Evaluation of perfusion changes using a 2D Parametric Parenchymal Blood Flow technique with automated vessel suppression following partial spleen embolization in patients with hypersplenism and portal hypertension

To evaluate the feasibility and potential value of 2D Parametric Parenchymal Blood Flow (2D-PPBF) for the assessment of perfusion changes following partial spleen embolization (PSE) in a retrospective observational study design. Overall, 12 PSE procedures in 12 patients were included in this study. The outcome of the study was the platelet response (PR), calculated as the percentage increase of platelet count (PLT), following PSE. To quantify perfusion changes using 2D-PPBF, the acquired digital subtraction angiography series were post-processed. A reference region-of-interest (ROI) was placed in the afferent splenic artery and a target ROI was positioned on the embolization territory of the spleen on digital subtraction angiography series pre- and post-embolization. The ratios of the target ROIs to the reference ROIs were calculated for the Wash-In-Rate (WIR), the Time-To-Peak (TTP) and the Area-Under-the-Curve (AUC). Comparisons between pre- and post-embolization data were made using Wilcoxon signed-rank test and Spearman's rank correlation coefficient (r). Afterwards, the study population was divided by the median of the TTP before PSE to analyze its value for the prediction of PR following PSE. Following PSE, PLT increased significantly from 43,000 ± 21,405 platelets/μL to 128,500 ± 66,083 platelets/μL with a PR of 255 ± 243% (P = .003). In the embolized splenic territory, the pre-/post-embolization 2D-PPBF parameter changed significantly: WIR(pre-PSE) 1.23 ± 2.42/WIR(post-PSE) 0.09 ± 0.07; -64 ± 46% (p = 0.04), TTP(pre-PSE) 4.41 ± 0.99/TTP(post-PSE) 5.67 ± 1.52 (P = .041); +34 ± 47% and AUC(post-PSE) 0.81 ± 0.85/AUC(post-PSE) 0.14 ± 0.08; -71 ± 18% (P = .002). A significant correlation of a 2D-PPBF parameter with the PLT was found for TTP(pre-PSE)/PLT(pre-PSE) r = -0.66 (P = .01). Subgroup analysis showed a significantly increased PR for the group with TTP(pre-PSE) >4.44 compared to the group with TTP(pre-PSE) ≤4.44 (404 ± 267% versus 107 ± 76%; P = .04). 2D-PPBF is an objective approach to analyze the perfusion reduction of embolized splenic tissue. TTP derived from 2D-PPBF has the potential to predict the extent of PR during PSE.