AJR June 2018
Chris L. Scelsi
Medical College of Georgia, Augusta University
“Egg-and-Banana Sign: A Novel Diagnostic CT Marker for Pulmonary Hypertension”
The “egg-and-banana sign,” defined as the visualization of the main pulmonary artery (PA) at the level of the aortic arch, shows great promise for aiding the early detection of pulmonary hypertension (PH), according to a study in the June 2018 issue of AJR.
The team of co-authors from the Medical College of Georgia at Augusta University, headed by Chris L. Scelsi, retrospectively evaluated 186 patients who between 2014 and 2017 received right heart catheterizations and underwent CT studies that included the aortic arch. Of these patients, 127 had 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 “egg” and “banana” refer to the appearance of the main PA and the aortic arch, respectively.
The results showed 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) (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).
In this Q&A, Scelsi discusses the origins of the AJR study and the usefulness of the egg-and-banana sign as a new CT marker that is specific for PH.
What is the background for this study? How did you and your co-authors come up with the idea?
Scelsi: Pulmonary hypertension is a complex disorder which is difficult to diagnose by imaging alone. Classically, diagnosis on CT has relied on quantitative measurements of the pulmonary artery. However, use of quantitative measurements such as main pulmonary artery diameter is limited as there is a wide variation in the published literature regarding recommended cut-offs. Our goal was to investigate other signs that may be useful markers for diagnosis of pulmonary hypertension. We came across the “egg-and-banana sign” in a manuscript written by Anand Devaraj, MD, and David M. Hansell, MD, and investigated it further.
What should readers take away from your article?
Scelsi: The main key point readers should take away from our article is that there are limitations with current quantitative CT measurements for the diagnosis of pulmonary hypertension. Utilizing a qualitative marker, such as the egg-and-banana sign which demonstrated a high specificity for pulmonary hypertension, in addition to current quantitative markers can increase diagnostic potential.
What recommendations do you have for future research as a result of this article?
Scelsi: It is important to understand that pulmonary hypertension is a complex disease with numerous pre-capillary and post-capillary etiologies. Our study included patients with all types of pulmonary hypertension, and future research focusing on evaluating this sign in selective World Health Organization pulmonary hypertension groups would be helpful.
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