Abstract 13206: Ultra High Field 7T MR Carotid Vessel Wall Imaging: Comparison with 3T

Abstract

Purpose: MRI of the vessel wall enables determination of vessel wall thickness and atherosclerotic plaque characteristics. Clinical application is currently hampered by spatial resolution, in turn limited by signal-to-noise-ratio (SNR) and contrast-to-noise-ratio (CNR). Vessel wall MRI is expected to benefit from higher magnetic field strength. Therefore, the purpose of the present study was to develop ultra-high field 7T MRI hardware and protocols for vessel wall imaging of the carotid artery and to compare quantitative parameters of vessel wall morphology and image quality between 3T and 7T MRI.

Material and Methods: 18 volunteers (11 males, mean age=29±7 yrs) underwent examinations at 7T and at 3T MRI of the left common carotid artery vessel-wall was performed at 7T with identical in-plane resolution as 3T MRI (0.46 x 0.46 mm²) providing transverse T1- and T2-weighted images. Blinded analysis of morphologic measurements (lumen area and vessel wall area), SNR for vessel wall (SNR_VW), and the contrast-to-noise ratio between lumen and wall (CNR) were compared between 7T and 3T.

Results: Morphologic carotid vessel wall measurements were comparable between 7T and 3T for both T1-weighted images (lumen area; ICC: 0.81, vessel wall area; ICC: 0.84) and T2-weighted images (lumen area; ICC: 0.97, vessel wall area; ICC: 0.92). At 7T, SNR_VW and CNR were significantly higher as compared to 3T MRI for both T1- (p<0.001) and T2-weighted images (P<0.05), with gain factors ranging from 1.3 to 3.6.

Conclusions: Ultra-high field 7T MR carotid vessel wall imaging is feasible. 7T MRI of the common carotid artery has comparable accuracy for determining luminal area and vessel wall area and has improved SNR_VW and CNR as compared to 3T MRI. Therefore, ultra-high field 7T vessel wall MRI may enable more detailed assessment of plaque morphology.