PET Imaging in Pulmonary Hypertension

Abstract

Pulmonary hypertension (PH) comprises a heterogeneous group of diseases characterized by elevated pulmonary arterial pressures and progressive right ventricular (RV) remodeling, with RV failure as the principal determinant of outcome. This review discusses PET imaging across PH, with particular emphasis on pulmonary arterial hypertension (PAH), in which pulmonary vascular remodeling and RV adaptation are central disease features. While echocardiography and cardiac MRI provide robust assessment of RV structure, function, and fibrosis, they are limited in detecting early molecular alterations that precede overt dysfunction. Positron emission tomography (PET) offers a unique opportunity to visualize these processes. In particular, [18F]FDG PET has demonstrated a shift in RV substrate utilization from fatty acid oxidation toward glycolysis, reflecting metabolic stress and maladaptation. More recently, fibroblast activation protein inhibitor PET has emerged as a promising modality, with first-in-human studies in PAH demonstrating uptake in the RV and pulmonary vasculature, consistent with active remodeling. Beyond fibroblast activation, additional metabolic and immunologic targets may provide complementary insight into pulmonary vascular disease activity, RV remodeling, and treatment response. Together, these advances position PET as a powerful tool for early detection, phenotyping, and risk stratification in PH, with particular relevance for PAH.