平成15年度前期国際研究集会派遣会員報告書

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Purpose : To analyze reproducibility of ADC measurements on different MRI scanners. Methods and Materials : Diffusion-weighted imaging (DWI) of a home-made phantom (gelatine of different concentration was enclosed in case of circle pillar shape) was performed with the following protocol ; spin-echo type echo planar imaging ; TR=7000 msec, TE=minimal, matrix=128×128, FOV=220 mm, slice thickness=5mm, NEX=1, b-factor=0, 500, and 1000 sec/mm^2 on four different 1.5T MR scanners [GE Signa Horizon (two of them), GE Signa Horizon Lx, and Siemens Magnetom Symphony]. Image analysis were performed on a workstation (GE Medical Systems) or on an operators console of Symphony (for data of Symphony). We used two-point method. Regions of interest (ROIs) were set on every part of ADC map of home-made phantom and ADCs were measured. A linear approximation graphs were also made with every MRI scanner and b-factor. Results : A linear approximation was performed, formulas were y=-0.08x+2.32, r^2=0.84 (Lx), y=-0.09x+2.58, r^2=0.89 (Horizon-1) y=-0.11x+2.67, r^2=0.95 (Horizon-2), y=-0.08x+2.42, r^2=0.97 (Symphony) at b-factor of 500sec/mm^2. Y=-0.08x+2.33, r^2=0.91 (Lx), y=-0.09x+2.43, r^2=0.93 (Horizon-1), y=-0.08x+2.48, r^2=0.92 (Horizon-2), y=-0.07x+2.39, r^2=O.96 (Symphony) at b-factor of 1000sec/mm^2 Conclusions : ADC values measured at two MRI scanners (same model and older than the other scanners) are higher than other scanners on b-factor=500sec/mm^2, but at b-factor=1000sec/mm^2, a good relationship between every scanners was obtained. This result seems to depend on generation of the MRI scanners ; newly scanners have good relations b-factor 500 and 1000sec/mm^2. Pulse sequence design may be improved and optimized in newly scanners. When ADCs were used as quantitative value, a proper b-factor must be used.
公益社団法人日本放射線技術学会の論文
2003-07-20

平成15年度前期国際研究集会派遣会員報告書

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