T1 Mapping by CMR Imaging

Fro Ge He Sie infl La Ph Ma OBJECTIVES The purpose of this study was to prospectively investigate the diagnostic and prognostic impact of cardiac magnetic resonance (CMR) T1 mapping and validate it against left ventricular biopsies. BACKGROUND Extracellular volume (ECV) expansion is a key feature of heart failure. CMR T1 mapping has been developed as a noninvasive technique to estimate ECV; however, the diagnostic and prognostic impacts of this technique have not been well established. METHODS A total of 473 consecutive patients referred for CMR (49.5% female, age 57.8 17.1 years) without hypertrophic cardiomyopathy, cardiac amyloidosis, or Anderson-Fabry disease were studied. T1 mapping with the modified Look-Locker inversion recovery (MOLLI) sequence was used for ECV calculation (CMR-ECV). For methodological validation, 36 patients also underwent left ventricular biopsy, and ECV was quantified by TissueFAXS analysis (TissueFAXS-ECV). To assess the prognostic value of CMR-ECV, its association with hospitalization for cardiovascular reasons or cardiac death was tested in a multivariable Cox regression model. RESULTS TissueFAXS-ECV was 26.3 7.2% and was significantly correlated with CMR-ECV (r 1⁄4 0.493, p 1⁄4 0.002). Patients were followed up for 13.3 9.0 months and divided into CMR-ECV tertiles for Kaplan-Meier analysis (tertiles were #25.7%, 25.8% to 28.5%, and $28.6%). Significantly higher event rates were observed in patients with higher CMR-ECV (log-rank p 1⁄4 0.013). By multivariable Cox regression analysis, CMR-ECV was independently associated with outcome among imaging variables (p 1⁄4 0.004) but not after adjustment for clinical parameters. CONCLUSIONS CMR T1 mapping allows accurate noninvasive quantification of ECV and is independently associated with event-free survival among imaging parameters. Its prognostic value on top of established clinical risk factors warrants further investigation in long-term studies. (J Am Coll Cardiol Img 2016;9:14–23) © 2016 by the American College of Cardiology Foundation. E xtracellular matrix expansion is a hallmark of heart failure. Data from animal and human studies suggest that increased extracellular volume (ECV) is a key finding in both systolic and diastolic heart failure regardless of the cause of the cardiomyopathy (1–7). Given the important prognostic m the *Division of Cardiology, Medical University of Vienna, Vienna, A rmany. This study received support from the Austrian Society of Ca rzfonds (Dr. Mascherbauer) and the Austrian fellowship grant KLI 245 (t mens Healthcare GmbH (Erlangen, Germany) provided the T1-mapping p uence on study design, data processing, or statistical analysis. Dr. Greise ng has received grants and speakers’ fees from Actelion Pharmaceutic armaceuticals. All other authors have reported that they have no relationsh nuscript received August 19, 2015; revised manuscript received October 3 role of myocardial extracellular matrix expansion, a simple and safe method for its quantification is most desirable. Recently, the ability of cardiac magnetic resonance (CMR) to quantify myocardial tissue characteristics by measuring the longitudinal relaxation (T1) time has been demonstrated (8–15). Several ustria; and ySiemens Healthcare GmbH, Erlangen, rdiology (Dr. Mascherbauer), the Österreichischer o Dr. Mascherbauer) and KLI 246 (Dr. Bonderman). rototype as a work-in-progress package but had no r is an employee of Siemens Healthcare GmbH. Dr. als, Bayer, United Therapeutics, and AOP Orphan ips relevant to the contents of this paper to disclose. 0, 2015, accepted November 3, 2015. AB BR E V I A T I O N S