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 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.