculty of Medicine, Department of Neurology, JARA, Aachen, Germany

The arterial input function (AIF) is essential for quantification in MRI and PET imaging. The ground truth for AIF estimation is arterial cannulation, which is a difficult procedure. Alternatively, an image-derived AIF can be estimated using MRI and/or PET images, but a reasonable temporal resolution of dynamic image series is necessary (<2s). In PET, high temporal resolution is limited (>5s) and images are rather noisy. Here, we propose a method to combine simultaneous MR-PET data to estimate the AIF. The MR AIF is based on an EPI with keyhole (EPIK) sequence and then can be converted to a PET AIF.

2336.   Robust Inter-Pulse Phase Correction for Brain Perfusion Imaging at Very High Field using Pseudo-Continuous Arterial Spin Labeling (pCASL)
Lydiane Hirschler1,2, Clément Stéphan Debacker1,2, Jérôme Voiron2, Jan Warnking1,3, and Emmanuel Luc Barbier1,3
1Université Grenoble Alpes, Grenoble Institut des Neurosciences, Grenoble, France, 2Bruker Biospin, Ettlingen, Germany, 3Inserm, U836, Grenoble, France

Performing pseudo-continuous arterial spin labeling (pCASL) at very high magnetic field is challenging as B0 inhomogeneities at the labeling plane, away from the isocenter, strongly affect the spins’ phase and thus inversion efficiency. This study shows that, for an unbalanced pCASL, performing a label and a control phase increment correction improves perfusion signal, corrects asymmetry between brain hemispheres arising when labeling far from isocenter at high field, and preserves high image quality at the same time.

2337.   Arterial Input Partial Volume Artifacts Correction applied for a T1-weighted 3D Gradient Echo Sequence
Stefan Hindel1, Nico Verbeek2, Anika Sauerbrey1, and Lutz Lüdemann1
1Strahlenklinik und Poliklinik, Universitätsklinikum Essen, Essen, North Rhine-Westphalia, Germany, 2Heinrich-Heine-Universität Düsseldorf, Düsseldorf, North Rhine-Westphalia, Germany

We accessed a method for voxel-based partial volume correction for DCE-MRI. The spiral like trajectory of the complex blood signal was plotted in the complex plain and fitted by a logarithmic spiral to calculate the spiral center. The results demonstrate a strong correlation between echo time and accuracy of the analyzed data. Our results illustrate the limitations for using the method when applied to a 3D-GRE (DCE-MRI) sequence. The T2* 2D-GRE AIF analyzing method helps detecting and correcting partial volume artifacts which affect measurements of the arterial input function.

2338.   Statistical mapping of cerebral blood flow territories using multi-phase pseudo-continuous arterial spin labeling
Wen-Chau Wu1,2
1National Taiwan University, Taipei, Taiwan, 2Department of Medical Imaging, National Taiwan University Hospital, Taipei, Taiwan

Depicting the primary flow territories of the brain is of clinical importance because collateral circulation is a common finding in patients with steno-occlusive disease. In this study, we proposed to generate statistical mapping of the flow territories of the left/right internal carotid arteries and vertebral arteries by using multi-phase vessel-encoded pseudocontinuous arterial spin labeling and the general linear model. The described method allows comparison between flow territories and/or subject populations to be carried out in a statistical framework similar to that in functional MR imaging.

2339.   Fully Bayesian Multi-model Inference for Parameter Estimation in DCE-MRI
Tammo Rukat1 and Stefan A Reinsberg1
1Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada

A fully Bayesian model mixing method for the estimation of haemodynamic parameters from DCE-MRI is being assessed. In particularly we examine the capability of weighing models of different complexity, such that the resulting parameter can be expected to be more accurate than the estimate from any single model. The Watanabe-Akaike information criterion (WAIC) is derived from the posterior likelihood distributions of the model parameters, which was sampled by adaptive MCMC. WAIC serves to calculate model mixing weights. This method is shown to be superior to the choice of any single model.

2340.   A modified deconvolution method to quantify brain tumour haemodynamic parameters in the presence of contrast agent extravasation.
Thaís Roque1, Amit Mehndiratta2, Lawrence Kenning3, Martin Lowry3, and Michael Chappell1
1Institute of Biomedical Engineering IBME, University of Oxford, Oxford, Oxfordshire, United Kingdom, 2Centre for Biomedical Engineering, Indian Institute of Technology Delhi, New Delhi, India, 3Centre for MR investigations CMRI, University of Hull, Hull, United Kingdom

In order to derive brain haemodynamic parameters such as CBF and the residue function, DSC-MRI analysis typically involves a deconvolution problem. If the blood-brain barrier is disrupted, these parameters are artificially modified due to contrast agent (CA) leakage. In this work, a model free, non-parametric deconvolution method was modified (mCPI) to account for CA leakage. In simulations, mCPI accurately estimated haemodynamic parameters in the presence of CA leakage. Glioma clinical data analysis yielded different shapes of residue function for different tumour areas, which permits assessment of flow heterogeneity within and around the tumour.

2341.   In Vitro and In Vivo Measurement of Pseudo Continuous Arterial Spin Labeling Efficiency
Adam Michael Bush1, Gregory Lee2, Matt Borzage1, Vincent Schmithorst2, Scott Holland2, and John Wood1
1Children's Hospital Los Angeles USC, Los Angeles, California, United States, 2Pediatric Neuroimaging Research Consortium, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States

To quantitatively assess PCASL labeling efficiency (LE) we used a technique that labels blood in the feeding vessels and measures the perfusion signal a short distance further downstream in the blood pool. We measured LE in a flow phantom and in-vivo, then compared these results to Bloch simulations of PCASL efficiency. Phantom LE measurements agree with Bloch predictions of LE with respect velocity. Generally, in-vivo LE could be explained by arterial velocity, however, in several in-vivo measurements, LE variability was significantly lower than predicted by velocity alone. These data suggest measurement of LE may be necessary for accurate ASL quantification.

2342.   Experimental assessment of pCASL labeling efficiency in the peripheral vasculature
Erin K Englund1, Zachary B Rodgers1, Thomas F Floyd2, and Felix W Wehrli1
1Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States, 2Department of Anesthesiology, Stony Brook University, Stony Brook, NY, United States

The blood flow waveform in the peripheral circulation differs substantially from that of the central vasculature. During baseline flow conditions, blood flows both antegrade and retrograde. During reactive hyperemia, average blood flow increases substantially, although the maximum velocity remains relatively unchanged. Here, we explored the implications of varying blood flow velocity at baseline and during reactive hyperemia on pCASL labeling efficiency by measuring signal in the femoral artery during an ischemia-reperfusion paradigm. Results suggest average labeling efficiency to be unaffected by changes in average blood flow velocity, likely because the maximum velocity is relatively unchanged.

2343.   Improving the reproducibility of labeling-efficiency measurements in vivo in pseudo-continuous arterial spin labeling
Kathrin Lorenz1,2, Toralf Mildner1, Torsten Schlumm1, and Harald E. Möller1,2
1Max Planck Institute for Human Cognitive & Brain Sciences, Leipzig, Germany, 2Faculty of Physics and Earth Sciences, University of Leipzig, Saxony, Germany

Although pseudo-continuous arterial spin labeling (pCASL) has become the recommended choice for non-invasive perfusion measurements in the human brain, perfusion quantification is still challenging. For instance, the detected ASL signal change, and hence the estimated perfusion value, is directly proportional to the labeling efficiency lower case Greek alpha. Purpose of the current study is to investigate requirements for a high reproducibility of lower case Greek alpha measurements. It is shown that this property can be improved significantly, if both the slice position and the sampling rate of the experiment are optimized. Thereby, procedural details towards measuring lower case Greek alpha robustly in one additional pre-scan were obtained.

Optimization of phase-contrast MRI for the quantification of whole-brain cerebral blood flow
Shin-Lei Peng1,2, Pan Su1,3, Fu-Nien Wang2, Yan Cao4, Rong Zhang5, Hanzhang Lu1,3, and Peiying Liu1
1Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, United States, 2Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan, 3Biomedical Engineering Graduate Program, UT Southwestern Medical Center, TX, United States, 4Department of Mathematical Sciences, University of Texas at Dallas, Richardson, TX, United States, 5Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX, United States

PC-MRI is a noninvasive technique for quantifying whole-brain CBF. However, PC-MRI measured velocity map is susceptible to partial voluming, leading to biases in CBF estimation. This work firstly aimed to optimize in-plane resolution of PC-MRI for CBF quantification. Furthermore, we assessed effects of non-perpendicular imaging slice orientation on CBF quantification. Results showed in-plane resolution of 0.5 mm could serve as an optimal protocol for quantifying whole-brain CBF. Moreover, non-perpendicular positioning of the imaging slice on the targeted artery could result in overestimated CBF. But if the slice orientation is within 10¢X of the ideal angulation, the bias is negligible.

2345.   Optimal Sampling Design in Quantitative DCE MRI
Ina Nora Kompan1,2 and Matthias Guenther1,2
1Fraunhofer MEVIS, Bremen, Bremen, Germany, 2mediri GmbH, Heidelberg, Baden-Württemberg, Germany

Pharmacokinetic (PK) modeling is used in DCE MRI to quantify tissue physiology. Here, optimal sampling design based on the Fisher information approach is applied to the Tofts model to find important time points for model fitting. For an assumed underlying parameter distribution it is found that fast sampling during the first two minutes after contrast agent onset is important for fitting accuracy. It is also shown that optimal sampling schemes outperform equidistant sampling schemes for small number of sampling points with respect to fitting accuracy.

2346.   Caipirinha acceleration for intracranial 3D DCE MRI: Determination of the optimal sampling pattern
Michael Ingrisch1, Michael Peller1, Birgit Ertl-Wagner2, Maximilian F Reiser2, and Olaf Dietrich1
1Josef-Lissner-Laboratory for Biomedical Imaging, Institute for Clinical Radiology, Ludwig-Maximilians-University Hospital, München, Germany, 2Institute for Clinical Radiology, Ludwig-Maximilians-University Hospital, München, Germany

Acceleration of the image acquisition is an ever important technique in dynamic contrast-enhanced (DCE) MRI. Conventional parallel imaging is limited by the SNR loss at higher acceleration factors and by potential reconstruction artefacts. A recently introduced method, CAIPIRINHA, promises a more robust image reconstruction by modifying the k-space sampling schema. In the present study, we perform phantom measurements to identify the optimal CAIPIRINHA sampling pattern for a 3D DCE MRI perfusion measurement with coverage of the entire neurocranium at high temporal resolution, and we demonstrate the application of CAIPIRINHA acceleration for cerebral DCE MRI in patient measurements

2347.   The Effect of Dynamic Contrast Enhanced Acquisition Duration on Estimated Pharmacokinetic Parameters: Study of Simulated and Real Data
Moran Artzi1,2, Gilad Liberman1,3, Guy Nadav1,4, Deborah T Blumenthal5, Orna Aizenstein1, and Dafna Ben Bashat1,6
1Functional Brain Center, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel, 2Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel, 3Department of Chemical Physics, Weizmann Institute, Rehovot, Israel, 4Functional Brain Center, Tel Aviv University, Tel Aviv, Israel, 5Neuro-Oncology Service, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel, 6Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel

The effect of dynamic contrast enhancement (DCE) acquisition duration on the pharmacokinetic-parameters estimation was investigated using simulated and real data obtained from seven patients with glioblastoma. DCE parameters were estimated using DUSTER, a method for DCE Up-Sampled-Temporal-Resolution, and with scan duration from 6 to 35 minutes. This study suggests an optimized protocol that can be easily implemented in routing clinical setup. Scan duration of 20 minutes was found to be sufficient to obtain reliable and accurate pharmacokinetic parameters from DCE, especially kep. Results emphasize that care should be taken when using model selection with data acquired with short scan duration.

2348.   Correcting for bolus delay and dispersion in the AIF using a constrained local AIF (LAIF) model
Chong Duan1, Jesper F Kallehauge2, Carlos J Perez-Torres3, Kari Tanderup4,5, Larry Bretthorst3, Joseph JH Ackerman1,3, and Joel R Garbow3
1Chemistry, Washington University, Saint Louis, Missouri, United States, 2Medical Physics, Aarhus University, Aarhus, Denmark, 3Radiology, Washington University, Saint Louis, Missouri, United States, 4Radiation Oncology, Washington University, Saint Louis, Missouri, United States, 5Oncology, Aarhus University, Aarhus, Denmark

Many DCE-MRI data models employ a directly determined upstream arterial input function (AIF). The actual AIF at the capillary inlet of any given region of interest is both delayed and dispersed compared with the upstream AIF measured in a major feeding vessel. We build a constrained local AIF (cLAIF) model to better model DCE-MRI data, accounting for both delay and dispersion. Voxel-wise model selection analyses show the cLAIF is preferred over the upstream measured AIF for ~80% of the voxels.

2349.   Validation of Random Vessel-Encoded Arterial Spin Labeling as Territorial Perfusion Imaging by Comparison to Conventional VEASL
Yi Dang1, Jia Guo2, Jue Zhang3,4, and Eric Che Wong5
1Magnetic Resonance Imaging Research Center,Institution of Psychology, Chinese Academy of Sciences, Beijing, Beijing, China, 2Department of Bioengineering, University of California San Diego, CA, United States, 3Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China, 4College of Enigneering, Peking University, Beijing, China, 5Department of Radiology and Psychiatry, University of California San Diego, CA, United States

Conventional vessel-encoded arterial spin labeling (VEASL) is a territorial perfusion imaging technique to identify the perfusion territories of cerebral arteries simultaneously with prior knowledge of their positions. Recently, random vessel encoded arterial spin labeling (R-VEASL) was proposed to automate the scan prescription process. Our study compared the output of R-VEASL with the perfusion maps acquired with conventional VEASL. Quantitative comparison of perfusion territories between R-VEASL and conventional VEASL has shown that perfusion territories of both methods agree reasonably well. However, it seems that R-VEASL performs better than conventional VEASL when detecting perfusion region with mixed perfusion.

2350.   Scan-Rescan Variability in DCE-MRI Comparing Signal Difference and Concentration-Based Methods
Edward Ashton1 and Jill Fredrickson2
1VirtualScopics, Inc., Rochester, NY, United States, 2Genentech, Inc., South San Francisco, CA, United States

Dual-baseline DCE-MRI data for 43 patients drawn from three Phase 1 clinical trials are analyzed both with and without conversion of data from signal intensity values to millimolar gadolinium concentration. Both model-based (KTrans) and model-free (AUCBN) parameters are calculated. Coefficients of variability are estimated for both parameters using both methods, and systematic bias between the two methods is calculated. Variability is approximately 25% lower for both parameters using signal intensity, primarily because conversion to gadolinium concentration is less robust to patient motion and other image quality issues. Absolute values of both parameters are systematically higher using signal difference methods.

2351.   Feasibility of free-breathing DCE-MRI: Phantom studies to compare VIBE, Radial-VIBE, and CAIPIRINHA-VIBE
Chang Kyung Lee1, Bohyun Kim1, Nieun Seo1, Jeong Kon Kim1, In Seong Kim2, Berthold Kiefer3, and Kyung Won Kim1
1Radiology, Seoul Asan Medical Center, Seoul, Seoul, Korea, 2Siemens Healthcare, Seoul, Seoul, Korea, 3Siemens Healthcare, Erlangen, Erlangen, Germany

We compared the breathing motion artifact and signal stability of conventional VIBE, Radial-VIBE with KWIC view-sharing, and CAIPIRINHA-VIBE with moving phantom to simulate breathing motion. Among the three sequences, the CAIPIRINHA-VIBE showed the best image quality, in that the phantom images maintained its shape and just moved its position anteriorly/posteriorly. Thus, the motion correction could align the CAIPIRINHA-VIBE images very well. In terms of signal stability, the CAIPIRINHA-VIBE with motion correction was the best. In conclusion, CAIPIRINHA-VIBE is quite feasible for free-breathing DCE-MRI with high image quality and high temporal resolution.

2352.   Comparison of 3 and 7 Tesla arterial spin labelling techniques for simultaneous functional perfusion and BOLD MRI studies
Dimo Ivanov1, Anna Gardumi1, Benedikt A Poser1, Josef Pfeuffer2, and Kâmil Uludağ1
1Department of Cognitive Neuroscience, Maastricht University, Maastricht, Netherlands, 2Application Development, Siemens Healthcare, Erlangen, Germany

In this study, a pCASL and two PASL variants at 3 T are compared with a PASL approach at 7 T to determine, which of the techniques is most suited for simultaneous high temporal resolution functional CBF and BOLD measurements. The 3 T techniques show no significant differences in either grey matter perfusion or temporal SNR values. In contrast, the 7 T variant tested delivers significantly lower grey matter CBF and temporal SNR values, while offering improved BOLD sensitivity. This indicates that further technical improvements might be necessary for 7 T ASL to be able to reach its full potential.

2353.   Application of Multi-TI arterial spin-labeling MRI in brain tumors: Comparison with dynamic susceptibility contrast
Shuang Yang1, Tianyi Qian2, Jianwei Xiang3, Yingchao Liu4, Peng Zhao4, Josef Pfeuffer5, Guangbin Wang1, and Bin Zhao1
1Shandong Medical Imaging Research Institute, Shandong University, Jinan, Shandong, China, 2MR Collaborations NE Asia, Siemens Healthcare, Beijing, China, 3Shandong Medical Imaging Research Institute, Taishan Medical University, Jinan, Shandong, China, 4Neurosurgery, Shandong provincial Hospital Affiliated to Shandong University, Shandong, China, 5Application Development, Siemens Healthcare, Erlangen, Germany

A 3D multi-TI arterial spin-labeling (mTI-ASL) protocol had been applied to measure the blood perfusion of patients with brain tumor. This study present the feasibility of mTI-ASL for brain tumors in the clinical environment and compare it with dynamic-susceptibility contrast-enhanced perfusion imaging (DSC) to test the hypothesis whether mTI-ASL could substitute DSC in brain tumor cases. The results shows the performances of mTI-ASL in measuring CBF and timing information of blood flow were consistent with DSC. Thus, the perfusion information and the results obtained by dynamic contrast-enhanced technique could be obtained with only one single contrast agent injection.

2354.   Quantifying Cerebral Blood Flow: A Comparison of Two Non-invasive Perfusion Imaging Techniques
Gena Matta1,2, Andrew D Robertson1, Sandra E Black1,3, and Bradley J MacIntosh1,3
1Canadian Partnership for Stroke Recovery, Sunnybrook Research Institute, Toronto, Ontario, Canada, 2University of Waterloo, Waterloo, Ontario, Canada, 3University of Toronto, Toronto, Ontario, Canada

Arterial-spin labelling (ASL) and phase-contrast angiography (PCA) provide two non-invasive methods to quantify the total cerebral blood flow. The primary aim of this study was to assess the agreement of CBFASL and CBFPCA in two cerebrovascular cohorts: overt stroke and small vessel diseases (SVD), and to (2) assess the repeatability of each technique within a stroke cohort. We observed significant differences between the total CBF estimates produced by each modality, therefore we state that caution is warranted when comparing total CBF between modalities among patients with cerebrovascular disease. Intra-subject repeatability was high, however, for both approaches.

2355.   Comparison of PASL, pCASL and background suppressed 3D pCASL in a Clinical Population
Sudipto Dolui1,2, Marta Vidorreta1, Ze Wang3,4, David A. Wolk1, and John A. Detre1,2
1Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania, United States, 2Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States, 3Hangzhou Normal University, Hangzhou, Zhejiang, China, 4Department of Psychiatry and Radiology, University of Pennsylvania, Pennsylvania, United States

We compared ASL MRI acquired from MCI patients and elderly control subjects using PASL and pCASL 2D EPI and pCASL background suppressed (BS) 3D spiral imaging. The methods demonstrate strong correlations between mean CBFs in different ROIs with strongest correlation between measures obtained using either same labeling (pCASL) or imaging strategy (2D). Temporal SNR of 3D BS is higher than the other approaches although its GM-WM contrast is lower than 2D pCASL. Observed control>patient differences in PCC CBF increased with the use of pCASL BS 3D vs pCASL non BS 2D and were not evident in PASL data.

2356.   An Outlier Rejection Algorithm for ASL Time Series : Validation with ADNI Control Data
Sudipto Dolui1,2, Ze Wang3,4, David A. Wolk1, and John A. Detre1,2
1Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania, United States, 2Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States, 3Hangzhou Normal University, Hangzhou, Zhejiang, China, 4Department of Psychiatry and Radiology, University of Pennsylvania, Pennsylvania, United States

The averaging procedure in ASL MRI to overcome low SNR can be undermined by large artifacts present in only a small number of tag-control pairs. We proposed a novel method, named structural correlation based outlier rejection (SCOR), for removing outlier pairs based on i) structural similarity between mean CBF and individual CBF maps and ii) mean GM CBF of individual maps outside physiologically meaningful range. The performance of SCOR is assessed using repeated control scans obtained at 3 months interval from the ADNI database. Compared to alternative options, SCOR demonstrates superior performance by providing much better agreement between the two sessions.

2357.   The impact of blood bolus dispersion on myocardial arterial spin labeling
Karsten Sommer1,2, Dominik Bernat1, Regine Schmidt1, and Laura M. Schreiber1
1Department of Radiology, Johannes Gutenberg University Medical Center, Mainz, Rhineland-Palatinate, Germany, 2Max Planck Graduate Center with the Johannes Gutenberg University Mainz, Mainz, Rhineland-Palatinate, Germany

While blood bolus dispersion has been shown to affect cerebral ASL, this effect has not yet been adressed for myocardial ASL. In this contribution, we employ computational fluid dynamics simulations in a realistic coronary artery model to evaluate the extent of dispersion in myocardial ASL and its impact on resulting myocardial blood flow values.

2358.   Three-Dimentional Stereotactic Surface Projections Applied to Arterial Spin Labeling in a Clinical Population
Jalal B. Andre1, Greg Wilson1, Yoshimi Anzai1, Mahmud Mossa-Basha1, Michael N. Hoff1, and Satoshi Minoshima1
1Radiology, University of Washington, Seattle, WA, United States

We investigate the diagnostic applicability and performance of three-dimensional stereotactic surface projections (3D-SSP), a commonly used tool for molecular brain PET imaging, as applied to arterial spin labeling in clinical MR examinations. Expert reader assessment found that the 3D-SSP method was generally preferred over the traditional method of ASL display. We conclude that 3D-SSP statistical mapping is feasible in a clinical population and enables quantitative data extraction and reliable localization of perfusion abnormalities by means of stereotactic coordinates in a condensed display. This technique may provide added value in the clinical assessment of a variety of neurological pathologies.

2359.   Application of pseudo-continuous arterial spin labeling for quantification of hepatic perfusion
Mike-Ely Cohen1,2, Isabelle Lajoie2, Kenneth Dyson2, Olivier Lucidarme1,3, Richard D. Hoge2,4, and Frédérique Frouin1,5
1Laboratoire d'imagerie biomedicale, Sorbonne Université Univ Paris 06, Inserm, CNRS, Paris, France, 2Centre de recherche de l’institut universitaire de gériatrie de Montréal, Montréal, Quebec, Canada, 3Service de Radiologie Polyvalente Diagnostique et Oncologique, CHU Pitié-Salpêtrière, AP-HP, Paris, France, 4McConnell Brain Imaging Centre, Montreal Neurological Institute - McGill University, Quebec, Canada, 5CEA/I2BM/SHFJ, IMIV, Orsay, France

The purpose of this study was to optimize a pseudo-Continuous Arterial Spin Labeling (pCASL) approach to quantify hepatic perfusion among healthy volunteers. Six volunteers were examined using a 3T Siemens scanner, pCASL sequences with 4 to 20 measurements in a plane orthogonal to portal vein with a post label delay (PLD) of 600 ms were acquired. For two subjects, four additional PLD (from 1000 to 1600 ms) were tested. Results show a more robust estimation when using 20 measurements. Furthermore the five PLD values provided hepatic perfusion weighted differently by the hepatic artery and the portal vein blood flows.

2360.   Feasibility of renal perfusion imaging using velocity selective ASL
Marijn van Stralen1, Margreet F Sanders2, Hanke J Schalkx3, Maurice A van den Bosch3, Clemens Bos4, Peter J Blankestijn2, Tim Leiner3, and Esben Thade Petersen3
1Image Sciences Institute, UMC Utrecht, Utrecht, Utrecht, Netherlands, 2Dept of Nephrology, UMC Utrecht, Utrecht, Netherlands, 3Dept of Radiology, UMC Utrecht, Utrecht, Netherlands, 4Image Sciences Institute, UMC Utrecht, Utrecht, Netherlands

Renal perfusion imaging using contrast media injection is potentially nephrotoxic. Arterial spin labeling (ASL), employing endogenous contrast, was shown using pulsed and pseudo-continuous labeling strategies. We investigated the feasibility of velocity selective ASL (VS-ASL), which eliminates label planning and possibly improves perfusion SNR by labeling closer to the target tissue. We show that renal VS-ASL is feasible, clearly showing the expected corticomedullary perfusion distribution in healthy volunteers. However, VS-ASL is sensitive to motion, especially during labeling. It could benefit from outlier rejection techniques or prospective and retrospective motion correction.

2361.   Whole Brain Measurement of Dynamics of Arterial Spin Labeling Using Multi-Band Look-Locker Technique in Hypertension
Yoojin Lee1 and Tae Kim1
1Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States

The dynamics of the arterial spin labeling (ASL) provides information on the kinetics of water exchange between tissue and blood, transit time, and the tissue relaxation time. In this study, multi-band technique was applied to look-locker ASL to get the perfusion dynamics for whole brain with a sufficient temporal resolution. We found the hypertensive group has significantly longer capillary transit time and maximal arterial arrival time in most ROIs, while the arterial transit time was not significantly different, compared to the normotensive group. We demonstrated that our technique enables the detection of regional hypertension-induced cerebrovascular impairment in whole brain.

2362.   Dual temporal resolution DCE-MRI reveals increased blood-brain barrier leakage in cerebral small vessel disease
Sau May Wong1, Eleana Zhang2, Harm J. van de Haar1, Julie E.A. Staals2, Cécile R.L.P.N. Jeukens1, Paul A.M. Hofman1, Robert J. van Oostenbrugge2, Jacobus F.A. Jansen1, and Walter H. Backes1
1Radiology, Maastricht University Medical Center, Maastricht, Limburg, Netherlands, 2Neurology, Maastricht University Medical Center, Maastricht, Limburg, Netherlands

Cerebral small vessel disease(cSVD) affects the small vessels in the brain, which can potentially lead to ischemic stroke and dementia. The blood-brain barrier (BBB) permeability is expected to play a pivotal role in the pathophysiology. We performed dual temporal resolution DCE-MRI to quantify BBB permeability. Significant higher permeability was found for cSVD patients compared with controls in the normal appearing brain tissue, which suggests that these regions might be at risk for further transition into white matter hyperintensities. Longitudinal studies can now be initiated to investigate the role of increased BBB permeability in the course of cSVD.

2363.   Effect of ketamine and isoflurane anesthesia on regional cerebral blood flow of macaque monkeys
Chun-Xia Li1, Doty Kempf1, Leonard Howell1, and Xiaodong Zhang1
1Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States

Ketamine and isoflurane are widely used for maintaining general anesthesia and induce a global CBF increase in humans and animals. However, it is not clear how differently the CBF is affected between the anesthetics. In the present study, adult rhesus monkeys were used to examine the effects of ketamine and isoflurane on CBF using the continuous arterial spin-labeling (CASL) perfusion MRI. The present study revealed the different effects of ketamine and isoflurane on CBF in monkeys under maintenance doses, suggesting the use of ketamine or isoflurane might interfere with the experimental outcome in neurovascular diseases and brain function studies.

2364.   Effect of long-duration isoflurane administration on regional cerebral blood flow
Chun-Xia Li1, Sudeep Patel1, and Xiaodong Zhang1
1Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States

Isoflurane is popularly used for long-duration anesthesia in clinic practice or preclinical researches. It is known that long-duration anesthesia could cause neurocognitive dysfunction in animal and human. However, the potential mechanism remains unclear. In the present study, the pseudo continuous arterial-spin-labeling (pCASL) technique was used to evaluate the isoflurane anesthesia effect on cerebral blood flow (CBF) of adult rhesus monkeys under maintenance dosage for 4 hours. The results demonstrate that long-duration isoflurane exposure could cause general CBF decrease in most brain areas, which may contribute to the neurocognitive dysfunction observed in clinical or preclinical studies.

2365.   MRI based quantification of cortical responses to exercise
Andrew P Hale1, Charlotte E Buchanan1, Johannes van Lieshout2, Penny A Gowland1, Paul L Greenhaff3, and Sue T Francis1
1Sir Peter Mansfield Imaging Centre, University of Nottingham, Nottingham, United Kingdom, 2School of Biomedical Sciences, University of Nottingham, Nottingham, United Kingdom, 3Faculty of Medicine & Health Sciences, University of Nottingham, Nottingham, United Kingdom

Low to moderate intensity dynamic exercise in healthy, young individuals has been directly linked to enhanced cerebral neuronal activity. Here we assess the feasibility of using MRI to measure global and regional changes in CBF to steady-state exercise. We demonstrate that it is possible to assess global and regional brain responses to exercise involving a large muscle mass at workloads of up to 50%VO2max. Moreover, at low intensity workloads (30%VO2max) it appears that there is an uncoupling of regional blood flow from brain activity, suggesting that cardiac output is the primary determinant of regional brain blood flow under these conditions.

2366.   Cerebral Blood Flow and Metabolism in Patients with Sickle Cell Disease
Adam Bush1, Matthew Borzage1, Thomas Coates1, and John Wood1
1Children's Hospital Los Angeles USC, Los Angeles, California, United States

In sickle cell disease (SCD) stroke is common, however accurate quantification of basal cerebral oxygen consumption (CMRO2) is unknown. We measured brain volume, cerebral blood flow (CBF) and cerebral venous saturation (SvO2) in patients with SCD using phase contrast and TRUST MRI to address questions regarding cerebral metabolism. We found patients with SCD to have 167% the CBF of healthy controls, a higher oxygen delivery and a calculated CMRO2. Our study is the first to demonstrate elevated cerebral metabolism in SCD, mirroring increases in global resting energy expenditure and peripheral metabolic rate described by others.

2367.   Evaluation of random vessel-encoded ASL in both healthy subjects and stroke patients
Lirong Yan1, Songlin Liu1, Jia Guo2, David S Liebeskind1, Jeffrey L Saver1, Noriko Salamon3, Neal Yao1, Sunil Sheth1, Conrad Liang1, Eric C Wong2, and Danny JJ Wang1
1Neurology, UCLA, Los Angeles, CA, United States, 2UCSD, San Diego, CA, United States, 3Radiology, UCLA, Los Angeles, CA, United States

In the current study, the feasibility of random vessel-encoded ASL (rVE-ASL) was evaluated by comparison with the standard vessel-encoded ASL (VE-ASL) in healthy subjects as well as in ischemic stroke patients. Our results showed the perfusion territory maps of rVE-ASL were well matched with those of VE-ASL. The collaterals detected by rVE-ASL were consistent with DSA in stroke patients, suggesting the potential clinical utility of rVE-ASL to characterize collateral circulation in stroke.

2368.   Diagnosis of Schizophrenia using CBF Measures as a Classification Feature – A FBIRN Phase 3 Multisite ASL Study at 3T
David Shin1, Burak Ozyurt1, Jerod Rasmussen2, Juan Bustillo3, Theodorus Van Erp2, Jatin Vaidya4, Daniel Mathalon5, Bryon Mueller6, James Voyvodic7, Douglas Greve8, Judith Ford5, Gary Glover9, Gregory Brown1, Steven Potkin2, and Thomas Liu1
1University of California, San Diego, La Jolla, CA, United States, 2University of California, Irvine, Irvine, CA, United States, 3University of New Mexico, Albuquerque, NM, United States, 4University of Iowa, Iowa City, IA, United States, 5University of California, San Francisco, San Francisco, CA, United States, 6University of Minnesota, Twin Cities, Minneapolis, MN, United States, 7Duke University, Durham, NC, United States, 8Harvard Medical School, Massachusetts General Hospital, Charlestown, MA, United States,9Stanford University, Stanford, CA, United States

Resting state CBF maps (n=234) collected from the multisite FBIRN Phase 3 Study ( were used as learning features in a support vector machines (SVM) classification technique to evaluate its performance in differentiating Schizophrenic patients (SCZ) from healthy controls (CNT). For feature extraction, clusters of voxels with group differences (SCZ vs. CNT) were first identified (t-test, p<0.01) and the mean CBF values across these clusters were used as the training data. The sensitivity, specificity, and accuracy for the leave-one-out cross validation were found to be 75.9%, 75.5%, and 75.7%, respectively. The results suggest that the CBF map acquired from a 5-minute ASL scan combined with SVM may be a useful complimentary tool for diagnosis of SCZ.

Non-contrast indirect MRI Quantification of Portal Hypertension severity
Daniel Aguirre-Reyes1,2, Juan P. Arab3, Marco Arrese3, Rodrigo Tejos3, Pablo Irarrazaval1, Cristian Tejos1, Sergio Uribe4, and Marcelo E. Andia4
1Biomedical Imaging Center - Electrical Engineering Department, Pontificia Universidad Catolica de Chile, Santiago, Region Metropolitana, Chile, 2Computational Sciences and Electronic Department, Universidad Tecnica Particular de Loja, Loja, Loja, Ecuador, 3Gastroenterology Department, School of Medicine, Pontificia Universidad Catolica de Chile, Santiago, Chile, 4Radiology Department, School of Medicine, Pontificia Universidad Catolica de Chile, Santiago, Chile

Patients with chronic liver diseases generally have portal hypertension (PH) characterized by an increased liver resistance to blood flow that mainly affect the portal system. In order to determine the severity of PH some invasive methods has been proposed. In this work we present a method to indirect estimate the severity of PH by the quantification of the intrahepatic portal vein blood flow with a non-contrast, flow depend technique (TIR-ASL).