The best in the whole

Despite several proposals, no strong recommendations have yet been established for postoperative surveillance in thoracic and thoraco-abdominal aortic disease, essentially due to the wide range of disease-specific mid- and long-term findings and the great heterogeneity in the evolution of the disease. Furthermore, methods used daily in clinical practice to detect post-procedural complications—such as computed tomography angiography (CTA) used to analyse aortic diameter measurements for aneurysmal sac enlargement or false lumen progression—do not seem to be fully comprehensive for such a complex disease that may hide relevant pathological modifications in a non-conventional target measurement location [1–3]. In this context, it would be essential to have an ‘overall view’ of the aorta to better identify aortic zones that may be of interest because of significant growth during the follow-up period.

The perspective proposed by Ahmed et al. [4] to improve the quality of the assessment of postoperative aortic dimensions using the vascular deformation mapping (VDM) technique could be useful in this scenario. The use of VDM analysis might reveal growth differences visible on follow-up CTA scans, highlighting issues with a 3-dimensional (3D) heat map. The authors showed good correlation between VDM and accurate manual re-measurement of the target diameter when assessing aortic growth, particularly in the descending thoracic segment, where they were able to detect localized postoperative aortic growth areas in patients who had open surgical repair of a thoracic aneurysm.

VDM introduces a new idea of ‘postoperative aortic growth’ that includes additional useful information:

• An automatic aortic volumetric and diameter analysis;

• Analysis of dimensions for each (both conventional and non-conventional) aortic segment;

• Analysis of all possible aortic diameters for each lumen scan;

• At a glance, a 3D overview of the extended area of aortic growth; and

• New possible cut-off values for ‘significant growth’ and ‘growth needs reintervention’, expressed in Jacobian units/year.

Probably the most important advantage of VDM, thanks to its ability to provide volumetric 3D growth details, is to highlight even minimal variations in aortic dimensions, especially in regions in which is difficult to identify these variations using only the classical axial perspective. However, to obtain such an analysis, VDM requires high-quality electrocardiographic-gated CTA with no artefacts, more time than standard measurements and validation studies on large patient cohorts, as mentioned by the authors. The definitive usefulness of this tool lies in the fact that it is easy to use, rapid and available to all specialists. Another key advantage of VDM is its potential usefulness in postoperative endovascular aortic analysis, an important setting in which it has not yet been tested.

Despite these limitations, VDM has the potential to provide additional innovative and attractive data on the postoperative fate of the aorta. In fact, several possible areas of application can be found to improve the diagnostic role of this tool: What growth values could indicate the need for reintervention? What are the best cut-off values, expressed in Jacobian units/year, to predict areas at higher risk of growth? How large should the area of growth be to consider it for further treatment? VDM could also be useful in case of conservative treatment to track changes in patients without an indication for or deemed unfit for invasive procedures or to change the anastomotic site if a ‘high-risk zone’ is identified, helping to decide if extend or not the surgical repair. After endovascular interventions, another potential use could be the study of the specific evolution related to the specific type of endoleak.

Computational 3D analysis will be essential in the future for both vascular and non-vascular issues. In the case of the aorta, having VDM as an everyday tool to better assess postoperative outcomes, and in particular the complication rate, would be a definite benefit. The paper of Ahmed et al. sets the stage for further implementation of and improvements in VDM applicability and use, supporting the importance of the role of healthcare specialists (e.g. cardiovascular surgeons, radiologists, cardiologists) in the follow-up analysis and management of these patients.

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