Evaluation of Dynamic Contrast-Enhanced MRI Measures of Lung Congestion and Endothelial Permeability in Heart Failure: A Prospective Method Validation Study.

Background: Methods for accurate quantification of lung fluid in heart failure (HF) are needed. Dynamic contrast-enhanced (DCE)-MRI may be an appropriate modality.

Purpose: DCE-MRI evaluation of fraction of fluid volume in the interstitial lung space (v ) and vascular permeability (K ).

Study Type: Prospective, single-center method validation.

Population: Seventeen evaluable healthy volunteers (HVs), 12 participants with HF, and 3 with acute decompensated HF (ADHF).

Field Strength/sequence: T mapping (spoiled gradient echo variable flip angle acquisition) followed by dynamic series (three-dimensional spoiled gradient-recalled echo acquisitions [constant echo time, repetition time, and flip angle at 1.5 T]).

Assessment: Three whole-chest scans were acquired: baseline (Session 1), 1-week later (Session 2), following exercise (Session 3). Extended Tofts model quantified v and K (voxel-wise basis); total lung median measures were extracted and fitted via repeat measure analysis of variance (ANOVA) model. Patient tolerability of the scanning protocol was assessed.

Statistical Tests: This was constructed as an experimental medicine study.

Primary Endpoints: K and v at baseline (HV vs. HF), change in K and v following exercise, and following lung congestion resolution (ADHF). K and v were fitted separately using ANOVA. Secondary endpoint: repeatability, that is, within-participant variability in v and K between sessions (coefficient of variation estimated via mixed effects model).

Results: There was no significant difference in mean K between HF and HV (P ≤ 0.17): 0.2216 minutes and 0.2353 minutes (Session 1), 0.2044 minutes and 0.2567 minutes (Session 2), 0.1841 minutes and 0.2108 minutes (Session 3), respectively. v was greater in the HF group (all scans, P ≤ 0.02). Results were repeatable between Sessions 1 and 2; mean values for HF and HV were 0.4946 and 0.3346 (Session 1), 0.4353 and 0.3205 (Session 2), respectively. There was minimal difference in K or v between scans for participants with ADHF (small population precluded significance testing). Scanning was well tolerated.

Data Conclusion: While no differences were detected in K , v was greater in chronic HF patients vs. HV, augmented beyond plasma and intracellular volume. DCE-MRI is a valuable diagnostic and physiologic tool to evaluate changes in fluid volume in the interstitial lung space associated with symptomatic HF.

Level Of Evidence: 2 TECHNICAL EFFICACY STAGE: 2.