Diffusion tensor MRI: preliminary anisotropy measures and mapping of breast tumors

To investigate whether diffusion tensor imaging (DTI) measures of anisotropy in breast tumors are different from normal breast tissue and can improve the discrimination between benign and malignant lesions.

The study included 81 women with 105 breast lesions (76 malignant, 29 benign). DTI was performed during breast MRI examinations, and fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were measured for breast lesions and normal tissue in each subject. FA and ADC were compared between cancers, benign lesions, and normal tissue by univariate and multivariate analyses.

The FA of carcinomas (mean +/- SD: 0.24 +/- 0.07) was significantly lower than normal breast tissue in the same subjects (0.29 +/- 0.07; P < 0.0001). Multiple logistic regression showed that FA and ADC were each independent discriminators of malignancy (P < 0.0001), and that FA improved discrimination between cancer and normal tissue over ADC alone. However, there was no difference in FA between malignant and benign lesions (P = 0.98).

Diffusion anisotropy is significantly lower in breast cancers than normal tissue, which may reflect alterations in tissue organization. Our preliminary results suggest that FA adds incremental value over ADC alone for discriminating malignant from normal tissue but does not help with distinguishing benign from malignant lesions.