Objective: We compared the intraobserver and interscan variability of carotid atherosclerosis measured using B-mode ultrasound for quantifying intima media thickness (IMT), 3-dimensional ultrasound (3DUS) for quantifying vessel wall volume (VWV) and total plaque volume (TPV), and magnetic resonance imaging (MRI) for measuring VWV. We also evaluated the associations of these measurements and sample sizes required to detect specific changes in patients with moderate atherosclerosis.
Methods: Ten patients were evaluated with B-mode ultrasound, MRI, and 3DUS twice within 14 +/- 2 days. Measurements of IMT, MRI VWV, 3DUS VWV, and 3DUS TPV were performed by single observers using manual (VWV and TPV) and semiautomated (IMT) segmentation.
Results: Intraobserver coefficients of variation were 3.4% (IMT), 4.7% (3DUS VWV), 6.5% (MRI VWV), and 23.9% (3DUS TPV). Interscan coefficients of variation were 8.1% (MRI VWV), 8.9% (IMT), 13.5% (3DUS VWV), and 46.6% (3DUS TPV). Scan-rescan linear regressions were significant for 3DUS TPV (R(2) = 0.57), 3DUS VWV (R(2) = 0.59), and IMT (R(2) = 0.75) and significantly different (P < .05) for MRI VWV (R(2) = 0.87).
Conclusions: B-mode ultrasound-derived IMT provided the highest intraobserver and interscan reproducibility. Three-dimensional measurements of VWV derived from 3DUS and MRI provided both high sensitivity and high intraobserver and interscan reliability.