engleski

The Role of 18-FDG-PET in Post-treatment Restaging of Recurrent Differentiated/Medullary Thyroid Carcinoma (DTC/MTC)

The aim of the study was to assess the utility of 18-FDG-PET in DTC/MTC patients with increased serum levels of thyroglobulin (Tg)/calcitonin, but negative morphologic and scintigraphic imaging. Between 2005-2007, 13 patients [age 52± 16 years, 9F/4M, histotype: papillary carcinoma (n=6), Hűrthle cell/follicular (n=2), MTC (n=5)] with biochemically suspicious recurrence, previously treated by total thyroidectomy and 131I ablation, underwent PET scan (Siemens ECAT-EXACT 47/GE Advance NXi, 3D-mode/30-35 min.) 45 min. following iv. administration of 296-444 MBq 18-FDG under TSH suppression ; all lesions were evaluated by SUVmax. Two TgAb-positive patients showed undetectable serum Tg levels off LT4 ; one developed recurrence during follow-up. PET showed hypermetabolic lesions in 8/13 patients (5/8 DTC, 3/5 MTC ; 3 pT2-4N1-1b, 2 pT3N0, 3 pT1-1bN0-1b) and changed intended management in 37% of them, while it was presumably false-negative in 4 (2 DTC/2 MTC ; 3 pT1-2bN0, 1 pT2N1 ; non-progressive disease), and true negative in 1 DTC patient (TgAb-positive, pT1N1) ; the involved regions were: head-neck (5/8), mediastinum (7/8), lungs (2/8), liver (2/8) and spleen (1/8). In all patients, 131I-WB-scan, CT-MRI, 111In-octreotide, 99mTc-DMSA(V), SESTAMIBI and ultrasound were initially negative or showed less number of lesions. Two patients with lymph node involvement underwent extensive surgery with histologically confirmed metastases. PET is an efficient tool to locate recurrent/metastatic disease in high-risk, I-131 non-avid DTC with increased Tg and MTC with elevated calcitonin. Superior sensitivity, provision of anatomic guidance for biopsy/surgical procedures and impact on management/prognostication are major advantages in carefully selected patients ; however, different pre-test probabilities, acquisition protocols and TSH-stimulation may yield different diagnostic efficiency.

Positron-Emission Tomography; Fluorodeoxyglucose F18; Thyroid Neoplasms

nije evidentirano