Joint Annual Meeting ISMRM-ESMRMB 2014 10-16 May 2014 Milan, Italy

Perfusion & Permeability

Thursday 15 May 2014    10:30 - 11:30

Space 1/Power Poster Theatre & Traditional Poster Hall
Moderators: Fernando Calamante, Ph.D. & Linda Knutsson, Ph.D.

Click on this video icon to view the introductory session.

Whole brain cerebral flow territory mapping using vessel selective dynamic arterial spin labeling within 30 seconds
Xingxing ZHANG1, Eidrees Ghariq1, Sophie Schmid1, Wouter Teeuwisse1, and Matthias J.P. van Osch1
1C.J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, Zuid-Holland, Netherlands

Vessel selective dynamic arterial spin labeling (VS-DASL) combined with 3D Turbo-Field Echo-Planar Imaging (TFEPI) was proposed to achieve fast whole brain flow territory mapping. The results showed good agreement with traditional vessel selective ASL (VS-ASL) as proven by the Dice similarity coefficient. These results imply that 3D VS-DASL has the potential to map whole brain flow territories within 30 seconds, enabling clinical use both in standard cerebrovascular imaging protocols as well as in the acute setting, i.e. patients with acute stroke.


  0716.   Arterial Spin Labeling with Simultaneous Multi- Slice EPI compared to EPI and 3D GRASE
David Feinberg1,2, Liyong Chen1,2, and Alexander Beckett1,2
1Helen Wills Neuroscience Institute, University of California, Berkeley, California, United States, 2Advanced MRI Technologies, LLC, Sebastopol, California, United States

Simultaneous multi-slice EPI has been combined with pulsed ASL to record several times more images than conventional EPI. Comparison of quantitative CBF maps and perfusion weighted images show good agreement to EPI. Comparisons to segmented 3D GRASE ASL shows differences in scan times and susceptibility artifacts with advantages of background suppression and higher SNR in 3D GRASE, while both achieve whole brain slice coverage.


  0717.   Whole Brain Perfusion Using Dynamic pCASL with Multiband Look-locker EPI
Ke Zhang1, Seong Dae Yun1, and N. Jon Shah1,2
1Institute of Neuroscience and Medicine 4, Forschungszentrum Jülich GmbH, Jülich, Germany, 2Faculty of Medicine, Department of Neurology, JARA, RWTH Aachen University, Aachen, Germany

To quantitatively measure CBF with ASL, multiple readout with different post-labeling delay is preferred incase of various blood arrival time. One approach for sampling the tracer kinetics curve with increasing post-labeling delays is using Look-Locker imaging. Due to the signal recovery of the labeled blood, the slice number in the readout is limited. In this study, multiband excitation technique was applied in Look-locker readout to triple the readout slices for the dynamic pCASL. Preliminary results show that the quantitative CBF can be acquired with whole brain coverage using multiband technique in the same measurement time as using singleband excitation.


  0718.   Cerebral arterial blood quantification with simultaneous multi-slice acquisition
Tae Kim1, Yoojin Lee1, and Kyongtae Ty Bae1
1Radiology, University of Pittsburgh, Pittsburgh, PA, United States

Multi-band (MB) excitation for data acquisition was successfully implemented into cerebral arterial blood volume (CBVa) and evaluated on healthy volunteers at 3T. CBVa quantification for MB excitation was highly comparable with that of a conventional single-band acquisition. Our study demonstrates that the MB technique facilitates an accelerated acquisition of high resolution, whole-brain CBVa quantification maps


Time efficient and robust perfusion measurement using Walsh-reordered time encoded pCASL
Federico von Samson-Himmelstjerna1, Jan Sobesky2, and Matthias Günther1
1Fraunhofer MEVIS, Bremen, Bremen, Germany, 2Center for Stroke Research (CSB), Charité University Medicine Berlin, Berlin, Germany

Time encoded (a.k.a Hadamard) pseudo continuous ASL decodes N-1 time steps from N image acquisitions. All N images are necessary for correct decoding. This means, that corrupted images, e.g. by motion, can lead to erroneous decoding and, thus, complete loss of data. To overcome this limitation a Walsh-ordered and extended Hadamard matrix is proposed for encoding. It allows the reconstruction of perfusion data from the second image acquisition on and a time resolution that increases with the number of acquisitions. This renders the technique robust against complete loss of data e.g. by motion of agitated patients in the clinical setup.


  0720.   Simultaneous acquisition of perfusion maps and 4D MR angiography by means of arterial spin labeling MRI
Yuriko Suzuki1, Wouter M Teeuwisse2, Sophie Schmid2, Peter Koken3, Marc Van Cauteren4, Michael Helle3, and Matthias JP van Osch2
1Philips Electronics Japan, Minato-ku, Tokyo, Japan, 2C.J.Gorter Center for High Field MRI, Departement of Radiology, Leiden University Medical Center, Leiden, Netherlands, 3Philips Research Laboratories, Hamburg, Germany, 4Philips Healthcare Asia Pasific, Tokyo, Japan

Both 4D magnetic resonance angiography (4D-MRA) and perfusion imaging have proved their value in the characterization of hemodynamic pathology in cerebrovascular disease, and their complementary information provides a complete picture of the hemodynamic status, which may prove especially important in conditions such as acute stroke. In this study, we propose the simultaneous acquisition of ASL-based perfusion image and MRA by combining a time-encoded ASL preparation with two sequential readout modules which have different spatial resolution: a high-resolved sequence for 4D MRA immediately followed by low resolution sequence for perfusion imaging.


Optimised encoding scheme for vessel-encoded pseudo-continuous arterial spin labelling
Eleanor S K Berry1, Peter Jezzard1, and Thomas W Okell1
1FMRIB Centre, University of Oxford, Oxford, Oxfordshire, United Kingdom

An automated method of calculating optimised encodings to label vessels using vessel-encoded pseudo-continuous arterial spin labelling is presented. The resulting encoding schemes have greater simulated SNR efficiency than those from other methods for a variety of vessel numbers and geometries. Preliminary healthy subject scans have resulted in images with higher SNR. The method requires further validation in subjects and more vessel scenarios.


Simultaneous measurement of microvascular and macrovascular blood flow and oxygenation in the leg
Erin K Englund1, Zachary B Rodgers2, Michael C Langham3, Emile R Mohler III4, Thomas F Floyd5, and Felix W Wehrli3
1University of Pennsylvania, Philadelphia, PA, United States, 2Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, United States,3Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States, 4Department of Medicine, University of Pennsylvania, Philadelphia, PA, United States, 5Department of Anesthesiology, Stony Brook University, Stony Brook, NY, United States

A method to simultaneously measure perfusion, arterial velocity, venous oxygen saturation, and skeletal muscle T2* using an interleaved pulsed arterial spin labeling and velocity-encoded multi-echo GRE sequence is presented. The method, termed velocity-encoded Perfusion, Intravascular Venous Oxygen saturation and T2* (velocity-encoded PIVOT) was assessed in healthy subjects during a series of ischemia reperfusion paradigms. Results demonstrate that the method is capable of faithfully measuring all four parameters at 3-second temporal resolution. Dynamic measurement of these parameters was also completed during isometric plantar flexion contractions. Results suggest that this technique may be useful in developing biophysical models of muscle metabolism.


  0723.   Brain tumor oxygen saturation mapping with magnetic resonance imaging corrected by a local hematocrit mapping assessed by nuclear imaging
Benjamin Lemasson1,2, Alexis Broisat3,4, Pauline Busieau1,2, Régine Farion1,2, Mitra Ahmadi3,4, Sandrine Bacot3,4, Catherine Ghezzi3,4, Chantal Rémy1,2, and Emmanuel Barbier1,2
1U836, Inserm, GRENOBLE, France, 2Grenoble Institut des Neurosciences, Université Joseph Fourier, GRENOBLE, France, 3U1039, Inserm, GRENOBLE, France, 4Radiopharmaceutiques Biocliniques, Université Joseph Fourier, GRENOBLE, France

We evaluated the impact of the local hematocrit (Hct) when mapping the brain tumor oxygen saturation (StO2). A multimodal experiment (MRI and autoradiography of 2 different isotopes) was performed on 8 rats bearing a brain tumor. The tumor Hct level, assessed by autoradiography, was significantly reduced as compared to healthy striatum. Using, for each animal, the Hct to compute the StO2 voxel-wise led to a significant reduction in tumor oxygenation in comparison to that of the healthy striatum. Our results indicate that change in Hct should not be overlooked when assessing oxygenation in brain tumors or in other brain diseases.


  0724.   Pseudo Extravasation Rate Constant of Dynamic Susceptibility Enhanced Magnetic Resonance Imaging Determined From Pharmacokinetic First Principles
Xin Li1, Csanad Varallyay2, Seymur Gahramonov2, William D Rooney1, and Edward A Neuwelt2
1Advanced Imaging Research Center, Oregon Health & Science University, Portland, Oregon, United States, 2Department of Neurology, Oregon Health & Science University, Portland, Oregon, United States

Though widely adopted for brain perfusion measurement, Dynamic Susceptibility Contrast (DSC) Magnetic Resonance Imaging (MRI) with low molecular weight Gadolinium (Gd) contrast reagent (CR) is often confounded by CR’s leakage into intersitium space. Based on pharmacokinetic first principles, we demonstrate a fast leakage correction method similar to that of the Patlak plot. This linearization approach uniquely identifies the leakage rate constant and significantly simplifies relative cerebral blood volume (rCBV) quantification.


  0725.   Simutaneous measurement of pharmacokinetic model parameters and T1/B1 using Active Contrast Encoding MRI
Jin Zhang1 and Sungheon Kim1
1Radiology, New York University, New York, New York, United States

In DCE-MRI studies, accurate estimation of pharmacokinetic model parameters requires B1-corrected T1 values. However, it is not trivial to measure B1and T1 accurately in addition to the long scan time. In this study, we proposed a novel approach, namely active contrast encoding (ACE) MRI, to measure both B1 and T1 values along with kinetic parameters from a single DCE-MRI data. A proof-of-concept study was conducted to demonstrate the proposed method using numerical simulations and an in vivo mouse study, and to show that ACE-MRI can eliminate the need to have separate B1 and T1mapping procedures.


  0726.   The Transfer Constant Ktrans in Glioblastomas is Limited by Permeability and not Perfusion
Atle Bjornerud1,2, A. Gregory Sorensen3,4, Patrick Y Wen5, Tracy T Batchelor6,7, Rakesh K Jain6, and Kyrre E Emblem1,3
1The Intervention Centre, Oslo University Hospital, Oslo, Norway, 2Dept of Physics, University of Oslo, Oslo, Norway, 3Department of Radiology and Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, United States, 4Siemens Healthcare Health Services, Pennsylvania, United States, 5Center for Neuro-Oncology, Dana-Farber/Brigham and Women’s Cancer Center and Harvard Medical School, Massachusetts, United States, 6Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Massachusetts, United States, 7Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Massachusetts, United States

Tumor perfusion (CBF) and capillary permeability transfer constant (Ktrans) have been proposed as sensitive biomarkers to monitor the effect of vascular-targeting and anti-angiogenic agents. Possible inter-dependence of these two metrics may, however complicate their interpretation in clinical data. We used dynamic susceptibility contrast (DSC) MRI to estimate both CBF, Ktrans and the initial contrast agent extraction fraction (E) in 30 patients with recurrent glioblastomas undergoing anti-angiogenic treatment. The results suggest that E is on average below 10% in this patient group and hence Ktrans and CBF can be considered independent parameters in glioblastomas.


Flow and permeability estimation from DCE data: 2-compartment exchange and Tofts models comparison
Guy Nadav1,2, Gilad Liberman2,3, Moran Artzi2,4, Nahum Kiryati1, and Dafna Ben Bashat2,4
1School of Electrical Engineering, Tel Aviv University, Tel Aviv, Israel, 2Functional Brain Center, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel,33Gonda Multidisciplinary Brain Research Center, Bar Ilan University, Israel, 4Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel

In order to extract flow from DCE data, a 2-compartment exchange model (2CXM) is needed. In this study we show that flow is misinterpreted as permeability using the standard 1-compartment model (ETM) on simulated data that is based on 2CXM parameters. In real data, obtained from a patient with brain tumor, highly vascularized brain areas (veins and tumor) showed high flow and no permeability using 2CXM, but high permeability using ETM. This study shows that when utilizing ETM, care should be taken when interpreting permeability maps and when temporal resolution allows, the 2CXM should be used.


  0728.   Estimation of the True Arterial Input Function using a Physiological Model in Dynamic Contrast Enhanced MRI
Dennis Lai-Hong Cheong1, Bo Zhang1, Limiao Jiang1,2, and Thian C Ng1,2
1Clinical Imaging Research Center, A*STAR & National University of Singapore, 117456, Singapore, 2Department of Diagnostic Radiology, National University of Singapore, 119074, Singapore

It is challenging to find an appropriate AIF in DCE MRI studies. Ideally, AIF is the contrast concentration time curve in incoming blood at the tissue of interest, but this is not measurable directly with current technologies. We estimated the true AIF using a physiological model for AIF that we have developed recently. The model gave good fittings to all concentration time curves measured at vessels. The estimated true AIF was used in tracer kinetic analysis using both a distributed parameter model and the modified Tofts model. This method offers a way to estimate the true AIF at the tissue of interest.


  0729.   The arterial response function: A new concept demonstrated in a simulation study investigating the influence of the injection rate on the quantification of plasma flow
Michael Ingrisch1, Steven Sourbron2, Felix Schwab1, Mike Notohamiprodjo3, Maximilian F Reiser3, Michael Peller1, and Olaf Dietrich1
1Josef Lissner Laboratory for Biomedical Imaging, Institute for Clinical Radiology, Ludwig-Maximilians-University Hospital Munich, München, Germany,2Division of Medical Physics, University of Leeds, Leeds, United Kingdom, 3Institute for Clinical Radiology, Ludwig-Maximilians-University Hospital Munich, München, Germany

The arterial input function (AIF) can be interpreted as the response of the arterial system to the injection of contrast agent, characterized by an unknown ‘arterial response function’ (ARF). This function can be determined from a measured AIF by numerical deconvolution and can be utilized for the generation of synthetic AIFs for arbitrary injection schemes. In this work, we use this approach for a simulation study, investigating the hypothesis that fast injections are required for the determination of plasma flow in tissues with short plasma transit times, whereas in tissues with long transit times slower injections suffice.