双层探测器光谱CT虚拟平扫替代常规平扫评估结直肠癌的可行性研究

Feasibility Study of Dual Layer Spectral Detector CT Derived Virtual Non-Contrast Images Substitute for True Non-Contrast Images in Evaluating Colorectal Cancer

目的探讨双层探测器光谱CT(SDCT)虚拟平扫(VNC)技术在结直肠癌诊断中的价值。方法搜集本院52例结直肠癌患者的影像资料,比较真实平扫(TNC)、动脉期VNC(VNC-A)、静脉期VNC(VNC-V)、延迟期VNC(VNC-D)四组图像中结直肠癌病灶、腹主动脉、椎旁肌/臀大肌、皮下脂肪的CT值、噪声、信噪比(SNR)、对比噪声比(CNR),并对四组图像质量进行评分。结果四组图像中结直肠癌病灶、椎旁肌/臀大肌CT值均无显著性差异(P均>0.05),而腹主动脉、皮下脂肪CT值均存在显著性差异(P均<0.05)。与TNC图像相比,各组织在三组VNC图像中的噪声均明显降低,且病灶及腹主动脉SNR高于TNC图像(P均<0.05)。四组图像均能满足诊断要求,两名观察者的主观评价一致性较好。采用“VNC+直接增强扫描”方案可降低约22.39%的辐射剂量。结论在评估结直肠癌方面,由SDCT获得的VNC图像质量接近于TNC,且辐射剂量更低。

Objective To explore the value of virtual non-contrast(VNC)derived from dual layer spectral detector CT(SDCT)in the diagnosis of colorectal cancer.Methods The imaging data of 52 patients with colorectal cancer were collected in our hospital.The CT value,SD,SNR and CNR of the colorectal cancer lesions,abdominal aorta,paravertebral muscle/gluteus maximus,subcutaneous fat were evaluated among TNC,VNC-A,VNC-V,VNC-D images,and the four groups subjective image quality were assessed.Results There were no significant differences in the CT values of lesions and paravertebral muscle/gluteus maximus among four groups images(all P>0.05),while there were significant differences in CT values of abdominal aorta and subcutaneous fat(all P<0.05).Image noise of all tissues was significantly lower in three-phase VNC images than that in TNC images.Meanwhile,the SNR of lesions and abdominal aorta was higher than that of TNC(P<0.05).All the four groups images could meet the diagnostic requirements,and the consistency of subjective evaluation by two observers was good.The radiation dose can reduce by about 22.39% using“VNC+enhanced CT”protocol.Conclusion The image quality of VNC derived from dual layer spectral detector CT is closer to that of TNC in evaluating colorectal cancer and the radiation dose was lower.