Effect of Body Position on Dynamic Apparent Diffusion Coefficient Changes During the Cardiac Cycle in the Human Brain

• Published in: Journal of magnetic resonance imaging Vol. 62; no. 1; pp. 295 - 302
• Main Authors: Ohno, Naoki, Miyati, Tosiaki, Uehara, Masatomo, Okamoto, Riho, Mase, Mitsuhito, Kobayashi, Satoshi
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01.07.2025; Wiley Subscription Services, Inc
• Subjects: Adult; apparent diffusion coefficient; Brain; Brain - diagnostic imaging; Brain - physiology; Diffusion coefficient; Diffusion Magnetic Resonance Imaging - methods; diffusion‐weighted imaging; Echo-Planar Imaging; Field strength; Healthy Volunteers; Heart - diagnostic imaging; Heart - physiology; Heart rate; Humans; Image Processing, Computer-Assisted - methods; Magnetic resonance imaging; Male; multi‐posture MRI; Neuroimaging; Occipital lobe; Phases; Posture - physiology; Prospective Studies; Rank tests; Sitting Position; Statistical analysis; Statistical tests; Supine position; Supine Position - physiology; Young Adult; apparent diffusion coefficient; diffusion‐weighted imaging; multi‐posture MRI
• ISSN: 1053-1807; 1522-2586; 1522-2586
• DOI: 10.1002/jmri.29758

ABSTRACT Background Dynamic changes in the apparent diffusion coefficient (ΔADC) during the cardiac cycle reflect water molecule fluctuations in the brain and intracranial conditions. While body position strongly affects intracranial conditions, the relationship between ΔADC and body position has been less explored, as conventional MRI is typically performed only in the supine position. Purpose To investigate ΔADC and mean ADC (ADCmean) of the brain in supine and sitting positions using a multi‐posture MRI system. Study Type Prospective. Subjects Nine healthy volunteers (all males; mean age, 23.5 years). Field Strength/Sequence 0.4 T, electrocardiographically synchronized single‐shot diffusion echo‐planar imaging sequence with b‐values of 0 and 500 s/mm2. Assessment ADC maps were generated at multiple cardiac phases in each subject in the sitting and supine positions. For each position, an ADCmean map was then generated as the voxel‐wise mean ADC across all phases, and a ΔADC map was generated as the voxel‐wise maximum difference in ADC across phases. ΔADC and ADCmean were measured in 2 frontal and 2 occipital lobe regions and averaged. ΔADC, ADCmean, and heart rate (HR) were compared between supine and sitting positions. Statistical Tests Wilcoxon signed‐rank test. Significance was set at p < 0.05. Results Both ΔADC and ADCmean were significantly higher in the sitting position compared with the supine position (ΔADC: 0.84 ± 0.06 × 10−3 mm2/s vs. 0.68 ± 0.05 × 10−3 mm2/s; ADCmean: 0.87 ± 0.02 × 10−3 mm2/s vs. 0.79 ± 0.06 × 10−3 mm2/s, respectively). These increases were consistent across all participants. In addition, HR was significantly higher in the sitting position compared with the supine position (73.8 ± 8.4 bpm vs. 58.1 ± 3.7 bpm). Data Conclusion ΔADC and ADCmean of the brain are significantly higher in the sitting position than in the supine position. Evidence Level: 2. Technical Efficacy: Stage 1.