能谱CT虚拟平扫在儿童腹部成像中的可行性研究

Study of Feasibility of Virtual Non-Enhanced CTin the Assessment of Pediatric Abdomen

目的 通过定量分析儿童腹部虚拟平扫(VNE)与常规平扫(TNE)图像,探讨VNE在儿童腹部CT成像中应用的可行性。方法 自2017年1月至2018年6月,前瞻性连续纳入于上海儿童医学中心行腹部能谱CT扫描的患儿35例。应用64排CT (GE Discovery CT 750 HD)行腹部平扫和增强扫描,采用低管电流(260m A)宝石能谱CT技术行动脉期扫描,TNE和门静脉期采用常规多层螺旋CT扫描模式,利用虚拟平扫技术重建动脉期VNE。测量比较VNE和TNE中肝脏、肾脏、胰腺、脾脏和肌肉的CT值、图像噪声值(SD值)、对比噪声比(CNR)、图像质量主观评分、有效辐射剂量(ED)。结果 VNE与TNE的各脏器SD值、CNR比较,差异无统计学意义(P>0.05)。VNE各脏器与竖脊肌的平均CT值略低于TNE,但具有良好的相关性(r:0.509-0.952)。VNE主观图像质量评分与TNE比较,差异无统计学意义(P>0.05)。省略TNE的两期方案的有效辐射剂量(动脉期采用能谱CT扫描模式、门静脉期采用常规多层螺旋CT扫描模式)略低于常规三期方案,差异无统计学意义(P>0.05)。结论 VNE图像CT值与TNE具有很好的相关性,图像质量较好,可满足临床诊断需求。VNE技术在儿童腹部CT成像中具有一定的可行性,并可能为儿童腹部CT成像提供了一种更简单的方案。

Objective To evaluate the feasibility of virtual non-enhanced(VNE)images generated from the contrastenhanced spectral CT images in the evaluation of pediatric abdominal imaging.Methods Thirty-five pediatric patients who underwent abdominal spectral CT scan were prospectively and consecutively enrolled in Shanghai Children’s Medical Center from from January 2017 to June 2018.A 64-slice CT(GE Discovery CT 750 HD)was used for plain and enhanced abdominal scanning,and a low tube current(260 mA)gemstone spectroscopy CT technique was used for arterial phase scanning,and conventional multi-slice spiral CT scanning was used for TNE and portal venous phases.Based on the original data of the energy spectrum scan,the arterial phase VNE was reconstructed using the virtual unenhanced scan technique.The CT value,image noise value(SD value),contrast-to-noise ratio(CNR),subjective score of image quality and effective radiation dose(ED)of liver,kidney,pancreas,spleen and muscle in VNE and TNE were measured and compared.Results There was no difference in CNR between VNE and TNE for liver,spleen,kidney and pancreas(all P>0.05).Mean CT attenuation values from VNE(at 70keV)were systematically lower than those on TNE(at 65keV)for all tissue types due to photon energy difference,but with good one-to-one correlation(r:0.509-0.952).Image noise was similar on VNE and TNE images.There was no difference in image quality score between VNE and TNE(P>0.05).Image quality score for VNE was lower than TNE,but was acceptable for diagnosis.Effective radiation doses of the two-phase protocol(arterial phase with spectral CT imaging mode and portal-venous phase performed by multi-slice spiral CT);omitting the TNE scan was similar to the conventional three phase protocol.Conclusion Image quality of VNE images is acceptable for diagnosis and CT numbers of VNE images correlate well with TNE images.VNE has certain feasibility in the assessment of pediatric abdomen,providing a simpler protocol.