**3. Results**

A total of 37 patients were retrospectively reviewed. Figure 1 shows the case screening. The patients (12 males and 25 females) had a mean age of 38.95 ± 12.03 years (range, 12–68 years). The time interval between PET examination and the first surgery ranged from 4 months to >5 years. In total, 25 patients had elevated non-stimulated Tg levels along with negative 131I-WBS, their median serum Tg was 11.01 ng/mL (range, 3.04– > 500 ng/mL), with thyrotropin levels all < 0 μIU/mL. The TgAb level of five patients rose to 2302.48 ± 1470.59 IU/mL (range 649.4– > 4000 IU/mL). One patient had an increase in both Tg and TgAb. After the PET/MR and PET/CT examinations, seven patients completed reoperation and histopathological examinations, and two patients underwent FNAB. The period of follow-up was between 8 and 24 months. Table 1 presents the general characteristics of the enrolled patients.

**Figure 1.** Flow chart of patients who were referred for assessment.



<sup>1</sup> PTC papillary thyroid carcinoma, <sup>2</sup> PTMC papillary thyroid microcarcinoma, <sup>3</sup> FTC follicular thyroid carcinoma, <sup>4</sup> Tg thyroglobulin, 5 131I-WBS 131Iodine whole body scan, <sup>6</sup> TgAb anti-thyroglobulin antibodies.
