Screening for Heritable Thoracic Aortic Disease with Chest Radiography: Historical Review and Proposal for the “Liberty Hat” Sign

Abstract Cross-sectional imaging (CSI) is the standard for diagnosis and surveillance of ascending thoracic aortic aneurysm (ATAA), the principal phenotype of heritable thoracic aortic disease (HTAD). However, CSI-based screening is limited by cost and availability. Posteroanterior and lateral chest radiography (CXR) is ubiquitous and inexpensive, yet its role in ATAA screening is underemphasized in contemporary training. A scoping review was conducted in accordance with PRISMA-ScR guidelines to synthesize literature describing CXR findings of ATAA. PubMed (1896–January 2026) was searched and supplemented by review of seminal radiology textbooks and reference lists. Sources with explicit descriptions of radiographic findings were synthesized qualitatively. The search identified 7,160 unique records; 192 underwent full-text review and 15 sources informed the synthesis. Historical CXR signs of ATAA were identified, including mediastinal widening, convex right mediastinal contour, enlargement of the aortic knob, and loss of the retrosternal clear space. Individually, these findings are anatomically grounded but diagnostically limited. Although gestalt-based signs have been described, none were logically articulated or integrated. To address this gap, we propose the CXR “Liberty Hat” sign, a perceptual heuristic integrating four anatomically linked features into a recognizable pattern. We hypothesize that this sign may improve CXR-based recognition of ATAA in younger (<50 years) relatives of patients with HTAD. Historical CXR signs of ATAA remain fragmented when applied individually. The proposed “Liberty Hat” sign integrates established findings into a unified perceptual framework suitable for teaching and future validation, potentially supporting renewed use of CXR as a low-cost screening tool for at-risk individuals.