Late Gadolinium Enhancement Cardiac Magnetic Resonance Tissue Characterization for Cancer‐Associated Cardiac Masses: Metabolic and Prognostic Manifestations in Relation to Whole‐Body Positron Emission Tomography

Abstract

Background Cardiac magnetic resonance ( CMR) differentiates neoplasm from thrombus via contrast enhancement; positron emission tomography ( PET) assesses metabolism. The relationship between CMR contrast enhancement and metabolism on PET is unknown. Methods and Results The population included 121 cancer patients undergoing CMR and 18 F‐fluorodeoxyglucose ( 18 F‐ FDG) – PET , including 66 with cardiac masses and cancer‐matched controls. Cardiac mass etiology (neoplasm, thrombus) on CMR was defined by late gadolinium enhancement; PET was read blinded to CMR for diagnostic performance, then colocalized to measure FDG avidity. Of CMR ‐evidenced thrombi (all nonenhancing), none were detected by PET . For neoplasm, PET yielded reasonable sensitivity (70–83%) and specificity (75–88%). Lesions undetected by PET were more likely to be highly mobile ( P =0.001) despite similar size ( P =0.33). Among nonmobile neoplasms, PET sensitivity varied in relation to extent of CMR ‐evidenced avascularity; detection of diffusely enhancing or mixed lesions was higher versus predominantly avascular neoplasms (87% versus 63%). Colocalized analyses demonstrated 2‐ to 4‐fold higher FDG uptake in neoplasm versus thrombus ( P <0.001); FDG uptake decreased stepwise when neoplasms were partitioned based on extent of avascularity on late gadolinium enhancement CMR ( P ≤0.001). Among patients with neoplasm, signal‐to‐noise ratio on late gadolinium enhancement CMR moderately correlated with standardized uptake values on PET ( r =0.42–0.49, P <0.05). Mortality was higher among patients with CMR ‐evidenced neoplasm versus controls (hazard ratio: 1.99 [95% CI, 1.1–3.6]; P =0.03) despite nonsignificant differences when partitioned via FDG avidity (hazard ratio: 1.56 [95% CI, 0.85–2.74]; P =0.16). Among FDG‐positive neoplasms detected concordantly with CMR , mortality risk versus cancer‐matched controls was equivalently increased (hazard ratio: 2.12 [95% CI, 1.01–4.44]; P =0.047). Conclusions CMR contrast enhancement provides a criterion for neoplasm that parallels FDG ‐evidenced metabolic activity and stratifies prognosis. Extent of tissue avascularity on late gadolinium enhancement CMR affects cardiac mass identification by FDG ‐ PET .