不同浓度对比剂联合能谱CT扫描在肾动脉CT血管成像中的应用

Different Concentrations of Contrast Media Combined with Spectral CT Imaging in Renal CT Angiography

目的采用不同浓度对比剂联合能谱CT进行肾动脉CT血管成像（CTA）检查,探讨减少患者碘摄入量并保证影像质量的可行性。资料与方法 100例患者随机分为5组行肾动脉能谱CT肾动脉造影检查,对比剂总量为1 ml/kg,5组患者注射对比剂浓度为370 mg I/ml、333 mg I/ml、296 mg I/ml、259 mg I/ml、222 mg I/ml,用层厚0.625 mm的最佳对比噪声比（CNR）ke V图像对肾动脉行容积再现和最大密度投影。计算图像信噪比（SNR）及CNR,比较5组图像质量主观评分,并评价2名医师对图像质量主观评价的一致性。结果肾动脉最佳CNR单能量范围为48～53 ke V。370 mg I/ml、333 mg I/ml、296 mg I/ml、259 mg I/ml组图像SNR、CNR及2名医师评分差异无统计学意义（P〉0.05）;上述对比剂浓度组与222 mg I/ml组图像SNR、CNR及2名医师评分差异有统计学意义（P〈0.05）。2名医师评价上述对比剂浓度组图像质量的一致性（Kappa=0.83,P〈0.05）高于222 mg I/ml组（Kappa=0.63,P〈0.05）。结论能谱CT在肾动脉CTA检查中能显著降低对比剂浓度。

Purpose To explore the feasibility of reducing patients iodine intake and ensuring image quality as well by using different concentration of contrast media combined with spectral CT imaging in renal CT angiography（CTA）. Materials and Methods One hundred patients who underwent renal spectral CT examination were randomly divided into 5 groups. The contrast media dose were offered at 1 ml/kg, and contrast media concentration for the 5 groups were 370 mg I/ml, 333 mg I/ml, 296 mg I/ml, 259 mg I/ml and 222 mg I/ml, respectively. The ke V maps of the optimal contrast noise ratio（CNR） with a thickness of 0.625 mm were used to obtain volume rendering（VR） and maximum intensity projection（MIP） to show the renal artery. The signal noise ratio（SNR） and contrast noise ratio（CNR） of the images were calculated. The overall imaging quality of 5 groups was evaluated by 2 radiologists. Consistence between 2 readers was evaluated. Results The monochromatic image at 48-53 ke V was found to demonstrate the best CNR for the renal artery. There was no statistic difference for SNR, CNR and the consistence among the groups of contrast media concentration of 370 mg I/ml, 333 mg I/ml, 296 mg I/ml and 259 mg I/ml（P〈0.05）. While SNR, CNR and the consistence at the contrast media concentration of 222 mg I/ml were significantly different with other contrast media concentration groups（P〈0.05）. When compared with 222 mg I/ml group, the consistence between the two readers was higher for the contrast media concentration of 370 mg I/ml, 333 mg I/ml, 296 mg I/ml, 259 mg I/ml groups（P〈0.05）. Conclusion The spectral CT can significantly reduce the contrast media concentration in renal artery CTA.