Assessment of aortic arch involvement in ascending thoracic aortic aneurysm by three-dimensional growth mapping using CT-angiography

Purpose: We investigated pre-surgical arch growth by vascular deformation mapping (VDM) and examined how well proximal arch diameter indicates arch involvement by the primary ascending aneurysm. Methods and materials: A total of 123 patients who underwent elective repair of ascending thoracic aortic aneurysm (aTAA) with or without concomitant arch repair and had 2 or more pre-operative computed tomography angiography (CTA) studies with a minimum interval of > 22 months were included. We compared growth at the proximal arch measured by three-dimensional VDM analysis with standard diameter measurements in overall, dilated (≥ 40 mm), and non-dilated (< 40 mm) arch subgroups. Results: Concurrent (hemi)arch replacement was performed in 30% of patients. In 59% of patients, VDM growth and arch diameter assessments were concordant VDM growth rate was higher in the dilated arch group (0.46 mm/year vs 0.26 mm/year, p = 0.007), however, pre-operative proximal arch diameter was similar in growth and non-growing arches among patients without arch dilation (36.2 mm vs 35.9 mm). Among non-dilated arches, 26% demonstrated significant growth by VDM but not by standard diameter measurements. Arch growth assessments by VDM and standard diameter measurements agreed with 73%; discrepancies up to 6 mm were observed. Within the post-operative subgroup, 12 (55%) patients demonstrated growth (> 0.3 mm/year) of the native aortic arch, with most (7/12, 59%) having non-dilated arches on pre-operative CT. Conclusion: Reliable assessment of arch involvement in aTAA by diameter thresholds is limited. VDM analysis allows for a more comprehensive analysis of arch growth and involvement by the ascending aneurysm, which may be useful to advance patient-specific surgical planning. Key Points: Question Can VDM measured proximal aortic arch diameter indicate proximal arch involvement by a primary ascending aneurysm? Findings Discrepancies between arch dilation status by conventional diameter thresholds and VDM exist; over half of patients with dilated proximal arches demonstrated no growth by VDM pre-operatively. Clinical relevance Arch involvement is common in ascending aortic aneurysms, though the degree of growth is not accurately assessed pre-operatively by standard measurements. VDM is an emerging technique that provides a three-dimensional assessment of arch growth and may inform patient-specific repair strategies.