弥散加权成像鉴别乳腺良恶性病变的价值初探

Differentiation of benign from malignant breast lesions by apparent diffusion coefficients

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 2 6例 ,良性病变 2 3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 96 0 8± 0 2 0 43)×10 -3 mm2 /s,明显低于良性病变组的 [(1 5 85 8± 0 32 3 4)× 10 -3 mm2 /s]及正常组的 [(1 76 17±0 40 3 1)× 10 -3 mm2 /s(P <0 0 5 ) ],良性病变组ADC值与正常组间无显著性差异。ADC诊断的敏感性为 92 3% (2 4/ 2 6 ) ,特异性为 85 0 % (17/ 2 0 ) ,准确性为 89 1% (4 1/ 46 )。其诊断能力与动态增强扫描近似 ,二者对病变良、恶性诊断结果的一致性很好 (P <0 0 1)。结论 DWI能清楚地显示乳腺良恶性肿瘤 ,ADC值是鉴别乳腺良恶性病变的一个很有价值的参数。

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 mm 2/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.