MRI Assessment of Lung Water Density in Individuals Previously Infected With COVID-19: A Cross-Sectional Study.

Abstract

Background: Lung damage in post-acute COVID-19 is a common clinical finding. Lung water density (LWD) imaging using ultrashort echo time (UTE) MRI with proton-density weighting is sensitive to edema and fibrosis.

Purpose: To characterize LWD in COVID-19 survivors, compared with a healthy cohort.

Study type: Retrospective cohort.

Populations: 185 COVID-19 survivors (63 male; age [median (interquartile range, IQR)]: 51 (25-83) years; 160 (66-363) days from COVID-19 infection to MRI) and 109 healthy controls (64 male; age: 52 (27-76) years) with no history of COVID-19 infection.

Field strength/sequence: 2.89T; Yarnball UTE pulse sequence.

Assessment: Free-breathing three-dimensional LWD images were acquired in both cohorts. Clinical demographics (age, sex, body mass index [BMI]), presence of comorbidities (hypertension, dyslipidemia, diabetes, obesity), COVID-19 hospitalization, pulmonary function, six-minute walking distance, and plasma biomarkers were recorded.

Statistical tests: Student's t-tests or Mann-Whitney U tests were used to compare lung water metrics between cohorts. The effect of comorbidities was assessed using Kruskal-Wallis tests followed by pairwise Wilcoxon tests with Bonferroni correction. Categorical variables were compared using chi-squared tests. p < 0.05 was considered significant.

Results: LWD (median (IQR)), was significantly greater in the post-COVID-19 cohort than in the healthy cohort, 31.3 (6.6)% versus 27.9 (6.5)% in men and 30.3 (7.4)% versus 27.5 (4.9)% in women. 37% of men and 24% of women in the post-COVID-19 cohort had LWD above the healthy cohort 95% confidence limit. Participants with elevated LWD had significantly higher BMI (kg/m²) (32 (5) versus 26 (4) in men, 33 (9) versus 26 (7) in women), incidence of comorbidities (78% vs. 50% in men, 72% vs. 38% in women), rates of COVID-19 hospitalization (52% vs. 23% in men, 38% vs. 18% in women), and elevated CRP (mg/L) (2.2 (3.4) vs. 1.1 (1.4) in men, 1.8 (4.2) vs. 1.2 (2.1) in women).

Data conclusion: MRI-derived LWD is elevated in COVID-19 survivors and is related to high BMI, COVID-19 hospitalization, inflammatory plasma biomarkers, and the presence of comorbidities.

Evidence level: 2.

Technical efficacy: Stage 3.