Transthoracic Ultrasound Evaluation of Arch and Descending Thoracic Aortic Pathology

Background: Duplex ultrasonography (DUS) currently has limited applicability in the diagnosis and surveillance of thoracic aortic pathologies because of associated limitations. This study investigates the feasibility of using an optimised DUS protocol to detect descending thoracic aortic pathology. Methods: This was a prospective, case control cohort study. Patients with computed tomography (CT) confirmed thoracic aortic pathology underwent DUS of the thoracic aorta. A control group known to have no thoracic pathology also underwent DUS. The sonographer performing DUS was blinded to the CT findings, and recorded the presence of pathology or any dilated aortic segment where visualised. Diameter cutoff points of 35 mm and 40 mm were compared. Results: Forty patients were scanned (20 cases and 20 controls). All patients but one had a technically adequate assessment of the thoracic aorta (at least one view of the descending thoracic aorta). Using a size threshold of 40 mm, 16 out of 19 cases and two out of 20 control patients would have been recommended for definitive imaging. Using a cutoff of 35 mm, this became 18 out of 19 cases and six of 20 controls. Sensitivity and specificity were 100% and 70% for a threshold of 35 mm, and 84% and 90% for a threshold of 40 mm. Conclusions: DUS has the potential to be used as a diagnostic modality for thoracic aortic pathology, and may have a role in surveillance for some patients for whom CT scanning is contraindicated. Further validation and refinements to this technique are required. However, this study provides proof of concept.