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SummaryAlthough fat suppression technique is used in breast MRI, artifacts often appear owing to susceptibility and defective fat suppression effect after breast surgery. This is due to the abundance of adipose tissue in the breast as well as the region of air around the circumference of the excision site. Therefore, we have evaluated the optimal pad material for achieving fat suppression in breast MRI to reduce image artifacts and patient discomfort while maintaining breast shape. Oil of the solidity was used as the breast phantom material after segmental resection surgery. Five pad materials, including rice, ball bullets, glass beads, acrylic beads, and bath salts were used to fill the defects. Fat-suppressed, T1 -weighted, three-dimensional imaging was performed using a breast array coil. Images with and without the five pad materials, were evaluated physically, visually, and by contact. Physical evaluation consisted of measuring the maximum signal and standard deviation in the regions of interest (ROIs). Discomfort and the amount of perceived resistance were evaluated during contact evaluation by inserting a finger into each pad material. In results, glass beads and bath salts produced a significantly larger fat suppression effect in the ROIs. Visual and contact evaluation also highlighted the benefits of glass beads, the latter demonstrating a significant decrease in discomfort and perceived resistance. In conclusion, we consider glass beads as the optimal pad material for fat suppression in breast MRI after surgery.

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Factors for Degaussing of a Cochlear Implant Magnet in the MR Scanner SummaryThis study examined the conditions influencing degauss of the magnet using magnetic resonance imaging (MRI). Poly methyl methacrylate (PMMA) was used to fix the measurement magnets to the MRI bed at angles from 0°to 180°for the magnetic flux vector of static magnetic field. The PMMA was moved in the MRI magnetic field. Magnetic flux density was measured before and after bed movement, and the rate of degauss was calculated. The contents examined are as follows: (1) the angle of the magnetic flux vector of the measurement magnets for the magnetic flux vector of the static magnetic field, (2) the number of movements, (3) moving velocity, and (4) the movement on the spatial gradient of magnetic field. Mann-Whitney U test was used for statistical analysis of the data. In conclusion, the effect of the angle of the magnetic flux vector of the implant magnet was high under the conditions of degauss in this study. Therefore, during the MRI examination of a patient with a cochlear implant magnet, the operators identified the directions of the magnetic flux vector and static magnetic field of the implant magnet.