Comparison of time-of-flight MR angiography and intracranial vessel wall MRI for luminal measurements relative to CT angiography

To assess whether intracranial vessel wall (IVW) MRI luminal measurements are more accurate than non-contrast 3D-TOF-MRA measurements for intracranial atherosclerotic stenosis, relative to CTA. Consecutive patients with non-calcified intracranial atherosclerotic stenosis seen on CTA, who had non-contrast 3D-TOF-MRA and IVW performed between 1 January 2013 and 20 April 2014 were selected, and images with stenosis were pre-selected by a single independent rater. The pre-selected CTA, MRA, and IVW ( -weighted) images were then reviewed by two independent raters blinded to the other measurements in random order. Measurements were made in a plane perpendicular to the lumen on each modality. MRA and IVW measurements were compared to CTA, to determine which more accurately matched the degree of stenosis. 18 patients with 33 intracranial atherosclerotic stenoses were included. Relative to CTA, IVW had 40% less variance than MRA ( = .004). IVW had a significantly higher concordance correlation coefficient (CCC) relative to CTA than MRA (.87 .68, = .002). IVW and MRA did not have significant bias relative to CTA, however, 8/33 lesions showed >20% overestimation of the degree of stenosis on MRA, compared to 1/33 for IVW. CCC between raters were 0.84 (95% CI 0.67-0.93) for CTA, 0.83 (0.67-0.93) for TOF-MRA, and 0.85 (0.71-0.94) for IVW. For stenosis >50% sensitivity was 82% for IVW and 64% for MRA, while specificity was 73% for both. IVW provides more accurate stenosis measurements than MRA when compared to CTA. Considering higher stenosis measurement accuracy of IVW, it can be more reliably used for quantitative evaluation relative to MRA.