Abstract
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Background: Primary cardiac tumors are rare, most of these tumors are benign. Metastases to the heart are far more common than primary cardiac tumors. They are usually diagnosed by use of transthoracic and transesophageal echocardiograms, MRI, and CT scan which provide only regional anatomical information, but not metabolic information and whole body involvement. Different types of disease have different treatment and prognosis, so it’s important to diagnose correctly before therapy. 18F-FDG PET/CT has the potential to overcome the aforementioned problems. The objective of this study was to evaluate the diagnostic and prognostic value of 18F-FDG PET/CT in patients with cardiac masses.
Methods: Whole-body 18F-FDG PET/CT scans of 64 patients with cardiac masses from August 2012 to August 2018 were retrospectively analyzed (34 men, 30 women; mean age, 51.2±17.5 y). Patients were divided into malignant group and benign group. Quantitative analysis of 18F-FDG uptake (SUVmax, SUVmean, Volume and TLG) of the tumors were performed and was compared between the 2 groups. Receiver operator characteristic (ROC) curve was applied to determine the best cut-off value of differentiating benign and malignant diseases. Histology or long-term follow-up served as ground truth. Follow-up evaluation was completed for 68.9% of the patients and extended up to 6 years. Kaplan-Meier estimates were used to evaluate the predictive value of SUVmax for progression-free survival (PFS) and overall survival (OS).
Results: Cardiac masses were diagnosed as follows: Malignancy, 38 (primary tumors [n=17], metastases [n=15], lymphomas [n=6]); Non-malignancy, 26 (myxoma [n=7], thrombus [n=5], diseases of mitral annulus [n=4], ventricular aneurysm [n=3], lipoma [n=2], cavernous hemangioma [n=1], fibroelastoma [n=1], vascular leiomyoma [n=1], unknown [n=2]). The SUVmax (11.7±5.2 vs. 5.3±2.7, P < 0.05), SUVmean (4.8±2.1 vs. 2.6±1.7, P < 0.05), volume (173.9±188.2 vs. 45.9±48.2, P < 0.05) and TLG (919.3±1115.3 vs. 108.8±120.3, P < 0.05) in malignant lesions was significantly higher than in benign cases. When a threshold of 6.7 was used, the sensitivity and specificity of SUVmax for differentiating malignant and begign diseases was 92.1% and 90.9%, respectively. The best cut-off value, sensitivity and specificity of SUVmean, Volume and TLG were 3.2, 84.2%, 86.4%; 94.6, 57.9%, 95.5%; 201.7, 76.3%, 90.9%, respectively. In addition, extracardiac lesions were detected in 25 patients by whole-body 18F-FDG PET/CT. Forty four patients have survival information, of the 20 patients with SUVmax < 6.7, two (10%) died (one patient with myxoma died during surgery, and the other one is died of widespread ovarian cancer with a metastasis in right atrium), whereas 17 (70.8%) patients progressed or died in those patients with SUVmax ≥ 6.7 (P < 0.05). Kaplan-Meier estimates revealed patients with SUVmax ≥ 6.7 were significantly likely to have inferior PFS (P < 0.05) and OS (P < 0.05). The 2-y and 5-y OS rates of patients with SUVmax < 6.7 were 88% and 88%, respectively, and 23% and 11% in patients with SUVmax ≥ 6.7.
Conclusions: 18F-FDG PET/CT is helpful in differentiating cardiac masses before treatment noninvasively, and has value in detecting extracardiac primary or metastases. SUVmax displayed potential predictive value for cardiac masses. KEY WORDS: 18F-FDG, PET/CT, cardiac masses, diagnosis, prognosis This work was supported by the National Natural Science Foundation of China (No. 81401444 and 81873906), and the Clinical Research Physician Program of Tongji Medical College, Huazhong University of Science and Technology (No. 5001530008).