Diagnostic value of mediastinal/chest ratio in acute traumatic aortic injury

Background: This study aimed to assess the diagnostic efficacy of mediastinum/chest-width ratio (MCR) derived from chest X-rays (CXR) in detecting acute traumatic aortic injury (ATAI) after blunt chest trauma. We compared MCR with standard mediastinal width for ATAI screening. Methods: All adult patients with blunt chest trauma who underwent screening CXR due to suspected ATAI in Chiang Mai University Trauma Center between 2008 and 2022 were included. Definitive diagnosis was confirmed through computerized tomographic angiography (CTA). The diagnostic performance of MCR at the aortic knob level and carina level was evaluated using the Area under the Receiver Operating Characteristic (AuROC) curve. Results: 421 patients were enrolled, consisting of 357 men and 64 women. 37 patients (8.7%) were diagnosed with the ATAI based on CTA findings. MCR values at the aortic knob level and carina level were significantly higher in ATAI group (0.35±0.05 vs. 0.31±0.04; p < 0.001 and 0.37±0.06 vs. 0.33±0.41; p < 0.001, respectively). The AuROC of MCR was significantly superior to that of mediastinal width at both measurement levels. AuROC further improved when considering patient age, presence of multiple organ injuries, aortopulmonary opacification on CXR, and MCR at the threshold of 0.35 for aortic knob level and 0.36 for carina level, without statistically significant difference. Conclusions: MCR can be used as one of the complementary diagnostic tools for ATAI in blunt chest trauma. Combining MCR with other clinical predictors can further enhance its accuracy. However, it cannot replace direct measurement of mediastinal width as a standard screening tool for blunt ATAI cases.