T1 Mapping in Cardiomyopathy at Cardiac MR: Comparison with Endomyocardial Biopsy

Abstract

Purpose:To determine the utility of cardiac magnetic resonance (MR) T1 mapping for quantification of diffuse myocardial fibrosis compared with the standard of endomyocardial biopsy. Materials and Methods:This HIPAA-compliant study was approved by the institutional review board. Cardiomyopathy patients were retrospectively identified who had undergone endomyocardial biopsy and cardiac MR at one institution during a 5-year period. Forty-seven patients (53% male; mean age, 46.8 years) had undergone diagnostic cardiac MR and endomyocardial biopsy. Thirteen healthy volunteers (54% male; mean age, 38.1 years) underwent cardiac MR as a reference. Myocardial T1 mapping was performed 10.7 minutes 6 2.7 (standard deviation) after bolus injection of 0.2 mmol/kg gadolinium chelate by using an inversion-recovery Look-Locker sequence on a 1.5-T MR imager. Late gadolinium enhancement was assessed by using gradientecho inversion-recovery sequences. Cardiac MR results were the consensus of two radiologists who were blinded to histopathologic findings. Endomyocardial biopsy fibrosis was quantitatively measured by using automated image analysis software with digital images of specimens stained with Masson trichrome. Histopathologic findings were reported by two pathologists blinded to cardiac MR findings. Statistical analyses included Mann-Whitney U test, analysis of variance, and linear regression. Results:Median myocardial fibrosis was 8.5% (interquartile range, 5.7-14.4). T1 times were greater in control subjects than in patients without and in patients with evident late gadolinium enhancement (466 msec 6 14, 406 msec 6 59, and 303 msec 6 53, respectively; P , .001). T1 time and histologic fibrosis were inversely correlated (r = 20.57; 95% confidence interval: 20.74, 20.34; P , .0001). The area under the curve for myocardial T1 time to detect fibrosis of greater than 5% was 0.84 at a cutoff of 383 msec. Conclusion:Cardiac MR with T1 mapping can provide noninvasive evidence of diffuse myocardial fibrosis in patients referred for evaluation of cardiomyopathy.q RSNA, 2012

T1 Mapping in Characterizing Myocardial Disease

“…More importantly, they revealed abnormal T1 values in the remote, noninfarcted myocardium and a significant relationship with histologically determined collagen volume fraction, allowing an insight into the state of pathological remodeling in what was commonly considered as a normal reference. Later studies reiterated this relationship in patients with HF, [42][43][44][45] severe aortic stenosis, [46][47][48][49][50] and HCM 46 ( Table 3). Although these studies reported significant relationship with collagen volume fraction for all T1 indices, there is a considerable variation in the strengths of observed relationships.…”

T1, T2 Mapping and Extracellular Volume Fraction (ECV): Application, Value and Further Perspectives in Myocardial Inflammation and Cardiomyopathies

“…In a study by Dass et al, for example, native T1 values in patients with HCM were significantly higher even in LGE unaffected myocardial tissue areas compared to healthy volunteers [4]. In addition, myocardial post-contrast T1 times are significantly lower in HCM compared to healthy volunteers [48] and are inversely correlated to the degree of fibrosis [46]. Finally, ECV values are significantly elevated in HCM and also in HCM sarcomere mutation carriers, even in the absence of left ventricular hypertrophy [49].…”

Molecular Imaging of the Cardiac Extracellular Matrix

“…33 In another study of patients with heart failure, postgadolinium T1 time was inversely correlated with histological fibrosis identified by endomyocardial biopsy (r=0.57; P<0.0001). 34 Prognostic data are now emerging as in a recent study of 100 patients with heart failure and preserved ejection fraction; T1 times below the median were associated with an increased risk of cardiac events compared with those above the median.…”