弥散加权成像鉴别乳腺良恶性病变的价值初探

目的　探讨弥散加权成像（diffusionweightedimaging,DWI）的表面弥散系数（apparentdiffusioncoefficients，ADC）鉴别乳腺良恶性病变的价值。方法　健康志愿者10人，经手术病理证实的乳腺病变49例，其中恶性肿瘤26例，良性病变23例。DWI采用单次激发回波平面成像（echo-planarimaging,EPI）技术，14例取5个b值（b为扩散敏感度），余者取2个b值，计算ADC值。以恶性肿瘤ADC值单侧上界95%容许区间为界限判断病灶的良恶性，诊断结果与动态增强比较。结果　除1例原位癌和1例小腺瘤外，DWI显示所有良恶性病变。恶性肿瘤组ADC值为(0.9608±0.2043)×10

Differentiation of benign from malignant breast lesions by apparent diffusion coefficients

Objective　To evaluate the value of diffusion weighted imaging(DWI) and apparent diffusion coefficients (ADC) in distinguishing benign and malignant breast lesions. Methods　Spin echo, Echo Planar diffusion imaging (TR 10 000 ms, TE 99 ms, thickness 5 mm)was used to scan 10 health volunteers and 49 patients with histologically proven benign (23) and malignant (26) breast lesions on a GE 1.5 T scanner using a GPFlex coil. Five b values (14 cases) or 2 b values (45 cases) were acquired with diffusion gradients applied in all 3 orthogonal directions. Geometric mean images were used in the analysis. Apparent diffusion coefficients (ADC) were calculated in all cases. One-side upper limit of 95% permissible interval of ADC was adopted as the point to separate the malignant from benign lesions. The ability of ADC to discriminate benign and malignant breast lesions was compared with that of dynamic MRI. Results　All benign and malignant lesions except 1 carcinomas in situ and 1 small adenoma were visible on DWI. Calculated ADC(in units of 10-3 mm2/s) of malignant lesions (0.960 8±0.204 3) was statistically different from that of benign lesions (1.585 8±0.323 4) and normal fibroglandular tissue (1.761 7±0.403 1). Mean ADC of 4 cystic lesions was 2.437 1. The sensitivity, specificity, and overall accuracy of diagnostic indices of ADC were 92.3%(24/26), 85.0%(17/20), and 89.1%(41/46), respectively. The ability of ADC in discriminating benign and malignant breast lesions was similar to that of dynamic MRI. Conclusion　DWI is a rapid and feasible method in detecting breast lesions. ADC is an effective parameter in discriminating malignant and benign breast lesions.