Evaluation of breast cancer extension with diffusion-weighted MR imaging / 中华放射学杂志

ABSTRACT

Objective To investigate the feasibility of determining the breast cancer extension with diffusion-weighted imaging(DWI)and the apparent diffusion coefficient(ADC).Methods Fifty-nine lesions(57 patients)were studied by using DWI and ADC measurement before surgical excision.The cancer extension was investigated on ADC maps with different b values(b=500 and 1000 s?mm~(-2))according to the threshold values discussed before.The lesion extension on dynamic enhanced images and on DWI was used for comparison.The tumor extension was determined by calculating two lines.Line one:the maximum diameter of lesion.Line two:perpendicular line crossing the midpoint of line one.All measurement was compared with the pathologic specimen.Results(1)There were 48 invasive ductal carcinomas,6 ductal carcinomas in situ with small invasive foci,3 mucinous carcinomas,and 2 medullary carcinomas.(2)The low ADC value on ADC maps at b=500 and 1000 s?mm~(-2)was described as cancer extension.The measurement results were compared to pathologic figures and the pattern of correlation was categorized into 3 groups:Group 1,the area of low ADC values was almost the same as the pathological tumor extension; Group 2(overdiagnosis),the area of low ADC values was wider and more than 20% larger than the area of tumor extension;Group 3(false negative),no area of low ADC value was observed.There were no significant difference between DWI with b of 500 and b of 1000 s?mm~(-2)(X~2=0.160,P=0.689;X~2= 0.172,P=0.679)in Groups 1 and Group 3.There were 2 lesions in Group 2,which were consistent in DWI with b of 500 and b of 1000 s?mm~(-2).There were 14 misdiagnosed lesions,including overdiagnosis in 2 lesions and false negative in 12 lesions.Eight lesions measured at DWI with b of 500 and b of 1000 s? mm~(-2)were not consistent.Five lesions were diagnosed correctly at DWI with b of 500 s?mm~(-2),three of them were duetal carcinomas in situ with small invasive foci.(3)The extension of lesion on dynamic enhanced imaging was measured at 4 minutes after enhancement,and was compared with the extension measured at the same slice on DWI map.Pathologic figures were regarded as the gold standard.The extension of 47 lesions(80%)on enhanced images accorded with DWI.The abnormal area on DWI,which was consistent with pathologic figures,was wider than the area on enhanced images in 8 lesions.Of them,3 lesions were mucinous carcinomas and 5 lesions were grade 3 invasive ductal carcinomas.Conclusion DWI and ADC value have the potential in evaluating the cancer extension.The accuracy of extension measured on DWI map was better than that on dynamic enhanced images for some kinds of breast cancers.