Limitations
The study defined aortic arch anomalies in patients undergoing CT scan chest for variety of indications at a single institution. Most of these indications were for non-cardiac/vascular reasons. While this eliminates investigator bias, we noticed that CT scans read by radiologists who are not fellowship trained in cardiovascular imaging underreport the presence of arch anomalies, particularly the “bovine arch” variant. The study included all types of CT scans (contrast CT scans=49.3%(n=10,508) and EKG gated scans=2.5%(n=540)) which allowed for a larger sample size, but might have resulted into significantly lower rates of the reported anomalies, which are known to be better visualized using contrast studies. We used a size threshold for diagnosing TAA (4 cm as cut-off value for defining the root, ascending and arch dilatations/aneurysms and 3 cm for the descending aorta) as aortic size continues to be the initial screening tool for TAA by most radiologists and physicians who can further refer the patients for appropriate consultation. Although, the impact of normalization to body characteristics (age, sex, BSA) in this study is unknown and might influence the prevalence of TAA. The study did not address the prevalence of arch anomalies in patients with thoracic aortic dissection as the number of dissection patients in this database was too low to analyze (n=32).