Comparison of variation in circumference derived diameter and transverse diameter at proximal landing zone of aortic...

We proposed a parameter, the circumference derived diameter (CDD), to size the stent-graft implanted in the thoracic endovascular aortic repair (TEVAR), and evaluated the variation and repeatability compared with the transverse diameter (TD) measured in the cross-sectional (axial) plane of computed tomography angiography (CTA).

Fifty patients undergoing TEVAR in our centre from June 2016 to July 2017 were enrolled retrospectively. The circumference of the aortic wall at the proximal landing zone (PLZ) was measured on the segment plane orthogonal to the centreline. The TD of the aortic wall at PLZ was measured in the cross-sectional (axial) plane. Three observers independently measured both CDD and TD for each patient twice with the interval of a month. The statistics was used to investigate the variation and repeatability of CDD and TD.

Bland-Altman plot exhibited no statistical difference in terms of main effects of both methods and simple effects of each observer (P > .05), whereas mean difference of > 3 mm (the general size interval of off-the-shelf stent-grafts) between CDD and TD was observed in 7/37 (18.9%) patients. CDD exhibited a significant consistency in both intra-observer and inter-observer variability (P > .05). Whereas, TD exhibited greater absolute mean differences than CDD in both variability tests (intra-observer: -0.210 ± 0.776 mm vs 0.014 mm ± 0.291, P < .0056; inter-observer: 0.578 ± 0.382 mm vs 0.188 ± 0.143 mm, P < .001).

Combining with the requirement of current clinical practice and available stent-graft specifications, CDD was a potential substitute parameter for sizing aortic geometry before TEVAR, with higher repeatability and less intra-observer and inter-observer variability.

We propose a parameter, CDD which has the potential to be a substitute parameter to size the stent-graft precisely before TEVAR.