Thyroid-Stimulating Hormone–Stimulated Fused Positron Emission Tomography/Computed Tomography in the Evaluation of Recurrence in 131 I-Negative Papillary Thyroid Carcinoma

Fluorine-18 2-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) detects recurrence of papillary thyroid carcinoma (PTC) in thyroidectomized patients with elevated thyroglobulin (Tg) levels and negative¹³¹I-whole–body scans. This paper describes the utility of thyroid-stimulating hormone (TSH)-stimulated fused FDG-PET/computed tomography (CT) scanning on our first 15 patients of this population. Methods: Patients were prepared for PET/CT imaging with thyroid hormone withdrawal (n = 7) or recombinant human TSH (n = 8). All other imaging before the PET/CT did not demonstrate evidence of recurrence. Results: PET/CT scans revealed active foci in 9 patients, 4 prepared with hypothyroidism, and 5 with exogenous TSH. Positive results were demonstrated even in those with relatively low stimulated-TSH Tg values (13 and 14 µg/L). Six patients with positive PET/CT scans were treated surgically, yielding malignant tissue for 5 of those patients.Conclusion: PET/CT scans performed under TSH stimulation are an effective method of detecting of recurrence of PTC and direct surgical interventions, even in those with persistently elevated but relatively low Tg levels.