Diffusion-weighted magnetic resonance imaging reveals the effects of different cooling temperatures on the diffusion of water molecules and perfusion within human skeletal muscle

AimTo evaluate the effect of local cooling on the diffusion of water molecules and perfusion within muscle at different cooling temperatures.Materials and methodsMagnetic resonance diffusion-weighted (DW) images of the leg (seven males) were obtained before and after 30 min cooling (0, 10, and 20 °C), and after a 30 min recovery period. Two types of apparent diffusion coefficient (ADC; ADC1, reflecting both water diffusion and perfusion within muscle, and ADC2, approximating the true water diffusion coefficient) of the ankle dorsiflexors were calculated from DW images. T2-weighted images were also obtained to calculate T2 values of the ankle dorsiflexors. The skin temperature was measured before, during, and after cooling.ResultsBoth ADC values significantly decreased after cooling under all cooling conditions; the rate of decrease depended on the cooling temperature used (ADC1: −36% at 0 °C, −27.8% at 10 °C, and −22.6% at 20 °C; ADC2: −26% at 0 °C, −21.1% at 10 °C, and −14.6% at 20 °C). These significant decreases were maintained during the recovery period. Conversely, the T2 value showed no significant changes. Under all cooling conditions, skin temperature significantly decreased during cooling; the rate of decrease depended on the cooling temperature used (−74.8% at 0 °C, −51.1% at 10 °C, and −26.8% at 20 °C). Decreased skin temperatures were not restored to pre-cooling values during the recovery period under any cooling conditions.ConclusionLocal cooling decreased the water diffusion and perfusion within muscle with decreased skin temperature; the rates of decrease depended on the cooling temperature used. These decreases were maintained for 30 min after cooling.