Abstract
OBJECTIVE: Aortic distensibility (AD) represents a well-established parameter of aortic stiffness. It remains unclear, however, whether AD can be obtained with high reproducibility in standard 4-chamber cine CMR images of the descending aorta. This study investigated the intra- and inter-observer agreement of AD based on different angles of the aorta and provided a sample size calculation of AD for future trials. METHODS: Thirty-one patients underwent CMR. Angulation of the descending aorta was performed to obtain strictly transversal and orthogonal cross-sectional aortic areas. AD was obtained both area and diameter based. RESULTS: For area-based values, inter-observer agreement was highest for 4-chamber AD (ICC 0.97; 95% CI 0.93-99), followed by orthogonal AD (ICC 0.96; 95% CI 0.91-98) and transversal AD (ICC 0.93; 95% CI 0.80-97). For diameter-based values, agreement was also highest for 4-chamber AD (ICC 0.97; 95% CI 0.94-99), followed by orthogonal AD (ICC 0.96; 95% CI 0.92-98) and transversal AD (ICC 0.91; 95% CI 0.77-96). Bland-Altman plots confirmed a small variation among observers. Sample size calculation showed a sample size of 12 patients to detect a change in 4-chamber AD of 1 × 10(-3) mmHg(-1) with either the area or diameter approach. CONCLUSION: AD measurements are highly reproducible and allow an accurate and rapid assessment of arterial compliance from standard 4-chamber cine CMR.