Increased apparent blood flow and volume of the choroid plexus in the Alzheimer’s Disease patients

Background Recent works suggested the association between the dysfunctional glymphatic system and Alzheimer's Disease, which shows as alternated cerebrospinal fluid production. It is believed that the choroid plexus is the major site of CSF production conventionally and the choroid plexus blood flow is related to the production rate directly. Therefore, we investigated the choroid plexus perfusion in AD patients using arterial spin labeling (ASL) and MRI retrospectively. Method 21 AD patients (15 males, 76.1±5.7 years), 36 MCI patients (20 males, 72.6±7.9 years), and 88 healthy controls (40 males, 74.8±8.0 years) from the ADNI3 were included in this study. The lateral choroid plexus regions were segmented automatically based on a 3D U‐net deep learning method, which has been demonstrated with higher accuracy compared to the Freesurfer. In addition, the gray matter mask was segmented from the T1 weighted images using SPM12, and it was used to transfer the ASL and M0 images to the T1 weighted image space. Relative cerebral blood flow was quantified by first dividing the ASL image with its smoothed M0 image (a Gaussian filter with the sigma of 4 pixels), and then normalizing the mean signal of the choroid plexus region with the mean of the gray matter region. The gray matter mask was chosen as the region with a probability higher than 0.5. Result In the nonparametric Mann‐Whitney U test, the choroid plexus volume of the AD patients (1.58±0.40ml) was significantly larger (p = 0.036) than that of the healthy controls (1.41±0.39). In addition, the AD patients (0.85±0.30) showed significantly higher (p = 0.017) relative perfusion of the choroid plexus regions than the healthy controls (0.70±0.20). Conclusion The enlarged volume and increased blood flow of the choroid plexus may suggest the over‐compensation of CSF production in AD patients. However, further investigation is required to separate the blood flow and CSF signal in ASL at the choroid plexus region.