Key result
Cardiovascular magnetic resonance native T1 and extracellular volume fraction of the right ventricular free wall significantly increased with pulmonary hypertension progression and strongly correlated with histological collagen density.
Why the study?
Right ventricular free wall fibrosis is an important component of adverse remodeling in pulmonary hypertension, but no previous reports had compared CMR findings with histological analysis.
Does CMR T1 mapping with ECV accurately evaluate the progression of right ventricular free wall fibrosis compared to histology in a rat model of pulmonary hypertension?
Does CMR T1 mapping with ECV accurately evaluate the progression of right ventricular free wall fibrosis compared to histology in a rat model of pulmonary hypertension?
Answers are grounded in this paper and cite their sources.
CMR T1 mapping with ECV is a feasible non-invasive method for evaluating the progression of right ventricular free wall fibrosis in pulmonary hypertension, correlating strongly with histological collagen density.
BACKGROUND: Right ventricular (RV) free wall fibrosis is an important component of adverse remodeling with RV dysfunction in pulmonary hypertension (PH). However, no previous reports have compared cardiovascular magnetic resonance (CMR) findings and histological analysis for RV free wall fibrosis in PH. We aimed to assess the feasibility of CMR T1 mapping with extracellular volume fraction (ECV) for evaluating the progression of RV free wall fibrosis in PH, and compared imaging findings to histological collagen density through an animal study. METHODS: Among 42 6-week-old Wistar male rats, 30 were classified according to disease duration (baseline before monocrotaline injection, and 2, 4, 6 and 8 weeks after injection) and 12 were used to control for aging (4 and 8 weeks after the baseline). We obtained pre and post-contrast T1 maps for native T1 and ECV of RV and left ventricular (LV) free wall for six animals in each disease-duration group. Collagen density of RV free wall was calculated with Masson's trichrome staining. The Kruskall-Wallis test was performed to compare the groups. Native T1 and ECV to collagen density were analyzed with Spearman's correlation. RESULTS: The mean values of native T1, ECV and collagen density of the RV free wall at baseline were 1541 ± 33 ms, 17.2 ± 1.3%, and 4.7 ± 0.5%, respectively. The values of RV free wall did not differ according to aging (P = 0.244, 0.504 and 0.331, respectively). However, the values significantly increased according to disease duration (P < 0.001 for all). Significant correlations were observed between native T1 and collagen density (r = 0.770, P < 0.001), and between ECV and collagen density for the RV free wall (r = 0.815, P < 0.001) in PH. However, there was no significant difference in native T1 and ECV values for the LV free wall according to the disease duration from the baseline (P = 0.349 and 0.240, respectively). CONCLUSIONS: We observed significantly increased values for native T1 and ECV of the RV free wall without significant increase of the LV free wall according to the disease duration of PH, and findings were well correlated with histological collagen density.
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Kim et al. (2021) studied Pulmonary hypertension (n=42). Monocrotaline-induced pulmonary hypertension vs. Baseline and aging controls was evaluated on Correlation of native T1 and ECV with histological collagen density in the RV free wall (r = 0.770 (native T1) and r = 0.815 (ECV), p=<0.001). Cardiovascular magnetic resonance native T1 and extracellular volume fraction of the right ventricular free wall significantly increased with pulmonary hypertension progression and strongly correlated with histological collagen density.
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