F-18 fluorodeoxyglucose positron-emission tomography in the diagnosis of tumor recurrence and metastases in the follow-up of patients with breast carcinoma: a comparison to conventional imaging.

AIM: To evaluate the role of F-18-fluorodeoxyglucose positron-emission tomography (F-18 FDG PET) in the follow-up of breast carcinoma in case of clinical suspicion of local recurrence or distant metastases and/or tumor marker increase in correlation to conventional imaging. MATERIAL AND METHODS: Retrospective analysis of the results of F-18 FDG PET (ECAT ART(R), Siemens CTI MS) of 62 patients (age 58.5 +/- 12.8) with surgically resected breast carcinoma (time interval after surgery, 86 +/- 82 months, mean follow-up 24 +/- 12.6 months). Patient- and lesion-based comparison with conventional imaging (CI) including mammography (MG), ultrasonography (US), computerized tomography (CT), magnetic resonance imaging (MRI), radiography (XR) and bone scintigraphy (BS). Furthermore, we evaluated the influence on tumor stage and therapeutic strategy. A visual qualitative evaluation of lesions was performed. RESULTS: On a patient base, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy for detecting local recurrence or distant metastases were calculated to be 97%, 82%, 87%, 96% and 90% compared with 84%, 60%, 73%, 75% and 74% with CI. On a lesion base, significantly more lymph node (84 vs. 23, P < 0.05) and fewer bone metastases (61 vs. 97, P < 0.05) could be detected by using F-18 FDG PET compared with CI. Sclerotic bone lesions were predominantly detected by BS. On the other hand, there were several patients with more FDG positive bone lesions and also mixed FDG positive/Tc-99m methylenediphosphonate (MDP) negative and FDG negative/Tc-99m MDP positive metastases. In case of normal tumor markers, sensitivity, specificity, PPV, NPV and accuracy for detecting local recurrence or distant metastases were calculated to be 100%, 85.0%, 78.6%, 100% and 90.3% for FDG PET and 80%, 50%, 50%, 80% and 61.5% for CI. An upstaging could be observed in 9.7% (6/62) and downstaging in 12.9% (8/62), leading to a change in therapeutic regimen in 13 patients (21%). CONCLUSIONS: F-18 FDG PET demonstrates apparent advantages in the diagnosis of metastases in patients with breast carcinoma, compared with conventional imaging on a patient base. On a lesion base, significantly more lymph node and less bone metastases can be detected by using F-18 FDG PET compared with conventional imaging, including bone scintigraphy. In patients with clinical suspicion but negative tumor marker profile, too, F-18 FDG PET seems to be a reliable imaging tool for detection of tumor recurrence or metastases. Considering the high predictive value of F-18 FDG PET, tumor stage and therapeutic strategy will be reconsidered in several patients.

Fluorine-18-fluorodeoxyglucose positron emission tomography in the preoperative assessment of thyroid nodules in an endemic goiter area.

BACKGROUND: The aim of this study was to evaluate the usefulness of fluorine-18-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) in the preoperative assessment of suspicious thyroid nodules. METHODS: A total of 43 patients were examined before surgical resection. In all patients, imaging was obtained at 70 minutes after the intravenous administration of 180 MBq (18)F-FDG. Standard uptake values (SUVs) were calculated. RESULTS: A total of 16 patients with thyroid carcinomas (11 papillary, 3 follicular, 2 anaplastic), 23 thyroid adenomas (11 microfollicular, 10 Hurthle cell, 2 macrofollicular), and 4 patients with degenerative goiter were found. (18)F-FDG uptake in Hurthle cell adenoma, thyroid cancer, microfollicular adenoma, degenerative goiter, and macrofollicular adenoma was 4.4 +/- 2.2, 3.7 +/- 1.9, 1.6 +/- 0.3, 1.2 +/- 0.2, and 0.9 +/- 0.1, respectively. Significant differences were observed between thyroid carcinomas and both microfollicular adenomas and degenerative goiters (P < 0.05), and between Hurthle cell adenomas and both microfollicular adenomas as well as degenerative goiter (P < 0.05). For diagnosis of thyroid carcinoma, 100% sensitivity, 63% specificity, and 100% negative predictive value was found when a cutoff value for SUV of 2 was used. CONCLUSIONS: Our results indicate that thyroid carcinomas, in contrast to most benign thyroid nodules, demonstrate significantly increased glucose metabolism. (18)F-FDG PET is unlikely to differentiate successfully all benign tumors from malignant tumors, but it can help select patients who need surgery, especially if cytology is inconclusive or malignancy cannot be excluded.

18F-FDG-PET in the follow-up of thyroid cancer.

Differentiated thyroid cancer is a rare tumour with an incidence of 4 - 9/100,000/year. For preoperative assessment of thyroid nodules, ultrasonography (US) and US-guided fine needle aspiration biopsy are the methods of choice to detect thyroid cancer. The value of preoperative fluorine-18 fluorodeoxyglucose positron emission tomography (18F-FDG-PET) in differentiating malignant from benign nodules, especially in cases of follicular proliferation, has not yet been evaluated. After thyroidectomy and radioiodine remnant ablation, several methods are used to follow patients with differentiated thyroid cancer, including serum thyroglobulin, ultrasonography of the neck, iodine-131 (131I) whole body scintigraphy (WBS) and scintigraphy with nonspecific tracers such as technetium-99 m ((99m)Tc) Tetrofosmin or Sestamibi. Whereas the specificity of 131I-WBS is high, sensitivity is low, especially if one takes into account that only two-thirds of recurrences or metastases store iodine. With the introduction of 18F-FDG in oncology, it is also used for the detection of local recurrences and metastases of differentiated thyroid cancer. Elevated thyroglobulin but negative 131I-WBS belongs to the 1a indications for 18F-FDG-PET in oncology according to the German Consensus Conference 2000. The sensitivity for detecting 131I-negative metastases with 18F-FDG-PET can be increased by elevated thyroid-stimulating hormone (TSH) after withdrawal of thyroid hormone therapy or after intramuscular injection of recombinant TSH. Most of the 131I-negative metastases demonstrate 18F-FDG uptake, which represents rapid tumour growth and poor differentiation, whereas most of the 131I-positive metastases are 18F-FDG negative. The combination of 131I-WBS and 18F-FDG-PET leads to an increase in the detection rate to more than 90 - 95 % in cases of elevated thyroglobulin, because well- and less-differentiated cancer cells may be present in one patient. In rare cases, a recurrent tumour or metastasis may accumulate 131I as well as 18F-FDG. In these patients, it may be possible that well- and less-differentiated cells are present in one metastasis. The early use of 18F-FDG-PET in patients with elevated thyroglobulin, especially in the case of negative 131I-WBS, changes the therapeutic strategy in up to half of the patients (surgery, external radiation).

Goiter prevalence and urinary iodide excretion in a formerly iodine-deficient region after introduction of statutory lodization of common salt.

The objective of this epidemiologic study was to determine the volume of the thyroid gland as well as urinary iodine excretion in dependence on age and gender in a population from an area of low natural iodine supply now receiving iodine prophylaxis. In 430 persons from three communities in the province of Carinthia, Austria, we determined thyroid volume via sonography as well as urinary iodide excretion. As in numerous other European countries, natural iodine supply is insufficient in Austria. Therefore, to reduce goiter incidence, iodization of common salt with 10 mg potassium iodide (KI) per kilogram of NaCl was made mandatory in Austria in 1963 by federal law. In 1990, the amount of iodine addition was increased to 20 mg KI per kilogram of NaCl. Our results show that mean urinary iodide excretion in the persons investigated was altogether satisfactory (males: 163.7 microg of iodine per gram of creatinine; females: 183.3 microg of iodine per gram of creatinine). Goiter prevalence was 34.3% in women and 21.3% in men. An increase in goiter occurrence with age was noted in both genders. The increase in goiter prevalence was particularly obvious in the age group older than 40, i.e., among those participants who had spent at least a certain span of their lives in an area of iodine deficiency. Thus, the most likely reason for the persistently high goiter prevalence is not current iodine deficit but rather the high number of goiters that had developed previously at the time of iodine deficiency and were unable to undergo regression in spite of today's comparatively good iodine supply situation.

[Value of F-18 fluorodeoxyglucose positron emission tomography in thyroid carcinoma]. / Stellenwert der F-18-Fluorodeoxy-Glukose-Positronenemissionstomographie beim Schilddrüsenkarzinom.

In the preoperative assessment of thyroid nodules, ultrasonography and ultrasonography-guided fine needle aspiration biopsy play the most important role, especially for papillary thyroid cancer. The problem to differentiate follicular adenoma from highly differentiated follicular carcinoma remains the problem in preoperative diagnostic. Also the additional use of a multi tracer imaging strategy (Tl-201/Tc-99 m subtraction scan, Tc-99 m Sestamibi, Tc-99 m Tetrofosmin dual phase scintigraphy) has not solved this problem. Although it is unlikely, the question whether F-18-fluorodeoxy-glucose-positron emission tomography is able to give a better differentiation between benign and malignant tumors in the preoperative assessment of thyroid nodules is not answered up to now. In contrast to preoperative diagnostics F-18-fluorodeoxyglucose-positron emission tomography is of great value in the postoperative follow up of differentiated thyroid cancer. In case of elevated serum thyroglobulin but negative I-131 WBS F-18-fluorodeoxy-glucose-positron emission tomography is the method of choice to detect I-131 negative recurrences and metastases. F-18-fluorodeoxy-glucose uptake in metastases from differentiated thyroid cancer is correlated to low differentiation and maybe bad prognosis. There is also evidence that F-18-fluorodeoxyglucose-positron emission tomography may have a role of in anaplastic and especially in medullary thyroid cancer in the future.