Abstract: Objective To evaluate the value of ¹¹C-methionine (¹¹C-MET ) positron emission tomography/computed tomography (PET/CT) in screeningisocitric dehydrogenase (IDH) mutation and 1p/19q co-deletion status in supratentorial lower-grade glioma (LrGG). Methods The preoperative ¹¹C-MET PET/CT images and pathological data of 37 patients with lower-grade supratentorial glioma were retrospectively analyzed. The maximum tumor/normal tissue ratio (TNR_max), mean tumor/normal tissue ratio (TNR_mean) and peak tumor/normal tissue ratio (TNR_peak) of lesions on were measured. According to IDH gene mutation and 1p/19q co-deletion status, patients were divided into three groups: IDH wild type (IDH^wt); IDH mutation-1p/19q co-deletion type (IDH^mut1p/19q^del) and IDH mutation-1p/19q intact type (IDH^mut1p/19q^int). TNR values of different molecular subtypes of LrGG were compared with each other. The differential diagnostic efficacy of semi-quantitative parameters for different molecular subtypes of LrGG was analyzed using receiver operating characteristic (ROC)curve. Logistic regression was used to establish a joint diagnostic model, and the ROC analysis was conducted to evaluate the predictive efficiency of joint diagnostic model. Results There were significant differences in TNR_max, TNR_mean and TNR_peak among the three groups of LrGG (P<0.05). TNR_max, TNR_mean and TNR_peak were the highest in the IDH^wt group, followed by the IDH^mut1p/19q^del group. Semiquantitative values were the lowest in the IDH^mut1p/19q^int group. The TNR_max, TNR_mean and TNR_peak of IDH^wt LrGG were higher than those of IDH^mut LrGG, and the difference was statistically significant(P<0.05). The results of ROC analysis showed that the area under the curves (AUCs) of TNR_max, TNR_mean, and TNR_peak for screening IDH mutations were 0.827, 0.847, and 0.807, with thresholds of 3.09, 1.84, and 2.58, respectively, and the accuracy rates were 70.3%、75.7% and 75.7%, respectively. The screening model based on Logistic regression analysis can improve diagnostic accuracy, with an AUC value of 0.943, sensitivity, specificity, and accuracy of 100%, 83.3%, and 94.6%, respectively. The TNR_max, TNR_mean and TNR_peak of IDH^mut1p/19q^del LrGG were significantly higher than those of IDH^mut1p/19q^int LrGG (P<0.05). The AUCs of TNR_max, TNR_mean, and TNR_peak for predicting 1p/19q co-deletion of IDH^mut LrGG were 0.766, 0.792, and 0.812, with thresholds of 3.35, 1.44, and 2.02, respectively, and the accuracies were 76.0%, 80.0%, and 80.0%, respectively. Joint diagnostic model cannot improve diagnostic efficiency. Conclusion ¹¹C-MET PET/CT is helpful for screening IDH mutation and 1p/19q co-deletion status in supratentorial lower-grade gliomas. The combination of multiple parameters can improve the efficiency of screening IDH gene mutation.

Key words: lower-grade glioma, ¹¹C-methionine, positron-emission tomography, isocitric dehydrogenase, 1p/19q