Computed Tomography Angiography in Pediatric Pulmonary Hypertension: Evaluating MPA-to-Aortic Ratios as Diagnostic Markers

Background: Pulmonary hypertension (PHT) is a rare but serious condition in children, requiring early diagnosis to prevent right ventricular failure. Non-invasive imaging modalities such as computed tomography angiography (CTA) have gained importance in assessing vascular changes, including main pulmonary artery (MPA) dilatation, increased vessel stiffness, and elevated pulmonary vascular resistance, which are characteristic of pulmonary hypertension (PHT). Objective: This study aimed to evaluate the diagnostic value of the main pulmonary artery-to-ascending aorta (MPA/AA) and main pulmonary artery-to-descending aorta (MPA/DA) ratios on CTA in pediatric patients with confirmed PHT. Methods: In this retrospective cohort study, 76 pediatric patients who underwent both cardiac catheterization and thoracic CTA were included. Patients were divided into PHT (mean pulmonary artery pressure ≥ 25 mmHg) and non-PHT groups. Vascular measurements were obtained from CTA, and MPA/AA and MPA/DA ratios were calculated. Statistical analyses included Mann–Whitney U tests and ROC curve analysis. Results: The MPA diameter and MPA/AA and MPA/DA ratios were significantly higher in the PHT group compared to controls (p < 0.05). ROC analysis showed strong diagnostic performance for both ratios. The MPA/DA ratio had an AUC of 0.927 with 78.5% sensitivity and 94% specificity at a cut-off value of 1.85. The MPA/AA ratio had an AUC of 0.896 with 76.5% sensitivity and 95% specificity at a cut-off value of 1.25. Conclusions: Both MPA/AA and MPA/DA ratios are reliable non-invasive indicators of pediatric PHT, with the MPA/DA ratio demonstrating slightly higher diagnostic accuracy. These findings support the use of CTA-derived vascular ratios, especially MPA/DA, as effective screening tools in clinical practice.