Validation of simple measures of aortic distensibility based on standard 4-chamber cine CMR: a new approach for clinical studies

Stoiber L, Ghorbani N, Kelm M, Kuehne T, Rank N, Lapinskas T, Stehning C, Pieske B, Falk V, Gebker R, Kelle S.
Clin Res Cardiol. 2020 Apr;109(4):454-464. doi: 10.1007/s00392-019-01525-8. Epub 2019 Jul 13.
PMID: 31302712 Free PMC Article
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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.


Fig. 1 Illustration of CMR angulation of the descending aorta at the time of image acquisition and corresponding 4-chamber (a), transversal (b) and orthogonal (c) aortic areas. Image a shows a standard 4-chamber SSFP image where the slightly oval areas of the descending aorta can easily be tracked without further technical planning. Images b and c demand proper planning and are not performed in daily practice clinical imaging of the heart

Fig. 2 Correlation between orthogonal AD and the classic 4-chamber AD with the corresponding R2 values. Results are provided for Observer 1 (A + B) and Observer 2 (C + D) for both area-based AD and diameter-based AD


Fig. 3 Bland–Altman plots demonstrating intra- and inter-observer variability for AD values obtained from contoured aortic areas (a) or diameter-based values (b) depending on the angulation of the aorta at the time of image acquisition

Fig. 4 Distribution of AD values depending on the angulation used at the time of image acquisition. Aortic areas were acquired either by directly contoured aortic areas (black spots) or based on diameter measurements (white spots)