探讨宽体探测器低kVp全肾脏CT灌注成像的可行性

Feasibility of CT Perfusion Imaging of Whole Kidney with Wide-Body Detector at Low kVp

目的 探讨基于宽体探测器低kVp CT扫描对全肾脏灌注参数稳定性的影响。方法 回顾性搜集全肾CT灌注成像(CTP)患者80例,其中包括肾脏无病变者56例,经手术病理证实为肾透明细胞癌(ccRCC)的患者24例。按照灌注扫描参数不同将患者分为A、B两组,A组采用管电压100 kVp(n=40,含12例ccRCC),B组采用管电压80 kVp(n=40,含12例ccRCC),其余参数、灌注期相均一致。采用AW4.6工作站CT perfusion 4D软件进行分析,输入动脉选取左右肾动脉分支水平主动脉,生成肾脏及病变灌注图像。两名观察者对图像进行分析,测量正常双肾皮髓质和肿瘤的血流量(BF)、血容量(BV)、到达脉冲剩余函数峰值通过时间(T_(max))、表面通透性(PS)及肿瘤对比剂平均通过时间(MTT)。分别比较两组组间双侧肾脏皮髓质和肿瘤各灌注参数及组内肿瘤与健侧肾脏皮质各灌注参数的差异。记录患者CT容积剂量指数(CTDIvol)和剂量长度乘积(DLP),计算有效辐射剂量(ED)。结果 A、B组间肾脏无病变者与ccRCC患者性别比例、年龄分布差异均无统计学意义(P均>0.05);两位观察者一致性较好[组内相关系数(ICC)值/相关系数=0.879~0.989];A、B组各灌注参数值比较中肾脏无病变者与ccRCC患者各灌注值差异均无统计学意义(P>0.05);A、 B组组内的肿瘤与对侧正常肾皮质相比PS值差异无统计学意义(P>0.05),其余参灌注参数差异均有统计学意义(P<0.05)。A组总辐射剂量(CTP+增强三期)ED平均为(33.15±4.23)mSv, B组为(21.35±2.69)mSv,差异有统计学意义(P<0.05)。结论 扫描参数kVp的改变对正常肾脏灌注、ccRCC灌注参数值无影响。临床应用中,可采用低管电压80 kVp进行灌注成像,可保证灌注参数稳定的同时,极大地减少患者的辐射剂量。

Objective To investigate the effect of low kVp scan based on wide-body detector CT on the stability of renal perfusion parameters.Methods Retrospective analysis was performed on 80 patients with whole-kidney CT perfusion(in-cluding 56 patients without renal lesions and 24 patients with clear cell renal carcinoma(ccRCC)confirmed by surgical pa-thology).The patients were divided into A(n=40,12 with ccRCC)and B(n=40,12 with ccRCC)groups according to different tube voltages:Group A:100 kVp and group B:80 kVp.Other parameters and perfusion period were consistent.AW4.6 CT perfusion 4D analysis was performed to select the horizontal aorta of the left and right renal artery branches from the input arteries to generate renal perfusion images.The images were analyzed by two observers.Blood flow(BF),blood volume(BV),peak pass time to pulse residual function(Tmax),surface permeability(PS),and average pass time of tumor contrast agents(MTT)were measured for normal double renal medulla and tumors.The differences in the perfusion parameters of bilateral renal skin,medulla and tumor between the two groups as well as the differences in the perfusion pa-rameters of the tumor and the healthy renal cortex within the group were compared.CTDIvol and DLP were recorded and ef-fective radiation dose ED was calculated.Results There were no statistically significant differences in gender ratio and age distribution of patients with renal clear cell carcinoma and patients without renal lesions between group A and group B(all P>0.05).The consistency of two observers was good(ICC/correlation coefficient=0.879-0.989).There was no statistical significance in the comparison of perfusion parameters between the patients without renal lesions and the patients with renal clear cell carcinoma(P>0.05).There was no significant difference in PS values between the tumor and the contralateral normal renal cortex in groups A and B(P>0.05),and there were significant differences in other parameters of perfusion(P<0.05).The mean ED of the total radiation dose(CTP+enhancement phase 3)in group A was(33.15±4.23)mSv,and that in group B was(21.35±2.69)mSv,with statistical significance(P<0.05).Conclusion The changes of scanning parameters kVp has no effect on normal renal perfusion and renal clear cell carcinoma perfusion parameters.In clinical application,a low tube voltage of 80 kVp can be used for perfusion imaging,which can ensure the stability of perfusion parameters and greatly reduce the radiation dose of patients.