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Background: Microvascular invasion (MVI) is very important in the evaluation of hepatocellular carcinoma (HCC), but diagnosis is determined by postoperative pathology; thus, preoperative noninvasive methods will play an active role. The purpose of the study was to assess the performance of metabolic parameters of preoperative 18F-fluorodeoxyglucose PET/computerized tomography (18F-FDG PET/CT) in the prediction of MVI and postoperative recurrence in primary hepatocellular carcinoma., Methods: We retrospectively collected 72 patients with HCC who have performed 18F-FDG PET/CT scan before partial hepatectomy between 2016 and 2019. We used both normal liver tissue and inferior vena cava as the reference background and combined with clinicopathological features, 18F-FDG PET/CT metabolic and volumetric indices to predict MVI and postoperative recurrence of primary HCC before surgery., Results: Twenty-one of the 72 patients recurred, in recurrent cases showed higher maximum standard uptake value (SUVmax), TNR (ratio of tumor SUVmax to mean SUV [SUVmean] of the background tissue), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) than nonrecurrence cases (P < 0.001). All 18F-FDG PET metabolic and volumetric indices for predicting postoperative HCC recurrence were significant on receiver-operating-characteristic (ROC) curve analyses (P < 0.05). TNRIVC, TNRNL, MTVIVC, MTVNL TLGIVC and TLGNL were significant factors for predicting MVI in HCC (P < 0.05). On multivariate analyses, MVI, SUVmax, TNRIVC, TNRNL, MTVIVC, MTVNL, TLGIVC and TLGNL (P < 0.05) are independent risk factors for predicting postoperative HCC recurrence. TNRIVC is the most relevant PET/CT parameter for predicting MVI in HCC, and MTVIVC is the most valuable for predicting postoperative HCC recurrence. Moreover, the PET/CT parameters are more accurate for prognosis with inferior vena cava as a reference background than with normal liver tissue., Conclusion: 18F-FDG PET/CT metabolic and volumetric indices are effective predictors, and could noninvasively provide more comprehensive predictive information on MVI and postoperative recurrence of primary HCC before surgery., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Introduction: In previous literature, 18 F-FDG-PET/ CT imaging significantly impacted differentiated thyroid cancer (DTC) therapy. Low thyroglobulin (Tg) levels and negative Iodine-131 (131I) whole-body scan (WBS), along with negative 18 F-FDG-PET/ CT, suggested a lesser likelihood of active illness. Positive 18 F-FDG-PET/CT findings, however, were associated with a variety of signs of local recurrence and regional or distant metastases in patients with suspected WBS. We aim to evaluate the utility of 18 F-FDG-PET/CT in managing DTC patients with negative 131I post-therapy WBS and elevated Tg., Material and Methods: We retrospectively reviewed 55 patients with DTC (76% papillary and 24% follicular). Patients underwent total thyroidectomy or several radioactive iodine (RAI) treatments or both. WBS was performed 5-7 days after RAI treatment. Inclusion criteria were elevated serum Tg, negative anti-Tg auto-antibodies (AbTg) during long-term follow-up, presence of 18F-FDG-PET/CT images, and negative or suspicious WBS., Results: 54% of 18 F-FDG-PET/CTs detected at least one lesion, mainly, cervical lymph nodes (49.9%), mediastinal lymph nodes (40.4%), local recurrence (34%), and bone or tissue metastasis (36.2%). The three major sites of metastasis were lung, bone, and liver. 18 F-FDG-PET/CT identified recurrence or metastasis in 45% of patients with high serum Tg and negative WBS, modifying therapeutic management in half the patients for suitable treatment modality (surgery vs. tyrosine kinase inhibitor)., Conclusion: The findings redemonstrate that elevated Tg with negative or suspicious WBS necessitates 18 F-FDG-PET/CT for localization of recurrence. 18 F-FDG-PET/CT is useful in managing locally recurrent or metastatic DTC with high Tg levels. It influences treatment and accurately assesses disease severity., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)