RESUMO
AIM: To evaluate the feasibility of two-dimensional parametric parenchymal blood flow (2D-PPBF) to quantify perfusion changes in the lung parenchyma following balloon pulmonary angioplasty (BPA) for treatment of chronic thromboembolic pulmonary hypertension. MATERIALS AND METHODS: Overall, 35 consecutive interventions in 18 patients with 98 treated pulmonary arteries were included. To quantify changes in pulmonary blood flow using 2D-PPBF, the acquired digital subtraction angiography (DSA) series were post-processed using dedicated software. A reference region of interest (ROI; arterial inflow) in the treated pulmonary artery and a distal target ROI, including the whole lung parenchyma distal to the targeted stenosis, were placed in corresponding areas on DSA pre- and post-BPA. Half-peak density (HPD), wash-in rate (WIR), arrival to peak (AP), area under the curve (AUC), and mean transit time (MTT) were assessed. The ratios of the reference ROI to the target ROI (HPDparenchyma/HPDinflow, WIRparenchyma/WIRinflow; APparenchyma/APinflow, AUCparenchyma/AUCinflow, MTTparenchyma/MTTinflow) were calculated. The relative differences of the 2D-PPBF parameters were correlated to changes in the pulmonary flow grade score. RESULTS: The pulmonary flow grade score improved significantly after BPA (1 versus 3; p<0.0001). Likewise, the mean HPDparenchyma/HPDinflow (-10.2%; p<0.0001), APparenchyma/APinflow (-24.4%; p=0.0007), and MTTparenchyma/MTTinflow (-3.5%; p=0.0449) decreased significantly, whereas WIRparenchyma/WIRinflow (+82.4%) and AUCparenchyma/AUCinflow (+58.6%) showed a significant increase (p<0.0001). Furthermore, a significant correlation between changes of the pulmonary flow grade score and changes of HPDparenchyma/HPDinflow (ρ=-0.21, p=0.04), WIRparenchyma/WIRinflow (ρ=0.43, p<0.0001), APparenchyma/APinflow (ρ=-0.22, p=0.03), AUCparenchyma/AUCinflow (ρ=0.48, p<0.0001), and MTTparenchyma/MTTinflow (ρ=-0.39, p<0.0001) could be observed. CONCLUSION: The 2D-PPBF technique is feasible for the quantification of perfusion changes following BPA and has the potential to improve monitoring of BPA.
