Egg-and-Banana Sign: A Novel Diagnostic CT Marker for Pulmonary Hypertension

Abstract

Objective: The purpose of this study was to retrospectively determine whether the egg-and-banana sign, defined as the visualization of the main pulmonary artery (PA) at the level of the aortic arch, is a sensitive and specific diagnostic marker for pulmonary hypertension.

Materials and methods: A total of 186 patients who, between January 2014 and July 2017, received right heart catheterizations and underwent CT studies that included the aortic arch within 140 days of catheterization were evaluated in this retrospective study. Of these patients, 127 had pulmonary hypertension (PH), and 59 who did not have PH served as control subjects. Two blinded radiologists reviewed each study for the egg-and-banana sign. The diameters of the main PA and ascending aorta were also measured. Contingency tables, ROC curves, and a t test were used for statistical analysis.

Results: The egg-and-banana sign was associated with a higher mean PA pressure, a higher ratio of the diameter of the PA to the diameter of the ascending aorta (Ao) (hereafter referred to as the "PA-to-Ao ratio"), and a larger PA diameter (p < 0.006). It had a specificity of 85% and a positive predictive value of 85%. When the egg-and-banana sign was used in combination with a main PA diameter larger than 29 mm and a PA-to-Ao ratio greater than 1, its specificity increased to 91% and 93%, respectively. When considered as individual markers, the PA diameter had a high sensitivity (80%; AUC value, 0.74) and the PA-to-Ao ratio had a high specificity (81%; AUC value, 0.73) for PH. Moderate correlations were noted between PA pressure and PA diameter (r = 0.37) and between PA pressure and PA-to-Ao ratio (r = 0.43).

Conclusion: The egg-and-banana sign has a high specificity and PPV for PH. Specificity increased when the sign was used in combination with other classic CT markers.

Keywords: egg and banana; main pulmonary artery diameter; pulmonary hypertension.