Funama Yoshinori, Shirasaka Takashi, Goto Taiga, Aoki Yuko, Tanaka Kana, Yoshida Ryo
Department of Medical Radiation Sciences, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan.
Graduate School of Health Sciences, Kumamoto University, Kumamoto, Japan.
Acta Radiol Open. 2022 Jun 17;11(6):20584601221109919. doi: 10.1177/20584601221109919. eCollection 2022 Jun.
Brain CT needs more attention to improve the extremely low image contrast and image texture.
To evaluate the performance of iterative progressive reconstruction with visual modeling (IPV) for the improvement of low-contrast detectability (IPV-LCD) compared with filtered backprojection (FBP) and conventional IPV.
Low-contrast and water phantoms were used. Helical scans were conducted with the use of a CT scanner with 64 detectors. The tube voltage was set at 120 kVp; the tube current was adjusted from 60 to 300 mA with a slice thickness of 0.625 mm and from 20 to 150 mA with a slice thickness of 5.0 mm. Images were reconstructed with the FBP, conventional IPV, and IPV-LCD algorithms. The channelized Hotelling observer (CHO) model was applied in conjunction with the use of low-contrast modules in the low-contrast phantom. The noise power spectrum (NPS) and normalized NPS were calculated.
At the same standard and strong levels, the IPV-LCD method improved low-contrast detectability compared with the conventional IPV, regardless of contrast-rod diameters. The mean CHO values at a slice thickness of 0.625 mm were 1.83, 3.28, 4.40, 4.53, and 5.27 for FBP, IPV STD, IPV-LCD STD, IPV STR, and IPV-LCD STR, respectively. The normalized NPS for the IPV-LCD STD and STR images were slightly shifted to the higher frequency compared with that for the FBP image.
IPV-LCD images further improve the low-contrast detectability compared with FBP and conventional IPV images while maintaining similar FBP image appearances.
脑CT需要更多关注以改善极低的图像对比度和图像纹理。
评估视觉建模迭代渐进重建（IPV）用于改善低对比度可探测性（IPV-LCD）的性能，并与滤波反投影（FBP）和传统IPV进行比较。
使用低对比度和水模体。使用具有64个探测器的CT扫描仪进行螺旋扫描。管电压设置为120 kVp；管电流在层厚为0.625 mm时从60 mA调整至300 mA，在层厚为5.0 mm时从20 mA调整至150 mA。图像采用FBP、传统IPV和IPV-LCD算法重建。将通道化霍特林观察者（CHO）模型与低对比度模体中的低对比度模块结合使用。计算噪声功率谱（NPS）和归一化NPS。
在相同的标准和强水平下，与传统IPV相比，IPV-LCD方法提高了低对比度可探测性，与对比棒直径无关。层厚为0.625 mm时，FBP、IPV STD、IPV-LCD STD、IPV STR和IPV-LCD STR的平均CHO值分别为1.83、3.28、4.40、4.53和5.27。与FBP图像相比，IPV-LCD STD和STR图像的归一化NPS略微向高频偏移。
与FBP和传统IPV图像相比，IPV-LCD图像在保持类似FBP图像外观的同时，进一步提高了低对比度可探测性。
