Department of Radiology, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China.
Network Information Center, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China.
J Appl Clin Med Phys. 2021 Dec;22(12):158-167. doi: 10.1002/acm2.13466. Epub 2021 Nov 9.
To investigate the effect of different pitches and corresponding scan fields of view (SFOVs) on the image quality in the ultrafast, high-pitch turbo FLASH mode of the third-generation dual-source CT using an anthropomorphic phantom.
The phantom was scanned using the ultrafast, high-pitch turbo FLASH protocols of the third-generation dual-source CT with the different pitches and corresponding SFOVs (pitches: 1.55 to 3.2 with increments of 0.1, SFOVs: 50 cm to 35.4 cm). The objective parameters such as the CT number, image noises, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and artifacts index (AI), and image features from the head, chest, and abdomen were compared between the CT images with a pitch of 1.55 and SFOV of Ø 50 cm and a pitch of 3.2 and SFOV of Ø 35.4 cm. Then, the 18 series of CT images of the head, chest, and abdomen were evaluated by three radiologists independently.
The differences in the CT numbers were not statically significant between the CT images with a pitch of 1.55 and SFOV of Ø 50 cm and a pitch of 3.2 and SFOV of Ø 35.4 cm from most body parts and potential combinations (p > 0.05), Most of the image noises and the AI from the images with the pitch of 1.55 were significantly lower than those with the pitch of 3.2 (p < 0.05), and the SNR and CNR from the images with the pitch of 1.55 were higher than those with the pitch of 3.2. There were significant differences in the first-order features and texture features of the head (59.3%, 28.3%), chest (66%, 35.7%), and abdomen (71.6%, 64.7%) (p < 0.05). The subjective image quality was excellent when the pitch was less than 2.0 and gradually decreased with the increasing pitch. In addition, the image quality decreased significantly when the pitch was higher than 3.0 (all k≥0.69), especially in the head and chest.
In the ultrafast, high-pitch turbo FLASH mode of the third-generation DSCT, increasing the pitch and lowering the corresponding SFOV will change the image features and cause more artifacts degrading the image quality. Specific to the clinical needs, decreasing the pitch not only can expand the SFOV but also can improve the image quality.
使用人体模型研究第三代双源 CT 超快高螺距 turboFLASH 模式下不同螺距和相应扫描视野（SFOV）对图像质量的影响。
使用第三代双源 CT 的超快高螺距 turboFLASH 协议对人体模型进行扫描，螺距分别为 1.55 至 3.2（增量为 0.1），SFOV 分别为 50cm 至 35.4cm。比较螺距为 1.55、SFOV 为 Ø 50cm 与螺距为 3.2、SFOV 为 Ø 35.4cm 的 CT 图像的客观参数，如 CT 值、图像噪声、信噪比（SNR）、对比噪声比（CNR）和伪影指数（AI），以及头、胸、腹部的图像特征。然后，三位放射科医生分别对 18 组头、胸、腹部 CT 图像进行评估。
从大多数身体部位和潜在组合来看，螺距为 1.55、SFOV 为 Ø 50cm 与螺距为 3.2、SFOV 为 Ø 35.4cm 的 CT 图像的 CT 值差异没有统计学意义（p＞0.05）。螺距为 1.55 的图像噪声和 AI 大多显著低于螺距为 3.2 的图像噪声和 AI（p＜0.05），螺距为 1.55 的 SNR 和 CNR 高于螺距为 3.2 的 SNR 和 CNR。头部（59.3%、28.3%）、胸部（66%、35.7%）和腹部（71.6%、64.7%）的一级特征和纹理特征有显著差异（p＜0.05）。当螺距小于 2.0 时，主观图像质量极好，随着螺距的增加，图像质量逐渐下降。此外，当螺距高于 3.0 时（所有 k≥0.69），图像质量显著下降，特别是在头部和胸部。
在第三代 DSCT 的超快高螺距 turboFLASH 模式下，增加螺距和降低相应的 SFOV 会改变图像特征，并导致更多的伪影，从而降低图像质量。根据临床需要，降低螺距不仅可以扩大 SFOV，还可以提高图像质量。
