Lisanne de Koster

343 Quantitative classification and radiomics of [18F]FDG-PET/CT 5 Netherlands. The funder of the trial had no influence on the design or conduct of the trial and was not involved in the collection or analysis of the data, or in the writing of the manuscript. Image acquisition and reconstruction During the EfFECTS trial, all participants underwent an [18F]FDG-PET/CT covering skull-base to upper thorax. These scans were acquired by 20 different scanners at 12 EARL-accredited study sites (Chapter 4 of this thesis, Table 1, and Supplementary data, Table 1) using a standard acquisition and reconstruction protocol in accordance with European Association of Nuclear Medicine (EANM) guidelines [468]. Patients were advised to fast for at least 6 hours. Serum glucose levels were between 4 and 11 mmol/L. PET-acquisition was scheduled 60 (55-75) minutes after intravenous bolus administration of [18F]FDG. The administered activity was dependent on body weight, scan speed, bed overlap and scanner sensitivity, equivalent to 3.45 MBq/kg (4 min/bed, <25% bed overlap). Low-dose, non-contrast-enhanced CT (ldCT) scans were acquired for attenuation correction of PET images. Additional details on patient preparation, data acquisition, image reconstruction, and image processing are reported in the Supplementary data, Table 2. [18F]FDG-PET/CT quantitative analysis Quantitative image analyses were performed using OsiriX Lite DICOM-viewer (Pixmeo SARL, Bernex, Switzerland). SUV-computation was validated after each mandatory software version update. All scans were centrally assessed by two independent, experienced nuclear medicine physicians (DV, LF). They were blinded to patient allocation and all clinical and cytological data except for the ultrasonographic size and location of the index nodule, to ensure its correct identification. For the visual assessment, any focal [18F]FDG-uptake within the thyroid that was visually higher than AUS/FLUS, atypia of undetermined significance or follicular lesions of undetermined significance. DTC, differentiated thyroid carcinoma. FN/SFN, (suspicious for a) follicular neoplasm. fT4, free thyroxine. FTC, follicular thyroid carcinoma. FT-UMP, follicular tumour of uncertain malignant potential. FVPTC, follicular variant PTC. HCC, Hürthle cell carcinoma. HCN/SHCN, (suspicious for a) Hürthle cell neoplasm. IQR, interquartile range. MTC, medullary thyroid carcinoma. PDTC, poorly differentiated thyroid carcinoma. PTC, papillary thyroid carcinoma. NIFTP, non-invasive follicular thyroid neoplasm with papillary-like nuclear features. SD, standard deviation. TSH, thyroid stimulating hormone. a: Baseline characteristics including SUV metrices were similar for AUS/FLUS (n=55) and FN/SFN (n=39) subgroups; the baseline data of these subgroups are presented in the Supplementary Data, table 4. b: In all patients, ultrasound nodule size was not correlated with the SUVmax (r(121)=0.13, p=0.154). c: Suspicious ultrasound characteristics were defined as presence of at least one of the following characteristics: marked hypoechogenicity (in a solid nodule), irregular shape (i.e., taller-than-wide), irregular margins, and/ or presence of microcalcifications. d: The reference range for TSH is 0.4–4.0 mU/L. e: The reference range for fT4 is approximately 10–25 pmol/L (sex and age dependent). f: Pearson’s chi-squared test. g: independent samples t-test. h: Mann-Whitney U test. i: Fisher’s exact test.

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