TY - JOUR T1 - <sup>68</sup>Ga-DOTATOC PET/CT in Patients with Iodine- and <sup>18</sup>F-FDG–Negative Differentiated Thyroid Carcinoma and Elevated Serum Thyroglobulin JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 1512 LP - 1517 DO - 10.2967/jnumed.115.171942 VL - 57 IS - 10 AU - Ina Binse AU - Thorsten D. Poeppel AU - Marcus Ruhlmann AU - Samer Ezziddin AU - Rainer Görges AU - Amir Sabet AU - Karsten Beiderwellen AU - Andreas Bockisch AU - Sandra J. Rosenbaum-Krumme Y1 - 2016/10/01 UR - http://jnm.snmjournals.org/content/57/10/1512.abstract N2 - This study evaluated the impact of 68Ga-DOTATOC PET/CT in detecting recurrence or metastases in differentiated thyroid carcinoma (DTC) patients with elevated serum thyroglobulin and both negative radioiodine imaging and negative 18F-FDG PET/CT. Methods: 68Ga-DOTATOC PET/CT (CT without contrast, low-dose) was performed on average 6 wk after negative 18F-FDG PET/CT (CT contrast-enhanced, full-dose) in 15 consecutive radioiodine-negative DTC patients with elevated and rising thyroglobulin. Visual assessment of 68Ga-DOTATOC PET/CT images used a 4-point scale for classification of lesions (0, no pathologic findings; 1, benign; 2, equivocal; 3, malignant). PET findings were correlated with the histologic subtype of tumor, levels of serum thyroglobulin, and morphologic findings on full-dose CT and neck ultrasound. Histology or clinical and imaging follow-up served as a reference standard. Analysis was performed on a patient and lesion basis. Results: 68Ga-DOTATOC PET/CT was true-positive in 5 patients (10 tumor lesions) and was false-positive in 1 patient. The rate of positive 68Ga-DOTATOC PET/CT was significantly higher in poorly differentiated/oxyphilic carcinomas (4/4 patients) than in papillary (1/5) or follicular (0/6) tumors. Thyroglobulin levels tended to be higher in patients with tumor localization on 68Ga-DOTATOC PET/CT, but differences were not significant. In 2 of 5 patients with true-positive findings on 68Ga-DOTATOC PET/CT, CT alone but not ultrasound identified 2 of 10 tumor lesions, but in both patients 68Ga-DOTATOC-PET/CT revealed further tumor lesions not detected on CT alone. Conclusion: 68Ga-DOTATOC PET/CT should be considered in the case of negative 18F-FDG PET/CT in radioiodine-negative DTC patients with elevated and rising thyroglobulin. Imaging with 68Ga-DOTATOC appears promising especially in poorly differentiated and oxyphilic subtypes of DTC. ER -