Inter-rater and scan-rescan reproducibility of the detection of intracranial atherosclerosis on contrast-enhanced 3D vessel wall MRI

Objective: The objective is to establish interscan, inter- and intra-rater reproducibility of a multicontrast three-dimensional contrast-enhanced intracranial vessel wall (IVW) MRI protocol with 0.6 mm acquired (0.3 mm interpolated) isotropic resolution in the detection of intracranial atherosclerosis. Methods: Subjects with established intracranial atherosclerosis were prospectively recruited and underwent two contrast-enhanced three-dimensional IVW scans within a 2-week period. Four raters with varying degrees of vessel wall imaging interpretation experience, through an iterative training process developed guidelines for plaque identification with no, possible and definite plaque categories. Using these guidelines, the raters reviewed the cases in pairs (consensus rating), while blinded to the interpretations of the other pair, clinical reports and patient history. The rater pairs reviewed 19 segments per patient for the presence and location of atherosclerotic plaques. Inter-scan, inter rater and intra rater reproducibility were assessed. Results: 19 subjects were scanned twice, with 361 total segments reviewed and 304-324 evaluable segments analyzed in the different reproducibility assessments. Overall inter-rater agreement for possible and definite plaque was 88.9 % [κ = 0.73; 95% confidence interval (CI) (0.62-0.81)], inter-scan/intra-rater agreement was 82.1 % [κ = 0.58; 95% CI (0.48-0.70)] and inter-scan/inter-rater agreement of 84.5% [κ = 0.64; 95% CI (0.51 - 0.76)]. Conclusion: Contrast-enhanced IVW imaging, with the utilization of detailed plaque definition guidelines for image review, can be a reproducible technique for the evaluation of intracranial atherosclerosis.