We investigated the characteristics of diffusion quantification values in a restricted structure with a capillary phantom in PGSTE and OGSE. Smaller structure sizes require shorter diffusion times for structure estimation. In OGSE, we observed a transition of diffusion coefficients under 10 ms for capillary sizes from 6-12 μm, but no differences for those from 25-100 μm. Moreover, it was necessary to consider the temperature dependence of the diffusion measurement at low temperatures. We developed a system to measure the effects on diffusion quantification values at three phases of different temperatures, structure sizes, and diffusion times.