灌注CT诊断胰岛素瘤最佳融合期相数目

Averaging Strategy to Form the Imaging for Routine Reading of Insulinoma from Pancreatic Perfusion Dataset

目的比较不同期相数目融合得出的自定义容积图像,找到灌注CT诊断胰岛素瘤的最佳融合期相数目。方法回顾性纳入因怀疑胰岛素瘤、在北京协和医院行灌注CT检查且经病理证实为胰岛素瘤的患者39例,采用后处理软件dynamic angio获取主动脉时间-密度曲线,之后将腹主动脉峰值及其邻近2、4、6、8、10期,共计3、5、7、9、11个时间点融合,得到5组自定义容积图像。对5组图像的客观图像质量[噪声、胰腺实质信噪比(SNR)、肿瘤对比度及对比噪声比(CNR)]及主观图像质量(总体图像质量、胰岛素瘤显示)进行比较。统计学方法采用单因素重复测量方差分析及Friedman M秩和检验。结果随着融合期相增多,图像噪声明显减低,胰腺SNR明显增加(P均<0.001)。5期融合图像胰岛素瘤对比度为69.81±41.35,与3期融合图像的72.77±45.25相比差异无统计学意义(P=0.103),但显著高于其他各组(P均≤0.001)。5~11期融合图像胰岛素瘤的CNR值差异无统计学意义(P均>0.99),但均显著高于3期融合图像(P均<0.05)。5组容积图像的总体图像质量差异无统计学意义(P=0.977)。结论5期融合图像胰岛素瘤对比度及CNR不劣于甚至优于其他融合图像,且拥有中等图像噪声及胰腺实质SNR。灌注CT诊断胰岛素瘤的最佳融合期相数目为5期。

Objective To determine the appropriate averaging strategy for pancreatic perfusion datasets to create images for routine reading of insulinoma.Methods Thirty-nine patients undergoing pancreatic perfusion CT in Peking Union Medical College Hospital and diagnosed as insulinoma by pathology were enrolled in this retrospective study.The time-density curve of abdominal aorta calculated by software dynamic angio was used to decide the timings for averaging.Five strategies,by averaging 3,5,7,9 and 11 dynamic scans in perfusion,all including peak enhancement of the abdominal aorta,were investigated in the study.The image noise,pancreas signal-to-noise ratio(SNR),lesion contrast and lesion contrast-to-noise ratio(CNR)were recorded and compared.Besides,overall image quality and insulinoma depiction were also compared.ANOVA and Friedman’s test were performed.Results The image noise decreased and the SNR of pancreas increased with the increase in averaging time points(all P<0.001).The lesion contrast(69.81±41.35)averaged from 5 scans showed no significant difference compared with that(72.77±45.25)averaged from 3 scans(P=0.103),both of which were higher than that in other groups(all P≤0.001).The lesion CNRs of the last four groups showed no significant difference(all P>0.99)and were higher than that of the first group(all P<0.05).There was no significant difference in overall image quality among the 5 groups(P=0.977).Conclusions Image averaged from 5 scans showed moderate image noise,pancreas SNR and relatively high lesion contrast and lesion CNR.Therefore,it is advised to be used in image averaging to detect insulinoma.