MRA & Flow of Neurovascular Disease
Monday 20 April 2009
Room 311 14:00-16:00


John Detre and J. Paul Finn

14:00  90.

SWI-Based Intracranial MR Venography Using Image-Domain High-Pass Filtering with Second-Order Phase Difference

    Yiping P. Du1, Zhaoyang Jin2,3
Psychiatry, Radiology, University of Colorado Denver, Aurora, CO, USA; 2Institute of Information and Control, Hangzhou Dianzi University, Hangzhou, Zhejiang, China; 3Biomedical Engineering, Zhejiang University, Hangzhou, Zhejiang, China
    An image-domain high-pass filtering with second-order phase difference is proposed to enhance the visibility of venous vasculature and suppress the off-resonance artifact in regions with severe field inhomogeneity in susceptibility weighted imaging (SWI). Using this filtering technique, 3D venography with positive venous contrast is generated. A Fermi weighting function is used to suppress the noise in air. The proposed filtering approach circumvents the signal loss commonly observed in the minimum-intensity projection of 3D SWI data processed with a conventional procedure.
14:12 91.

3D Fast Inversion Recovery Magnetic Resonance Angiography (FIR-MRA)

    Ek Tsoon Tan1, John III Huston1, Stephen J. Riederer1
Radiology, Mayo Clinic, Rochester, MN, USA
    A non-contrast-enhanced MRA technique for imaging the intracranial arteries is described. The complex difference between selective and non-selective cycles of inversion-prepared gradient echo subtracts out static tissue, leaving only the vascular signal from proximal blood flow during the inversion interval. Each cycle also produces T1-weighted tissue contrast, which may be fused with the angiogram-only image for anatomical reference. A two-slab FIR-MRA acquisition is compared against a three-slab standard 3D time-of-flight sequence. FIR-MRA has significantly improved vessel conspicuity, background and artifact suppression but has a longer scan time (11 min vs. 6.5 min).
14:24 92. High Resolution, Non-Contrast Imaging of Both Cerebral Veins and Arteries by Use of Gradient Echo T2 Star Weighted Angiography (SWAN)
    Jennifer Linn1, Jürgen Lutz1, Michael Burke2, Tim Wesemann1, Hartmut Brückmann1
1Dept. of Neuroradiology, University Hospital Munich, Munich, Germany; 2GE Healthcare, Solingen, Germany

Problem: To assess the potential of T2 Star Weighted Angiography (SWAN) for the depiction of cerebral veins and arteries.

Methods: A SWAN sequence, and an arterial (MRA) and a venous (MRV) TOF-MRA were performed on 12 volunteers using a 3T MRI. MinIP and MIP images were analysed by two readers regarding the depiction of cerebral veins and arteries, respectively.

Results: The SWAN sequence was superior compared to tMRV with regard to the veins, and comparable to MRA with respect to the arteries.

Conclusions: SWAN allows for high-resolution, non-contrast visualization of both cerebral veins and arteries without application of contrast agent.

14:36 93. Non Contrast MRA of the Extracranial Carotid Arteries Utilizing a 3D ECG-Triggered Balanced Steady State Free Precession Technique with Spatial Saturation

Calvin Lo1, Bidyut K. Pramanik1, Daniel Kim1, Xiaoming Bi2, Peter Weale2, Anna Nazarenko1, Thomas P. Mulholland1, Edmond A. Knopp1, Vivian S. Lee1, Ruth P. Lim1
1Radiology, NYU Langone Medical Center, New York, USA; 2Siemens Medical Solutions USA, Inc., Chicago, IL, USA

    An ECG-gated 3D balanced steady state free precession (b-SSFP) MRA sequence, utilizing an inversion pulse to null out background tissue and a spatial saturation pulse to null out slowly flowing venous blood, has been described to visualize "fresh" arterial blood flowing into the image. We assessed the feasibility, diagnostic quality and accuracy of 3D b-SSFP MRA, compared with conventional TOF MRA for evaluation of the extracranial carotid arteries with reference to CE MRA. We found significantly superior SNR, CNR, image quality and diagnostic confidence for b-SSFP MRA compared with TOF MRA, and high concordance for stenosis with the reference standard.
14:48  94.

High Resolution 3D MR Angiography Using Arterial Spin Labeling

    Yi Wang1, Seong-Eun Kim2, Dennis L. Parker1
Utah Center for Advanced Imaging Research , University of Utah, Salt Lake City, UT, USA; 2Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, UT, USA

In this work, we used arterial spin labeling to acquire 3D high resolution angiography with increased signal to noise ratio. A 3D turbo-FLASH sequence was modified by incorporating the in-plane slice-selective double inversion magnetization preparation. Arterial blood inflow time was determined experimentally and high resolution 3D MR angiography was obtained at three inversion times.

15:00 95. 

 4D Contrast Enhanced MRA with Flow Measurements (HYPR FLOW) in Arteriovenous Malformations


Yijing Wu1, Kevin M. Johnson1, Elizabeth J. Nett1, Patrick Turski2, Charles A. Mistretta3
1Medical Physics, University of Wisconsin, Madison, MADISON, WI, USA; 2Radiology, University of Wisconsin, Madison, MADISON, WI, USA; 3Medical Physics and Radiology, University of Wisconsin, Madison, MADISON, WI, USA

    Phase Contrast (PC) HYPR FLOW, which employs post contrast PC VIPR images as the composite and reconstructs the first pass time resolved contrast enhanced VIPR acquisition using HYPR LR technique, is able to achieve 4D Contrast Enhanced (CE) MRA with both high temporal resolution and isotropic spatial resolution and quantitative flow dynamics from the PC images. PC HYPR FLOW was performed on normal subjects and patients with brain AVMs. 4D CE MRA images with sub-second temporal resolution and sub-millimeter isotropic spatial resolution were generated as well as the flow dynamic maps including the wall shear stress and pressure. Quantitative measurements of velocity, WSS and pressure gradients were conducted and compared between control and patient groups.
15:12 96.

4D-MRA in Combination with Selective Arterial Spin Labelling for Functional Characterization of Arteriovenous Malformations at 3 T

    Guido Matthias Kukuk1, Dariusch Reza Hadizadeh1, Jürgen Gieseke1,2, Julia Bergener1, Gabriele Beck2, Lisbeth Geerts2, Petra Mürtz1, Azize Boström3, Horst Urbach1, Johannes Schramm3, Hans Heinz Schild1, Winfried Albert Willinek1
Department of Radiology, University of Bonn, Bonn, NRW, Germany; 2Philips Healthcare, Best, Netherlands; 3Department of Neurosurgery, University of Bonn, Bonn, NRW, Germany
    4D-MRA is a promising diagnostic tool for characterization of cerebral arteriovenous malformations (cAVMs), however it lacks the selectivity that is inherent to DSA. Therefore we combined selective arterial spin labelling (sASL) with 4D-MRA for anatomic and functional characterization of cAVMs at 3.0 Tesla. 4D-MRA enabled the correct Spetzler-Martin classification in 10/10 symptomatic patients. In addition the sensitivity of identification of arterial feeders and anatomic variants could be markedly improved due to the combination with sASL. Our data suggest, that 4D-MRA in combination with sASL can provide functional information that so far has been gained only with selective DSA.
15:24 97.  

The Influence of K-T BLAST on Intracranial Aneurismal PC Velocity Mapping Data


Pim van Ooij1, Joppe J. Schneiders1, Marieke E.S. Sprengers1, Ed van Bavel2, Charles B.L.M. Majoie1, Aart J. Nederveen1
Radiology, AMC, Amsterdam, Noord - Holland, Netherlands; 2Biomedical Engineering & Physics, AMC, Amsterdam, Noord - Holland, Netherlands

    k-t BLAST is a measurement acceleration technique by undersampling k-t space. This indicates that some data will be lost during acquisition. It has been shown that phase contrast angiography measurements in the aorta can be accelerated without significant loss of data. In this study it is tested if k-t BLAST can also be used in PCA measurements of intracranial aneurysms without significant loss of accuracy. It is shown that if an aneurysm is large, results are more accurate than in a small aneurysm. A possible explanation is that small aneurysms contain a relatively large amount of pixels where velocity is low and thus where difference between full measurement and k-t BLAST velocities is large. If aneurysms are large enough (>5 mm), k-t BLAST can be used without much loss of accuracy.
15:36 98.

Cerebral Collateral Imaging in Patients with Carotid Stenosis Using MR Perfusion Territory Arterial Spin Labeling, Compared with DSA

    Bing Wu1, Xiaoying Wang1, Jia Guo2, Eric C. Wong3, Jue Zhang2, Xuexiang Jiang1
1Radiology of Dept., Peking Uni. 1st hospital, Beijing, China; 2Interdisciplinary academy, Peking University; 3Center for Functional Magnetic Resonance Imaging and Departments of Radiology and Psychiatry, University of California, San Diego
    This study was to investigate the presence of collaterals in patients with carotid stenosis and the change of perfusion territory after internal carotid artery stent therapy using the MR perfusion territory imaging.
15:48 99. 

TOF MR Angiography at 3.0 Tesla During Acetazolamide Provocation Demonstrates Decreased Vasomotor Reactivity Ipsilateral to a Carotid Artery Stenosis


Reinoud Pieter Harmen Bokkers1, Frank J. Wessels2, H B. van der Worp3, Jaco Zwanenburg4, Jeroen Hendrikse1
1Department of Radiology, UMC Utrecht, Utrecht, Netherlands; 2Faculty of Medical Sciences, University of Groningen, Groningen, Netherlands; 3Department of Neurology, UMC Utrecht, Utrecht, Netherlands; 4Image Sciences Institute, UMC Utrecht, Utrecht, Netherlands

    The vasomotor reactivity of the proximal and distal cerebral vasculature was investigated in healthy subjects and patients with a symptomatic stenosis of the ICA. High-resolution MRA was performed at 3T before and 20 minutes after an intravenous administration of acetazolamide. In healthy subjects, vessel diameter increased significantly in 10 of 11 measured arteries. Arteries in hemispheres ipsilateral to the symptomatic ICA showed no significant increase in diameter, whereas in hemispheres contralateral to the stenosis diameters increased significantly in the proximal vasculature. Findings show that high-field MRA combined with a vasodilatory challenge may contribute to a better understanding of vasomotor reactivity.