正常胰腺小视野高分辨DWI研究

Study on the reduced field-of-view diffusion weighted imaging of healthy pancreas

目的:对比研究正常胰腺小视野扩散加权成像(rFOV DWI)和单次激发平面回波成像(SS-EPI)图像质量、ADC值及临床应用价值。方法:对20例胰腺健康志愿者分别行上腹部自由呼吸触发的SS-EPI DWI和rFOV DWI检查(b=600s/mm2)。从形态学方面,分别计算两种方法获得的胰腺头、体及尾部的ADC值,并进行统计学分析。结果:①rFOV DWI及SS-EPI DWI图像分辨力分别为0.55mm×0.55mm和1.56mm×1.56mm。②SS-EPI DWI获得正常胰腺头、体及尾部ADC值分别为(1.61±0.37)×10-3、(1.93±0.43)×10-3和(1.77±0.36)×10-3 mm2/s;rFOV DWI获得正常胰腺头、体及尾部ADC值分别为(1.10±0.48)×10-3、(1.21±0.38)×10-3和(1.11±0.34)×10-3 mm2/s。符号秩检验表明两种方法获得的胰腺头、体及尾部ADC值间差异无统计学意义(s=5,P=0.700>0.05)。③Wilcoxon秩和分析表明SS-EPI DWI获得的胰腺头、体及尾部ADC值间差异具有统计学意义(χ2=6.226,P=0.045<0.05),而rFOV DWI获得的胰腺头、体及尾部ADC值间差异无统计学意义(χ2=1.970,P=0.373>0.05)。结论:rFOV DWI较SS-EPI DWI图像分辨力高,且胰腺组织及总管显示更为清楚;统计学分析表明rFOV DWI获得的胰腺ADC均值不随胰腺形态学区域发生显著变化,具有较好的稳定性,而SS-EPI DWI获得的ADC均值在胰头部最小,胰体部最大,且差异具有统计学意义;较高分辨力和稳定的ADC测量值,将使rFOV DWI在胰腺疾病早期及准确诊断等方面发挥重要作用。

Objective：To compare the imaging qualities and application values between reduced field-of-view diffusion weighted imaging（rFOV DWI） and single-shot echo-planar-imaging diffusion weighted imaging（SS-EPI DWI） of healthy pancreas.Methods：Subjects comprised twenty healthy volunteers.SS-EPI DWI and rFOV DWI（b values=600s/mm2） were employed to calculate the apparent diffusion coefficient（ADC）.Furthermore,ADC values on the anatomical regions were calculated using Wilcoxon analysis.Results：① Resolution of rFOV DWI images was 0.55mm×0.55mm,which was much higher than the resolution（1.56mm×1.56mm） of SS-EPI DWI images.②Mean ADC values of pancreatic head,neck and tail were（1.61±0.37）×10-3,（1.93±0.43）×10-3 and（1.77±0.36）×10-3mm2/s calculated by SS-EPI DWI,and mean ADCs of pancreatic head,neck and tail were（1.10±0.48）×10-3,（1.21±0.38）×10-3 and（1.11±0.34）×10-3mm2/s calculated by rFOV DWI.Wilcoxon analysis showed no significant difference（s=5,P=0.7000.05） in the measurement of the ADC values of pancreas head,body and tail between the two methods.③The ADC values of pancreatic head,body and tail calculated by SS-EPI DWI were significantly different（χ2=6.226,P=0.0450.05）,but the opposite results were found in the ADC values calculated by rFOV DWI（χ2=1.970,P=0.3730.05）.Conclusion：rFOV DWI has higher resolution than SS-EPI DWI,and shows more clearly the pancreas and pancreatic duct.Statistical analysis showed that the ADC values of the pancreas obtained from rFOV DWI have better homogeneity.Stable ADCs and higher imaging resolution will make rFOV DWI to be useful in the accurate and early diagnosis of pancreatic diseases.