The value of positron emission tomography in the surgical management of recurrent papillary thyroid carcinoma

Background: Patients with papillary thyroid carcinoma (PTC) may suffer recurrence despite thyroidectomy and complete radioiodine (RAI) ablation. Reoperation is vitally dependent on accurate and complete disease localization, typically utilizing cervical ultrasonography (US) and/or computed tomography. Our aim was to determine the comparative value of F18-fluorodeoxyglucose positron emission tomography (PET) to US for localization of locoregional recurrence in patients who underwent reoperation for recurrent PTC. Methods: From 1999 to 2004, 30 patients who underwent re-exploration and 100 nonoperated patients who were investigated with PET for possible recurrent PTC were reviewed. The surgical group [9 males, 21 females; mean age = 50 years (range = 18-84 years)] all had received RAI ablation. Preoperative thyroid-stimulating hormone (TSH), thyroglobulin (Tg), and location of metastasis were recorded for each imaging study and surgical exploration. All separate sites that contained disease pathologically must have been identified by imaging for a patient to be considered true positive (TP). Results: PET scans were TP in 43%, false positive in 7%, false negative (FN) in 50%, and had a sensitivity of 46%. Comparable US results were 86%, 10%, 3%, and 96%. Of the 15 patients with FN PET scans, 13 had lymph node metastasis less than 2 cm in diameter, 11 had Tg ≤ 10 μg/L, and the TSH < 20 in 13. In only 3 of the 30 (10%) patients was PET deemed to add value. Conclusions: At least with suppressed TSH, PET scanning in reoperative PTC patients appears to offer modest benefit beyond high-resolution US.