Masuda Shota, Sugisawa Koichi, Minamishima Kazuya, Yamazaki Akihisa, Watanabe Toshio
Department of Radiological Technology, Keio University Hospital.
Nihon Hoshasen Gijutsu Gakkai Zasshi. 2019;75(3):254-262. doi: 10.6009/jjrt.2019_JSRT_75.3.254.
The purpose of this study was to assess the feasibility of high-speed CT technology for head without deterioration of low-contrast detectability using the brain LCD (Canon Medical Systems) of iterative reconstruction.
System performance (SP) function analysis, low-contrast object specific contrast-to-noise ratio (CNR) analysis, and visual evaluation using Scheffe's paired comparison were performed. Additionally, analysis of the correlation of CNR and visual scores was performed. SP was performed with the self-made phantom. CNR was calculated with the catphan 504 phantom (CTP 515). Visual evaluation was performed using the brain phantom which simulated such as cerebral infarction and investigated on a fivepoint scale. All images were acquired with pitch factor of 0.61 (low pitch) and 1.40 (high pitch). All images were reconstructed with filtered back projection (FBP), brain LCD standard (LCD STD) and strong (LCD STR).
SP of brain LCD improved compared with FBP. CNR of FBP decreased in high pitch compared with low pitch. CNR of brain LCD images acquired by low- and high pitch were improved compared with FBP. Visual scores denoted similar trends to that of CNR and there was high correlation with CNR.
It was suggested that using brain LCD can achieve the high speed CT technology for head without deterioration of low-contrast detectability.
本研究旨在评估使用迭代重建的脑LCD（佳能医疗系统公司）在不降低低对比度可探测性的情况下，高速CT技术用于头部成像的可行性。
进行了系统性能（SP）函数分析、低对比度物体特定对比度噪声比（CNR）分析以及使用谢费尔配对比较法的视觉评估。此外，还进行了CNR与视觉评分的相关性分析。使用自制体模进行SP分析。使用猫模504体模（CTP 515）计算CNR。使用模拟脑梗死等情况的脑体模进行视觉评估，并采用五点量表进行评分。所有图像均在螺距因子为0.61（低螺距）和1.40（高螺距）的条件下采集。所有图像均采用滤波反投影（FBP）、脑LCD标准（LCD STD）和强化模式（LCD STR）进行重建。
与FBP相比，脑LCD的SP有所改善。FBP的CNR在高螺距时比低螺距时降低。与FBP相比，低螺距和高螺距采集的脑LCD图像的CNR均有所提高。视觉评分与CNR呈现相似趋势，且与CNR具有高度相关性。
提示使用脑LCD可实现用于头部的高速CT技术，且不会降低低对比度可探测性。
