Abstract 3691: High Resolution Imaging of Brain Vessels at 7 Tesla

Abstract

Introduction: Brain vessel wall MRI has the potentiality to visualize abnormal thickness and/or structure in intracranial vessel wall and could provide critical biomarkers to diagnose atherosclerosis.This, however, is a challenging task with MR images, given the small size of the vessels, variability in directions and their localization deep in the brain. A human 7T system was chosen to benefit from expected gains in Signal to Noise Ratio (SNR) and tissue contrast. Brain vessel wall MRI at 7T has been demonstrated, but the spatial resolution utilized so far (0.8mm isotropic) makes it difficult to assess the size of the brain vessel walls. Methods: We describe the preliminary results of a multi modality approach that investigates both ex-vivo and in-vivo achievable cerebral vessel MR limits at 7 Tesla. Samples are imaged with the same sequence and on the same system used for in-vivo studies, facilitating sequence and parameter transfer. Both ex vivo and in vivo studies are conducted on a human 7T MR scanner, facilitating sequences and parameters transfer. Samples of circle of Willis (CW), excised from human cadaver brains were immersed in a perfluoropolyether fluid (no signal in proton MRI) and imaged with a 3D turbo spin echo sequence with TR/TE= 1500/13 ms, an acquisition time of 1h 30 min and 0.16 mm isotropic resolution. In vivo, healthy subjects were scanned with TR/TE/TI= 3000/22/1100 ms, acquisition time of 13min and a 0.64 mm isotropic resolution. Results: Ex-vivo MR images of CW at high-resolution allow for clear distinction of vessel boundaries. The same sequence was used to acquire in vivo images at high resolution, imaging the brain vessel walls with the additional difficulty to suppress the CSF signal surrounding the brain vessels. Conclusion: Preliminary results show the potentiality of this multi modality study to image brain vessel walls at 7T. Our goal is to ultimately provide rationales to optimize contrast and spatial resolution tradeoff in clinical protocols aiming at imaging intracerebral arteries within limits of scanning time acceptable for neurological patients. The next step will be to directly compare histopathology with ex-vivo MR images to accurately measure the wall thickness.