Acceleration of Brain TOF-MRA with Compressed Sensitivity Encoding: A Multicenter Clinical Study

Abstract

BACKGROUND AND PURPOSE:The clinical practice of three-dimensional TOF-MRA, despite its capability in brain artery assessment, has been hampered by the relatively long scan time, while recent developments in fast imaging techniques with random undersampling has shed light on an improved balance between image quality and imaging speed. Our aim was to evaluate the effectiveness of TOF-MRA accelerated by compressed sensitivity encoding and to identify the optimal acceleration factors for routine clinical use. MATERIALS AND METHODS:One hundred subjects, enrolled at 5 centers, underwent 8 brain TOF-MRA sequences: 5 sequences using compressed sensitivity encoding with acceleration factors of 2, 4, 6, 8, and 10 (CS2, CS4, CS6, CS8, and CS10), 2 using sensitivity encoding with factors of 2 and 4 (SF2 and SF4), and 1 without acceleration as a reference sequence (RS). Five large arteries, 6 medium arteries, and 6 small arteries were evaluated quantitatively (reconstructed signal intensity, structural similarity, contrast ratio) and qualitatively (scores on arteries, artifacts, overall image quality, and diagnostic confidence for aneurysm and stenosis). Comparisons were performed among the 8 sequences. RESULTS:The quantitative measurements showed that the reconstructed signal intensities of the assessed arteries and the structural similarity consistently decreased as the compressed sensitivity encoding acceleration factor increased, and no significant difference was found for the contrast ratios in pair-wise comparisons among SF2, CS2, and CS4. Qualitative evaluations showed no significant difference in pair-wise comparisons among RS, SF2, and CS2 (P . .05). The visualization of all the assessed arteries was acceptable for CS2 and CS4, while 2 small arteries in images of CS6 were not reliably displayed, and the visualization of large arteries was acceptable in images of CS8 and CS10. CONCLUSIONS: CS4 is recommended for routine brain TOF-MRA with balanced image quality and acquisition time; CS6, for examinations when small arteries are not evaluated; and CS10, for fast visualization of large arteries.

Follow-Up Assessment of Intracranial Aneurysms Treated with Endovascular Coiling: Comparison of Compressed Sensing and Parallel Imaging Time-of-Flight Magnetic Resonance Angiography

“…Nonetheless, in 89.3% of readings the parent vessel was equally visualized on both sequences and in one case it was better depicted on CS TOF images. Previous studies showed that CS TOF MRA may result in worse visualization of smaller vessels compared to PI TOF MRA [21,28], therefore our results could be better explained by the small diameter of the stented vessels rather than the presence of susceptibility artifact due to the stent itself. This hypothesis is also supported by the observation that in the majority of cases in which CS TOF images showed a worse depiction of vascular structures adjacent to the aneurysm dome, the affected vessel was the anterior choroidal artery, which has a smaller diameter compared to the other examined vessels (Figure 4B,E).…”

High-resolution compressed sensing time-of-flight MR angiography outperforms CT angiography for evaluating patients with Moyamoya disease after surgical revascularization

“…Yamamoto et al compared CS TOF-MRA with different acceleration factors (CS 3 versus CS 5) for evaluating collaterals in MMD patients. They found that CS with lower acceleration factor (CS 3) better visualized Moyamoya collaterals [ 19 ].Another studies of Fushimi et al and Ding et al also supported that small arteries (anterior choroidal arteries, distal branches like A2/3, M4, P4 segments) could be better visualized by CS TOF-MRA with an acceleration factor less than 6 [ 18 , 26 ]. Therefore, considering that the bypass and collateral vessels are all with small size, we set the acceleration factor as 5.…”

Acceleration of pCASL-Based Cerebral 4D MR Angiography Using Compressed SENSE: A Comparison With SENSE

“…Image artifacts may appear as ghosts inside or outside the ROI if the SENSE acceleration factor is too high ( 23 ). A previous study mentioned that specked noise and SENSE artifacts were observed in the central area of 3D time-of-flight (TOF) MRA images with a large SENSE factor = 4, while these artifacts were rarely found on the images acquired by C-SENSE acceleration ( 24 ). In this study, the source images of 4D-PACK with C-SENSE with 5, 6.5, and 8 showed reduced artifacts compared with the artifacts present when SENSE4.5 was used.…”