直肠扩散峰度成像与扩散加权成像定量参数反映直肠癌组织学特性的优劣

Rectal diffusional kurtosis imaging: clinical value in detection of rectal cancer compared with diffusion weighted imaging

目的:比较扩散峰度成像(diffusional kurtosis imaging,DKI)与扩散加权成像(diffusion weighted imaging,DWI)定量参数反映直肠癌组织学特性的优劣。方法:20例直肠癌患者及23例健康志愿者经过3.0T磁共振DKI扫描。扫描参数:采用5个b值(b=0、500、1 000、1 500、2 000 s/mm2),扩散敏感梯度场同时取X、Y和Z轴3个方向。健康组与直肠癌组定量参数[平均表观扩散系数(mean diffusion,MD)、平均表峰度系数(mean kurtosis,MK)、表观扩散系数(apparent diffusion coefficient,ADC)]比较采用两独立样本t检验及曲线下面积(area under curve,AUC)分析。结果:健康组MD、MK及ADC均值分别为1.37×10-3 mm2/s、0.96±0.11、(0.76±0.12)×10-3 mm2/s,直肠癌组MD、MK及ADC均值分别为(1.10±0.12)×10-3 mm2/s、1.22±0.16、(0.60±0.06)×10-3 mm2/s,差异有统计学意义。诊断直肠癌的MD值具有最大的AUC(0.928),MK值的AUC(0.909)居中,ADC值的AUC最小(0.907)。结论:初步研究结果支持DKI能反映直肠癌组织结构的复杂性,其定量参数MD和MK比ADC对直肠癌组织结构的复杂性更敏感。

Objective： To compare the quantitative parameters of diffusion kurtosis imaging（DKI） with diffusion weighted imaging（DWI） for assessment of the histological characteristics of rectal cancer. Methods： Twenty rectal cancer patients and twenty-three healthy volunteers underwent DKI scans（b=0, 500, 1 000, 1 500, 2 000 s/mm2, respectively; three diffusion directions）. The values of mean diffusion（MD）, mean kurtosis（MK）, apparent diffusion coefficient（ADC） and pathologic findings between the two groups were compared using independent sample t test and receiver operating characteristic（ROC） analyses. Results： The values of MD, MK and ADC in healthy volunteers were 1.37×10-3 mm2/s, 0.96±0.11,（0.76±0.12）×10-3 mm2/s, respectively, and in rectal cancer patients were（1.10±0.12）×10-3 mm2/s, 1.22±0.16,（0.60±0.06）×10-3 mm2/s, respectively. There were significant differences between the two groups（P〈0.05）. The area under the curve（AUC） for MD value（0.928） could better distinguish rectal cancer from healthy volunteers than that for MK value（0.909） and ADC value（0.907）. Conclusion： The preliminary findings suggest that DKI can predict rectal cancer. The parameters MD and MK are better than ADC in predicting rectal cancer.