Abstract Rationale Previous work on post-acute sequelae of SARS-CoV-2 (Long-COVID) using dynamic contrast-enhanced (DCE) MRI has shown that global pulmonary perfusion metrics (pulmonary blood flow (PBF) and blood volume (PBV)) may not differ significantly from healthy controls. However, temporal dynamics of the tissue contrast-time curve after first passage of the contrast agent may capture subclinical remodeling. In this study, we used DCE-MRI to estimate global pulmonary perfusion metrics in Long-COVID and idiopathic pulmonary fibrosis (IPF) to determine whether Long-COVID exhibits perfusion alterations distinct from IPF, a disease characterized by well-established vascular remodeling. Methods Patients with ongoing symptoms (dyspnea, fatigue, loss of taste/smell) a year post-acute COVID-19 (Long-COVID) were recruited. DCE-MRI data from stable IPF, and controls from a previous study were included. Controls and IPFstable subjects received a gadolinium-based contrast agent (MultiHance; gadobenate dimeglumine) at a dose of 0.05 mmol/kg at 4 mL/s, followed by a 35 mL saline flush. Long-COVID subjects were imaged following administration of ProHance (gadoteridol) at the same dosage and rate. All participants were scanned at end-expiratory breath-hold on 3T systems. Long-COVID participants on a GE Premier, while IPFstable patients and controls on a GE Discovery MR750. Quantitative metrics (PBF and PBV) were estimated using singular value decomposition (SVD) deconvolution of an arterial input function measured from the concentration of contrast at the main pulmonary artery. First-moment transit time (FMTT) and time-to-peak (TTP) were derived from the tissue contrast-time curve. Global analysis used the whole-lung median of each parametric map per participant. Results Participant demographics and quantitative measurements are summarized in Table 1. Global analysis showed no significant difference in PBF and PBV between controls and IPFstable nor between controls and Long-COVID. DCE-MRI revealed significant differences between IPFstable and Long-COVID participants in age (p = 0.004), FMTT (p = 0.038), and TTP (p = 0.006). FMTT and TTP were longest in IPFstable compared to Long-COVID and controls Conclusion We found physiologically consistent differences in kinetic timing metrics (FMTT, TTP) between Long-COVID and IPFstable, whereas PBF and PBV did not differ significantly. These findings suggest that wash-in/wash-out kinetics may capture disease-specific differences in pulmonary perfusion in global analyses. The difference in kinetic timing metrics seen in IPFstable and Long-COVID maybe partly age-driven not purely disease specific. Further regional analysis may help detect subclinical alterations in perfusion that are hypothesized in this cohort, and help detect differences between the two groups, that may go undetected by global metrics. This abstract is funded by: The American Lung Association’s COVID-19 & Emerging Respiratory Virus Research Award,
Aboderin et al. (Fri,) studied this question.