ABSTRACT
OBJECTIVE: To clarify the cause of higher water fluctuation of the brain in idiopathic normal pressure hydrocephalus (iNPH), we assessed change in hemodynamic-independent apparent diffusion coefficient during the cardiac cycle (ΔADC) in iNPH. METHODS: Electrocardiographically synchronized single-shot diffusion echo-planer imaging (b = 0, 500, and 1000 s/mm2) was performed in healthy volunteers, atrophic ventricular dilation group, and iNPH group, respectively. The ΔADC (b = 0 and 1000 s/mm2) and maximum ADC (b = 0 and 500 s/mm2) in the cardiac cycles were measured at the frontal white matter in the brain. Then, self-corrected ΔADC was obtained from the ΔADC divided by the maximum ADC (ADCpeak: perfusion-related diffusion) to correct the blood flow effect. RESULTS: The ΔADC after correction was significantly higher in the iNPH group than in the other two groups. However, there was no significant difference in ADCpeak values among the groups. CONCLUSION: Self-corrected ΔADC in iNPH increased because of changes in the biomechanical properties of the brain. Self-corrected ΔADC analysis makes it possible to obtain information on hemodynamically independent water fluctuation as well as perfusion in iNPH. ADVANCES IN KNOWLEDGE: Analysis self-corrected ΔADC provides simultaneously information on biomechanical properties, perfusion, and water fluctuation in iNPH.
