Assessment of the incremental value of recombinant thyrotropin stimulation before 2-[18F]-Fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography imaging to localize residual differentiated thyroid cancer.

PURPOSE: The purpose of the study was to assess prospectively the impact of recombinant human TSH (rhTSH) administration on positron emission tomography (PET)/computed tomography (CT) imaging in differentiated thyroid cancer patients who, after primary treatment, had a suppressed or stimulated serum thyroglobulin greater than 10 ng/ml and no radioactive iodine uptake consistent with thyroid cancer on a whole body scan. PATIENTS AND METHODS: PET/CT was performed before (basal PET) and 24-48 h after rhTSH administration (rhTSH-PET) in 63 patients (52 papillary and 11 follicular thyroid cancers). Images were blindly analyzed by two readers. The proposed treatment plan was prospectively assessed before basal PET, after basal PET, and again after rhTSH-PET. RESULTS: A total of 108 lesions were detected in 48 organs in 30 patients. rhTSH-PET was significantly more sensitive than basal PET for the detection of lesions (95 vs. 81%; P = 0.001) and tended to be more sensitive for the detection of involved organs (94 vs. 79%; P = 0.054). However, basal PET and rhTSH-PET did not have significantly different sensitivity for detecting patients with any lesions (49 vs. 54%; P = 0.42). Changes in treatment management plan occurred in 19% of the patients after basal PET. Lesions found only by rhTSH-PET contributed to an altered therapeutic plan in eight patients, among whom only four were true-positive on pathology (6%). CONCLUSION: The use of rhTSH for 2-[18F]-fluoro-2-deoxy-D-glucose-PET/CT significantly increased the number of lesions detected, but the numbers of patients in whom any lesion was detected were no different between basal and rhTSH-stimulated PET/CT scans. Treatment changes due to true positive lesions occurred in 6% of cases.

Practical application of recombinant thyrotropin testing in clinical practice.

OBJECTIVE: To review the indications for use of recombinant thyrotropin (rTSH) and outline the details of implementation of rTSH diagnostic testing in patients with treated thyroid cancer. METHODS: We discuss the results of published clinical trials that have compared rTSH-stimulated testing with conventional withdrawal of thyroid hormone suppressive therapy. Appropriate candidates for rTSH testing are described, and the typical schedule for rTSH testing and follow-up is presented. An overview of coding and documentation for reimbursement is also provided. RESULTS: Clinical studies have found no significant difference in the combined sensitivity of (131)I scans and serum thyroglobulin measurements for detection of recurrent thyroid cancer after rTSH stimulation versus withdrawal of thyroid hormone therapy. As expected, patients have fewer symptoms and a more favorable mood state after use of rTSH. Patients with thyroid cancer who have undergone total or near-total thyroidectomy followed by 131I ablation can be considered for rTSH testing. For low-risk patients, two cycles of rTSH testing 1 to 2 years apart, followed by testing every 3 to 5 years, are recommended. For moderate- to high-risk patients who have undergone one cycle of negative levothyroxine-withdrawal testing, two cycles of rTSH testing at a 6- to 12-month interval, followed by testing every 1 to 3 years for at least the first decade of follow-up, are recommended. Most commercial insurance, Medicare, and Medicaid carriers now cover rTSH, either in a prescription drug plan or under major medical benefits. CONCLUSION: Radioiodine scanning and serum thyroglobulin measurement after intramuscular injection of rTSH are valuable new monitoring options in patients with treated thyroid cancer, avoiding the adverse effects of hypothyroidism.