宝石高分辨CT自适应统计迭代重建方法在儿童颈椎外伤低剂量扫描中的应用

Application of adaptive statistical iterative reconstruction on high-definition CT in post traumatic low dose cervical CT scan of children

目的对比儿童颈椎外伤后宝石高分辨CT(GE Discovery HDCT750)及64排容积CT(GE LightSpeedVCT64)扫描的辐射剂量,评价自适应统计迭代重建(ASiR)方法对儿童颈椎低剂量扫描的价值。方法将47例因颈椎外伤来我院影像中心接受颈椎CT扫描的患儿按照性别、年龄及就诊顺序分为A组(n=24)和B组(n=23)。A组以GEDiscovery HDCT750行颈椎CT扫描,预设噪声指数(NI)为14,使用ASiR对图像进行后重建,ASiR权重值为30%。B组以GE LightSpeed VCT64进行扫描,预设NI 12,使用滤波反向投影(FBP)对图像进行重建。分别记录各组CT扫描的最大电流、最小电流及容积CT剂量指数(CTDIvol),测量并记录颈椎椎体及同层面颈部肌群客观噪声,同时评价和记录图像的主观图像质量。使用SPSS 13.0统计软件对各组数据进行统计学分析。结果A组的平均管电流和CTDIvol值为(42.38±9.56)mA和(1.45±0.65)mGy,B组为(64.21±11.95)mA和(2.18±0.73)mGy,差异均有统计学意义(F=6.94、11.34,P均<0.01)。A组椎体松质骨及颈部肌群的客观噪声为26.04±7.83、5.65±1.00,B组分别为27.01±8.63、6.46±1.26,两组差异无统计学意义(P=0.72、0.84);两组图像的主观噪声评分分别为4.03±0.81、4.02±0.69(P=0.65)。结论在获得同样质量图像的前提下,与GE LightSpeed VCT64的FBP方法相比,GE Discovery HDCT750使用30%ASiR重建并提高2个单位NI值的扫描方案可有效减低儿童颈椎外伤CT扫描的辐射剂量。

Objective To compare the radiation dose between high-definition CT （GE Discovery HDCT750） with the adaptive statistical iterative reconstruction （ASiR） technology and 64-slice volume CT （GE LightSpeed VCT64） with filtered back projection （FBP） reconstruction in pediatric post-traumatic cervical CT scans. Methods Forty-seven children for post-traumatic cervical CT were included, and were divided into two groups according their sex, age and the order they came to the department. Group A （n=24） were scanned on the HDCT750 with nois index （NI） of 14, and images were reconstructed with 30%ASiR. Group B （n=23） underwent conventional VCT64 with NI of 12 and FBP reconstruction. The minimum and maximum tube currents and CT dose index （CTDIvol） were recorded. Image noises on the vertebral spongy bone and muscle were measured, and subjective image quality was assessed. These values were statistically compared between the two groups with SPSS 13.0. Results The average tube current and CTDIvol were （42.38±9.56）mA and （1.45±0.65）mGy, （64.21±11.95）mA and （2.18±0.73）mGy for group A and B, respectively （all P〈0.01）. The objective image noises for the vertebral spongy bone and muscle for group A and B was 26.04±7.83, 5.65±1.00 and 27.01±8.63, 6.46±1.26, respectively （P=0.72, 0.84）. There was no significant difference of subjective image quality scores between group A and B （4.03±0.81 and 4.02±0.69, P=0.65）. Conclusion Compared with conventional GE LightSpeed VCT64 with FBP, pediatric cervical CT on GE Discovery HDCT with 30%ASiR and 2 unit noise index increase provide 33% dose reduction, while maintaining similar image quality.