03:00 PM Abstract No. 151 2D parametric parenchymal blood flow (2D-PPBF) measurements for monitoring of balloon pulmonary angioplasty (BPA) as treatment of chronic thromboembolic pulmonary hypertension (CTEPH)

To evaluate the feasibility of 2D Parametric Parenchymal Blood Flow (2D-PPBF) to quantify perfusion changes of the lung parenchyma following balloon pulmonary angioplasty (BPA) for treatment of chronic thromboembolic pulmonary hypertension. Overall, 35 consecutive interventions in 18 patients with 98 treated pulmonary artery segments and subsegments were included. Selective digital subtraction angiographies (DSA) were acquired with manual contrast injection and post-processed using dedicated software. Changes in pulmonary blood flow were quantified by use of 2D-PPBF. A reference ROI (arterial inflow) in the treated pulmonary artery and a distal target ROI, including the whole lung parenchyma distal to the targeted lesion, 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) pre- and post-BPA were calculated. The relative differences of the 2D-PPBF parameters were correlated to changes in the pulmonary-flow-grade-score, a commonly used visually based score to assess the immediate therapeutic effect of BPA. The pulmonary-flow-grade-score improved significantly after BPA (1 vs. 3; p<0.0001). Likewise, the mean HPDparenchyma/HPDinflow (-10%; p<0.0001), APparenchyma/APinflow (-24%; p=0.0007) and MTTparenchyma/MTTinflow (-4%; p=0.0449) decreased significantly, whereas WIRparenchyma/WIRinflow (+82%) and AUCparenchyma/AUCinflow (+59%) showed a significant increase (p<0.0001). Moreover, 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) were found. The evaluated 2D-PPBF technique is feasible for quantifying perfusion changes following BPA and has the potential to improve monitoring of BPA.