The Usefulness of Diffusion-Weighted Imaging in MRI Test for Breast Cancer

Abstract

This study evaluated the utility of diffusion-weighted imaging (DWI) on breast magnetic resonance imaging (MRI). Using the T2-weighted images as a reference, the ability of DWI to detect samples placed in self-constructed phantoms according to their size was compared with that of actual patients. For the phantom subjects, two phantoms with identical size that could be inserted in both breast coils were prepared. Five samples with different sizes were prepared and immobilized, and T2-weighted images, and the DW images were obtained using a 3.0-T MR scanner. The patients were 20 cases with a histological diagnosis of intraductal carcinoma, and their DW images and apparent diffusion coefficient map images were obtained. For quantitative analysis of the phantoms, the ratio of the sample volume on DWI was presented as the mean b value with reference to the T2-weighted images, in which the detection ability of the lesions on the MR images was excellent. The b value of the following samples was 0.5 x 0.5 cm = 0.33/0.34 cm(2) (103 %), 1 x 1 cm = 1.28/1.25 cm(2) (102.4 %), 1.5 x 1.5 cm = 2.28/2.67 cm(2) (85.39 %), 2 x 2 cm = 3.56/4.08 cm(2) (87.25 %), and 2.5 x 2.5 cm = 7.53/8.77 cm(2) (85.86 %). In the patients, the signal-to-noise and contrast-to-noise ratios were higher in the lesion tissues than the normal tissues. The lesion tissues showed lower apparent diffusion coefficients than the normal areas.