Pilot study utilizing MRI 3D TGSE PASL (arterial spin labeling) differentiating clearance rates of labeled protons in the CNS of patients with early Alzheimer disease from normal subjects.
OBJECTIVE
To determine the feasibility of 3D TGSE PASL MRI with long inversion times to estimate CNS perfusion clearance, comparing normals to Alzheimer disease patients.


METHODS
This pilot study used 3D TGSE PASL MRI with long TIs to estimate the signal clearance of labeled blood/ultra-filtrate (CSF) from brain signal averages of seven inversion times (TI) from six regions of the brain in 18 normal subjects of ages 18-70 years before and after exercise. Arterial pulse corrected signal average per TI versus TI was plotted. The slope (linear regression) indicated the clearance rate. Three subjects with mild Alzheimer disease (AD) were studied pre-exercise only.


RESULTS
In normals, signal decay rate variance among brain regions, age groups and post-exercise failed to demonstrate statistical significance except in middle-age group pre- to post-exercise-dominant temporal lobe. We found highly statistically significant reduced signal clearance rate in the AD group.


DISCUSSION
Signal decay in normal age groups correlates with decay of T1blood, thus CSF paravascular flow egresses and is inseparable from venous outflow. The AD group correlates with decay rate T1CSF, indicating a proportion of labeled blood ultra-filtered within the brain (paravascular fluid) is retained. This provides indirect evidence of reduced paravascular clearance in AD. Further development may produce an efficient biomarker identifying neurodegenerative diseases and future treatment efficacy.
['Joseph|Charles R|CR|http://orcid.org/0000-0002-8057-8704', 'Benhatzel|Christopher M|CM|', 'Stern|Logan J|LJ|', 'Hopper|Olivia M|OM|', 'Lockwood|Michael D|MD|']
D000293:Adolescent D000328:Adult D000368:Aged D000544:Alzheimer Disease D001921:Brain D002490:Central Nervous System D002560:Cerebrovascular Circulation D005260:Female D006801:Humans D007090:Image Interpretation, Computer-Assisted D007091:Image Processing, Computer-Assisted D021621:Imaging, Three-Dimensional D008279:Magnetic Resonance Imaging D008297:Male D008875:Middle Aged D010477:Perfusion D010865:Pilot Projects D013113:Spin Labels D055815:Young Adult
Alzheimer Disease Paravascular flow 3D TGSE (turbo gradient spin echo) PASL (pulsed arterial spin labeling) MRI imaging Arterial spin labeling perfusion MRI Glymphatic system