Objective:To investigate the effects of low-dose contrast medium on image quality of dual source CT dual energy lung perfusion imaging (DEPI). Methods:Thirty consecutive patients with suspected pulmonary embolism (PE) underwent dual source CT perfusion imaging with low-dose (0. 7 ml/kg) contrast medium, another 30 patients with conventional doses of contrast medium (1. 5 ml /kg). CT pulmonary angiography (CTPA) and lung perfusion images were acquired at the same time. Injection rates of two groups were 4. 5 ml /s. The enhanced CT values of pulmonary artery were measured. The quality and grade of lung perfusion image were determined and comparative analysis was performed between the two groups. Results: There was no significant difference between low-dose group and the conventional dose group in enhanced CT value of pulmonary artery ( P > 0. 05). Segment and sub segmental pulmonary were clearly showed. The lung perfusion images were homogeneous signal in majority cases of low-dose group (26/30). But the majority of conventional-dose group were heterogeneous signal (24/30). Conventional-dose group was significantly higher than low-dose group in artifacts due to the high density of contrast medium of superior vena cava and right atrium (48: 10). Conclusion: There was no significant difference between low-dose and conventional-dose DEPI in image quality and reduced dose of contrast medium can reduce the artifacts of DEPI.%目的:探讨对比剂剂量对双源CT双能量肺灌注成像质量的影响.方法:疑肺动脉栓塞患者行双源CT双能量肺灌注扫描,30例使用低剂量(0.7ml/kg)对比剂,30例使用常规剂量对比剂(1.5ml/kg),注射速率均为4.5ml/s.扫描后同时获得肺动脉CTA及肺灌注图像.测量左、右叶肺动脉干及各肺叶动脉增强后的CT值,对比分析两组间增强后的CT值.判断肺灌注图像质量并分级,比较两组的肺灌注图像质量差异.结果:低剂量组与常规剂量组左、右叶肺动脉干及各肺叶动脉增强后的CT值无明显差异(P＞0.05).肺段及亚段肺动脉图像清晰显示.低剂量组肺灌注图像大部分信号均匀(26/30),常规剂量组肺灌注图像大部分信号均匀(24/30).常规剂量组上腔静脉、右心房高密度对比剂所致灌注伪影明显多于低剂量组(48:10).结论:低剂量与常规剂量双能量肺灌注成像的肺动脉图像质量无明显差异,降低对比剂剂量可以减少双能量肺灌注图像的伪影.
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