T1 mapping in dilated cardiomyopathy with cardiac magnetic resonance: quantification of diffuse myocardial fibrosis and comparison with endomyocardial biopsy

Abstract

ECV measurement with CMR reflects myocardial collagen content in DCM. Therefore, CMR-based assessment of ECV may have the potential to serve as a non-invasive tool for the quantification of diffuse MF in order to monitor therapy response and aid risk stratification in different stages of DCM.

T1 Mapping in Characterizing Myocardial Disease

“…Because of its ability to recognize subclinical diffuse myocardial involvement, as well as a measure of longitudinal changes of myocardial inflammation, T1 mapping seems promising for detecting subclinical pathophysiological changes, potentially allowing us to modify the course of disease. This is supported by histological data 45,51 on accumulation of diffuse fibrosis and the parallel relationships of T1 mapping with progressive ventricular remodeling and stiffness in DCM. 11,45,[83][84][85][86] Abnormal T1-mapping indices were also found in other common causes of DCM, including patients with cardiac amyloidosis, [87][88][89] diabetic cardiomyopathy, 34,90 and iron overload cardiomyopathies.…”

“…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.…”

“…These differences are partially because of technical issues discussed earlier: T1-accurate sequences will show stronger relationship with postcontrast T1 or ECV, but not native T1, and vice versa for T2-sensitive sequences. In some studies, areas of replacement fibrosis (seen as LGE) were included in histological collagen volume fraction, showing stronger relationships, [44][45][46]49 compared with those studies that focused primarily on the diffuse interstitial component. 35,41,42,47,50 The majority of studies relied on minute amounts of tissue from endomyocardial biopsy; explanted hearts were analyzed in only 2 studies.…”

“…Discriminative focus on replacement versus interstitial fibrosis is a paramount factor influencing the diversity of observed relationships; whereas some authors steered away from the inclusion of replacement fibrosis/LGE affected areas in histological CVF (or accounted for them separately), 35,41,47,51 or all-inclusive. 44,45,49 CVF indicates collagen volume fraction; DCM, dilative cardiomyopathy; ECV, extracellular volume fraction; FLASH-IR, fast low angle shot-inversion recovery; GCA, gadolinium contrast agents; IHD, ischemic heart disease; MOLLI, modified LookLocker imaging; NICM, nonischemic cardiomyopathies; and VAST, variable temporal sampling of k-space. for the presence of or exclusion of myocardial edema, thus supporting confirmation and exclusion of disease.…”

The Prognostic Role of T1 Mapping Sequences: Can T1 Mapping Parameters Have a Role in Risk Stratification?

“…Several studies have explored tissue validation of T1 mapping [1][2][3]. Currently, T1 relaxation time and calculated extracellular volume fraction (ECV) are accepted as reliable markers of the degree of diffuse interstitial fibrosis [4].…”