Effects of doubling and tripling the spatial resolution in standard 3D contrast-enhanced magnetic resonance angiography of carotid artery disease

Abstract

Purpose: To determine whether three-dimensional (3D) contrast-enhanced MR angiography (CE-MRA) of carotid artery disease may be more effective when performed at double or triple the spatial resolution of the present common clinical standard at 1.5T. Materials and Methods: A total of 110 consecutive patients with suspected carotid artery disease were imaged with elliptical centric 3D CE-MRA. The total acquisition time was increased from the standard clinical protocol of 21 seconds up to 60 seconds in 10-second steps, with corresponding voxel volume reductions from 0.95 mm3 down to 0.35 mm3. Quantitative and blinded qualitative measurements were then performed to determine the preferred imaging time. Results: In patients with significant stenosis, the 40-second acquisition with 0.53-mm3 voxels produced significantly sharper images of the carotid bifurcation than the 21-second standard using 0.95-mm3 voxels, but did not have a significant effect in patients without disease. Conclusion: In patients with carotid artery stenosis, decreasing the voxel volume to 0.5 mm3 by increasing the scan time from 21 to 40 seconds resulted in sharper depiction of the carotid stenosis. Further decreases in voxel volume, by extending the acquisition time further, did not improve the vessel depiction due to both signal-to-noise ratio (SNR) and sharpness losses. © 2007 Wiley-Liss, Inc.