Altered dynamic amplitude of low-frequency fluctuation in individuals at high risk for Alzheimer's disease.

The brain's dynamic spontaneous neural activity is significant in supporting cognition; however, how brain dynamics go awry in subjective cognitive decline (SCD) and mild cognitive impairment (MCI) remains unclear. Thus, the current study aimed to investigate the dynamic amplitude of low-frequency fluctuation (dALFF) alterations in patients at high risk for Alzheimer's disease and to explore its correlation with clinical cognitive assessment scales, to identify an early imaging sign for these special populations. A total of 152 participants, including 72 SCD patients, 44 MCI patients and 36 healthy controls (HCs), underwent a resting-state functional magnetic resonance imaging and were assessed with various neuropsychological tests. The dALFF was measured using sliding-window analysis. We employed canonical correlation analysis (CCA) to examine the bi-multivariate correlations between neuropsychological scales and altered dALFF among multiple regions in SCD and MCI patients. Compared to those in the HC group, both the MCI and SCD groups showed higher dALFF values in the right opercular inferior frontal gyrus (voxel P < .001, cluster P < .05, correction). Moreover, the CCA models revealed that behavioural tests relevant to inattention correlated with the dALFF of the right middle frontal gyrus and right opercular inferior frontal gyrus, which are involved in frontoparietal networks (R = .43, P = .024). In conclusion, the brain dynamics of neural activity in frontal areas provide insights into the shared neural basis underlying SCD and MCI.

Effect of laterality, gender, age and body mass index on the fat fraction of salivary glands in healthy volunteers: assessed using iterative decomposition of water and fat with echo asymmetry and least-squares estimation method.

OBJECTIVES:: To evaluate the effect of laterality, gender, age and body mass index (BMI) on fat fraction (FF) measurements of both parotid glands (PGs) and submandibular glands (SMGs) by using: Iterative decomposition of water and fat with echo asymmetry and least-squares estimation method (IDEAL-IQ). METHODS:: A total of 87 healthy participants were enrolled in our study. IDEAL-IQ image was scanned using a 3.0 T scanner. Paired t test was performed to compare the difference on FF of both PGs and SMGs between left and right side. The FF of two glands between male and female healthy participants were compared using an unpaired t-test. The correlation between the FF of two glands and participant age or BMI were analyzed by Pearson's correlation. RESULTS:: Excellent inter- and intrareader agreements were obtained during the measurements of FF by IDEAL-IQ method (ICC, 0.952-0.981). FF values correlated positively with the age and BMI in both left and right PGs and SMGs (p < 0.05). No significant difference was found on FF between left and right PGs and SMGs (p > 0.05). There was also no difference on FF between male and female healthy participants (p > 0.05). CONCLUSIONS:: FFs of PGs and SMGs were age- and BMI- dependent, but not laterality- and gender-dependent. The effect of age and BMI need to be considered in further studies using Ideal-IQ technology to evaluate FFs of salivary gland diseases.