Thyroid incidentalomas on fluorine-18-fluorodeoxyglucose positron emission tomography-computed tomography: incidence, malignancy risk, and comparison of standardized uptake values.

INTRODUCTION: To determine the incidence of fluorine-18-fluorodeoxyglucose (FDG) avid thyroid incidentalomas detected on positron emission tomography (PET) with integrated computed tomography (CT), and correlate the FDG-PET-CT findings to cytology. METHODS: A total of 942 FDG-PET-CT reports were retrospectively reviewed. Patients with FDG-avid thyroid incidentalomas were further reviewed for correlative cytology. RESULTS: The incidence of FDG-avid thyroid incidentalomas is 2.2%. Thyroid malignancies were identified in 3 of 6 patients who underwent cytologic correlation, with a positive predictive value of 50% (95% confidence interval, 14%-86%). The mean maximum standardized uptake values of benign and malignant FDG-avid thyroid incidentalomas were 5.6 and 6.6, respectively. CONCLUSION: A FDG-avid thyroid incidentaloma may predict underlying malignancy. Cytologic assessment should be considered for FDG-avid thyroid incidentalomas.

Management of the neck after chemoradiotherapy for head and neck cancers in Asia: consensus statement from the Asian Oncology Summit 2009.

The addition of a planned neck dissection after radiotherapy has traditionally been considered standard of care for patients with positive neck-nodal disease. With the acceptance of chemoradiotherapy as the new primary treatment for patients with locally advanced squamous-cell head and neck cancers, and the increasing numbers of patients who achieve a complete response, the role of planned neck dissection is now being questioned. The accuracy and availability of a physical examination or of different imaging modalities to identify true complete responses adds controversy to this issue. This consensus statement will address some of the controversies surrounding the role of neck dissection following chemoradiotherapy for squamous-cell carcinomas of the head and neck, with particular reference to patients in Asia.

Diagnostic accuracy of 18F-FDG PET in restaging patients with medullary thyroid carcinoma and elevated calcitonin levels.

UNLABELLED: Medullary thyroid carcinoma (MTC) is a rare endocrine tumor arising from the C-cells of the thyroid gland. Calcitonin is the principal serum tumor marker. A rising calcitonin level after total thyroidectomy for localized disease generally indicates residual, recurrent, or metastatic disease. The role of (18)F-FDG PET in MTC remains somewhat unclear. We reviewed our own experience with (18)F-FDG PET in postthyroidectomy MTC patients with elevated calcitonin. METHODS: From our database, we identified patients with suspected residual, recurrent, or metastatic MTC and elevated calcitonin who had been referred for (18)F-FDG PET between January 2000 and October 2005. (18)F-FDG PET findings were classified as positive or negative on the basis of visual interpretation of the scan. Standardized uptake values (SUVs) were also calculated. The (18)F-FDG PET findings were verified by histopathologic examination, when available, or other imaging studies and clinical follow-up. Any negative (18)F-FDG PET result was considered false-negative. RESULTS: Twenty-eight patients underwent a total of 38 (18)F-FDG PET studies. Calcitonin levels ranged from 106 to 541,000 pg/mL (median, 7,260 pg/mL). There were 23 true-positive, 1 false-positive, and 14 false-negative (18)F-FDG PET scans, yielding an overall sensitivity of 62%. There was no true-positive finding when calcitonin levels were below 509 pg/mL (n = 5). Using an arbitrary cutoff of 1,000 pg/mL, we found that the sensitivity in scans with calcitonin levels greater than 1,000 pg/mL increased to 78% (21/27; 95% confidence interval, 58%-91%). The mean SUV of all lesions with (18)F-FDG uptake was 5.3 +/- 3.2 (range, 2.0-15.9). Among the 14 patients with false-negative (18)F-FDG PET findings, 8 had concurrent anatomic imaging studies and only 2 of these had positive findings. CONCLUSION: (18)F-FDG PET can detect residual, recurrent, or metastatic MTC with a reasonable sensitivity of 78% when the calcitonin level is above 1,000 pg/mL but appears of limited use if the calcitonin level is below 500 pg/mL.

Initial results with (11)C-acetate positron emission tomography/computed tomography (PET/CT) in the staging of urinary bladder cancer.

PURPOSE: To investigate the utility of (11)C-acetate positron emission tomography/computed tomography (PET/CT) for staging of bladder cancer and response assessment after neoadjuvant chemotherapy. PROCEDURES: Seventeen patients underwent (11)C-acetate PET/CT ≤1 month before radical cystectomy (RC) and pelvic lymph node dissection (PLND). Ten patients had undergone neoadjuvant chemotherapy prior to PET. Histopathology from RC and PLND (n = 16) or nodal biopsy (n = 1) served as gold standard. RESULTS: Eight of 10 residual tumors showed abnormal (11)C-acetate uptake; two cases of residual TiS were false negative, three cases were false positive, and three true negative. Three patients showed true positive uptake in LN. False positive uptake occurred in 14 LN regions secondary to granulomatous disease after prior intravesical Bacillus Calmette-Guerin (BCG) therapy. CONCLUSIONS: (11)C-acetate has good sensitivity for bladder cancer and LN metastases. However, false positive uptake due to inflammation or granulomatous infection can occur, limiting the staging utility of (11)C-acetate after prior intravesical BCG therapy.