Multiparameter diagnostic model based on 18F-FDG PET and clinical characteristics can differentiate thymic epithelial tumors from thymic lymphomas

Abstract

Objective To evaluate the diagnostic performance of combined multiparametric 18F-fluorodeoxyglucose positron emission tomography (18FDG PET) with clinical characteristics in differentiating thymic epithelial tumors (TETs) from thymic lymphomas. Patients and methods A total of 173 patients with 80 TETs and 93 thymic lymphomas who underwent 18F-FDG PET/CT before treatment were enrolled in this retrospective study. All patients were confirmed by pathology, and baseline characteristics and clinical data were also collected. The semi-parameters of 18F-FDG PET/CT, including lesion size, SUVmax (maximum standard uptake value), SUVmean (mean standard uptake value), TLG (total lesion glycolysis), MTV (metabolic tumor volume) and SUVR (tumor-to-normal liver standard uptake value ratio) were evaluated. The differential diagnostic efficacy was evaluated using the receiver operating characteristic (ROC) curve. Integrated discriminatory improvement (IDI) and net reclassification improvement (NRI), and Delong test were used to evaluate the improvement in diagnostic efficacy. The clinical efficacy was evaluated by decision curve analysis (DCA). Results Age, clinical symptoms, and metabolic parameters differed significantly between patients with TETs and thymic lymphomas. The ROC curve analysis of SUVR showed the highest differentiating diagnostic value (sensitivity = 0.763; specificity = 0.888; area under the curve [AUC] = 0.881). The combined diagnostics model of age, clinical symptoms and SUVR resulted in the highest AUC of 0.964 (sensitivity = 0.882, specificity = 0.963). Compared with SUVR, the diagnostic efficiency of the model was improved significantly. The DCA also confirmed the clinical efficacy of the model. Conclusions The multiparameter diagnosis model based on 18F-FDG PET and clinical characteristics had excellent value in the differential diagnosis of TETs and thymic lymphomas.

A diagnostic model based on 18F-FDG PET/CT parameters in improving the differential diagnosis of invasive thymic epithelial tumors and anterior mediastinal lymphomas

“…Mediastinal lymphomas is predominantly occurred in young adult life [ 25 ]. Previous studies reported that there was a certain value for the age in differentiating TETs and anterior mediastinal lymphomas [ 18 , 26 ]. In this current study, the mean age of patients with invasive TETs was significantly higher than that of anterior mediastinal lymphomas patients (55.84 ± 11.43 years vs 28.97 ± 10.37 years, P < 0.001).…”

“…Giorgio Treglia et al demonstrated that the mean SUVmax in thymic carcinomas was significantly higher than low-risk thymomas [ 30 ]. Moreover, SUVmax also can be used in differentiating TETs and anterior mediastinal lymphomas [ 18 , 31 ]. Catherine T Byrd et al reported that anterior mediastinal tumors with SUVmax less than 7.50 were likely thymoma while anterior mediastinal lymphomas were likely with SUVmax greater than 12.85, and as for tumors with SUVmax between 7.50 and 12.85, it was still need to be biopsied to rule out lymphoma [ 19 ].…”

“…Several studies have confirmed the value of 18 F-FDG PET/CT in the differentiation of benign and malignant anterior mediastinal masses [ 16 , 17 ]. Furthermore, some studies also have found that 18 F-FDG PET/CT has excellent application value in the differentiating thymoma and anterior mediastinal lymphomas [ 18 , 19 ]. Most studies have focused on differentiating thymoma and anterior mediastinal lymphomas while ignoring the different degree of malignancy among thymoma subtypes.…”