Objective: To determine the cardiothoracic ratio (CTR) cut-off value on chest computed tomography (CT) in non-cardiomegaly patients.

Materials and Methods: The authors reviewed 97 patients who underwent both posteroanterior view chest radiograph and chest CT between September 2010 and September 2013. The interval time between the two image studies was two weeks. Patient demographic and clinical data, including age, gender, underlying pulmonary and heart disease, and CTRs from posteroanterior chest radiograph and chest CT were reviewed and recorded.

Results: Of the 97 non-cardiomegaly patients, 50 (51.5%) patients were male and 47 (48.5%) were female. Patient age ranged from 23 to 78 years (mean 55.9±13.4). Eighteen patients (19%) had CTR from chest radiograph between 0.350 and 0.400, with mean CTR from chest CT at level of biggest heart of 0.42±0.02. Forty-two patients (43%) had CTR from chest radiograph between 0.401-0.450, with mean CTR from chest CT at level of biggest heart of 0.47±0.03. The remaining 37 patients (38%) had CTR from chest radiograph between 0.451 and 0.500, with mean CTR from chest CT at level of biggest heart of 0.51±0.03.

Conclusion: The CTR cut-off value on chest CT for indicating cardiomegaly was found to be 0.53

Keywords: Cardiothoracic ratio, Cardiomegaly, CT cardiothoracic ratio

DOI: doi.org/10.35755/jmedassocthai.2020.10.12093

Received 17 June 2020 | Revised 16 September 2020 | Accepted 30 September 2020