PET-CT scans in recurrent or persistent differentiated thyroid cancer: Is there added utility beyond conventional imaging?

BackgroundIntegrated positron emission tomography (PET)–computed tomography (CT) may have advantages over conventional imaging in localizing recurrent or persistent differentiated thyroid cancer.MethodsA retrospective review of patients who underwent PET-CT scans was performed. Results were compared with contrast CT, magnetic resonance imaging, ultrasonography, and radioactive iodine (RAI) scans.ResultsThirty patients (mean age, 49.9 ± 17 years) underwent 36 PET-CT scans, mostly for elevated thyroglobulin levels and negative RAI scans (30 scans). Fifty percent (18/36) of PET-CT scans showed increased uptake in the neck, 11 of 36 (31%) in the chest, 3 of 36 (8.3%) in bone, and 6 of 36 (16.6%) in other areas. PET-CT had overall sensitivity, specificity, and positive predictive values of 73.9%, 61.5%, and 77.3% respectively. To assess the added value of PET-CT, we focused on the 21 scans performed after conventional imaging in 20 patients. PET-CT provided additional information in 2 (10%) patients, both of whom were spared interventions. However, PET-CT underestimated extent of disease in 3 (15%) patients and led to unnecessary interventions in 3 (15%) additional patients.ConclusionPET-CT has reasonable sensitivity in the detection of recurrent thyroid cancer. However, the added value of PET-CT may be seen only in a limited number of patients after good quality, conventional imaging. Further studies are needed to determine the most cost-effective approach to managing these patients.