Vergleich nuklearmedizinischer Untersuchungsmethoden der Schilddrüse : TC99m-Pertechnetat-Szintigraphie versus Jod124-Niedrigdosis-PET/CT

Darr, Andreas Martin

Purpose of the report: The standard thyroid functional imaging method, Tc-99m pertechnetate (Tc-99mPT)-planar scintigraphy, has technical drawbacks decreasing its sensitivity in detecting nodules or anatomical pathology. I-124-positron emission tomography (I-124-PET), lacking these disadvantages and allowing simultaneous computed tomography (CT), may have greater sensitivity for these purposes. We performed a blinded pilot comparison of I-124-PET(/CT) versus Tc-99mPT-planar scintigraphy or its cross-sectional enhancement, Tc-99mPT-single photon emission CT (SPECT), in characterizing the thyroid gland with benign disease. Materials and methods: Twenty-one consecutive adults with goiter underwent low-activity (1 MBq/ 0.027 mCi) I-124-PET/(low-dose [30 mAs] CT), Tc-99mPT-planar scintigraphy and Tc-99mPT-SPECT. Endpoints included the numbers of “hot spots” with/without central photopenia and “cold spots” detected, the proportion of these lesions with morphological correlates, the mean volume and diameter of visualized nodules, and the number of cases of lobus pyramidalis or retrosternal thyroid tissue identified. Results: I-124-PET detected significantly more “hot spots” with/without central photopenia (P <0.001), significantly more nodules (P <0.001), and more “cold spots” than did Tc-99mPT-planar scintigraphy or Tc-99mPT-SPECT, including all lesions seen on the Tc-99mPT modalities. Ultrasonographic correlates were found for all nodules visualized on all three modalities and 92.5% of nodules seen only on I-124-PET. Nodules discernible only on I-124-PET had significantly smaller mean volume or diameter (P <0.001) than did those visualized on Tc-99mPT-planar scintigraphy or Tc-99mPT-SPECT. I-124-PET/(CT) identified significantly more patients with a lobus pyramidalis (P <0.001) or retrosternal thyroid tissue (P <0.05). Conclusions: I-124-PET/(CT) may provide superior imaging of benign thyroid disease compared to planar or cross-sectional Tc-99mPT-scintigraphy.Key words: I-124-positron emission scintigraphy/computed tomography; Tc-99m pertechnetate-planar scintigraphy; Tc-99m pertechnetate-single photon emisson computed tomography; thyroid gland; benign thyroid diseases; goiter


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