Quantitative evaluation of computed and voxelwise computed diffusion-weighted imaging in breast cancer.

Objectives: To assess the value of computed diffusion-weighted imaging (cDWI) and voxelwise computed diffusion-weighted imaging (vcDWI) in breast cancer. Methods: This retrospective study involved 130 patients (age range, 25-70 years; mean age +/- standard deviation, 48.6 +/- 10.5 years) with 130 malignant lesions, who underwent MRI examinations, including a DWI sequence, prior to needle biopsy or surgery. cDWls with higher b-values of 1500, 2000, 2500, 3000, 3500, and 4000s/mm(2), and vcDWl were generated from measured (m) DWI with two lower b-values of 0/600, 0/800, or 0/1000 s/mm(2). The signal-to-noise ratio (SNR) and contrast ratio (CR) of all image sets were computed and compared among different DWIs by two experienced radiologists independently. To better compare the CR with the SNR, the CR value was multiplied by 100 (CR100). Results: The CR of vcDWI, and cDWIs, except for cDWI(1000), differed significantly from that of measured diffusion-weighted imaging (mDWI) (cDWI(1000) : CR = 0.4904, p = 0.394; cDWI(1500) : CR = 0.5503, p = 0.006; cDWI(2000) : CR = 0.5889, p < 0.001; cDWI(2500) : CR = 0.6109, p < 0.001; cDWI(3000) : mean = 0.6214, p < 0.001: cDWI(3500) : CR = 0.6245,p < 0.001; cDWI(4000) : CR = 0.6228, p < 0.001). The vcDWI provided the highest CR, while the CRs of all cDWI image sets improved with increased b-values. The SNR of neither cDWI(1000) nor vcDWI differed significantly from that of mDWI, but the mean SNRs of the remaining cDWIs were significantly lower than that of mDWI. The SNRs of cDWIs declined with increasing b-values, and the initial decrease at low b-values was steeper than the gradual attenuation at higher b-values; the CR100 rose gradually, and the two converged on the b-value interval of 1500-2000 s/mm(2). Conclusions: The highest CR was achieved with vcDWI; this could be a promising approach easier detection of breast cancer. Advances in knowledge: This study comprehensively compared and evaluated the value of the emerging post-processing DWI techniques (including a set of cDWIs and vcDWI) in breast cancer.