Nakaura Takeshi, Iyama Yuji, Kidoh Masafumi, Yokoyama Koichi, Oda Seitaro, Tokuyasu Shinichi, Harada Kazunori, Yamashita Yasuyuki
Diagnostic Radiology, Amakusa Medical Center, Kameba 854-1, Amakusa, Kumamoto, 863-0046, Japan.
Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan.
Neuroradiology. 2016 Mar;58(3):245-51. doi: 10.1007/s00234-015-1631-4. Epub 2015 Dec 29.
The purpose of this study was to evaluate the utility of iterative model reconstruction (IMR) in brain CT especially with thin-slice images.
This prospective study received institutional review board approval, and prior informed consent to participate was obtained from all patients. We enrolled 34 patients who underwent brain CT and reconstructed axial images with filtered back projection (FBP), hybrid iterative reconstruction (HIR) and IMR with 1 and 5 mm slice thicknesses. The CT number, image noise, contrast, and contrast noise ratio (CNR) between the thalamus and internal capsule, and the rate of increase of image noise in 1 and 5 mm thickness images between the reconstruction methods, were assessed. Two independent radiologists assessed image contrast, image noise, image sharpness, and overall image quality on a 4-point scale.
The CNRs in 1 and 5 mm slice thickness were significantly higher with IMR (1.2 ± 0.6 and 2.2 ± 0.8, respectively) than with FBP (0.4 ± 0.3 and 1.0 ± 0.4, respectively) and HIR (0.5 ± 0.3 and 1.2 ± 0.4, respectively) (p < 0.01). The mean rate of increasing noise from 5 to 1 mm thickness images was significantly lower with IMR (1.7 ± 0.3) than with FBP (2.3 ± 0.3) and HIR (2.3 ± 0.4) (p < 0.01). There were no significant differences in qualitative analysis of unfamiliar image texture between the reconstruction techniques.
IMR offers significant noise reduction and higher contrast and CNR in brain CT, especially for thin-slice images, when compared to FBP and HIR.
本研究的目的是评估迭代模型重建（IMR）在脑部CT尤其是薄层图像中的效用。
本前瞻性研究获得了机构审查委员会的批准，并获得了所有患者参与研究的事先知情同意。我们纳入了34例接受脑部CT检查的患者，并使用滤波反投影（FBP）、混合迭代重建（HIR）以及层厚为1和5毫米的IMR重建了轴向图像。评估了CT值、图像噪声、对比度、丘脑与内囊之间的对比噪声比（CNR），以及不同重建方法之间1毫米和5毫米厚度图像中图像噪声的增加率。两名独立的放射科医生以4分制评估图像对比度、图像噪声、图像清晰度和整体图像质量。
层厚为1毫米和5毫米时，IMR的CNR（分别为1.2±0.6和2.2±0.8）显著高于FBP（分别为0.4±0.3和1.0±0.4）和HIR（分别为0.5±0.3和1.2±0.4）（p<0.01）。IMR从5毫米厚度图像到1毫米厚度图像的平均噪声增加率（1.7±0.3）显著低于FBP（2.3±0.3）和HIR（2.3±0.4）（p<0.01）。不同重建技术之间对不熟悉图像纹理的定性分析没有显著差异。
与FBP和HIR相比，IMR在脑部CT中能显著降低噪声，并具有更高的对比度和CNR，尤其是对于薄层图像。
