Value of preoperative diagnostic modalities in patients with recurrent thyroid carcinoma

Background. Patients with well-differentiated thyroid cancer (WDTC) regular ly have an excellent prognosis. However, tumor recurrence either involving the thyroid bed or the regional lymph nodes, or both, can be associated wit h significant morbidity and even mortality. The aim of the follow-up after primary surgery is to detect recurrent disease at its earliest stage. We as sessed the value of different diagnostic methods in detecting locoregional recurrence in patients with WDTC. Methods, We prospectively identified 150 patients with WDTC. Of those, 43 ( 28.7%) presented with recurrent disease. Ultrasonography-guided fine needle biopsy (US-FNB), iodine 131 (I-131) whole-body scintigraphy, thyroglobulin (Tg) measurement, and fluorine-18 fluorodeoxyglucose positron emission tom ography (FDG-PET) were carried out. Results. Ultrasonography detected malignant lesions in 95.3% of the patient s. The true positive rate of US-FNB was 95.3%. I-131 scanning had true posi tive, false negative, and false positive results in 54.2%, 40.0%, and 5.7% of the cases, respectively. In 85.7% of the patients, Tg levels were within pathologic range. Among the 13 patients who underwent FDG-PET 84.6% showed pathologic uptake indicating malignancy. US and US-FNB provided the highes t specificity for detecting recurrence (P < .001). Conclusions. In patients with WDTC and locoregional recurrence, US and US-F NB are the most sensitive methods in detecting local recurrence or regional lymph node metastases. FDG-PET is valuable in case of negative I-131 scann ing results and elevated serum Tg levels. The method has limitations in fin ding minimal disease.