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

Abstract

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 QQuantified (QQuant). 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 QQuant were compared to a Fourier decomposition perfusion quantification presented by Kjørstad et al (QKjørstad) and validated toward pulmonary blood flow derived by DCE‐MRI (PBFDCE). 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 QQuant showed only 2 mL/min/100 mL mean deviation to PBFDCE in the patient cohort and showed less bias than QKjørstad. Significant increases of regional correlation with PBFDCE were achieved (r = 0.3 vs. r = 0.2, P < .01*). The trend of global correlation toward PBFDCE is not uniform, showing higher values for QKjørstad in the chronic obstructive pulmonary disease cohort than for QQuant and vice versa in the chronic thromboembolic pulmonary hypertension cohort. In contrast to QKjørstad, QQuant perfusion maps indicate a physiologic dorsoventral gradient in supine position similar to PBFDCE 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 QQuant reveals a higher accuracy compared to QKjørstad.

State-of-the-art review of lung imaging in cystic fibrosis with recommendations for pulmonologists and radiologists from the “iMAging managEment of cySTic fibROsis” (MAESTRO) consortium

“…The upcoming introduction of commercially available software for thoracic imaging and, in particular, for automatic CT scoring might revolutionise clinical practice [178]. Finally, AI applications for MRI in CF are still limited, with chest CT far more advanced in terms of technique validation compared to chest MRI [119,126,128,133,135,139,179].…”

Inter‐ and intravisit repeatability of free‐breathing MRI in pediatric cystic fibrosis lung disease

“…Another limitation of this study was that measures of lung function focused on ventilation only (in comparison with Xe‐MRI), and perfusion‐weighted images were not explored at this time. PREFUL MRI can use the signal intensity within a major blood vessel to sort free‐breathing images into a synthesized cardiac cycle and extract perfusion‐related parameters, such as normalized perfusion (Q N ) 41 and pulmonary pulse wave transit time (pPTT), 42 and could be included in future. PREFUL MRI has been used to evaluate perfusion in diseased lungs such as COPD, CTEPH, and CF as compared to healthy controls 20 .…”

Functional lung imaging using novel and emerging MRI techniques

“…Phase-resolved functional lung MRI (PREFUL) is another unique approach that shares similarities to FD-MRI ( 16), with both methods Several ventilation and perfusion parameters can be derived from PREFUL ventilation and perfusion maps. These include regional ventilation, ventilation derived by cross-correlation, VDP, perfusion (arbitrary units), quantified perfusion, perfusion defect percentages and VQ match maps (16,(256)(257)(258).…”

“…Several ventilation and perfusion parameters can be derived from PREFUL ventilation and perfusion maps. These include regional ventilation, ventilation derived by cross-correlation, VDP, perfusion (arbitrary units), quantified perfusion, perfusion defect percentages and VQ match maps ( 16 , 256–258 ).…”

“…Without detracting too much from the focus of this review, PREFUL derived perfusion measures have been used to study a variety of cohorts including healthy subjects and those with COPD, CTEPH and CF ( 16 , 256 , 258 , 272 , 273 ). Validation against dynamic contrast-enhanced MRI ( 256 , 273 , 274 ), and repeatability have also been demonstrated ( 258 ).…”