Diagnostic I-131 scintigraphy in patients with differentiated thyroid cancer: no additional value of higher scan dose.

OBJECTIVE: After initial treatment with total thyroidectomy and radioiodine ablation, most follow-up protocols for patients with differentiated thyroid carcinoma contain cyclic diagnostic I-131 imaging and serum thyroglobulin measurements. The applied diagnostic I-131 doses vary between 37 and 370 MBq. The aim of this study was to determine the yield of a diagnostic scan with 370 MBq I-131 in patients with a negative diagnostic scan with 74 MBq I-131. METHODS: Retrospective evaluation of 158 patients who received a high-dose diagnostic scan with 370 MBq I-131 because of a negative low-dose diagnostic scan with 74 MBq I-131. Special attention was paid to the patients with positive high-dose diagnostic scanning and undetectable serum thyroglobulin levels after thyroid hormone withdrawal. RESULTS: In 127 (80%) of patients the 370 MBq I-131 scan was negative, just like the preceding low-dose scan. In 31 (20%) of patients abnormal uptake was present on the 370 MBq diagnostic scan. In 19 of these 31 patients serum thyroglobulin was undetectable. In 15/19 the high-dose diagnostic scan proved either false positive or demonstrated clinically irrelevant minor ablation rests. In only four patients (2.5%) did the high-dose diagnostic scans reveal possibly relevant uptake caused by residual differentiated thyroid cancer. CONCLUSION: In 98% of patients a 370 MBq dose of I-131 for diagnostic WBS had no additional value. The combination of a low-dose diagnostic I-131 scan using only 74 MBq combined with a serum Tg level measurement proved sufficient for correct clinical decision making regarding whether the patient requires additional I-131 therapy.

Surgical experience in children with differentiated thyroid carcinoma.

BACKGROUND: The optimal surgical treatment in children with well-differentiated thyroid carcinoma remains an important point of discussion. In this study, we evaluated our surgical experience and reviewed the literature accordingly to identify the most adequate treatment. METHODS: We retrospectively analyzed 21 children, all under the age of 18 years at the time of diagnosis, with differentiated thyroid carcinoma (17 papillary, 3 follicular, and 1 Hürthle cell carcinoma). Total thyroidectomy was performed, followed by radioiodine therapy, as a part of the initial treatment in all patients. The results were compared with data from the literature. RESULTS: Eleven children (52%) who presented with cervical lymph node metastases were treated by a modified radical neck dissection. Pulmonary metastases were seen at diagnosis in three patients. Six patients developed temporary complications. During follow-up, with a median of 11 years (range, 2-26 years), two patients (10%) developed recurrences, and no patient died during this observation period. A literature search confirmed our experience of excellent results without an increase of complications in the more aggressively treated patients. CONCLUSIONS: In children with differentiated thyroid cancer, treatment should consist of total thyroidectomy, followed by a modified radical neck dissection (when indicated) and iodine-131 ablation treatment. This aggressive approach seems to be justified because of the high incidence of nodal involvement and the low complication and recurrence rate after surgery.

Better yield of (18)fluorodeoxyglucose-positron emission tomography in patients with metastatic differentiated thyroid carcinoma during thyrotropin stimulation.

To determine whether (18)fluorodeoxyglucose-positron emission tomography (FDG-PET) for the detection of recurrences or metastases of differentiated thyroid carcinoma should be performed during thyrotropin (TSH) suppression or TSH stimulation, eight patients were studied sequentially. After the second FDG-PET scan, a therapeutic (131)I dose was administered with posttherapy scans obtained 10 days later. Both FDG-PET scans were compared with each other and with the (131)I posttherapy whole body scans by two independent observers. Findings were verified using other imaging modalities or biopsies. Median TSH was 0.04 mU/L during TSH suppression and 64 mU/L during TSH stimulation. The FDG-PET scans during TSH suppression showed abnormalities in four patients and the FDG-PET scan during TSH stimulation in five patients. One patient was only positive during TSH stimulation. In two other patients the FDG-PET scan during TSH stimulation clearly identified more lesions, and in all positive patients lesion contrast was better during TSH stimulation. In two patients FDG-PET findings during TSH stimulation led to a change in clinical management. Thus, the performance of FDG-PET during TSH stimulation was either superior or equal to FDG-PET during TSH suppression, but never inferior. To detect metastatic or recurrent differentiated thyroid carcinoma FDG-PET should be performed during hypothyroidism, leading to TSH stimulation.