双源 CT 双能量虚拟平扫在胸部疾病的临床应用研究

目的：探讨双源 CT(DSCT)双能量虚拟平扫(VNC)技术在胸部疾病的应用价值。方法对60例患者行胸部常规 CT平扫和双能量 CT 增强扫描。对比分析常规 CT 平扫图像与 VNC 图像，测量降主动脉、左心房及胸椎椎体后方肌肉的平均 CT 值、计算信噪比(SNR)、评价二者图像质量、比较辐射剂量。结果60例患者降主动脉的常规平扫与 VNC 平均 CT 值差异有统计学意义(P <0.05)；左心房及胸椎椎体后方肌肉平均 CT 值无差异(P >0.05)。VNC 降主动脉、左心房及胸椎椎体后方肌肉的 SNR 均高于常规平扫(P <0.05)。运用增强序列卷积核重建得到的肺窗图像与常规平扫肺窗图像基本一致，对肺实变47例，空洞4例，结节26例，肿块24例，纤维化病变31例，胸膜病变29例二者均能清楚显示(P >0.05)。VNC 图像仅对4(4/49)例肺门区微小钙化灶显示较常规平扫图像模糊。常规平扫与 VNC 图像的质量评分差异无统计学意义。VNC 的容积 CT 剂量指数(CTDIvol)、剂量长度乘积(DLP)、有效剂量(ED)均稍高于常规平扫(P <0.05)，但节省1次常规平扫剂量，平均每人可减少2.22 mSv ED。结论DSCT双能量 VNC 技术应用于胸部扫描，其图像质量能达到诊断要求，可有效降低辐射剂量，具有较好的临床应用价值。

Clinical application of dual-energy virtual non-contrast of dual source CT for thoracic diseases

Objective To investigate the applicational value of dual-energy virtual non-contrast (VNC)of dual source computed tomography (DSCT)for the thoracic diseases.Methods 60 patients with thoracic diseases were performed with conventional plain scan and dual energy enhanced scan.The image qualities of conventional plain scan and VNC of the patients were retrospectively evaluated.The mean CT values and the signal to noise ratio(SNR)of descending aorta,left atrium and muscles adjacent the thoracic vertebral spine were measured.The image quality and the radiation dosage were compared between conventional plain scan and virtual dual-energy scan.Results Of the 60 cases of patients,the mean CT values of descending aorta between conventional plain scan and VNC scan was statistically significant (P <0.05).No significant differences were found between conventional plain scan and VNC scan for the mean CT values of the left atrium and the muscles (P >0.05).VNC scan were higher than conventional plain scan in SNR of the descending aorta,left atrium and muscles (P <0.05).The lung window images of reconstruction using enhanced sequence convolution kernel and conventional plain scan were basically identical.In 47 cases of lung consolidation,4 cases of cavities,26 cases of nodules,24 cases of masses,31 cases of fibrotic lesions,29 cases of pleural lesions,these lesions could be found clearly displaying between conventional plain scan and VNC scan (P >0.05).For the image quality of thoracic lesions,the features of VNC scan were very close to those of conventional plain scan except 4 (4/49)cases of VNC images with blurrier borders.No significant difference was found in the average scores of image quality between the conventional plain scan and VNC scan.The radiation doses of dual-energy virtual non-contrast were slightly higher than conventional plain scan in the values of computed tomography dose index volume (CTDIvol),dose-length product (DLP)and effective dose (ED)(P <0.05).The VNC technology saved the radiation dose of a conventional plain scan and reduced an average of 2.22 mSv ED.Conclusion Dual-energy VNC technology of DSCT in the thoracic diseases can effectively reduce radiation dosage and ensure image quality,and therefore has a potential clinical application values.