Micro-vascular imaging experiences of time-of-flight MRA at 7T for cerebrovascular diseases

Surgical or endovascular approaches have proved effective for large-vessel diseases over the past decade. However, approaches for small vessel diseases are unlikely to be accomplished by those for large vessels and only few have been applied, because it is hard to access to those small vessels and one could not directly delineate the affected small vessels due to a lack of detection modalities. This study is to examine patients with vascular diseases using ultra-high field 7T MRI with conventional time-of-flight TOF sequence, 3D fast low-angle shot FLASH gradient-echo. We have evaluated several radio-frequency RF coils to find the optimal one for 7T magnetic resonance angiography MRA, especially for micro-vascular imaging. We have conducted several comparison studies with vascular disease patients. The results showed that micro-vessels such as lenticulostriate arteries in the subjects with risk factors like hypertension or stroke patients were significantly less than in the healthy subjects. 7T MRA images in steno-occlusive patients also showed clearly numerous collateral vessels not visible by 1.5T or 3T MRA. Furthermore, 7T MRA images were comparable to those obtained by digital subtraction angiography DSA, particularly for micro-vascular imaging. In this article, we would like to share the clinical experiences on 7T MRA that vascular images of 7T MRA were superior to conventional angiography images including 1.5T and 3T MRA, and even comparable to DSA. We also expect that further technical development and clinical applications of 7T MRA would be a clinically important diagnostic tool, in terms of an early detection of the stroke in a totally non-invasive manner. © 2014 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 24, 121-128, 2014