Comparison of phase-resolved functional lung (PREFUL) MRI and CT parametric response mapping (PRM) in COSYCONET COPD

To compare regional ventilation assessed by non-contrast enhanced ventilation-weighted phase-resolved functional lung (PREFUL) MRI with parametric response mapping (PRM) and with pulmonary function test (PFT) parameters in patients with chronic obstructive pulmonary disease (COPD).

This study was a retrospective analysis of a single-center subset of the prospective COPD cohort COSYCONET. PREFUL MRI coronal sections were obtained during free breathing at 1.5 T using a spoiled gradient echo sequence. PRM was derived from paired low-dose inspiratory and expiratory CT scans. Matched coronal slices of PREFUL and PRM were co-registered. PREFUL ventilation defect percentage (PREFUL-VDP), as well as functional small airway disease (PRM^fSAD), emphysema (PRM^emph), and their combined metric (PRM^fSAD+emph), were calculated. Global comparisons employed Spearman's correlation coefficient (r) and Wilcoxon signed-rank tests. Spatial agreement was assessed using spatial overlap and the Dice coefficient.

Fifty-one patients (median age 65 [58-70]) were included in this study. PREFUL-VDP strongly correlated with combined PRM^fSAD+emph (r = 0.86. p < 0.001) and with PFT parameters (PREFUL-VDP vs FEV1, r = -0.75, p < 0.001). Correlations between PREFUL-VDP with PRM^fSAD and PRM^emph separately were weaker (r = 0.57 and r = 0.82, p < 0.001 for both). In concordance, the highest spatial congruence was observed between PREFUL-VDP and PRM^fSAD+emph (spatial overlap: 0.60 [0.55-0.66], Dice coefficient for defects: 0.53 [0.28-0.62]), indicating that PREFUL-VDP does not distinguish between small airway disease and emphysema.

PREFUL-VDP correlates most strongly with the PRM measurement of emphysema and functional small airways disease combined and is a promising noninvasive, radiation-free tool for quantifying regional ventilation in COPD.

QuestionHow does regional ventilation in COPD, measured by PREFUL MRI, correspond to CT-based PRM metrics? FindingsPREFUL MRI's VDP showed strong correlation and the highest spatial agreement with the combined CT PRM metric representing emphysema and functional small airways disease. Clinical relevancePREFUL MRI offers a non-invasive, radiation-free method for assessing regional ventilation in COPD. Although PREFUL cannot distinguish emphysema from small airways disease, its strong correlation with CT PRM highlights its value for disease characterization and functional monitoring.