Usefulness of PET/CT with 18F-FDG in Patients with Differentiated Thyroid Carcinoma after Radioiodine Therapy: An Italian Multicenter Study

Abstract

Background: our aim was to assess the diagnostic performance and clinical impact of 18F-FDG PET/CT in patients with differentiated thyroid carcinoma (DTC), previously treated with surgery and radioiodine therapy (RAI). Methods: patients subjected to 18F-FDG PET/CT for suspected DTC recurrence in three Italian nuclear medicine units were evaluated. Two different clinical settings were identified: clinical setting 1 included patients (n = 40) that were enrolled according to the American Thyroid Association guidelines (i.e., negative 1311-WBS and Tg level > 10 ng/mL); and clinical setting 2, that encompassed subjects (n = 26) with serum Tg ≤ 10 ng/mL but morphological findings suspected of relapse. PET/CT’s impact was scored as significant if it provided an indication for surgery, or led to a novel therapeutic decision. Results: In total, 51/66 patients (77.3%) were 18F-FDG positive, while 15 (22.7%) were negative. PET/CT showed an overall sensitivity and specificity of 84.4% and 75%, respectively. Sensitivity was higher in clinical setting 1 (89.1%) as compared to clinical setting 2 (76.1%), although this difference was not statistically significant (p = 0.83). PET/CT influenced clinical management in 28 cases (42.4%), without a significant difference between the 2 groups of patients (p = 0.6). Conclusions: our preliminary data, although limited by the retrospective nature of the study and possible selection bias, suggest that 18F-FDG PET/CT may be utilized for the detection of DTC recurrence in different clinical settings, with a meaningful impact on clinical management.

Hashimoto’s Thyroiditis and Papillary Thyroid Carcinoma: A Follow-Up Study in Patients with Absence of Aggressive Risk Factors at the Surgery of the Primary Tumor

“…Among these, ultrasound was employed and sometimes associated with fine-needle aspiration biopsy (FNAB), as well as nuclear medicine exams, and in particular, 131 I-SPECT/CT, more recently applied in the clinical field [48][49][50][51][52], and sequential serum thyroglobulin and AbTg assays in the two groups of patients and AbTPO in PC/HT cases. In general, CT and MRI, and when the carcinomas are poorly differentiated by 18 F-FDG PET/CT [53], represented the other diagnostic imaging highly sophisticated procedures.…”

How [18F]FDG-PET/CT Affects the Management of Patients with Differentiated Thyroid Carcinoma in Clinical Routines

“…Larg et al showed that [ 18 F]FDG-PET/CT can influence clinical decision making for DTC with elevated hTg levels and a negative 131 I WBS, leading to a change in treatment strategy in 33.5% (58/173) of cases [17]. Filippi et al demonstrated an impact on clinical patient management in 42.4% of cases in a similar setting (DTC with elevated hTg levels and a negative 131I whole-body scan) [34]. Furthermore, it has been demonstrated that certain PET/CT parameters (total MTV and total TLG) possess a prognostic predictive value under specific conditions [35].…”

I‐PET score: Combining whole body iodine and 18F‐FDG PET/CT imaging to predict progression in structurally or biochemically incomplete thyroid cancer

“…FDG PET imaging has become increasingly important in management of patients with thyroid cancer, with FDG avid disease associated with poor prognosis 16–22 . FDG PET imaging have a role in detecting recurrence or persistent disease in both patients with negative WBS and elevated Tg (>10 ng/ml), and those with Tg < 10 ng/ml after initial treatment 21,23–26 . The degree of FDG avidity has been associated with poor survival 5,17,25,27,28 and associated with poor response to RAI 29 .…”

“…[16][17][18][19][20][21][22] FDG PET imaging have a role in detecting recurrence or persistent disease in both patients with negative WBS and elevated Tg (>10 ng/ml), and those with Tg < 10 ng/ml after initial treatment. 21,[23][24][25][26] The degree of FDG avidity has been associated with poor survival 5,17,25,27,28 and associated with poor response to RAI. 29 In our cohort, I-PET [3] identified patients who had become refractory to RAI with high rates of progression; these patients were more likely to receive a mutlikinase inhibitor and were at increased risk of death from their disease.…”