Optimal Threshold of Stimulated Serum Thyroglobulin Level for 18F-FDG PET/CT imaging in Patients with Thyroid Cancer / 华中科技大学学报（医学）（英德文版）

This study was to explore the optimal threshold of thyroid-stimulating hormone (TSH)-stimulated serum thyroglobulin (s-Tg) for patients who were to receive 18F-fluorodeoxyglucose (18F-FDG) PET/CT scan owing to clinical suspicion of differentiated thyroid cancer (DTC) recurrence but negative post-therapeutic 131I whole-body scan (131I-WBS).A total of 60 qualified patients underwent PET/CT scanning from October 2010 to July 2014.The receiver operating characteristic (ROC) curve analyses showed that s-Tg levels over 49 μg/L led to the highest diagnostic accuracy of PET/CT to detect recurrence,with a sensitivity of 89.5％ and a specificity of 90.9％.Besides,bivariate correlation analysis showed positive correlation between s-Tg levels and the maximum standardized uptake values (SUVmax) of 18F-FDG in patients with positive PET/CT scanning,suggesting a significant influence of TSH both on Tg release and uptake of 18F-FDG.So,positive PET/CT imaging is expected when patients have negative 131I-WBS but s-Tg levels over 49 μg/L.

Value of PET/CT for diagnosis of recurrence and metastasis of differentiated thyroid carcinoma / 中华内分泌外科杂志

Objective To analyze the value of PET/CT for diagnosis of recurrence and metastasis of dif-ferentiated thyroid carcinoma ( DTC) .Methods 65 patients with DTC in Thyroid Surgery Department of the First Affiliated Hospital of Zhengzhou University from Dec .2005 to Jan.2015 were collected.Based on the values of serum thyroglobulin(Tg),the patients were divided into 2 groups.29 cases with positive Tg were the observation group and 36 cases with negative Tg were the control group .All patients underwent PET/CT examination one year after surgery.Patients with positive findings from image studies underwent surgical excision and postoperative pathological diagnosis .Clinical data of the 2 groups were then summarized and discussed .Results There was no significant difference on the general conditions between the 2 groups(P>0.05).Tg values were statistically dif-ferent 6 months and 1 year after surgery between the 2 groups(P0.05).9 cases in the observation group and 1 case in the control group had positive findings on image study .All the cases with cervical lymph nodes presented as high uptake of 18 F-FDG.All patients who had positive findings on PET/CT underwent surgical removal of the abnormal lymph nodes which confirmed by pathology as lymph node metastasis .Conclusion PET/CT is very important for diagno-sis of recurrence and metastasis on Tg(Tg>2μg/L)positive,131I Dx-WBS imaging and US negative patients.

Effectiveness of 124I-PET/CT and 18F-FDG-PET/CT for Localizing Recurrence in Patients with Differentiated Thyroid Carcinoma

Although the prognosis of patients with differentiated thyroid carcinoma (DTC) is generally encouraging, a diagnostic dilemma is posed when an increasing level of serum thyroglobulin (Tg) is noted, without detection of a recurrent tumor using conventional imaging tools such as the iodine-131 whole-body scanning (the [131I] scan) or neck ultrasonography (US). The objective of the present study was to evaluate the diagnostic value of [124I]-PET/CT and [18F]-FDG-PET/CT in terms of accurate detection of both iodine- and non-iodine-avid recurrence, compared with that of conventional imaging such as the [131I] scan or neck ultrasonography (US). Between July 2009 and June 2010, we prospectively studied 19 DTC patients with elevated thyroglobulin levels but who do not show pathological lesions when conventional imaging modalities are used. All involved patients had undergone total thyroidectomy and radioiodine (RI) treatment, and who had been followed-up for a mean of 13 months (range, 6-21 months) after the last RI session. Combined [18F]-FDG-PET/CT and [124I]-PET/CT data were evaluated for detecting recurrent DTC lesions in study patients and compared with those of other radiological and/or cytological investigations. Nine of 19 patients (47.4%) showed pathological [18F]-FDG (5/19, 26.3%) or [124I]-PET (4/19, 21.1%) uptake, and were classed as true-positives. Among such patients, disease management was modified in six (66.7%) and disease was restaged in seven (77.8%). In particular, the use of the described imaging combination optimized planning of surgical resection to deal with locoregional recurrence in 21.1% (4/19) of patients, who were shown to be disease-free during follow-up after surgery. Our results indicate that combination of [18F]-FDG-PET/CT and [124I]-PET/CT affords a valuable diagnostic method that can be used to make therapeutic decisions in patients with DTC who are tumor-free on conventional imaging studies but who have high Tg levels.

99mTc-tetrofosmin, 131I Whole Body Scan and Thyroglobulin in Detecting Differentiated Thyroid Carcinoma Metastases

PURPOSE: The purpose of this study was to assess the detectability of differentiated thyroid carcinoma metastases by 99mTc-tetrofosmin and to compare these results with a 131I whole body scan (131I WBS). The results of two scans were also compared with the T4 off-thyroglobulin (Tg) concentration. METHODS: A prospective study was performed on 43 patients (40 females, 3 males) with differentiated thyroid carcinomas (41 papillary, 2 follicular) having undergone a total thyroidectomy, and received 100~200 mCi (3,700~7,400 MBq) of radioiodine for ablation of residual thyroid tissue, or treatment of metastasis. All patients (n=43) had a 99mTc- tetrofosmin scan, and a 131I WBS following the discontinuation of thyroid hormone replacement. The T4 off-Tg level was checked immediately prior to the radioiodine therapy, with T4 off-Tg levels above 20 ng/ml defined as positive for metastasis or a remnant disease. RESULTS: Cervical metastases were considered in 6 patients and distant metastases in 7, based on the clinical, radiological, and histopathological findings. The 131I WBS (70.2%) was much more sensitive than the 99mTc-tetrofosmin scan (29.8%) in demonstrating the residual thyroid tissue following surgery. The 131I WBS revealed cervical metastases in 3 of the 6 patients, but only 2 of the 6 were revealed by the 99mTc-tetrofosmin scan. Of the 3 patients with negative 131I WBS, two were detected by the 99mTc-tetrofosmin scan. The sensitivities of the 131I WBS and 99mTc-tetrofosmin scan in diagnosing distant metastases were comparable (71%, and 57% respectively), but in 2 patients with negative 131I WBS, the 99mTc-tetrofosmin revealed distant metastases. The specificities of the 131I WBS and 99mTc-tetrofosmin scan were not comparable (100%, 97%, respectively) in the diagnosis distant metastases. The mean T4 off-Tg level of the patients with cervical or distant metastases was 317 ng/ml, with a sensitivity and specificity of 100%, and 83% respectively. In the patients with a T4 off-Tg level above 50 ng/ml, the two scans and clinical studies could not reveal any metastases in 3 of the patients. CONCLUSION: Although the specificity of the 99mTc-tetrofosmin scan was slightly lower than that of the 131I WBS, it is a useful tool for detecting cervical or distant metastases in differentiated thyroid carcinomas and does not require prior withdrawal from thyroid hormones. Therefore the concomitant use of a 99mTc-tetrofosmin scan, a 131I WBS and Tg, is more effective in detecting metastases in differentiated thyroid carcinomas.