End-of-treatment F-FDG PET/CT was a predictor of lymph node response and prognosis. Most of metabolic response variables related to histopathological response showed association with the prognosis.

Aim: Based on the response criteria of the 2015 American Thyroid Associations guidelines, our objectives were to ­determine the response rate when using a low dose of ­131-I GBq in patients with low-risk differentiated thyroid cancer (LRDTC) and the influence of clinical and analytical variables on the prediction of complete response. Methods: We performed a multicentre and longitudinal study, including patients who were operated for LRDTC and who underwent radioiodine remnant ablation with a low-dose of 131-I. All patients were assessed at 6–12 months, and their status was classified as complete (excellent response) or incomplete response (structural incomplete, biochemical incomplete or indeterminate response). Various factors including age, gender, histology, tumour focality and size, stage, time from surgery to treatment, type of thyroid-stimulating hormone (TSH) stimulation, preablation serum thyroglobulin (pTg), antiTg antibodies (pAntiTgAb) and TSH (pTSH) levels were also analysed in order to predict the complete response rate. Results: Of 108 patients, 79.6% achieved complete response and the remaining showed incomplete response (2.9, 5.5 and 12% due to biochemical incomplete, structural incomplete and indeterminate response respectively). Six patients received a new dose of 131-I. Tumour size and pAntiTgAb were the only factors related to therapeutic response (p = 0.03 and p < 0.01, respectively). However, pAntiTgAb was the only independent factor related to complete ­response. Patients with complete response showed lower pTg than those with incomplete response (5.1 ± 12.9 vs. 11.2 ± 25 ng/mL) although without statistical significance (p = 0.14). There was no significant difference in the response rate depending on the thyrotropin stimulation methods. Conclusions: A low dose of 131-I was sufficient for reaching a complete response at 6–12 months of follow-up in the majority of patients with LRDTC. Tumour size and pAntiTgAb variables were related to therapeutic response.

Aim To study the association of metabolic features of 18F-fluorocholine in gliomas with histopathological and molecular parameters, progression-free survival (PFS) and overall survival (OS). Methods Prospective multicenter and nonrandomized study (Functional and Metabolic Glioma Analysis). Patients underwent a basal 18F-fluorocholine PET/CT and were included after histological confirmation of glioma. Histological and molecular profile was assessed: grade, Ki-67, isocitrate dehydrogenase status and 1p/19q codeletion. Patients underwent standard treatment after surgery or biopsy, depending on their clinical situation. Overall survival and PFS were obtained after follow-up. After tumor segmentation of PET images, SUV and volume-based variables, sphericity, surface, coefficient of variation, and multilesionality were obtained. Relations of metabolic variables with histological, molecular profile and prognosis were evaluated using Pearson χ2 and t test. Receiver operator caracteristic curves were used to obtain the cutoff of PET variables. Survival analysis was performed using Kaplan-Meier and Cox regression analysis. Results Forty-five patients were assessed; 38 were diagnosed as having high-grade gliomas. Significant differences of SUV-based variables with isocitrate dehydrogenase status, tumor grade, and Ki-67 were found. Tumor grade, Ki-67, SUVmax, and SUVmean were related to progression. Kaplan-Meier analysis revealed significant associations of SUVmax, SUVmean, and multilesionaly with OS and PFS. SUVmean, sphericity, and multilesionality were independent predictors of OS and PFS in Cox regression analysis. Conclusions Metabolic information obtained from 18F-fluorocholine PET of patients with glioma may be useful in the prediction of tumor biology and patient prognosis.

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Ischemic complications after resection of high-grade glioma are frequent and may constitute potential cause of false-positive results in postsurgical evaluation using 18F-fluorocholine PET/CT. On the other hand, hypoxia caused by ischemia promotes invasive glioma growth. We present 3 cases of patients with different grades of ischemic injury after resection of high-grade glioma. The combined interpretation of diffusion-weighted imaging and apparent diffusion coefficient map on MRI, in this clinical setting, is mandatory to avoid PET/CT misinterpretations.