Predictive value of the metabolic tumor volume ratio of cardiac mass to maximal extra cardiac mass for the origin of cardiac tumors

Abstract

Objective To explore the value of metabolic volume of cardiac tumor (MTV1) to that of the maximum extracardiac tumor (MTV2) ratio in predicating the cardiac tumor origin. Methods A total of 35 consecutive cases (19 males, 16 females, age range: 18-68 years) with multiple cardiac and extracardiac tumors were enrolled in this retrospective analysis. All of them were confirmed by pathology or clinical follow-up results and examined by 18F-fluorodeoxyglucose PET/CT from January 2010 to February 2016. Maximum standardized uptake value (SUVmax) 3.63 was used as the background threshold. MTV1 and MTV2 were automatically obtained by PETVCRA software. Receiver operating characteristic (ROC) curve was drawn to obtain the diagnostic threshold of MTV1/MTV2 ratio for cardiac tumors, and the sensitivity, specificity and accuracy were calculated. Mann-Whitney u test was used to analyze the data. Results Twelve patients were confirmed to have primary cardiac malignant tumors (PCMT), and 23 cases were metastatic cardiac malignant tumors (MCMT). There was statistical difference of MTV1 between PCMT and MCMT patients: 52.9(33.3, 703.4) cm3vs 8.1(1.2, 24.6) cm3 (z=-3.70, P<0.05). MTV2 was 11.7(1.8, 38.4) cm3 in PCMT patients, which was lower than that in MCMT patients (182.0(100.1, 238.0) cm3;z=-4.17, P<0.05). MTV1/MTV2 ratio of PCMT was 16.20(9.40, 71.80), which was significantly higher than that of MCMT (0.10(0.01, 0.60), z=-4.66, P<0.05). When MTV1/MTV2 ratio=1.2 was selected as the cut-off value, the sensitivity, specificity and accuracy were 12/12, 91.30%(21/23), 94.29%(33/35) respectively. Conclusion It may be an important criterion for the diagnosis of PCMT that MTV1 is greater than MTV2. Key words: Heart neoplasms; Positron-emission tomography; Tomography, X-ray computed; Deoxyglucose