Accuracy of non–electrocardiographically gated thoracic ct angiography for right atrial and right ventricular enlargement

Abstract

Purpose: To assess the role of long-axis (LA) and short-axis (SA) measurements of the right atrium (RA) and right ventricle (RV) at non–electrocardiographically (ECG) gated thoracic CT angiography for identification of RA enlargement and RV enlargement. Materials and Methods: This study was a retrospective case review of 138 patients who underwent both non–ECG-gated CT angiography and ECG-gated CT angiography concurrently from November 2016 through November 2018. The SA and LA of the RA and RV were measured by two observers blinded to the ECG-gated CT angiography data. ECG-gated CT angiography–derived RA end-systol-ic and RV end-diastolic volumes were used as standard of reference to derive cutoff values for diagnosis of RA and RV enlargement. Results: In this study, 138 patients were evaluated (70 men, 68 women; mean age, 70.0 years ± 18.4 [standard deviation]; mean body mass index, 29.3 kg/m2 ± 8.1). Of these patients, ECG-gated CT angiography revealed 36.2% had RA enhancement and 19.0% had RV enhancement. The best predictor of RA enhancement was the product of atrial LA and SA measurements, for which a threshold value of 3210 mm2 yielded a 94% sensitivity and 81.8% specificity (area under the curve [AUC], 0.92). A threshold of 55.5 mm for LA diameter had 86% sensitivity and 78.4% specificity in identifying RA enlargement. RV enlargement could be predicted if the SA diameter was greater than 48.5 mm (76.9% sensitivity and 64.9% specificity) and with a body surface area indexed value of 27.0 mm/ m2 (92.3% sensitivity and 74.8% specificity [AUC, 0.87]). Conclusion: RA and RV enlargement can be accurately diagnosed by using non–ECG-gated CT angiography.