宽体探测器CT低剂量扫描在婴幼儿先天性心脏病中的图像质量及辐射剂量研究

目的 探讨宽体探测器CT低剂量扫描在婴幼儿先天性心脏病检查中的图像质量及辐射剂量。方法 回顾性连续选取本院先天性心脏病患儿100例纳入研究，年龄均<3岁。根据扫描方案不同分为两组：低剂量组50例，男31例，女19例，年龄12 d至32个月，使用宽体探测器CT行低剂量心电门控轴扫；对照组50例，男26例，女24例，年龄19 d至27个月，应用多排CT容积螺旋穿梭技术扫描。分别测量两组图像升主动脉、主肺动脉、左心室、膈肌水平降主动脉及邻近肌肉组织的CT值和图像噪声，并计算信噪比（SNR）及对比噪声比（CNR）。采用双盲法评价心内结构、心外结构及冠状动脉的客观图像质量。记录每位患儿的容积CT剂量指数（CTDI_vol）和剂量长度乘积（DLP），并计算有效剂量（E）。结果 两组4个解剖区域的CT值、图像噪声、SNR及CNR，差异均无统计学意义（P>0.05）。两组心内结构及心外结构的客观图像质量评分差异无统计学意义（P>0.05），冠状动脉的图像质量评分低剂量组显著高于对照组（4.10±0.90 vs. 2.88±0.82，Z=-5.818，P<0.05）。低剂量组有效剂量（0.57±0.30）mSv较对照组（2.39±1.15）mSv下降了76%，差异有统计学意义（t=-11.642，P<0.05）。结论 宽体探测器CT低剂量方案扫描婴幼儿先天性心脏病，在不影响图像质量的前提下，有效辐射剂量显著降低。

The investigation on image quality and radiation dose of low dose wider detector array CT scanning for young children with congenital heart disease

Objective To investigate the image quality and radiation dose of the wider detector array CT scanner with low dose scanning mode in young children with congenital heart disease.Methods Totally 100 consecutive pediatric patients younger than 3 years with congenital heart disease were enrolled. They were divided into two groups. The low dose group with fifty patients underwent axial CT scanning with ECG gating, and the control group with fifty patients were scanned with volume helical shuttle (VHS) technique. CT number and noise of two groups images at the level of ascending aorta, main pulmonary artery, left ventricle, descending aorta and adjacent muscle were measured, and the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. The double blind method was used to evaluate subjective image quality of the level of intra-cardiac, extra-cardiac and coronary artery. Effective dose was also calculated for both groups.Results No significant difference was found in the CT number, image noise, SNR, and CNR between the two groups in the same anatomic regions(P>0.05). No significant difference was found in subjective image quality between the two groups for the intra-cardiac and extra-cardiac structure(P>0.05). The subjective image quality of coronary artery was significant higher in low dose group than the control group(4.10±0.90 vs.2.88±0.82, Z=-5.818, P<0.05). Effective dose was (0.57±0.30)mSv in group A and (2.39±1.15)mSv in group B with dose savings of 76%(t=-11.642, P<0.05).Conclusions The wider detector array CT scanner with low dose scanning mode can improve image quality with lower radiation dose.