感兴趣区和层面变化对前列腺外周带组织表观扩散系数图一级统计学特征测量的影响

Effects of variety in region of interest and slice on measurement of first-order statistical features in apparent diffusion coefficient map of prostate peripheral zone

目的:探讨感兴趣区(region of interest,ROI)的大小和层面变化对前列腺外周带正常和前列腺癌组织表观扩散系数(apparent diffusion coefficient,ADC)图一级统计学特征测量的影响。方法:回顾性分析18例前列腺外周带癌患者的ADC图和常规MRI图像,对照病理结果,应用不同ROI测量前列腺癌与正常组织的一级统计学特征。ROI 1:根据T2WI图像特征在最大层面确定前列腺癌及正常组织;ROI 2:根据ADC图确定组织;ROI 3、ROI 4:大小分别为ROI 1的3/4和1/2;ROI 5:为多层面组成的整体病灶或组织。筛选前列腺癌与正常组织有显著差异的参数,进一步评价不同ROI之间测量结果差异。结果:共测量19个病灶和21个正常外周带组织的数据。肿瘤与正常组织的峰度值和偏度值无显著差异,而各ROI测量的正常组织ADC值均值及百分位数均显著高于前列腺癌。随着ROI缩小,肿瘤组织ADC值降低,正常组织变化不明显,两者平均ADC值对应的标准差(standard deviation,SD)在所有ROI之间均无显著差异。但正常组织不同百分位数ADC值对应的大部分SD值明显高于前列腺癌。测量整体体积与最大层面获得的ADC值及其百分位数、SD值不同并无显著差异。结论:不同面积ROI测量对ADC均值及百分位数均有显著影响,一级统计学特征测量可获得比平均ADC值更多有统计学意义的参数。

Objective:To investigate the effects of variety in region of interest(ROI)and slice on the measurement of the first-order statistical features of apparent diffusion coefficient(ADC)map of prostate peripheral zone.Methods:Retrospective analysis of18subjects with prostate cancer in peripheral zone was performed.The first-order statistical features of cancer and normal tissues were measured with different ROIs referring to the pathological data.ROI1:the cancer lesions and normal tissues were identified by T2WI image characteristic on the largest slice;ROI2:identified by ADC map;the areas of ROI3and ROI4were3/4and1/2of ROI1,respectively;ROI5was the whole volume of the cancer lesions and normal tissues with multi-slice.Data which were significantly different between cancer lesions and normal tissues were selected and further assessed their variety in different ROIs.Results:Data were obtained from19cancer lesions and21normal tissues.There was no significant differences in skewness and kurtosis between cancer lesions and normal tissues.The mean and percentile ADC values from all ROIs were all significantly higher in normal tissues than cancer lesions.As the area of ROI reduced,the mean ADC value in the cancer lesions decreased,but in the normal tissues remained stable.Their standard deviation(SD)values were not significantly different,but the SD values for most of the percentile ADC values were significantly higher in normal tissues compared with cancer lesions.The ADC values,the percentile ADC values and their SD values measured on the largest slice were not significantly different from those by whole volume.Conclusion:The area of ROI has remarkable effect on the mean and percentile ADC values,and first-order statistical features could provide more significative data.