自适应统计迭代重建技术在髋关节64排CT低管电流检查中的应用

目的：探讨自适应统计迭代重建（ASIR）技术在髋关节64排CT低管电流检查中的应用。方法：106例髋关节64排螺旋CT扫描患者,随机选取53例患者采用常规管电流220 m As扫描,并采用滤过反投影（FBP）方式重建。另外53例患者采用低管电流50 m As扫描,并采用30%ASIR技术。对两组髋关节图像的辐射剂量和图像质量进行评价,并比较不同重建图像在同一层面的图像噪声值和信噪比。结果：常规管电流组与低管电流组的CT剂量指数（CTDIvol）分别为（15.55±0.20）m Gy、（3.56±0.15）m Gy,低管电流组平均CTDIvol较常规管电流组降低77.1%;常规管电流组与低管电流组的剂量长度乘积（DLP）分别为（297.82±2.9）m Gy·cm、（67.59±3.3）m Gy·cm,低管电流组平均DLP较常规管电流组降低77.3%,低管电流组与常规管电流组相比,辐射剂量大大降低（P〈0.05）。常规管电流组图像质量评分为优、良、差的患者分别为49、4和0例;低管电流组图像质量评分为优、良、差的患者分别为42、11及0例。两组图像的差异无统计学意义（P〉0.05）。图像噪声值分别为31.44、44.29,差异有统计学意义（P〈0.05）。图像信噪比分别为11.03、10.06,差异有统计学意义（P〈0.05）。结论：ASIR技术应用于64排螺旋CT髋关节低管电流扫描,大幅降低辐射剂量的同时,图像质量也能满足临床诊断的需要。

Application of ASIR Techniques in Hip with Low Tube Current 64 Row CT

Objective： To explore the feasibility of adaptive statistical iterative reconstruction（ASIR） technique in 64-slice CT of hip with low tube current application. Methods： Of 106 patients with 64 row helical CT scan of hip,53 patients were treated with conventional tube current of 220 m As scanning, and were reconstructed with filtered back projection（FBP）, 53 patients were treated with low tube current of 50 m As scanning and were reconstructed with 30% of adaptive statistical iterative reconstruction（ASIR）.The radiation dose, image noise（S D value） and signal-to-noise ratio of different reconstruction images of two groups were compared respectively at the same level. Results： The CTDIvol value was（15.55 ± 0.20） m Gy in the conventional group and（3.56 ± 0.15） m Gy in the low tube current group, the CTDIvol in the low tube current group was 77.1% of that in the conventional group, the DLP was（297.82 ± 2.9） m Gy·cm in the conventional group and（67.59 ± 3.3） m Gy·cm in the low tube current group, the DLP in the low tube current group was 77.3% of that in the conventional group. Compared with the conventional group, the radiation dose of low tube current group was reduced greatly（P 〈 0.05）. The image quality with excellent、good、bad was 49, 4 and 0 cases, respectively, in the conventional group. 42, 11 and 0 cases in the low tube current group,difference of image quality between two groups were no statistically significant（P 〉 0.05）. The difference of image noise value and SNR between two groups were statistically significant, respectively（P 〈 0.05）. Conclusion： It is feasible to apply 30% of ASIR technology in 64 row helical CT of hip with low-current of 50 m A, resulting with the reduction of radiation dose, meanwhile, the image quality can meet the need of clinical diagnosing.