l コントラスト l Contrast-to-noise ratio l リカバリ係数 l Coefficient of variance l 定量値（Bq/mL, SUV） l Line profile (FWHMも含む) l 検出能 l etc. ファントムを用いた骨SPECTの画質評価 1~15) ROI（VOI）の設定 1) Zeintl J, et al. J Nucl Med. 2010; 51(6). 2) Nakahara T, et al. EJNMMI Res. 2017; 7(53). 3) Zhang R, et al. EJNMMI Phys. 2021;8(66). 4) 市川 肇 他. 日放技学誌. 2015;71(12). 5) 市川 肇 他. 核医学技術. 2017;37(3). 6) 三輪 建太 他.核医学技術. 2017;37(4). 7) 佐越 美香 他．日放技学誌. 2018;74(5). 8) Miyaji N, et al. EJNMMI Res. 2020;10(71). 9) Motegi K et al. Rad Phys Tech. 2020. 10) Ichikawa H, et al. Ann Nucl Med. 2021;35(8). 11) Ichikawa H, et al. Nucl Med comm. 2021;35(8). 12) Ito T, et al. Rad Phys Tech. 2021 13) Fukami M, et al. J Nucl Med Tech. 2021;49(2). 14) Shibutani T, et al. scientificreports. 2021; 11:2644 15) Ichikawa H, et al. Ann Nucl Med. 2022; 36(2).
l ROI（VOI）設定の再現性 11) n Aliasing 誤差 n ピクセル補完の有無 l SPECT画像特性 n 部分容積効果 n Gibbsアーチファクト 2) l 評価指標に基準値がない n 画像間の比較によって評価 骨SPECT画質評価の課題 2) Nakahara T, et al. EJNMMI Res. 2017; 7(53). 11) Ichikawa H, et al. Ann Nucl Med. 2021;35(8). 放射能分布 減弱係数分布
検出能：Rose criteria 17) Contrast-to-noise ratio (CNR) > 5 17) Rose A. Vision. 1 ed: Springer US; 1973. 18) Oen SK, et al. EJNMMI Phys. 2019;6(1):16. 病変の検出 Oen SK, et al.18) CNR for detected (green) and non-detected (red) acquisition times than normally used in clinical routine. In general, the PET/CT showed slightly increased CRC and CNR for the OSEM+PSF(+TOF) reconstructions compared to PET/MRI. CRC and CNR in- creased when PSF was incorporated in the reconstruction, and a further increase was found when both PSF and TOF were included. Improvements by PSF and TOF have also been demonstrated previously [4, 13, 15–17, 19, 20], and this indi- cates that these algorithms should be used to increase the possibility of detecting small lesions. PSF is a geometry correction that provides higher and more uniform spatial resolution over the transaxial FOV and will therefore have the most impact at the outer edges of the FOV [32]. The inclusion of TOF increases the signal-to- Fig. 7 Histograms of contrast-to-noise ratio (CNR) for detected (green) and non-detected (red) spheres for a PET/MRI and b PET/CT for all the reconstructions with similar number of true counts for the two systems. The black line represents CNR = 5 (Rose criterion). There are twice as many reconstructions for the PET/CT than for the PET/MRI due to the TOF option Fig. 2 Spherical VOIs placed over the hot spheres in OSEM with PSF and TOF with activity concentration of 8:1 (3 iterations, 2 mm voxel size) (purple: d = 20 mm, cyan: d = 12 mm, green: d = 8 mm, pink: d = 6 mm, orange: d = 5 mm, red: d = 4 mm) and seven spherical background VOIs (yellow: d = 20 mm) (a) (b) Øen et al. EJNMMI Physics (2019) 6:16 Page 7 of 16
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