能谱CT低浓度对比剂最佳单能量成像显示胃肠道恶性肿瘤供血动脉的研究

A Preliminary Study of Energy Spectrum CT on Showing Feeding Arteries of Gastrointestinal Tract Malignant Tumors with Low Concentration Contrast Medium

目的探讨能谱CT低浓度对比剂最佳单能量成像技术对胃肠道恶性肿瘤供血动脉血管成像质量的影响,以期合理降低对比剂浓度,减少对比剂不良反应的发生率。资料与方法前瞻性将71例经能谱CT扫描、体重指数〉25 kg/m^2的胃肠道恶性肿瘤患者分成两组,高浓度对比剂常规扫描组：33例,对比剂浓度350 mg I/ml;低浓度对比剂能谱成像组：38例,对比剂浓度270 mg I/ml。机器生成动脉期最佳单能量图像,比较两组肿瘤细小供血动脉图像的主观质量评分、肿瘤细小动脉CT值、图像噪声、对比噪声比（CNR）及容积CT剂量指数（CTDIvol）。结果低浓度组最佳单能量ke V值为51～60 ke V。低浓度组肿瘤细小供血动脉图像质量主观评分高于高浓度组（Z=-4.280,P〈0.01）,2名观察者对两组图像的评价结果一致性很好（Kappa=0.824、0.843,P〈0.05）。2名观察者获得两组的肿瘤细小供血动脉的CT值、右侧竖脊肌的CT值、图像噪声与CNR的结果一致性均良好（ICC高浓度组=0.998、0.968、0.959、0.990,ICC低浓度组=0.988、0.981、0.969、0.937）。低浓度组肿瘤细小供血动脉CT值、CNR均高于高浓度组,图像噪声低于高浓度组,差异均有统计学意义（t=-14.937、4.263、-17.264,P〈0.01）;两组CTDIvol差异无统计学意义（t=1.278,P〉0.05）。结论对于高体重指数患者,能谱CT低浓度对比剂最佳单能量成像技术能够提高胃肠道恶性肿瘤供血动脉血管成像的图像质量,且不增加辐射剂量。

Purpose To investigate the effects of the low concentration contrast medium combined with optimal single source spectral imaging on displaying feeding arteries of gastrointestinal tract malignant tumors. Materials and Methods Seventy-one patients of body mass index（BMI） 25 kg/m^2 with gastrointestinal tract malignant tumors were prospectively studied. All the cases were randomly divided into two groups： high concentration group（33 cases with high concentration contrast medium of 350 mg I/ml in routine scan） and low concentration group（38 cases with low concentration contrast medium of 270 mg I/ml in optimal single source spectral imaging）. The optimal single source images were generated automatically. The subjective image scores, CT value of the tumor feeding arteries, image noise, contrast-to-noise ratio（CNR） and CT dose index of volume（CTDIvol） of optimal single source spectral images in two groups were compared. Results The optimal single source of low concentration group were 51-60 ke V. The subjective image score of low concentration group was higher than high concentration group（Z=- 4.280, P〈0.01）. The consistency between the two investigators was good（Kappa=0.824 and 0.843, P〈0.05）. The consistency between the two investigators in evaluating CT value of the tumor feeding arteries, CT value at the right erector spinal muscle, image noise and CNR data was good（ICChigh concentration group=0.998, 0.968, 0.959 and 0.990; ICClow concentration group=0.988, 0.981, 0.969 and 0.937）. The CT values of the tumor feeding arteries and CNR of the low concentration group were higher than that of the high concentration group, but the image noise was lower than that of high concentration group（t=- 14.937, 4.263 and- 17.264, P〈0.01）. There was no statistical difference of CTDIvol between the two groups（t=1.278, P〈0.05）. Conclusion The low concentration contrast medium with optimal single source spectral imaging in patients with large BMI may improve CTA image quality of feeding arteries of gastrointestinal tract malignant tumors without increasing radiation dose.