“Egg-and-Banana Sign” on CT Scan for Diagnosis of Pulmonary Hypertension

Abstract

OBJECTIVE The “egg-and-banana” sign refers to an increased main pulmonary diameter (MPAD) seen in the main pulmonary artery (PA) at the same level as the most caudal point of the aortic arch. This study aimed to determine whether identification of the egg-and-banana sign on CT scans can help in the diagnosis of pulmonary hypertension (PH). METHODS A retrospective study was conducted of 110 patients at Siriraj Hospital between January 2017 and November 2020. Clinical characteristics, CT scans, and echocardiograms were reviewed. The egg-and-banana sign, MPAD and ascending aorta were reviewed and their diagnostic performance as CT features of PH were analyzed. RESULTS The egg-and-banana sign showed 41.6% sensitivity, 84.9% specificity, 86.5% positive predictive value and 38.4% negative predictive value for the detection of PH. When it was used together with MPAD > 29 mm and PA:AAo ratio > 1, specificity increased to 87.9%, sensitivity of MPAD was high (97.4%; AUC value, 0.866) and specificity of the PA:AAo ratio showed a high value (81.8%; AUC value, 0.838) for PH individually. The egg-and-banana sign was found to be related to a higher mean PA pressure (mPAP), a higher PA:AAo ratio, and a larger MPAD. Moderate correlations between mPAP and MPAD and between mPAP and PA:AAo ratio were found. CONCLUSIONS The egg-and-banana sign may be useful in the detection of PH. It has high specificity and high PPV for PH. The use of the egg-and-banana sign in conjunction with other well-known CT features, the MPAD and PA:AAo ratio, can boost the specificity and PPV for detection of PH.