The Role of TSH for 18F-FDG-PET in the Diagnosis of Recurrence and Metastases of Differentiated Thyroid Carcinoma with Elevated Thyroglobulin and Negative Scan: a Meta-analysis

Purpose: To establish the effects of TSH stimulation on the uptake of fluorine-18-labeled 2-fluoro-2-deoxy-d-glucose for differentiated thyroid carcinoma (DTC) with thyroglobulin-positive and scan negative metastases.

Materials And Methods: We searched the MEDLINE, EMBASE and the Cochrane Library for prospective controlled trials using TSH stimulation as an intervention. The outcomes of positron emission tomography (PET)-positive lesions, tumor-to-background ratio, maximum standard uptake value of the detected lesions were extracted and synthesized, and patients with the altered clinical management were studied. A meta-analysis was carried out using the Review Manager software.

Results: Seven prospective controlled clinical trials with 168 patients were found. All studies had a low risk of bias. PET scans under TSH stimulation versus thyroid hormone suppression showed statistically significant differences in the number of patients with PET true-positive lesions (odds ratio (OR) 2.45, 95% confidence interval (CI) 1.23-4.90) and in the number of the PET-detected lesions (OR 4.92, 95% CI 2.70-8.95) and tumor-to-background ratios. PET scans taken under TSH stimulation altered clinical management in altogether 12/130 (9%) patients in five paired studies (OR 2.40, 95% CI 1.11-5.22).

Conclusion: The data indicate that TSH stimulation should be recommended for DTC patients undergoing PET scanning in these circumstances. However, further well-designed studies emphasizing on the clinical significance of altered management by PET under TSH stimulation are needed.