LBW指数结合能谱CT在合理降低肝脏增强CT的CM剂量中的应用

Application of LBW index combined with energy spectrum CT in reducing the contrast agent dose of liver enhanced CT

目的比较能谱CT扫描条件下去脂体质量(lean body weight, LBW)与全体质量(total body weight, TBW)作为指数计算肝脏增强CT对比剂药量的增强效果。方法连续纳入2018年11月至2019年1月在本院影像科行肝脏增强CT的218例患者,LBW组101例,TBW组117例。两组均采用能谱CT扫描,扫描和重建参数一致。使用的CM计算方法:LBW组的对比剂量为500 mgI/kg(LBW),TBW组的对比剂量为450 mgI/kg(TBW),注射速率均为2.8 mL/s。检查结束后将图像传输到GE AW4.7工作站,对50 keV单能量图像进行分析。比较两组患者的CM使用量、动脉期主动脉CT值(HU-aorta)、静脉期肝脏增强CT值(△-liver)、主动脉和肝脏增强达标率及变异度。结果与TBW组比较,LBW组CM剂量、HU-aorta和△-liver更低(P<0.05),LBW组和TBW组HU-aorta(91.09%vs. 90.60%)和△-liver(92.08%vs. 88.89%)的增强达标率无统计学差异(P>0.05)。LBW组HU-aorta和△-liver的变异度均明显低于TBW组,增强效果更一致。结论在能谱CT扫描前提下,使用LBW作为指数计算肝脏增强CT的药量,不仅可以减少造影剂用量,而且可以使患者的肝实质增强效果更加一致。

Objective To compare the enhancement effects of lean body weight(LBW) and total body weight(TBW)as indexes to calculate the contrast agent dosage under the condition of energy spectrum CT scanning. Methods A total of 218 patients who received liver enhancement CT from November 2018 to January 2019 were enrolled in this study. There were 101 patients in LBW group and 117 patients in TBW group. Both groups were scanned by energy spectrum CT, and the parameters of scanning and reconstruction were identical. The contrast agent dose was 500 mgI/kg(LBW) in LBW group and 450 mgI/kg(TBW) in TBW group, and the injection rate was 2. 8 mL/s. Images were transferred to a GE AW4. 7 workstation and the 50 keV monochromatic images were analyzed. We compared the dosage of contrast medium,CT value of aorta in arterial phase(HU-aorta),hepatic enhancement CT value in venous phase(-liver),the rate of reaching the enhancement standard and variability in the two groups. Results Compared with TBW group,LBW group had lower contrast agent dosage,HU-aorta and △-liver(P<0. 05),LBW and TBW group had no statistically different enhanced rate of HU-aorta as(91. 09% vs. 90. 60%) or △-liver(92. 08% vs. 88. 89%)(P>0. 05). The variation rate of HU-aorta and △-liver in LBW group was lower than that in TBW group. Using LBW as an index to calculate the dosage of liver enhanced CT also made the enhancement of liver parenchyma more consistent in different patients. Conclusion Even on the premise of energy spectrum CT scanning,using LBW-based contrast injection in liver enhanced CT can not only reduce contrast dose, but also make the enhancement in liver parenchyma more consistent among different patients.