Background The prognosis of differentiated thyroid carcinoma is usually excellent, but the majority of patients who develop a recurrence have a higher risk of death from the disease. Beside clinical examination, several diagnostic tools, such as ultrasonography, 131I scanning, [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) and thyroglobulin (TG) measurement under raised thyroid-stimulating hormone in serum can detect tumour recurrences. This prospective study compared the value of different diagnostic modalities in the detection of recurrent differentiated thyroid cancer. Methods From April 1992 to October 1999, 181 patients with thyroid carcinoma, of whom 150 had a well differentiated tumour, subjected to surgical treatment were identified prospectively. Some 107 patients (71 per cent) presented with primary tumour and 43 patients (29 per cent) with recurrent disease. The patients with tumour recurrence were evaluated regarding the mode of detection of recurrent disease, including clinical examination, ultrasonography, fine-needle biopsy (FNB), TG measurement and FDG-PET, the surgical treatment and outcome. Results Some 63 per cent of patients presented with regional lymph node metastases and 37 per cent with local recurrence. None of the patients with local recurrence was operated on for primary tumour in this department. In 87 per cent the recurrence was detected by clinical examination. Ultrasonography and 131I scan revealed suspicious findings in 97 and 69 per cent respectively. FNB disclosed abnormal cytological findings in 95 per cent. There were pathological TG levels in 86 per cent of patients. Among patients with a raised level of TG and negative scan results, 13 underwent FDG-PET, with pathological findings in 82 per cent. Conclusion In patients with well differentiated thyroid carcinoma, ultrasonography and FNB are the most sensitive methods for the detection of local recurrence or regional lymph node metastases. FDG-PET is a useful diagnostic tool in patients with a negative 131I scan and a raised level of TG.

Context: Serum calcitonin (hCT) measurement may be useful for detecting medullary thyroid carcinoma (MTC), but the routine use of hCT after pentagastrin stimulation to screen patients with nodular thyroid disease remains controversial. Patients: A total of 1007 patients (567 females and 440 males) with nodular thyroid disease and a mean age of 55G14 (meanGS.D.) years were included in the study. All patients did not have impaired renal function, bacterial infection, alcohol and drug abuse, pseudohypoparathyroidism, or protonpump inhibitor therapy. Individuals referred with known elevation of hCT, Graves' disease, or autoimmune thyroid disease were not considered or included in this investigation. Methods: Serum hCT levels were determined under basal conditions, and when basal values were R10 and !100 pg/ml, testing was repeated after pentagastrin stimulation. Patients with basal or stimulated levels O100 pg/ml were referred for surgery. Results: hCT levels O10 pg/ml were increased in 17 patients (1.7%). One patient had a basal hCT level of 4400 pg/ml with a histological confirmation of a MTC. In this patient, pentagastrin test was not performed. Sixteen patients with basal hCT between 10 and 100 pg/ml underwent pentagastrinstimulated hCT measurement. Of 16 patients, 4 had stimulated hCTO100 pg/ml. Of 17 patients with hCTO10 pg/ml, 2 had MTC, and of 17 patients, 3 had C-cell hyperplasia. In total, two patients (0.20%) had a histologically verified MTC. Conclusions: Basal hCT measurement together with pentagastrin-stimulated hCT measurement in cases of basal hCTO10 pg/ml detects MTC in 0.20% of patients with nodular thyroid disease. Whether this high incidence of MTC has major implications or not has to be discussed, but it should be considered as a useful and recommended tool for early detection of MTC and to save patients' life.

Purpose Molecular imaging with 99mTc-methoxy-isobutyl-isonitrile (99mTc-MIBI, MIBI) has been used in the assessment of thyroid nodules (TNs) for more than two decades. Many studies showed that MIBI imaging is a suitable tool to rule-out malignancy when negative. However, relatively low specificity and accuracy have been described, thus, limiting its acceptance in clinical practice. Additionally, different technologies, protocols, and interpretation criteria are adopted accounting for heterogeneous data reported in the literature. Therefore, the present study was undertaken to assess the clinical use and methodology of MIBI imaging in patients with nodular thyroid disease in Europe. Methods A questionnaire was sent to 12 European centers of Nuclear Medicine. The questionnaire encompassed ultrasound (US) and fine-needle aspiration cytology (FNAC) procedures and their evaluation as well scintigraphy imaging indications, technical procedures, and interpretation criteria of MIBI imaging. Results The survey showed a good agreement of different centers in approaching TNs by TSH measurement, US evaluation and 99mTc-pertechnetate thyroid scintigraphy. MIBI imaging is mainly used to assess TNs with inconclusive/indeterminate cytological findings and selection of target nodule(s) for FNAC in patients with multi-nodular goiter. Technical procedures adopted in different centers are globally comparable and the recorded differences are unlikely to impact clinical results. However, as the main result of the present study, substantial differences were found in interpretation criteria adopted in different centers. Conclusions Our survey supports the urgent need of standardized interpretation criteria of thyroid MIBI imaging in order to improve its diagnostic performance and make results comparable in clinical practice.