Neurovascular Angiography Techniques - Clinical Studies
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Wednesday May 11th
Room 511A-C  10:30 - 12:30 Moderators: Timothy J. Carroll and Oliver Weiben

10:30 358.   A New High Resolution MR DSA Protocol for Intracranial Vascular Malformations 
Parmede Vakil1, Sameer A Ansari2, Michael C Hurley2, and Timothy J Carroll2
1Biomedical Engineering, Northwestern University, Chicago, IL, United States, 2Radiology, Northwestern University, Chicago, IL, United States

A novel, high resolution MR DSA protocol is presented for visualizing high-flow intracranial vascular malformations. In addition, a gradient spoiling technique is presented to be used with RF-spoiling for eliminating artifacts associated with 2D radial FLASH MRI.

10:42 359.   Unenhanced four dimensional magnetic resonance angiography: preliminary experience in patients with cerebrovascular disorders 
Kaiyuan Zhang1, Jie Lu1, Jing An2, Mo Zhang1, Xiaoming Bi3, and Kuncheng Li1
1Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing, Beijing, China, People's Republic of, 2Siemens Mindit Magnetic Resonance, Shenzhen, Guangdong, China, People's Republic of, 3Cardiovascular MR R&D, Siemens Healthcare, Chicago, Illinois, United States

The purpose of this work is to evaluate the feasibility of using NCE-4DMRA for the diagnosis of cerebral vascular steno-occlusive disease and vascular malformations.The 4DMRA shows the abnormal inflow and shape of different cerebrovascular disorders.The technique provide a safe alternativ without ionizing radiation, risk of catherization and reactions to contrast agent as in DSA.

10:54 360.   Time-Resolved Angiography with a Highly Undersampled Multi-echo 3D Radial Trajectory 
Gregory R Lee1, Nicole Seiberlich1, Jeffrey L Sunshine1,2, Timothy J. Carroll3,4, and Mark A Griswold1,5
1Radiology, Case Western Reserve University, Cleveland, OH, United States, 2Radiology, University Hospitals Case Medical Center, Cleveland, OH, United States,3Radiology, Northwestern University, Chicago, IL, United States, 4Biomedical Engineering, Northwestern University, Chicago, IL, United States, 5Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States

3D Time-Resolved angiography remains challenging due to the high spatial and temporal resolutions required. In the present work, a multishot 3D radial VIPR acquisition with multi-echo readout and pseudorandom undersampling is combined with the recently developed GraDeS reconstruction algorithm. GraDeS allows the reconstruction of sparse images from highly undersampled data. A B0 fieldmap for correction of susceptibility artifact was derived from the same dataset. The resulting angiograms demonstrate clear arterial and venous separation. 1 mm^3 isotropic resolution is achieved at acceleration factors of 100-400 (1.1 s / 0.27s per frame) without the use of view sharing or a composite image.

11:06 361.   High Resolution Hemodynamics of Small Intracranial Aneurysms with Phase Contrast Stack of Stars 
Steven Kecskemeti1, Kevin Johnson1, Yijing Wu1, Patrick Turski2, and Oliver Wieben1
1Medical Physics, University of Wisconsin - Madison, Madison, Wisconsin, United States, 2Radiology, University of Wisconsin - Madison, Madison, Wisconsin, United States

A hybrid radial-Cartesian k-space trajectory was used to acquire cine 4D PC MR with ultra-high spatial resolution for anatomical and hemodynamic visualization of small intracranial aneurysms. Specifically, we targeted 12 aneurysms of sizes 2-10mm, with 7 of them 4mm or less. This abstract demonstrates the improved hemodynamic visualization and quantification compared to lower resolution exams typically acquired with Cartesian exams of the same scan length.

11:18 362.   Visualizing Small Intra-cranial Arteries using TOF with Compressed Sensing 
Jerome Yerly1,2, Michel Louis Lauzon2,3, and Richard Frayne2,3
1Department of Electrical and Computer Engineering, University of Calgary, Calgary, AB, Canada, 2Foothills Medical Centre, Seaman Family MR Research Centre, Calgary, AB, Canada, 3Departments of Radiology, and Clinical Neurosciences, University of Calgary, Calgary, AB, Canada

Time-of-flight (TOF) MRA has been successfully used to diagnose stenoses in large arteries. However, imaging stenoses in smaller arteries requires acquiring high-resolution images, which is particularly challenging in TOF data acquisition because of the tradeoff between spatial resolution, acquisition time and signal-to-noise ratio (SNR). Accelerated approaches such as compressed sensing (CS) may prove favorable for accurate reconstruction of undersampled k-space datasets. Here, we investigated the potential of improving the spatial resolution by using the CS paradigm to acquire and reconstruct vastly undersampled high-resolution TOF k-space datasets, while maintaining reasonable scan time and SNR.

11:30 363.   High resolution time-of flight MRA using slice selective saturation transfer contrast and water excitation technique for the visualization of the Lenticulostriate arteries at 1,5T 
Faiza Admiraal-Behloul1, Evert Blink1, Bei Zhang1, and Mitsue Miyazaki2
1MR-BU, Toshiba Medical Systems Europe, Zoetermeer, Netherlands, 2Toshiba Medical Research Institute, Vernon Hills, Illinois, United States

It has been well accepted that Lenticulostriate arteries (LSAs) are nearly impossible to visualize on 1,5T and very difficult at 3T clinical MR systems in healthy volunteers. Therefore, LSAs are mainly studied at 7T. The aim of this preliminary study was to investigate the ability of high resolution 3D time-of flight (TOF) angiography to visualize the LSAs at 1,5 T,using a Slice-Selective Off-Resonance Sinc Pulse-Saturation Transfer Contrast with inclined profile selective excitation and water excitation technique.

11:42 364.   Superselective MR-angiography based on pseudo-continuous arterial spin labeling and first applications in AVM patients 
Michael Helle1, Susanne Rüfer1, Wouter Teeuwisse2, Olav Jansen1, David Gordon Norris3,4, and Matthias van Osch2
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

Intra-arterial digital subtraction angiography (DSA) is considered the gold-standard for cerebral angiography but the procedure is invasive and bears the risk of severe complications. Existing MR angiography techniques offer non-invasive approaches but the selectivity is restricted to major brain feeding vessels. In this study, we combined superselective arterial spin labeling with an optimized image acquisition which was applied in healthy volunteers as well as in patients suffering from arterio-venous-malformation (AVM). This approach for selective ASL angiography not only mimics DSA but also combines advantages of superselective labeling and high-resolution 3D image acquisition in a complete non-invasive way.

11:54 365.   Application of Temporally Constrained Compressed Sensing for High Spatial and Temporal Resolution Intracranial CE MRA 
Julia V Velikina1, Kevin M Johnson1, Steven R Kecskemeti1, Patrick A Turski2, and Alexey A Samsonov1,2
1Medical Physics, University of Wisconsin - Madison, Madison, WI, United States, 2Radiology, University of Wisconsin - Madison

We apply temporally constrained compressed sensing reconstruction of hybrid radial (in-plane)/Cartesian (through-plane) data acquisition to time-resolved contrast-enhanced MRA. We were able to obtain images with high spatial (0.86x0.86x2 mm) and temporal (1.2 s) resolution in patients with intracranial aneurysms.

12:06 366.   Fast Analysis of Vessel Encoded ASL Perfusion and Angiographic Images 
Michael A Chappell1,2, Tom W Okell2, Stephen J Payne1, Peter Jezzard2, and Mark W Woolrich2
1Institute of Biomedical Engineering, University of Oxford, Oxford, United Kingdom, 2FMRIB Centre, University of Oxford, Oxford, United Kingdom

Vessel Encoded Arterial Spin Labelling (VEASL) preparations permit vessel selectivity for both dynamic angiographic and perfusion acquisitions. The calculation of flow contributions can be very sensitive to choice of encoding and subject position, this can be accounted for using a recently proposed general framework for VEASL analysis. However, the original implementation of this framework was too slow for many practical applications. Here faster solutions to the framework were sought that reduced computational time from hours to minutes or in some cases seconds without substantially affecting the accuracy of the resulting images.

12:18 367.   Validation of a simple anatomical classification method of the circle of Willis: a MR angiographical and selective arterial spin labeling MRI study at 3 Tesla 
Jeroen Hendrikse1, Xavier Golay2, and Esben Thade Petersen3
1UMC, Radiology, Utrecht, Netherlands, 2Institute of Neurology, UCL, London, United Kingdom, 3CIRC, NUS-A*STAR, Singapore

In this work, we introduce a simple classification method and evaluated its hemodynamic relevance in terms of flow contributions to the anterior and posterior cerebral arteries. Five variants are based on MR angiographic diameter comparisons on the posterior side of the circle of Willis: P1 absent, P1PCoM, PCoM absent and on the anterior side: A1 absent, A1ACoM, ACoM absent. We correlated the results of our circle of Willis classification method with the perfusion territory contributions of the carotid and vertebrobasilar arteries measured with selective arterial spin labeling (ASL) MRI, in a series of subacute stroke patients.