Time-of-Day Analysis of Brain Sodium TSC Maps

Previous investigations into brain sodium imaging have avoided the potential of variability due to circadian effects. Thus, in a pilot study we investigated whether time-of-day contributes to tissue sodium concentration (TSC) variance. Three TSC maps were acquired from 7 subjects, at three different times of day (8:00, 16:00, 22:00). Each TSC map was segmented into 10 ROIs before being analyzed using ANOVA with SNR and signal linewidth as added covariates. Time-of-day was a significant source of variance as was spectral linewidth. Between subject variance and SNR were not significant factors in the model.