自适应统计迭代重建算法在儿童头部CT扫描中的应用

目的 探讨自适应统计迭代重建(ASiR)算法在儿童头部CT扫描中的应用价值。方法 对1个水模进行CT扫描,管电压100 kV,管电流分别为200、180、160、140、120和100 mA,ASiR比例分别设置为0、10%、20%、30%、40%、50%,采用FBP和ASiR迭代重建两种重建算法进行图像重建,比较不同条件下图像CNR、SNR和图像噪声。将80例接受头部CT扫描的患儿分为对照组(n=40)和试验组(n=40)。对照组采用管电压100 kV、管电流200 mA,FBP重建算法进行图像重建;试验组采用管电压100 kV、管电流140 mA,分别采用FBP和ASiR两种重建法进行图像重建;将重建后的图像分别记为试验FBP亚组和试验ASiR亚组;对两组中图像的CNR、SNR、图像噪声、CTDIvol、DLP、ED进行比较。结果 水模研究中,采用ASiR(30%)、管电流140 mA、ASiR算法重建图像的SNR、CNR及空气噪声值与管电流 200 mA、FBP重建图像最为接近。对照组与试验ASiR亚组图像的图像噪声、灰白质CNR和灰质SNR值差异均无统计学意义(P均>0.05);对照组和试验ASiR亚组图像的噪声、灰质SNR、灰白质CNR均优于试验FBP亚组,且差异均有统计学意义(P均<0.001)。结论 采用ASiR重建算法的头部CT扫描,既可降低患儿接受的辐射剂量,又保证了图像质量,具有较高的临床应用价值。

Application of adaptive statistical iterative reconstruction algorithm in head CT scan of children

Objective To explore the value of application of adaptive statistical iterative reconstruction (ASiR) algorithm in head CT scan of children. Methods A CT water phantom was scanned using 100 kV tube voltage and different tube current (200, 180, 160, 140, 120, 100 mA). The ratio of ASiR was set as 0, 10%, 20%, 30%, 40%, 50%, respectively. The imaging data were reconstruction by FBP and ASiR, respectively. CNR, SNR and image noise were compared. Totally eighty children were divided into control group (n=40) and experimental group (n=40). In control group, tube voltage of 100 kV, tube current of 200 mA and FBP were adopted. In experimental group, tube voltage of 100 kV, tube current of 140 mA were adopted, and FBP and ASiR were both used, and marked as FBP and ASiR experimental subgroups respectively. CNR, SNR, image noise, CT dose index volume, dose length product, effective dose in 2 experimental subgroups were compared. Results In the water phantom study, SNR, CNR, air noise were closest by using the method of ASiR algorithm (140 mA tube current, 30% ASiR ratio) and FBP algorithm (200 mA tube current). The defference of image noise, CNR and SNR between control group and ASiR experimental subgroup had no statistically significant (all P>0.05). The image noise, CNR, SNR in control group and ASiR experimental subgroup were better than that of FBP experimental subgroup, and the difference had statistically significant (all P<0.05). Conclusion It can not only reduce the radiation dose by ASiR reconstruction algorithm in children head CT scan, but also guarantee the image quality. It has high clinical application value.