Morita Takahiro, Tatsumi Mitsuaki, Ishibashi Mana, Isohashi Kayako, Kato Hiroki, Honda Osamu, Shimosegawa Eku, Tomiyama Noriyuki, Hatazawa Jun
Department of Nuclear Medicine and Tracer Kinetics, Graduate School of Medicine, Osaka University, Suita, Japan.
Department of Radiology, Osaka University Hospital, Suita, Japan.
Asia Ocean J Nucl Med Biol. 2017 Winter;5(1):22-29. doi: 10.22038/aojnmb.2016.7996.
This study aimed to evaluate the role of pretreatment SUV and volumetric FDG positron emission tomography (PET) parameters in the differentiation between benign and malignant mediastinal tumors. In addition, we investigated whether pretreatment SUV and volumetric FDG-PET parameters could distinguish thymomas from thymic carcinomas, and low-risk from high-risk thymomas.
This study was conducted on 52 patients with mediastinal tumors undergoing FDG-PET/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 (SUV), volumetric parameters, metabolic tumor volume (MTV), and total lesion glycolysis (TLG) for primary tumors using SUV cut-off value of 2.5. SUV, MTV and TLG of benign and malignant tumors were compared using the Mann-Whitney U test. Moreover, receiver-operating curve (ROC) analysis was applied to identify the cut-off values of SUV, MTV and TLG for the accurate differentiation of benign and malignant tumors. SUV, MTV and TLG were compared between thymomas and thymic carcinomas, as well as low-risk and high-risk thymomas.
Mean SUV, 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 SUV 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 cut-off values for the differentiation of benign and malignant mediastinal tumors were determined at 4.2 and 22.3 mL and 79.7 g for SUV, MTV and TLG, respectively. Mean SUV, 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 low-risk and high-risk thymomas.
Although SUV, MTV and TLG could not distinguish between low-risk and high-risk 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, FDG-PET/CT parameters seem to be accurate indices for the detection of malignant mediastinal tumors.
本研究旨在评估治疗前标准化摄取值（SUV）和容积性氟代脱氧葡萄糖正电子发射断层扫描（PET）参数在纵隔良性和恶性肿瘤鉴别中的作用。此外，我们还研究了治疗前SUV和容积性氟代脱氧葡萄糖PET参数能否区分胸腺瘤和胸腺癌，以及低风险和高风险胸腺瘤。
本研究对52例接受氟代脱氧葡萄糖PET/CT检查的纵隔肿瘤患者进行。组织学检查显示，29例纵隔肿瘤为良性，23例为恶性。为获得定量PET/CT参数，我们使用SUV截止值2.5确定了原发性肿瘤的最大标准化摄取值（SUV）、容积参数、代谢肿瘤体积（MTV）和总病变糖酵解（TLG）。使用Mann-Whitney U检验比较良性和恶性肿瘤的SUV、MTV和TLG。此外，应用受试者操作特征曲线（ROC）分析确定SUV、MTV和TLG的截止值，以准确区分良性和恶性肿瘤。比较胸腺瘤和胸腺癌以及低风险和高风险胸腺瘤之间的SUV、MTV和TLG。
恶性纵隔肿瘤的平均SUV、MTV和TLG显著高于良性肿瘤（P<0.001）。SUV的敏感性、特异性、准确性、阳性预测值和阴性预测值分别为78.2%、86.2%、82.6%、81.8%和83.3%。MTV和TLG的这些值分别估计为82.6%、96.6%、90.4%、95%和87.5%。此外，区分纵隔良性和恶性肿瘤的最佳截止值分别确定为SUV为4.2、MTV为22.3 mL和TLG为79.7 g。胸腺癌的平均SUV、MTV和TLG显著高于胸腺瘤（P<0.01），而低风险和高风险胸腺瘤之间的平均定量参数未观察到显著差异。
尽管SUV、MTV和TLG不能区分低风险和高风险胸腺瘤，但这些参数可能能够无创地区分纵隔良性肿瘤和恶性肿瘤。这些参数也可用于区分胸腺瘤和胸腺癌。因此，氟代脱氧葡萄糖PET/CT参数似乎是检测纵隔恶性肿瘤的准确指标。
