Myocardial Extracellular Volume Fraction From T1 Measurements in Healthy Volunteers and Mice

Abstract

Objectives We aimed to test the characteristics of the myocardial extracellular volume (ECV) fraction derived from pre and post-contrast T1 measurements among healthy volunteers. Background Cardiac magnetic resonance (CMR) T1 measurements of myocardium and blood before and after contrast allow quantification of the ECV, a tissue parameter that has been shown to change in proportion to the connective tissue fraction. Methods Healthy volunteers underwent a standard CMR with administration of gadolinium. T1 measurements were performed with a Look-Locker sequence followed by gradient-echo acquisition. We tested the segmental, inter-slice, inter-, intra-, and test-retest characteristics of the ECV, as well as the association of the ECV with other variables. Juvenile and aged mice underwent a similar protocol and cardiac sections were harvested for measurement of fibrosis. Results In healthy volunteers (n=32, 56% female; ages 21 to 72), the ECV averaged 0.28 ± 0.03 (range 0.23 to 0.33). The intra-class coefficients for the intra-observer, inter-observer, and test-retest absolute agreements of the ECV were 0.94 (95% confidence interval, 0.84 to 0.98), 0.93 (95% confidence interval, 0.80 to 0.98), and 0.95 (95% confidence interval, 0.52 to 0.99), respectively. In volunteers, the ECV was associated with age (r=0.74, p< 0.001), maximal LA volume index (r=0.67, p< 0.001), and indexed LV mass. There were no differences in the ECV between segments in a slice or between slices. In mice (n=12) the myocardial ECV ranged from 0.20 to 0.32 and increased with age (0.22 ± 0.02 vs. 0.30 ± 0.02, juvenile vs. aged mice, p< 0.001). In mice, the ECV correlated with the extent of myocardial fibrosis (r=0.94, p< 0.001). Conclusion In healthy volunteers, the myocardial ECV ranges from 0.23 to 0.33, has acceptable test characteristics, and is associated with age, LA volume, and LV mass. In mice, the ECV also increases with age and strongly correlates with the extent of myocardial fibrosis.

Sickle cell anemia mice develop a unique cardiomyopathy with restrictive physiology

“…3D), demonstrating that Berk-SS mice do indeed have evidence of diffuse myocardial fibrosis, which likely results in impaired relaxation, restrictive ventricular filling, and LAE. Our ECV values for normal mice (25 ± 7%) are within the range of published ECV values for mice [22% for juvenile mice and 32% for aged mice (54)]. However, it should be noted that because of various forms of errors in T1 measurement at high field strengths (55), MRIderived ECV measurements at 7T are best at depicting relative measures of fibrosis between groups rather than absolute values.…”

Anthracycline‐Induced Cardiomyopathy in Adults

“…However, late gadolinium enhancement (LGE), the imaging method of choice to detect myocardial necrosis and replacement fibrosis as seen in myocardial infarction, is not routinely detected among patients treated with anthracyclines (39,140,142). The low incidence of LGE abnormalities in this population reflects a limitation of LGE-based assessment of myocardial fibrosis, namely, that LGE requires a normal reference to define abnormal and has supported research into novel quantitative measures of diffuse myocardial fibrosis (141). Measurement of native T1, T1 mapping, or measurement of the myocardial extracellular volume (ECV) provides a quantitative measure of diffuse myocardial fibrosis (Fig.…”

T1 Measurements for Detection of Expansion of the Myocardial Extracellular Volume in Chronic Obstructive Pulmonary Disease

“…9 Determination of the myocardial extracellular volume (ECV) by T1 measurements is a robust method for quantifying diffuse myocardial fibrosis. 10-12 The ECV by CMR has been validated against histological measures of fibrosis, 10, 11 is associated with measures of myocardial function, 13 and is an independent predictor of mortality among broad populations with cardiovascular disease. 14 We hypothesized that an expanded ECV would provide this marker of increased cardiovascular risk in patients with COPD.…”