Assessment of bone lesions with 18 F-FDG PET/MRI in patients with nasopharyngeal carcinoma.

PURPOSE: The purpose of this study is to evaluate the role of 18 fluorodeoxyglucose ( 18 F) PET/MRI ( 18 F-FDG PET/MRI) for detecting bone metastasis in nasopharyngeal carcinoma (NPC). PATIENTS AND METHODS: Between May 2017 and May 2021, 58 histologically proven NPC patients who underwent both 18 F-FDG PET/MRI and 99m Tc-MDP planar bone scintigraphy (PBS) for tumor staging were included. With the exception of the head, the skeletal system was classified into four groups: the spine, the pelvis, the thorax and the appendix. RESULTS: Nine (15.5 %) of 58 patients were confirmed to have bone metastasis. There was no statistical difference between PET/MRI and PBS in patient-based analysis ( P = 0.125). One patient with a super scan was confirmed to have extensive and diffuse bone metastases and excluded for lesion-based analysis. Of the 57 patients, all 48 true metastatic lesions were positive in PET/MRI whereas only 24 true metastatic lesions were positive in PBS (spine: 8, thorax: 0, pelvis: 11 and appendix: 5). PET/MRI was observed to be more sensitive than PBS in lesion-based analysis (sensitivity 100.0% versus 50.0 %; P < 0.001). CONCLUSIONS: Compared with PBS for tumor staging of NPC, PET/MRI was observed to be more sensitive in the lesion-based analysis of bone metastasis.

Clinical significance of extra-thyroid 99mTc-pertechnetate uptake before initial radioiodine therapy for differentiated thyroid carcinoma.

OBJECTIVE: To analyse the clinical characteristics of extra-thyroid 99mTc-pertechnetate uptake in order to explore the effect of the phenomenon on radioactive iodine (RAI) therapy for differentiated thyroid carcinoma (DTC) and its clinical significance. METHODS: This study retrospectively selected patients with DTC and extra-thyroid 99mTc-pertechnetate uptake. The clinical features, location, location count and extra-thyroid 99mTc-pertechnetate uptake distribution were analysed, combined with the uptake rate, stimulated thyroglobulin (sTg) level, post-therapy whole-body scan and curative effect. RESULTS: A total of 38 patients were enrolled in the study and 65 extra-thyroid 99mTc-pertechnetate foci were detected. Thirty-four patients showed abnormal 99mTc-pertechnetate uptake in the lymph nodes (26 of 38; 68.4%), lungs (four of 38; 10.5%) and bones (four of 38; 10.5%). The corresponding uptake rates were 0.2%, 0.2% and 0.8%, respectively. The uptake rate and sTg were significantly positively correlated (r = 0.36). 131I uptake was found in 36 patients at the 99mTc-pertechnetate uptake site. The number of iodine uptake foci was significantly higher than that of 99mTc-pertechnetate uptake foci. The sTg value and pathological staging significantly differed between the excellent and nonexcellent response groups (Z = -2.947 and Z = -2.348, respectively). CONCLUSION: Extra-thyroid 99mTc-pertechnetate uptake mostly indicated metastases with specific clinical features, which may have prognostic value for the judgment of iodine uptake function and the RAI therapy plan.

Combined use of radioiodine therapy and radiofrequency ablation in treating postsurgical thyroid remnant of differentiated thyroid carcinoma.

PURPOSE: To determine whether postoperative radioiodine (RAI) combined with radiofrequency ablation (RFA) is an effective, safe, and feasible method for elimination of excessive postsurgical thyroid remnant for differentiated thyroid carcinoma (DTC). MATERIALS AND METHODS: We took a prospective study and treated 12 DTC patients (4 males, 8 females, age 20-78 years) who underwent thyroidectomy for RFA followed by 131 I ablation. The pretreatment requires iodine-free diet and thyroid hormone withdrawal for 3-4 week. All the patients showed the level of serum thyroid-stimulating hormone (TSH) <30 mU/L, and obvious thyroid remnant in 99m Technetium (99m Tc) imaging. Serum TSH level was determined 1 day before RFA and on days 1, 7, 14 after RFA, and 99m Tc imaging was performed on day 14 after RFA. Subsequently, the patients were given an oral dosage of 3700 MBq 131 I for remnant ablation, and posttreatment whole body scan was performed on day 5 after ablation. Efficacy evaluation was done 4-6 months after treatment. The changes of variants before and after RFA were analyzed using Wilcoxon signed rank sum test. RESULTS: Serum TSH was <30 µIU/ml (mean value 10.27 ± 6.16 µIU/ml) before RFA, and increased to more than 30 µIU/ml (34.73 ± 3.93 µIU/ml) 2 weeks later (P = 0.002, Wilcoxon rank sum test). The 99m Tc uptake ratio on day 14 postRFA was (0.31 ± 0.12)%, which is significantly lower than before RFA (0.80 ± 0.16)% (P = 0.002, Wilcoxon rank sum test). The success rate of thyroid remnant ablation was 91.7% (11/12), which was assessed 4-6 months after treatment. All patients reported neck discomfort and some are self-limiting, with no hoarseness, choking, or radiation thyroiditis symptoms. Five patients had puncture area pain, among which one patient had neck edema, which was relieved after prednisone treatment. CONCLUSION: Combined use of RAI therapy and radiofrequency ablation in treating excessive postsurgical thyroid remnant of DTC can be an effective approach and avoids re-operation. Long-term efficacy monitoring would further determine its feasibility.