The use of contrast-enhanced CT scans for attenuation correction in PET/CT does not cause clinically relevant artifacts in PET scan reconstruction, regardless of the iodine concentration used. Standard- and high-iodine contrast media can be used equivalently.

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A man (age: 74 years) presented with complaints of strong pain and recurring fluid build-up in the right knee. The patient had received a total endoprosthesis of this knee three years ago, and had undergone two further surgical revisions. We performed a radiosynovectomy using 185 MBq (5 mCi) 90 Y-citrate (3, 7). After the procedure we acquired a standard planar Bremsstrahlung scintigram (ǠFig. 1a) of the knee (4). 90 Y produces positron decay in about 32 ppm of the total radioactivity which generally enables PET imaging with highly sensitive scanners (1, 5, 6). Inspired by recent reports of 90 Y-PET imaging of the liver after selective internal radiotherapy (SIRT) of the liver (2, 8), we also decided to acquire a 90 Y-PET image of the knee covering one bed position using a Philips Gemini TF16 PET-CT scanner with an acquisition time of 20 minutes and preceding acquisition of an 80 mAs low dose CT for attenuation correction and anatomic localisation (ǠFig. 1).

Introduction After non-invasive diagnostic modalities high risk thyroid nodules are investigated with fine needle aspiration cytology in order to find the right surgical strategy for suspected malignancies. Despite the clear recommendation by the European and the American associations (ETA, ATA) its clinical value is doubted and its importance in clinical practice not fully clarified. Methods A multicentric study of 119 patients with differentiated thyroid cancer operated on in 24 surgical departments was conducted. The aim was not only to evaluate the use of FNAC as a diagnostic tool, but also to investigate its diagnostic validity and compare it with that of other, non-invasive diagnostic methods. Results FNAC was used only in 25 % of malignant thyroid nodules. In these patients sensitivity of FNAC was 60 %. In 40 % with preoperative FNAC, the result had an impact on the surgical approach. 17 % underwent surgery only because of the FNAC result, and 23 % underwent a planned surgical resection with total thyroidectomy and lymphadenectomy on account of the FNAC result. In comparison to non-invasive diagnostics (ultrasonography in conjunction with scintigraphy with Na99mTcO4) FNAC reached the same sensitivity. Discussion The results of our study reveal a limited application of preoperative FNAC in diagnosing thyroid nodules as well as a limited conclusiveness in our study population if not performed according to standards. In order to increase the benefits of this diagnostic modality, it seems to be important to perform FNAC according to the guidelines and in a standardized manner. FNAC should always be conducted in combination with ultrasonography. An experienced cytopathologist should be consulted and the Bethesda classification system should be established.