The role of early 18F-FDG PET/CT in therapeutic management and ongoing risk stratification of high/intermediate-risk thyroid carcinoma

Abstract

Little is known about the role in ongoing risk stratification of fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) performed early after radioactive iodine (RAI) ablation in differentiated thyroid carcinoma (DTC). The aim of the study is to investigate whether 18F-FDG PET/CT performed early after RAI ablation is useful to detect disease and to influence therapy and ongoing risk stratification. Patients with high/intermediate risk of recurrent DTC were included. 18F-FDG PET/CT scan was performed within 6 months after RAI ablation. We confirmed results with other imaging techniques, pathology reports, or follow-up. We classified the patient response as excellent, acceptable, or incomplete. Modified Hicks criteria were used to evaluate clinical impact. We included 81 patients with high/intermediate risk of recurrent DTC. Forty-one (50.6%) had positive uptake in 18F-FDG PET/CT, with negative (131)I whole-body scan ((131)I WBS). Sensitivity, specificity, and diagnostic accuracy of 18F-FDG PET/CT were 92.5, 90.2, and 91.4%, respectively. 18F-FDG PET/CT results had an impact on therapy in 38.3% of patients. One year after initial therapy, 45.7% showed excellent response, 8.6% acceptable response, and 45.7% incomplete response. A statistically significant relationship was found between negative 18F-FDG PET/CT and excellent response (80 vs. 12.2%, p < 0.001; OR 52.8). 18F-FDG PET/CT scan performed early in surveillance of patients with high/intermediate-risk thyroid carcinoma provides important additional information not available with conventional follow-up methods and had a high impact on therapy. A negative 18F-FDG PET/CT predicts an excellent response to therapy in the new ongoing risk stratification.

Prognostic role of FDG PET/CT in patients with differentiated thyroid cancer treated with 131-iodine empiric therapy

“…On the other hand, FDG-PET/CT is able to exclude recurrence or metastases [ 24 ] and negative FDG-PET/CT could be predictive of a very good response to therapy. [ 25 ] Similar to our findings, other retrospective studies demonstrated that a negative FDG-PET would predict an excellent outcome despite an elevated Tg value. [ 13 , 14 ] Likewise a study on the outcome of medical and surgical management in DTC patients showed that a positive FDG-PET predicts a worse prognosis and can help to distinguish between patients with distant metastases and not candidates for reoperation and patients with localized neck lesions that should be resected.…”

The utility of 18F-fluorodeoxyglucose positron emission tomography/computed tomography in differentiated thyroid cancer patients with biochemical recurrence and negative whole-body radioiodine scintigraphy and evaluation of the possible role of a limited regional scan

“…Few previous studies have also shown that most of the recurrences are noted in the area of the neck and thorax, although most of them have not detailed the sites of distant metastases [ Table 4 ]. [ 18 27 28 29 30 31 32 33 ] In our study, only four patients showed distant metastases to the brain, skull, acetabulum, and sacrum outside the proposed limited PET CT field of view. However, all these lesions were known by previous WBS or clinical history.…”

The use of positron emission tomography in thyroid cancer: a bibliometric analysis

“…At the same time, glucose metabolism activity is enhanced, and glucose transporter-1 (GLUT-1) expression is significantly increased ( 19 ). On the contrary, a low expression of GLUT-1 in differentiated thyroid carcinoma may lead to a decrease in glucose metabolism activity, thus achieving a relatively good prognosis ( 20 ). A previous study has shown that 18 F-FDG PET-CT has a vital reference value for the early diagnosis and prognosis of thyroid cancer ( 21 ).…”