Phase‐Resolved Functional Lung (PREFUL) MRI May Reveal Distinct Pulmonary Perfusion Defects in Postacute COVID‐19 Syndrome: Sex, Hospitalization, and Dyspnea Heterogeneity

Background Pulmonary perfusion defects have been observed in patients with coronavirus disease 2019 (COVID‐19). Currently, there is a need for further data on non‐contrast‐enhanced MRI in COVID patients. The early identification of heterogeneity in pulmonary perfusion defects among COVID‐19 patients is beneficial for their timely clinical intervention and management. Purpose To investigate the utility of phase‐resolved functional lung (PREFUL) MRI in detecting pulmonary perfusion disturbances in individuals with postacute COVID‐19 syndrome (PACS). Study Type Prospective. Subjects Forty‐four participants (19 females, mean age 64.1 years) with PACS and 44 healthy subjects (19 females, mean age 59.5 years). Moreover, among the 44 patients, there were 19 inpatients and 25 outpatients; 19 were female and 25 were male; 18 with non‐dyspnea and 26 with dyspnea. Field Strength/Sequence 3‐T, two‐dimensional (2D) spoiled gradient‐echo sequence. Assessment Ventilation and perfusion‐weighted maps were extracted from five coronal slices using PREFUL analysis. Subsequently, perfusion defect percentage (QDP), ventilation defect percentage (VDP), and ventilation‐perfusion match healthy (VQM) were calculated based on segmented lung parenchyma ventilation and perfusion‐weighted maps. Additionally, clinical features, including demographic data (such as sex and age) and serum biomarkers (such as D‐dimer levels), were evaluated. Statistical Tests Spearman correlation coefficients to explore relationships between clinical features and QDP, VDP, and VQM. Propensity score matching analysis to reduce the confounding bias between patients with PACS and healthy controls. The Mann–Whitney U tests and Chi‐squared tests to detect differences between groups. Multivariable linear regression analyses to identify factors related to QDP, VDP, and VQM. A P ‐value <0.05 was considered statistically significant. Results QDP significantly exceeded that of healthy controls in individuals with PACS (39.8% ± 15.0% vs. 11.0% ± 4.9%) and was significantly higher in inpatients than in outpatients (46.8% ± 17.0% vs. 34.5% ± 10.8%). Moreover, males exhibited pulmonary perfusion defects significantly more frequently than females (43.9% ± 16.8% vs. 34.4% ± 10.2%), and dyspneic participants displayed significantly higher perfusion defects than non‐dyspneic patients (44.8% ± 15.8% vs. 32.6% ± 10.3%). QDP showed a significant positive relationship with age ( β = 0.50) and D‐dimer level ( β = 0.72). Data Conclusion PREFUL MRI may show pulmonary perfusion defects in patients with PACS. Furthermore, perfusion impairments may be more pronounced in males, inpatients, and dyspneic patients. Evidence Level 2 Technical Efficacy Stage 2