Detection of calcification using high-pass filtered phase image in magnetic resonance imaging for breast cancer screening

To achieve detection of calcifications using magnetic resonance imaging (MRI) for breast cancer screening, we investigated combinations of an echo time (TE) and a high-pass filter size on phase images using a breast phantom. The breast phantom was made from gel area of 0.1 mmol/L gadopentetate dimeglumine and 2.0 wt% agar containing imitation calcifications to simulate calcification in the breast. To use the phase image for calcification assessment, optimization of TE was required since a difference of phase is enhanced at sufficiently long TE. However, longer TE tends to increase the static field inhomogeneity effects. To remove the static field inhomogeneity effects, we employed a high-pass filter processing. Then, several different filter sizes were tested to optimize the visualization of calcification. TE of 48 msec had the highest contrast between imitation calcifications and gel area. The high-pass filter size of 64×64 pixels was able to remove efficiently the background phase effects. The high-pass filtered phase image was able to show imitation calcifications as hyperintense areas. Although the limit of detection of imitation calcifications was 1.0 mm, it suggests a possibility that the high-pass filtered phase image is able to use for breast cancer screening and diagnosis without pain by compression or the use of ionizing radiation.