Effects of motion and b-value on apparent temperature measurement by diffusion-based thermometry MRI: eye vitreous study

Does cerebrospinal fluid pulsation affect diffusion-weighted imaging thermometry? A study in healthy volunteers

Diffusion-weighted imaging (DWI)-based thermometry offers potential as a noninvasive method for measuring temperatures deep inside the human brain. However, DWI might be influenced by the pulsatile flow of cerebrospinal fluid (CSF). This study aimed to investigate the influence of such pulsations on DWI thermometry in healthy individuals. A total of 104 participants (50 men, 54 women; mean [± standard deviation] age, 44.2 ± 14.3 years; range 21-69 years) were investigated. DWI-based brain temperature (T_DWI ) was acquired at three speeds (maximum and minimum speeds of ascending flow and random timing at the cerebral aqueduct) of CSF pulsation using a 3-T magnetic resonance imaging scanner. Magnetic resonance spectroscopy (MRS)-based temperature (T_MRS ) at the thalamus was also obtained as a reference standard for brain temperature. The three different CSF pulsatile flows were monitored by heart rate during the scan. The difference between reference temperature and brain temperature (ΔT = T_DWI - T_MRS ) along with the three CSF speeds were statistically compared using Student's matched pair t-test. No significant difference in ΔT was evident among CSF speeds (p > 0.05). No significant linear correlation between ΔT and CSF flow speed at the cerebral aqueduct was observed. Using DWI thermometry with clinical acquisition settings, which utilizes mean values within thresholds, no effect of CSF pulsation speed was observed in the estimation of ΔT.