To describe CT findings in paediatric idiopathic pulmonary arterial hypertension (PAH).

Lung and cardiac CT of 30 children with idiopathic PAH or heritable PAH (median age 7.5years [range 11months–15.5years]) were compared to 30 children without cardiac or lung disease matched for age. PAH diagnosis was always confirmed by a right heart catheterization. All patients were considered as having idiopathic or heritable PAH after a complete diagnostic work-up according to the Nice international recommendations. Seven/30 patients had mutations in one of the known PAH genes (BMPR2, Alk1, TBX4, EIF2AK4).

CT findings were significant increase of the ratio of main pulmonary artery/ascending aorta (median 1.5 [1–1.9] versus 0.98 [0.7–1.1] in controls and of right ventricle/left ventricle (median 1.4 [0.9–3] versus 0.8 [0.6–1]). Mediastinal adenopathies were observed in 9 cases. Parenchymal anomalies were present in 25/30 patients with mosaic pattern of attenuation in 9, ground glass nodules in 17, micronodules in 12, interlobular septal thickening in 13, consolidation in 3, and distal pulmonary arteries anomalies in 16. No correlation was found between CT findings and WHO functional class or hemodynamic characteristics of patients. Veno-occlusive disease was diagnosed at CT in 3 patients and confirmed subsequently either genetically or histologically. Two/4 diagnoses of Rendu-Osler (ALK1 mutations) were diagnosed at CT before genetic confirmation.

CT is a valuable tool in the diagnostic work-up of PAH in children. Specific parenchymal anomalies are highly suggestive of EIF2AK4 or ALK1 mutations and may orientate genetic confirmation of the disease.