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Abstract
BACKGROUND AND PURPOSE: Oscillatory shear stress could not be directly measured in consideration of direction, although cerebrospinal fluid has repetitive movements synchronized with heartbeat. Our aim was to evaluate the important of oscillatory shear stress in the cerebral aqueduct and foramen magnum in idiopathic normal pressure hydrocephalus by comparing it with wall shear stress and the oscillatory shear index in patients with idiopathic normal pressure hydrocephalus.
MATERIALS AND METHODS: By means of the 4D flow application, oscillatory shear stress, wall shear stress, and the oscillatory shear index were measured in 41 patients with idiopathic normal pressure hydrocephalus, 23 with co-occurrence of idiopathic normal pressure hydrocephalus and Alzheimer-type dementia, and 9 age-matched controls. These shear stress parameters at the cerebral aqueduct were compared with apertures and stroke volumes at the foramen of Magendie and cerebral aqueduct.
RESULTS: Two wall shear stress magnitude peaks during a heartbeat were changed to periodic oscillation by converting oscillatory shear stress. The mean oscillatory shear stress amplitude and time-averaged wall shear stress values at the dorsal and ventral regions of the cerebral aqueduct in the idiopathic normal pressure hydrocephalus groups were significantly higher than those in controls. Furthermore, those at the ventral region of the cerebral aqueduct in the idiopathic normal pressure hydrocephalus group were also significantly higher than those in the co-occurrence of idiopathic normal pressure hydrocephalus with Alzheimer-type dementia group. The oscillatory shear stress amplitude at the dorsal region of the cerebral aqueduct was significantly associated with foramen of Magendie diameters, whereas it was strongly associated with the stroke volume at the upper end of the cerebral aqueduct rather than that at the foramen of Magendie.
CONCLUSIONS: Oscillatory shear stress, which reflects wall shear stress vector changes better than the conventional wall shear stress magnitude and the oscillatory shear index, can be directly measured on 4D flow MR imaging. Oscillatory shear stress at the cerebral aqueduct was considerably higher in patients with idiopathic normal pressure hydrocephalus.
ABBREVIATIONS:
- AD
- Alzheimer-type dementia
- iNPH
- idiopathic normal pressure hydrocephalus
- OSI
- oscillatory shear index
- OSS
- oscillatory shear stress
- TAWSS
- time-averaged wall shear stress
- WSS
- wall shear stress
Footnotes
The funding sources for the study had no role in the design and conduct of the study; in the collection, analysis, and interpretation of the data; or in the preparation, review, or approval of the manuscript.
This research received grants from the G-7 Scholarship Foundation for 1 year in 2020, the Taiju Life Social Welfare Foundation for 1 year in 2020, and the Fujifilm Corporation for 2 years since 2019.
Disclosures: Shigeki Yamada—RELATED: Grant: Fujifillm Corporation, Comments: This study received funding of 500,000/year × 2 years from Fujifillm Corporation in Japan. Our institute (Shiga University of Medical Science) has signed a research contract with Fujifillm Corporation for the joint development of 3D workstation applications*; UNRELATED: Grants/Grants Pending: G-7 Scholarship Foundation, Comments: research grant*; Payment for Lectures Including Service on Speakers Bureaus: Fujifilm Medical Systems, Integra Japan, and Daiichi Sankyo, Comments: Speakers honoraria. Masatsune Ishikawa—RELATED: Grant: Health and Labor Sciences Research Grants for the Research on Intractable Diseases, Ministry of Health, Labor and Welfare, Japan, Comments: 2017-Nanci-General-037. Kazuhiko Nozaki—UNRELATED: Grants/Grants Pending: Japan Agency for Medical Research and Development, grants from KAKENHI, grant from the Japan Society for the Promotion of Science*; Payment for Lectures Including Service on Speakers Bureaus: honoraria from Pfizer Japan, Daiichi Sankyo. *Money paid to the institution.
- © 2021 by American Journal of Neuroradiology