engleski

The role of FDG-PET in posttreatment restaging of recurrent differentiated/medullary fhyroid carcinoma (DTC/MTC)

The aim of the study was to assess the utility of 18-FDG-PET in DTC/MTC patients with increased se¬ rum levels of thyroglobulin (Tg)/calcitonin, but nega¬ tive morphological and scintigraphic imaging. Between 2005-2007, 13 patients [age 52± 16 yrs, 9F/4M, histo-type: papillary carcinoma (n=6), Hurthle cell/follicular (n=2), MTC (n=5)] with biochemically suspect recur¬ rence, previously treated by total thyroidectomy and 1311 ablation, underwent PET scan (Siemens ECAT- EXACT47/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 undetec-table serum Tg levels off LT4 ; one developed recur¬ rence during follow up. PET showed hypermetabolic lesions in 8/13 patients (5/8 DTC, 3/5 MTC ; 3 pT2-4Nl-lb, 2 pT3NO, 3 pTl- lbNO-lb) and changed in¬ tended management in 37% of them, while it was pre¬ sumably false-negative in 4 patients (2 DTC/2 MTC ; 3 pTl-2bNO, 1 pT2Nl ; non-progressive disease) and true negative in 1 DTC patient (TgAb-positive, pTINI) ; the involved regions were: head-neck (5/8), mediasti¬ num (7/8), lungs (2/8), liver (2/8) and spleen (1/8). In all patients, 131I-WB-scan, CT-MRI, lllln- octreotide, 99mTc-DMSA(V), SESTAMIBI and ultrasound were initially negative or showed a lower number of lesions. Two patients with lymph node involvement underwent extensive surgery with histologically confirmed metas-tases. PET is an efficient tool to locate recurrent/meta-static disease in high-risk, 1-131 non-avid DTC with increased Tg and MTC with elevated calcitonin. Supe¬ rior sensitivity, provision of anatomic guidance for biop¬ sy/surgical procedures and impact on management/prog¬ nostication are major advantages in carefully selected patients ; however, different pre-test probabilities, ac¬ quisition protocols and TSH-stimulation may yield dif¬ ferent diagnostic efficiency.

18-FDG-PET ; DTC/MTC

Abstract of the Scientific Syposium with International Participation "40 Years of Nuclear Medicine in Osijek", November 15 - 17, 2007. Osijek, Croatia.