ISSN: 1305-3876
Hakkında: Özel sayılar şeklinde yayınlanır.
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Clinical Value Of Positron Emission Tomography In Thyroid Cancers
Dr. Zeynep YAPARa
aNükleer Tıp ABD, Çukurova Üniversitesi Tıp Fakültesi, ADANA
Fluorine-18 fluorodeoxyglucose positron emission tomography (F-18 FDG-PET) has become an increasingly important functional imaging modality in clinical oncology. The modality offers various advantages in monitoring patients with thyroid cancer and therapeutic decision. In patients with differentiated thyroid cancer (DTC), the lacking of iodine 131 (I-131) trapping by metastatic tissue does not allow I-131 whole-body scan (I-131 WBS) to visualize metastatic spread and the use of I-131 in treatment. Prognosis of I-131 negatif DTC metastasis is significantly worst. In these patients an early diagnosis of I-131 negative metastasis and their surgical extirpation is the optimal therapeutic approach. In this view, a high sensitive imaging procedure other than I-131 WBS is necessary. Considering reports, the sensitivity of F-18 FDG-PET does not seem adequate in diagnosing I-131 positive metastasis. On the contrary, the modality revealed high sensitivity (up to %90-96) in the diagnosis of I-131 negative metastasis. This relationship between these two imaging tracers, characteristic with reverse uptake, has been called flip-flop phenomenon and has been attributed to the differentiation of the thyroid cancer. The typical indication of F-18 FDG-PET is the DTC patient previously treated by total thyroidectomy and I-131 ablative theraphy, with increased serum Tg during follow up but with negative I-131 WBS. The reports about hybrid positron emission tomography/Computed tomography (PET/CT) system, showing a synergistic effect, revealed additional advantages over PET alone and caused differences in therapeutic desicions. F-18 FDG-PET also showed promising results in different types of thyroid cancers with a relatively low incidence such as Hurthle cell Ca, anaplastic Ca and medullary thyroid Ca. Comparing with the conventional imaging modalities, F-18 FDG-PET seems more sensitive and specific according to the preliminary reports regarding these types of thyroid cancers.Keywords: Thyroid cancers, F-18 FDG-PET, PET/CTTurkiye Klinikleri J Surg Med Sci 2007, 3(49):17-22
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