Clinical Study Of Tg Positive And¹³¹ID_x-WBS Negative In DTC Patients

Differentiated thyroid carcinoma is the most common endocrine carcinoma,most natural progression of DTC is slow, invasive weakly and has a long survival. Inrecent years, due to the extensive use of various imaging examination and fine-needleaspiration in thyroid nodules, the diagnosis of thyroid cancer increases rapidly. ForDTC patients after thyroidectomy and ablation therapy, their residual carcinoma andrecurrent or matestatic lesions often presented simultaneously with increased Tg andpathological uptake on131I Dx-WBS image. However, approximately10-15%patientsclinically represented131I Dx-WBS negative and serum Tg-positive, the managementof these patients is a widely debated problem. Empirical therapy is advocated,nowadays, but the therapeutic benefit of this treatment is not clear.It has been reported that131I Dx-WBS had lower sensitivity compared with otherexaminations.131I Dx-WBS negative patients can be recognized to harbor residualdisease with other examinations, such as neck US,18F-FDG PET/CT and99mTc-sestamib（iMIBI） scan. Now serum Tg and neck ultrasonography is advocatedto supplanted the131I Dx-WBS. Then, new problems have emerged: how to manageUS-negative, Tg-positive patients, and the timing of empirical131I therapy is notclear.ObjectiveTg positive and131I Dx-WBS negative patients were retrospectively studied. Bycomparing the changes of Tg level between empirical treatment patients andnon-treatment patients, and evaluating the diagnostic value of neck US and99mTc-sestamibi （MIBI） scan, to find appropriate diagnosis and treatment managements of these patients.Meterials and Methods923patients with thyroid carcinoma, all patients underwent total thyroidectomyor subtotal resection and confirmed by postoperative pathology.1to2months later,patients underwent131I ablation therapy. During the follow-up,120patients withpositive serum Tg (Tg>2ug/ml), negative131I Dx-WBS imaging. According to acceptempiric131I therapy or not, the120patients were classified into treatment group andnon-treatment group. According to the neck US results, they were divided to the neckUS negative and US positive groups.18Tg-positive,131I Dx-WBS negative patientsunderwent99mTc-MIBI scan and6patients underwent18F-FDG PET/CT.Results1．There’s no statistically significant values (P>0.05) between the treatmentgroup and non-treatment group. The Tg value of non-treatment group decresed oneyear later without statistically significant values (P=0.07). The Tg value of20patients decreased, among them9patients decreased more than50%,11patients Tgvalue decreased less than50%. At the end of follow-up, in the treatment group, Tgvalues after treatment were lower, the difference was statistically significant (P<0.05). The Tg value of62patients decreased, among them41patients decreasedmore than50%,21patients Tg value decreased less than50%. After treatment, bothpositive and negative imaging groups’ serum Tg values were significantly decreased,the difference has statistical value.2．After high-dose131I therapy,38(50%) patients in treatment group foundabnormal iodine uptake lesions, where the thyroid bed iodine uptake lesions werefound in22cases, cervical lymph iodine uptake found in8cases, both thyroid bedand cervical lymph nodes were found in8people.3．Ultrasound found22cases who had neck recurrence or pathologic lymphnodes. Remain98cases were not found abnormal lesions by cervical US. At the firstof follow-up, the mean value of Tg in US positive group was238.58μg/L (20.25~ 637.9), Tg values in US negative group was38.72μg/L (2.24~632.7), two Tg valueswere significantly different, P=0.02(<0.05). Pathological neck lymph nodes werenot by diagnostic WBS but by ultrasound,22patients underwent131I therapy again,20cases (90.9%) patients after treatment found abnormal iodine uptake lymph nodesby131I Rx-WBS.4．18patients except one had suspected positive neck uptake, the rest of thepatients found no abnormal uptake lesions.3/6cases of18F-FDG PET/CT imagingshowed high18F-FDG uptake in neck lymph nodes, which were pathologicallyconfirmed PTC lymgh nodes metastasis.Conclusion1．After thyroid ablation therapy, DTC patients with Tg-positive，131I Dx-WBSnegative, if neck US positive and18F-FDG PET/CT positive, can be treated bysurgery or empirical131I therapy. Otherwise, patients can be observed closely. The Tglevel of them if increased, they can select131I therapy.2．Neck US has an important diagnostic value for these patients and complementseach other with131I Rx-WBS imaging. It is an important method in the follow-up andshould be paid more attention.3．99mTc-MIBI scan has limited diagnostic value for Tg-positive,131I Dx-WBSnegative patients, however,18F-FDG PET/CT is very important for these patients.