能谱计算机断层扫描智能最佳管电压技术在提高食管癌患者胸部增强扫描图像质量中的应用价值

Application Value of Intelligent Optimum Tube Voltagein Improving the Image Quality of Chest Computed Tomography Enhancement for Patients with Esophageal Cancer

目的 探讨能谱计算机断层扫描(CT)智能最佳管电压技术联合低碘对比剂注射量在食管癌患者胸部双期增强CT扫描中的应用价值。方法 收集104例于我院行能谱CT双期胸部增强扫描的食管癌患者,并随机分为A组、B组,每组52例。其中A组行120kVp常规CT扫描模式,对比剂含碘450mg·kg^-1,B组采用CT智能管电压匹配扫描模式,对比剂含碘300mg·kg^-1。依据患者体质量指数(BMI)分别将A组、B组2组再各分为3个亚组:A1组和B1组各12例,BMI<18.5kg·m^-2;A2组和B2组各20例,18.5kg·m^-2≤BMI<24.9kg·m^-2;A3组和B3组各20例,BMI≥24.9kg·m^-2。首先对图像质量进行主观评分,然后再观察主肺动脉窗、气管分叉、右肺动脉、左右房室层面降主动脉的CT值、噪声、信噪比(SNR)和对比噪声比(CNR),并记录辐射剂量。结果 所有图像均达到诊断要求。动脉期A1组、A2组图像质量评分高于B1组、B2组(P均<0.05),静脉期2组间主观评分比较差异均无统计学意义(P均>0.05)。A3组与B3组动脉期、静脉期比较差异均无统计学意义(P均>0.05)。B组在2期各层面降主动脉的CT值低于A组,图像噪声均低于A组(P均<0.05)。组间CNR比较,静脉期A1和B1组间支气管分叉层面和右肺动脉层面、A2和B2组间左右房室层面、A3和B3组间左右房室层面比较差异均无统计学意义(P均>0.05),其余层面B组的CNR均高于A组,差异均有统计学意义(P均<0.05)。SNR在B组的各个BMI亚组均高于A组,差异均有统计学意义(P均<0.05)。A1组、A2组较B1组、B2组的有效射线剂量分别降低16.39%(1.46/8.91)和14.50%(0.67/4.62),A3组与B3组比较差异无统计学意义(P>0.05)。结论 在食管癌患者胸部CT增强扫描时,能谱CT智能最佳管电压技术能够依据患者不同BMI选择合适的管电压,从而有效降低辐射剂量并提高图像质量,联合低碘对比剂注射方案能够减少患者造影剂的摄入,并维持良好的图像质量。

Objective To investigate the influence of intelligent optimum tube voltage combined with low total dose of iodinated contrast medium injection based on body mass index (BMI) on radiation dose and image quality of chest computer tomography (CT) enhancement for patients with esophageal cancer. Methods One hundred and four patients with esophageal cancer who received spectral chest CT enhancement were randomly divided into group A and group B (52 patients each group). Group A with conventional 120 kVp, 450 mg·kg ^-1 contrast medium injection;group B with intelligent optimum tube voltage, 300 mg·kg ^-1 contrast medium injection. Patients were divided into three sub-groups based on BMI value, respectively. A1 and B1sub-groups (12 patients each sub、1group), BMI<18.5 kg·m^-2;A2 and B2 sub-groups (20 patients each sub-group), 18.5 kg·m ^-2 ≤BMI< 24.9 kg·m^-2;A3 and B3 sub-groups (20 patients each sub-group), BMI≥24.9 kg·m ^-2 . Subjective image quality score for each group were evaluated. CT attenuation, image noise, signal to noise ratio(SNR),contrast noise-to-ratio (CNR)of descending aorta at different layers (main pulmonary artery, tracheal bifurcation, right pulmonary artery and left/right atrium) and radiation dose were compared. Results All the CT images met the requirement. Image quality scores of the A1 and A2 sub-groups were higher than those of the B1 and B2 sub-groups during arterial phase ( P <0.05), while no significant difference during venous phase ( P >0.05).The A3 and B3 sub-groups showed no statistical difference during arterial and venous phase ( P >0.05). CT attenuation and image noise of descending aorta in group B at different layers were lower than those in group A. CNR of descending aorta at tracheal bifurcation, right pulmonary artery layer in A1 and B1 the sub-groups, left/right atrium layer in the A2 and B2 sub-groups, left/right atrium layer in the A3 and B3 sub-groups during venous phase had no statistical difference, other layer in group B were higher than those of group A( P <0.05). SNR in group B for all the sub-groups were superior to those of group A. The effective radiation dose in the A1 and A2 sub-groups were lower than in the B1 and B2 sub-groups, and were dropped by 16.39% and 14.50%, respectively;however, no significant difference between A3 and B3 sub-groups ( P >0.05). Conclusion Optimal tube voltage can be selected according to BMI value by using intelligent optimum tube voltage technique, which can effectively reduce the radiation dose and improve the image quality. Combined with low total dose of iodinated contrast medium injection can reduce the contrast agent injection dose and maintain the image quality.