Published in:
Open Access 01-10-2018 | Research Article
Scan–rescan reproducibility of segmental aortic wall shear stress as assessed by phase-specific segmentation with 4D flow MRI in healthy volunteers
Published in: Magnetic Resonance Materials in Physics, Biology and Medicine | Issue 5/2018
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Objective
The aim was to investigate scan–rescan reproducibility and observer variability of segmental aortic 3D systolic wall shear stress (WSS) by phase-specific segmentation with 4D flow MRI in healthy volunteers.
Materials and methods
Ten healthy volunteers (age 26.5 ± 2.6 years) underwent aortic 4D flow MRI twice. Maximum 3D systolic WSS (WSSmax) and mean 3D systolic WSS (WSSmean) for five thoracic aortic segments over five systolic cardiac phases by phase-specific segmentations were calculated. Scan–rescan analysis and observer reproducibility analysis were performed.
Results
Scan–rescan data showed overall good reproducibility for WSSmean (coefficient of variation, COV 10–15%) with moderate-to-strong intraclass correlation coefficient (ICC 0.63–0.89). The variability in WSSmax was high (COV 16–31%) with moderate-to-good ICC (0.55–0.79) for different aortic segments. Intra- and interobserver reproducibility was good-to-excellent for regional aortic WSSmax (ICC ≥ 0.78; COV ≤ 17%) and strong-to-excellent for WSSmean (ICC ≥ 0.86; COV ≤ 11%). In general, ascending aortic segments showed more WSSmax/WSSmean variability compared to aortic arch or descending aortic segments for scan–rescan, intraobserver and interobserver comparison.
Conclusions
Scan–rescan reproducibility was good for WSSmean and moderate for WSSmax for all thoracic aortic segments over multiple systolic phases in healthy volunteers. Intra/interobserver reproducibility for segmental WSS assessment was good-to-excellent. Variability of WSSmax is higher and should be taken into account in case of individual follow-up or in comparative rest–stress studies to avoid misinterpretation.