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PurposeTo compare mutation analysis of cytology specimens and 99mTc-MIBI thyroid scintigraphy for differentiating benign from malignant thyroid nodules in patients with a cytological reading of follicular neoplasm.MethodsPatients ≥18 years of age with a solitary hypofunctioning thyroid nodule (≥10 mm), normal thyrotropin and calcitonin levels, and a cytological diagnosis of follicular neoplasm were prospectively enrolled. Mutation analysis and 99mTc-MIBI scintigraphy were performed and patients were subsequently operated on to confirm or exclude a malignant lesion. Mutations for KRAS, HRAS and NRAS and for BRAF and translocations of PAX8/PPARγ, RET/PTC1 and RET/PTC3 were investigated. Static thyroid scintigraphic images were acquired 10 and 60 min after intravenous injection of 200 MBq of 99mTc-MIBI and visually assessed. Additionally, the MIBI washout index was calculated using a semiquantitative method.ResultsIn our series, 26 % of nodules with a follicular pattern on cytology were malignant with a prevalence of follicular carcinomas. 99mTc-MIBI scintigraphy was found to be significantly more accurate (positive likelihood ratio 4.56 for visual assessment and 12.35 for semiquantitative assessment) than mutation analysis (positive likelihood ratio 1.74). A negative 99mTc-MIBI scan reliably excluded malignancy.ConclusionIn patients with a thyroid nodule cytologically diagnosed as a follicular proliferation, semiquantitative analysis of 99mTc-MIBI scintigraphy should be the preferred method for differentiating benign from malignant nodules. It is superior to molecular testing for the presence of differentiated thyroid cancer-associated mutations in fine-needle aspiration cytology sample material.

FTIs are observed in about 2% of 18F-FDG-PET or PET/CT scans and carry a significant risk of malignancy. Therefore, further investigation is warranted whenever FTIs are detected by 18F-FDG-PET or PET/CT.

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We conclude that, in this preliminary experimental setting, short-term severe thyroid hormone deficiency per se does not cause sleep disturbances and a feeling of fatigue as described in other studies may be due to changes in perception or brain metabolism during hypothyroidism.

Human calcitonin (hCT) is a tumor marker essential to the diagnosis and follow-up of medullary thyroid cancer (MTC). Current consensus recommends hCT measurement when initially evaluating thyroid nodules; if slightly elevated, a confirmatory stimulated calcitonin test is commonly performed, usually using pentagastrin. In recent years the supply of pentagastrin was not guaranteed with long periods of unavailability; the outlook for future availability is unknown. Therefore it is desirable for many institutions to establish a procedure for calcitonin stimulation using a stimulant with a secure supply; stimulation of calcitonin using calcium represents the easiest alternative.Several schemes and dosages have been used in the past for calcium stimulated calcitonin measurement. In this paper we propose a procedure for calcium stimulated calcitonin measurement based on our experiences. Furthermore we will briefly point out the limitations of this method with regard to available data in literature.

SummaryMeasurements of thyroglobulin (Tg) levels 72 h after administration of recombinant human thyrotropin (rhTSH) are recommended by the manufacturer in the follow-up of patients with differentiated thyroid carcinoma (DTC). In our department, Tg measurements are performed both 24 h and 72 h after administration of rhTSH, together with 72 h post rhTSH 131I whole body scintigraphy (WBS). The objective of this study is to compare the diagnostic usefulness of Tg measurements 24 and 72 h after rhTSH administration, and 131I WBS. Patients and methods: 181 patients were included who had been referred to our Nuclear Medicine Department for follow-up after 131I ablation of DTC. Tg measurements 24 h (Tg24) and 72 h (Tg72) after rhTSH, and 131I WBS, were done in all patients. The lower detection limit of Tg was 0,2 μg/l. Results: 47 patients (26%) had detectable Tg levels: in 4/47 cases (8%) only Tg24 was detectable (always <1 μg/l), and in 6/47 cases (11%), only Tg72 was detectable. In 10/47 patients with detectable Tg-levels, Tg24 and Tg72 tested equally. In 27/47 cases, Tg24 was lower, and in 10/47 higher, than Tg72. Two patients with one or two positive Tg-test results also had a positive 131I WBS. In 8 patients (14%) only the 131I WBS was positive; an anatomical substrate for such a Tgnegative positive WBS was confirmed in only 2 patients. Conclusion: Tg-measurement 72 hours after rhTSH injection reveals all clinically relevant detectable Tg-levels. Diagnostic 131I scintigraphy may be omitted, even in highrisk patients.