Abstract 10729: Parametric T1 Mapping for Quantitative Differentiation of Cardiac Metastases and Thrombus on Cardiac Magnetic Resonance

Abstract

Introduction: Cardiac magnetic resonance (CMR) is widely used to assess cancer patients (pts) with cardiac masses (C MASS ); contrast uptake on late gadolinium enhancement (LGE) is a reference to distinguish cardiac metastases (C MET ) from thrombus (C THR ). Parametric T1 mapping is an alternate approach to quantify pre and post-contrast tissue properties: Utility of T1 mapping to differentiate C MET and C THR is unknown. Hypothesis: Among cancer pts with cardiac masses, pre and post contrast T1 mapping can distinguish C MET from C THR . Methods: The population comprised cancer pts with C MASS ; etiology was classified by presence (C MET ) or absence (C THR ) of enhancement on LGE-CMR. T1 mapping entailed a MOLLI pulse sequence acquired in co-registered locations (pre, post contrast) within C MASS as localized on cine-CMR - mobile masses (prohibiting T1 evaluation) were excluded. T1 analyses were performed blinded to clinical, LGE, cine-CMR data. Results: 94 C MASS pts (54±18 yo, 53% M) with an array of cancers (29% sarcoma, 19% GI, 13% GU) were studied, among whom 81% (n=76) had C MET and 19% (n=18) C THR on LGE-CMR. Cardiac structure, function, and clinical characteristics were similar (p=NS) between groups, but location differed with C THR right-sided [RA 94%, RV 6%) and C MET variable (LV 29%, RV 25%, LA 30%, RA 32%). On T1 mapping, C MET had longer pre-contrast T1 (1355±359 vs. 1135±195 msec, p=0.001) and shorter post contrast T1 (437±196 vs. 755±199 msec, p<0.001), with resultant higher ECV (41±19 and 10±6%, p<0.001) than did C THR ( Figure ). ROC analyses showed high overall diagnostic performance for T1 mapping to differentiate C MET from C THR based on AUC (pre: 0.71, post: 0.88, ECV: 0.92 [all p<0.01): Maximum partition cutoffs for pre (1284msec) post (578msec) and ECV (22%) yielded good sensitivity and specificity to delineate C MASS subtypes. Conclusion: Among cancer pts with cardiac masses, T1 mapping - including pre and post contrast tissue characterization - can distinguish C MET from C THR .