关键词: 乳腺病变, 扩散加权成像, 表观扩散系数, 相对表观扩散系数, 诊断效能

Abstract:

Objective: To investigate the diagnostic efficiency of the apparent diffusion coefficient(ADC)and the relative apparent diffusion coefficient (rADC)in the differentiation between benign and malignant breast lesions in diffusion weighed imaging(DWI).Methods: One hundred twenty-three females with suspected breast lesions who underwent breast MRI examination and proved by pathology and surgery were included in this study. The axial DWI,sagittal T2WI and dynamic contrast enhanced (DCE)scan were performed. With reference to the location and size of lesions on the DCE image,the regions of interest (ROI)were placed in the lesions and their adjacent normal gland regions (more than 2 cm to the lesion). The ADC values of corresponding regions were recorded,and the standardized rADC values were calculated. The mean values of ADC and rADC between benign and malignant breast lesions were compared. The optimal threshold values of ADC and rADC in differentiation between benign and malignant lesions were defined based on receiver operating characteristic (ROC)curve. Their diagnostic efficiency in breast lesions were assessed by comparing the area under curve(AUC). Results: Among the 134 lesions,the mean ADC values of 84 malignant lesions and 50 benign lesions were (1.04±0.26)×10^-3 and (1.60±0.40)×10^-3 mm²·s^-1,respectively. The mean ADC value of 134 ROI in the normal,glands was (1.89±0.31)×10^-3 mm²·s^-1. The ADC value of malignant lesions was significantly lower than those of benign lesion and normal gland tissues(P<0.01). The mean rADC values of malignant lesions and benign lesion were 0.59±0.18 and 0.83±0.30,respectively;the rADC value of malignant lesion was lower than that of benign lesion (P<0.01).When the ADC cutoff value of 1.22×10^-3 mm²·s^-1 was selected,its sensitivity and specificity were 86.0% and 84.50%,respectively;its AUC was 0.89. While the rADC cutoff value of 0.80 was selected,its sensitivity and specificity were 74.0% and 75.0%,respectively;its AUC was 0.80. The AUC of standardized rADC was lower than that of unstandardized ADC(P<0.05).Conclusion: Quantitative analysis of ADC and rADC values is an efficient method for differentiation between benign and malignant breast lesions.The standardized rADC value does not improve the diagnostic efficiency of ADC value.

Key words: breast lesion, diffusion weighted imaging, apparent diffusion coefficient, relative apparent diffusion coefficient, diagnostic efficiency