[Use of 18F FDG-PET in patients with suspicion of recurrent differentiated thyroid cancer by elevated antithyroglobulin antibodies levels and negative ¹³¹I scan]. / Uso de la PET-18F-FDG en pacientes con sospecha de recurrencia de cáncer diferenciado de tiroides por anticuerpos anti-tiroglobulina elevados y rastreo ¹³¹I negativo.

AIM: To evaluate the utility of (18F)FDG-PET for patients diagnosed of differentiated thyroid carcinoma who present risk of disease and invaluable levels of thyroglobulin (Tg) by the presence of antibodies antithyroglobulin (AbTg). MATERIAL AND METHODS: Retrospective study of 7 women of 40 years old and histological diagnosis of differentiated thyroid cancer (7 papillary tumours) that were sent to our department for the accomplishment of(18F)FDG-PET study because of suspicion of disease, due to ¹³¹I negative and high levels of AbTg, between the year 2002 and 2007. 11 PET scans were obtained after the intravenous injection of 370-434 MBq of (18F)FDG in normoglycemia conditions and previous administration of muscle relaxant, hydration and diuretic. The results of (18F)FDG-PET scans were confirmed by pathologic examination or clinical outcome and radiographic examination for more than 24 months. RESULTS: The prevalence of recurrence in our population was 57.14%. All patients presented levels of Tg lower than 3 ng/dl and AbTg superior to 200 UI/ml. Three patients had precedent thyroiditis. Out of 11 scans performed 3 of them were negative and 8 cases were found positive. It ruled out the existence of disease in three patients and localized the presence of recurrence in 4 patients. CONCLUSION: (18F)FDG-PET CONCLUSION: 18F-FDG-PET is a useful diagnostic tool for the detection of recurrence as well as to rule out the existence of disease with a high accuracy, in patients with differentiated thyroid carcinoma with ¹³¹I whole body scan negative but with pathological elevation of antithyroglobulin antibodies.

[Bone metastases from unknown primary. FDG-PET detection of two synchronous tumors]. / Metástasis óseas de tumor primario desconocido. Detección mediante PET-FDG de dos tumores sincrónicos.

A 60-year-old woman presented with noncardiac chest pain over months and negative laboratory findings. Conventional imaging methods and bone scintigraphy detected bone lesions suggesting metastatic disease from an unknown primary tumor. An 18FDG-PET scan performed to orient the search for the primary tumor found focal lesions suggesting lymphoma and identified a focal thyroid lesion and a cervical lymph node accessible for biopsy. The biopsy of this lymph node incidentally detected a papillary differentiated thyroid cancer (DTC), since the existence of a non-Hodgkin's lymphoma was confirmed after a new biopsy. After confirming the presence of a lymphoma, 18FDG-PET enabled the initial staging of the tumor, the evaluation of the response to treatment, and follow-up for detection of recurrence. On the other hand, 18FDG-PET incidentally detected a DTC.

[Patients treated for differentiated thyroid cancer with negative 131I whole-body scans and elevated thyroglobulin levels: a possible course]. / Pacientes tratados por carcinoma diferenciado de tiroides con rastreos de 131I negativos y niveles de tiroglobulina elevada. Una evolución posible.

OBJECTIVE: To verify the existence of patients with treated differentiated thyroid cancer (DTC) with negative 131I whole-body scanning (WBS) and high serum thyroglobulin (Tg) in the follow-up who evolve towards normalization without other therapy interventions. MATERIAL AND METHODS: Retrospective revision of the periodic examinations established in the protocol for patients with DTC, analyzing the levels of Tg found with IRMA annually in those with hormonal treatment and every 1-5 years in absence of previous hormonal treatment to WBS. Minimum surveillance of 2 years. Those who had elevated levels of Tg and WBS and other negative imaging tests in their course were selected. The characteristics of the patients selected were analysed in those whose Tg levels evolved to normalization without specific medical or surgical treatment (Group I) and those who did not reach normalization of Tg (Group II). RESULTS: A total of 130 patients (17.93 %) with high levels of Tg and negative WBS were detected. Group I: 31 patients (4.28 %), 11 men and 20 women; average age at the moment of the diagnosis of 33.4 years (rank: 5-60); average surveillance: 12.4 years (+/- 7.4). HISTOLOGY: 27 papillary and 4 follicular carcinoma. Average ablation dose: 3.260 GBq (88,1 mCi); average total I131 dose: 6.850 GBq (185.13 mCi). Tg normalization average time: 8.2 years. Group II: 99 patients (13.65 %), 27 men and 72 women. Average age of 40.4 years (rank: 7-76). Average surveillance: 9.8 years. HISTOLOGY: 86 papillary and 13 follicular carcinoma. Average ablation dose: 3.266 GBq (88.28 mCi); average total 131I dose: 9.363 GBq (253,06 mCi). Two of the patients in group I had negative PET-FDG. There were 13 patients in whom progressive reduction of the levels of thyroglobulin without reaching normalization with negative PET-FDG was detected. CONCLUSIONS: In patients with radiated DTC, deferred normalization of the levels of the serum thyroglobulin is possible. Empirical treatments cannot be considered the only factor that contributes to this result, which can occur without the administration of high-doses of 131I.

[F-18-fluordeoxyglucose positron emission tomography on patients with differentiated thyroid cancer who present elevated human serum thyroglobulin levels and negative I-131 whole body scan]. / PET con 18FDG en pacientes con cáncer diferenciado de tiroides que presentan niveles elevados de tiroglobulina sérica y rastreos con 131I negativos.

UNLABELLED: This study aimed to evaluate the role of Fluorine-18-fluorodeoxyglucose positron emission tomography (PET-FDG) in patients with elevated serum thyroglobulin (hTg) levels where thyroid cancer tissue does not concentrate radioiodine, rendering false-negative results on I-131 scanning. MATERIAL AND METHODS: Whole-body PET imaging using FDG was performed in 54 patients (37 female, 17 male) aged 17-88 years: 45 with papillary tumors and 9 with follicular tumors who were suspected of having recurrent thyroid carcinoma due to elevated thyroglobulin levels (hTg > 2 ng/ml) under thyroid-stimulating hormone (TSH > or = 30 microIU/ml) in whom the iodine scan was negative. All whole body scans were obtained with diagnostic doses (185 MBq). Whole body PET imaging was performed in fasting patients following i.v. administration of 370 MBq FDG while the patients were receiving full thyroid hormone replacement. Before PET, 99mTc methoxyisobutylisonitrile scintigraphy (99mTc-MIBI) was done in 14 patients and morphologic imaging in 26 by CT scan. RESULTS: Positive PET results confirmed the presence of hypermetabolic foci in 25/54 patients (46.29 %). Positive findings were found for PET-FDG in patients with hTg levels higher than 10 ng/ml receiving full thyroid hormone replacement. 99mTc-MIBI demonstrated lesions in 7/14 patients (50 %). PET-FDG and 99mTc-MIBI had congruent positive results in 4/7 patients. All the lesions found by CT were detected by PET-FDG, while recurrent disease was found in 12/21 patients with previous negative CT. CONCLUSIONS: These results suggest that PET-FDG seems to be a promising tool in the follow-up of thyroid cancer and should be considered in patients suffering from differentiated thyroid cancer with suspected recurrence and/or metastases by elevated thyroglobulin levels, and negative I-131 whole body scans. PET-FDG might be more useful at hTg levels > 10 ng/ml.

[Recombinant human thyrotropin in the follow-up of patients with differentiated thyroid carcinoma]. / La TSH humana recombinante en el seguimiento de pacientes con cáncer diferenciado de tiroides.

PURPOSE: To determine the value of the use of radio-iodine scanning diagnostic and radio-iodine therapy during the follow-up of advanced differentiated thyroid cancer without stopping thyroid hormone suppression therapy. MATERIAL AND METHODS: We performed 7 radio-iodine scans and 4 radioiodine therapies in 5 men and 1 woman, aged 39 to 79 years. Five patients had papillary thyroid cancer and one follicular thyroid cancer. Human recombinant thyrotropin was given intramuscularly at a dose of 0.9 mg/ml once a day for two days. Twenty-four hours after the second dose, serum thyrotropin, thyroglobulin (Tg) and thyroglobulin autoantibodies were measured and each patient was given 2 mCi of 131I in postsurgery scans and 5 mCi of 131I in patients previously treated with 131I. Whole-body scans were obtained within 54 hours of injection and in the cases of diagnostic uncertainty a second scan was performed 72 hours after the injection. RESULTS: Four scans were positive and two were negative. One positive scan patient was not treated due to a serious clinical condition. An effective increase of serum TSH was observed in all 6 patients. Four patients had an effective increase of serum Tg; the other 2 cases had a decrease of serum Tg: One case was undifferentiated and in the other case the mass was smaller after surgery. CONCLUSIONS: rhTSH is an effective means of stimulating TSH levels and allowing scan and/or radioiodine treatment. rhTSH has no significant adverse effects. The use of rhTSH avoids all the disadvantages of hypothyroidism and maintains quality of life.

[Brain scanning in children (author's transl)]. / Valoración de la gammagrafía en los tumores cerebrales de la infancia

This report is concerned with evaluation of brain scintigraphy in the detection of brain tumors in children. Brain scans have been reviewed in 309 cases and were evaluated in 182 patients; brain tumor suspicious was present in 41 childrens. True positive results were obtained in 73% of brains tumors and true negative results in 5% with other diseases. There were either false positive or false negative results in 21% of scans. Results are compared to other series reported, showing similar findings. Finally the importance of this type of investigation is stressed.