assessment of mediastinal tumors using suvmax and volumetric parameters on fdg pet/ct

Objective(s): this study aimed to evaluate the role of pretreatment suvmax and volumetric fdg positron emission tomography (pet) parameters in the differentiation between benign and malignant mediastinal tumors. in addition, we investigated whether pretreatment suvmax and volumetric fdgpet parameters could distinguish thymomas from thymic carcinomas, and lowrisk from highrisk thymomas.methods: this study was conducted on 52 patients with mediastinal tumors undergoing fdgpet/ct. histological examination indicated that 29 mediastinal tumors were benign, and 23 cases were malignant. to obtain quantitative pet/ct parameters, we determined the maximum standardized uptake value (suvmax), volumetric parameters, metabolic tumor volume (mtv), and total lesion glycolysis (tlg) for primary tumors using suvmax cutoff value of 2.5. suvmax, mtv and tlg of benign and malignant tumors were comparedusing the mannwhitney u test. moreover, receiveroperating curve (roc) analysis was applied to identify the cutoff values of suvmax, mtv and tlg for the accurate differentiation of benign and malignant tumors. suvmax, mtv and tlg were compared between thymomas and thymic carcinomas, as well as lowrisk and highrisk thymomas.results: mean suvmax, mtv and tlg of malignant mediastinal tumors were significantly higher compared to benign tumors (p<0.001). sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of suvmax were 78.2%, 86.2%, 82.6%,81.8%, and 83.3%, respectively. these values were estimated at 82.6%, 96.6%, 90.4%,95%, and 87.5% for mtv and tlg, respectively. additionally, optimal cutoff values for the differentiation of benign and malignant mediastinal tumors were determined at 4.2 and 22.3 ml and 79.7 g for suvmax, mtv and tlg, respectively. mean suvmax, mtv and tlg of thymic carcinomas were significantly higher compared to thymomas (p<0.01), while no significant differences were observed in the mean quantitative parameters between lowrisk and highrisk thymomas.conclusion: although suvmax, mtv and tlg could not distinguish between lowrisk and highrisk thymomas, these parameters might be able to differentiate benign tumors from malignant mediastinal tumors  noninvasively. these parameters could be used to distinguish between thymomas and thymic carcinomas as well. therefore, fdgpet/ct parameters seem to be accurate indices for the detection of malignant mediastinal tumors.