高低b值不同信号激励次数对直肠癌弥散加权成像图像质量的影响  

The Effect of Number of Excitations on Image Quality of Diffusion Weighted Imaging

作　　者：周慧赟 李纪强 董海鹏[1] 夏益涵 王康宁 吴梦雄[1] 丁蓓[1] ZHOU Huiyun;LI Jiqiang;DONG Haipeng;XIA Yihan;WANG Kangning;WU Mengxiong;DING Bei(Department of Radiology,Rujin Hospital,Shanghai Jiao Tong University School of Medicine,Shanghai,200025,China)

机构地区：[1]上海交通大学医学院附属瑞金医院放射科,上海市200025

出　　处：《中国医学计算机成像杂志》2024年第6期693-697,共5页Chinese Computed Medical Imaging

基　　金：国家自然科学基金青年项目(82271934,82101986)。

摘　　要：目的:探讨当扫描时间一定时,高、低b值不同信号激励次数(NEX)的设置对于弥散加权图像(DWI)以及表观弥散系数(ADC)图像质量的影响。方法:回顾性分析2023年2月至2023年6月于本院行直肠MR扫描的直肠癌患者38例,其中包括2种NEX的不同设置但扫描时间一致的2种DWI,即DWI22 (b=0 s/mm^(2)和1 000 s/mm^(2)时NEX均为2)和DWI13 (b=0 s/mm^(2)时NEX为1,b=1 000 s/mm^(2)时NEX为3)以及ADC图。2名医生分别对2种DWI高、低b值的图像进行主观和客观图像质量评价。结果:无论高b值或低b值,弥散图像的信噪比(SNR)在2名放射科医师间无统计学差异(P>0.05)。2名医生测量的DWI13的高b值图像的SNR均明显高于DWI22者(P<0.05)。同时,相较于NEX为2的高b值图像,NEX为3时的图像的形变及伪影更小、锐利度及病灶的清晰度更高(P<0.05)。DWI13对应的ADC图的变形和伪影较DWI22明显。结论:当扫描时间固定时,较大的NEX用于高b值图像的采集有利于获得更高质量的高b值图像,但可能导致ADC图像出现变形和伪影,需要根据临床实际取舍。Purpose: To compare the subjective and objective image quality of diffusion-weighted imaging(DWI) with different numbers of excitations(NEX) at different high and low b-values when the scan time is fixed.Methods: A retrospective analysis was conducted on 38 patients with rectal cancer who underwent rectal MR scans at our institution from February 2023 to June 2023. Two different DWI protocols with different NEX settings but the same scan time(DWI22 and DWI13) were included. Two radiologists independently evaluated the subjective and objective image quality of the DWI images with different b-values. Results: There was no significant difference in signal-tonoise ratio(SNR) between the high and low b-value images of the two DWI protocols(P>0.05). However, the SNR was higher in the high b-value images of DWI13 when compared to DWI22(P<0.05). Additionally, both radiologists considered that the images acquired with 3 NEX had less distortion and artifacts, higher sharpness, and better lesion clarity compared to the high b-value images acquired with 2 NEX(P<0.05). The distortion and artifacts of the ADC maps corresponding to DWI13 were more obvious than those of DWI22.Conclusion: When scan time is limited, the acquisition of larger NEXs for high-b-value images is beneficial for obtaining higher quality images, but ADC maps may have significant distortion and artifacts. Therefore, choices should be made according to the actual needs.

关 键 词：直肠肿瘤 激励次数 弥散加权成像 图像质量 

分 类 号：R445.2[医药卫生—影像医学与核医学]