Inflow-weighted pulmonary perfusion: Comparison between dynamic contrast-enhanced MRI versus perfusion scintigraphy in complex pulmonary circulation

Abstract

Background: Due to the different properties of the contrast agents, the lung perfusion maps as measured by 99mTc-labeled macroaggregated albumin perfusion scintigraphy (PS) are not uncommonly discrepant from those measured by dynamic contrast-enhanced MRI (DCE-MRI) using indicator-dilution analysis in complex pulmonary circulation. Since PS offers the pre-capillary perfusion of the first-pass transit, we hypothesized that an inflow-weighted perfusion model of DCE-MRI could simulate the result by PS. Methods. 22 patients underwent DCE-MRI at 1.5T and also PS. Relative perfusion contributed by the left lung was calculated by PS (PS L%), by DCE-MRI using conventional indicator dilution theory for pulmonary blood volume (PBV L%) and pulmonary blood flow (PBF L%) and using our proposed inflow-weighted pulmonary blood volume (PBV iwL%). For PBV iwL%, the optimal upper bound of the inflow-weighted integration range was determined by correlation coefficient analysis. Results: The time-to-peak of the normal lung parenchyma was the optimal upper bound in the inflow-weighted perfusion model. Using PS L% as a reference, PBV L% showed error of 49.24% to 40.37% (intraclass correlation coefficient R I=0.55) and PBF L% had error of 34.87% to 27.76% (R I=0.80). With the inflow-weighted model, PBV iwL% had much less error of 12.28% to 11.20% (RI=0.98) from PS L%. Conclusions: The inflow-weighted DCE-MRI provides relative perfusion maps similar to that by PS. The discrepancy between conventional indicator-dilution and inflow-weighted analysis represents a mixed-flow component in which pathological flow such as shunting or collaterals might have participated. © 2013Lin et al; licensee BioMed Central Ltd.