Value of preoperative diagnostic modalities in patients with recurrent thyroid carcinoma

Background. Patients with well-differentiated thyroid cancer (WDTC) regularly have an excellent prognosis. However, tumor recurrence either involving the thyroid bed or the regional lymph nodes, or both, can be associated with significant morbidity and even mortality. The aim of the follow-up after primary surgery is to detect recurrent disease at its earliest stage. We assessed 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 tomography (FDG-PET) were carried out. Results. Ultrasonography detected malignant lesions in 95.3% of the patients. The true positive rate of US-FNB was 95.3%. I-131 scanning had true positive, 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 highest specificity for detecting recurrence (P < .001). Conclusions. In patients with WDTC and locoregional recurrence, US and US-FNB are the most sensitive methods in detecting local recurrence or regional lymph node metastases. FDG-PET is valuable in case of negative I-131 scanning results and elevated serum Tg levels. The method has limitations in finding minimal disease.