Can (18)F-FDG-PET/CT be generally recommended in patients with differentiated thyroid carcinoma and elevated thyroglobulin levels but negative I-131 whole body scan?
ABSTRACT Exact localization of recurrent iodine-negative thyroid cancer is mandatory, since surgery is the only curative therapy option in patients with iodine-negative tumor tissue. The aim of this study was to evaluate the impact of (18)F-FDG-PET/CT as a routine diagnostic tool on clinical management in patients with suspected thyroid cancer recurrence and elevated serum thyroglobulin (Tg) but negative radioiodine whole body scan.
After total thyroidectomy followed by radioiodine ablation, 30 consecutive patients with differentiated thyroid cancer, elevated serum thyroglobulin levels and negative whole body radioiodine scan underwent (18)F-FDG-PET/CT. Results were verified by histology, ultrasound, or clinical follow-up. Diagnostic accuracy was determined for the whole study population and for subgroups with serum thyroglobulin below and above 10 ng/ml, respectively. Impact of PET/CT on clinical management was assessed.
PET/CT identified FDG accumulating lesions in 19 of 30 patients. 17 were true-positive and 2 false-positive. In the true-positive group, 11 of the 17 patients had loco-regional disease, 3 had distant metastases only and 3 patients had both loco-regional and distant metastatic involvement. (18)F-FDG-PET/CT was true-negative in 3 patients and false-negative in 8 patients. Overall sensitivity, specificity and accuracy were 68.0, 60.0, and 66.7%, respectively. In the subgroup of patients with serum thyroglobulin above 10 ng/ml (n = 21) the sensitivity, specificity and accuracy were substantially higher with 70.0, 100.0, and 71.4%, respectively. Clinical management was changed for 17 (57%) of 30 patients, guiding to a curative surgical intervention in 9 patients (30%).
(18)F-FDG-PET/CT enables detection and precise localization of loco-regional recurrence and distant metastases of differentiated thyroid cancer in patients with elevated serum thyroglobulin but negative radioiodine with significant impact on patient management and can therefore be recommended as a routine diagnostic tool.
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ABSTRACT: (18)F-fluorodeoxyglucose-positron emission tomography/computed tomography (PET/CT) has proved effective in detecting recurrent or metastatic differentiated thyroid carcinoma (DTC) in the follow-up of operated DTC patients with high thyroglobulin (Tg) levels and negative findings on radioiodine whole-body scan. The aim of this retrospective study was to assess the impact of PET/CT on the planning of appropriate treatment for known recurrent disease in operated DTC patients. The study concerned 44 consecutive DTC patients (36 papillary, 8 follicular), who underwent total thyroidectomy and thyroid remnant ablation with (131)I and PET/CT. All patients had proven or strongly suspected recurrent disease judging from neck ultrasound (US) and fine-needle aspiration cytology, and detectable basal Tg levels. PET/CT findings were positive in 25/44 patients (56.81 %) and negative in 19. A positive PET/CT result predicted resectable tumour recurrences in 19/25 patients, but also detected additional tumour sites that prompted changes to the treatment plan in 6/25 patients (24 %). A negative PET/CT result led to clinical monitoring for 11/19 patients (57.89 %). PET/CT can help select patients, who might benefit from a tailored therapy by improving the detection of local recurrences not apparent on neck US or metastases.La radiologia medica 11/2013; · 1.37 Impact Factor
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ABSTRACT: Background: Rebound thymic hyperplasia (RTH) is not an uncommon finding after radiation or chemotherapy in patients with various malignancies. However, there are limited case reports of this phenomenon after radioactive iodine ablation therapy (RIAT) in differentiated thyroid cancer (DTC). The goal of this study was to evaluate the incidence, patterns, and affecting factors of RTH after RIAT by using 18F-FDG PET/CT. Methods: The study design was a retrospective review of 2550 patients (568 men, 1982 women; age, 13-79 years) who underwent FDG PET/CT imaging after total thyroidectomy and RIAT from June 2009 through June 2012. Patients were divided into 4 age-related subgroups. Overall incidence, age-related incidences, and gender distribution were evaluated in patients with thymic FDG uptake on PET/CT (RTH+). The correlation between incidence of RTH and age was assessed using the Cochran-Armitage trend test, and the Wilcoxon rank-sum test and multiple regression were applied to investigate the effect of applied dose of radioactive iodine (RAI) and age on the incidence of RTH. Correlations of standardized uptake value (SUV) and thymic volume with age and morphologic type were also evaluated. Results: Overall incidence of RTH after RIAT was 1.49%, and all of the RTH+ patients except one were female. The Cochran-Armitage trend test revealed significantly decreased incidence from the second to fifth decade (8.84%, 1.74%, 0.98%, and 0.39%, respectively; P < 0.001). In each age-related subgroup, the RAI dose was significantly higher in the RTH+ than RTH- group (P < 0.001), while there was no difference in RAI dose in RTH+ patients among age-related subgroups (P = 0.838). SUVmean and SUVmax of RTH revealed no meaningful correlation with RAI dose or age. There were no differences among morphologic patterns of RTH in age distribution and ablation dose. Conclusions: RTH after RIAT showed a strong female predominance despite the higher administration dose of RAI in male patients. Although the decreased incidence of RTH after RIAT with age is similar to the pattern of RTH induced by other causes, the fact that older patients, even sixth decade patients, can present with RTH after RIAT is noteworthy in the management of DTC.Thyroid: official journal of the American Thyroid Association 07/2014; · 2.60 Impact Factor
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ABSTRACT: The aim of the study was to disclose the place of (18)F-FDG PET/CT to predict recurrent disease in patients with differentiated thyroid cancer (DTC), negative radioiodine whole-body scan (WBS) and high serum thyroglobulin (Tg). Seventy-one patients who underwent total thyroidectomy followed by radioactive iodine ablation and had negative radioiodine WBS but elevated Tg levels underwent PET/CT. They were followed up for 6-50 months (median 23) for the occurence of recurrent disease as detected by either clinical findings, other imaging modalities or histopathological examination. The place of PET/CT findings at baseline to predict the presence of recurrent disease was evaluated. Correlation between PET/CT findings and Tg levels was examined and a threshold for Tg level above which the predictive value of PET/CT was highest was determined. PET/CT was positive for recurrent disease in 38 (53.5 %) patients. The sensitivity, specificity, PPV, NPV and diagnostic accuracy of PET/CT to predict the occurence of recurrent disease at follow-up were 68.8, 78.3, 86.8, 54.5 and 71.9 %, respectively. The sensitivity, accuracy and PPV of PET/CT increased with increasing Tg levels. The highest diagnostic accuracy of PET/CT, with a sensitivity of 76.2 % and a specificity of 100 % to detect recurrent disease appeared to be at a Tg level greater than 29 ng/mL. Our findings suggest that (18)F-FDG-PET/CT is a valuable tool to predict the occurence of recurrent disease in patients with DTC, negative WBS and elevated Tg levels. PET/CT positivity has been shown to be strongly and positively correlated with Tg levels in this patient subset.Annals of Nuclear Medicine 12/2013; · 1.41 Impact Factor