Perfusion quantification using voxel-wise proton density and median signal decay in PREFUL MRI

Science and Research

PURPOSE: Contrast-free lung MRI based on Fourier decomposition is an attractive method to monitor various lung diseases. However, the accuracy of the current perfusion quantification is limited. In this study, a new approach for perfusion quantification based on voxel-wise proton density and median signal decay toward the steady state for Fourier decomposition-based techniques is proposed called Q(Quantified) (Q(Quant) ). METHODS: Twenty patients with chronic obstructive pulmonary disease and 18 patients with chronic thromboembolic pulmonary hypertension received phase-resolved functional lung-MRI (PREFUL) and dynamic contrast-enhanced (DCE)-MRI. Nine healthy participants received phase-resolved functional lung-MRI only. Median values of Q(Quant) were compared to a Fourier decomposition perfusion quantification presented by Kjørstad et al (Q(Kjørstad) ) and validated toward pulmonary blood flow derived by DCE-MRI (PBF(DCE) ). Blood fraction maps determined by the new approach were calculated. Regional and global correlation coefficients were calculated, and Bland-Altman plots were created. Histogram analyses of all cohorts were created. RESULTS: The introduced parameter Q(Quant) showed only 2 mL/min/100 mL mean deviation to PBF(DCE) in the patient cohort and showed less bias than Q(Kjørstad) . Significant increases of regional correlation with PBF(DCE) were achieved (r = 0.3 vs. r = 0.2, P < .01*). The trend of global correlation toward PBF(DCE) is not uniform, showing higher values for Q(Kjørstad) in the chronic obstructive pulmonary disease cohort than for Q(Quant) and vice versa in the chronic thromboembolic pulmonary hypertension cohort. In contrast to Q(Kjørstad) , Q(Quant) perfusion maps indicate a physiologic dorsoventral gradient in supine position similar to PBF(DCE) with similar value distribution in the histograms. CONCLUSION: We proposed a new approach for perfusion quantification of phase-resolved functional lung measurements. The developed parameter Q(Quant) reveals a higher accuracy compared to Q(Kjørstad) .