Cardio-pulmonary involvement in pulmonaryarterial hypertension: A perfusionand innervation scintigraphic evaluation

Background. Pulmonary arterial hypertension (PAH) is characterized by the right ventricle(RV) remodeling and pulmonary endothelial dysfunction. We studied cardiac perfusionand innervation in PAH with a cadmium-zinc-telluride (CZT) scanner and lung uptakeimpairment of 123I-metaiodobenzylguanidine (123I-MIBG).Methods. In 13 patients with newly diagnosed PAH and 11 dilated cardiomyopathies(DCM, for comparative purposes), we assessed early and delayed 123I-MIBG uptake ratios oflung-to-mediastinum (L/M) and heart-to-mediastinum (H/M) on anterior planar images. Aquantitative myocardial innervation with 123I-MIBG and perfusion with 99mTc-tetrofosminusing CZT-SPECT was performed. All patients underwent right heart catheterization.Results. Early and delayed L/M ratios in PAH were lower than DCM (1.47 ± 0.14 vs1.98 ± 0.11 and 1.40 ± 0.13 vs 1.83 ± 0.09; P < .001), while early and delayed H/M wereimpaired but not different (1.73 ± 0.20 vs 1.65 ± 0.18 and 1.73 ± 0.27 vs 1.58 ± 0.19). RVperfusion and early innervation were significantly higher in PAH compared to DCM(68.4 ± 13.4 vs 28.6 ± 4.1 and 58.8 ± 9.3 vs 27 ± 2.2; P < .001); delayed RV innervation was notevaluable. RV/LV perfusion and innervation ratios were significantly related (R = 0.74;P < .0001) and had a significant correlation with clinical, hemodynamic, and morpho-functionalparameters, including L/M ratios.Conclusion. Cardio-pulmonary scintigraphy through a perfusion and innervation study isfeasible and may identify pulmonary vascular and RV remodeling, as in PAH. (J Nucl Cardiol2019)