1998 Fiscal Year Final Research Report Summary
Functional Imaging with Photic Stimulation -Diffusion Weighted MRI-
| Project/Area Number |
09670937
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Radiation science
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| Research Institution | HIROSHIMA UNIVERSITY |
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Principal Investigator |
KAJIMA Toshio Hiroshima University Faculty of Medicine, Research Associate, 医学部, 助手 (00224410)
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| Co-Investigator(Kenkyū-buntansha) |
ITO Katsuhide Hiroshima University Faculty of Medicine, Professor, 医学部, 教授 (20034035)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Functional MRI / Diffusion Weighted Image / Photic Stimulation |
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| Research Abstract |
[Background and Purpose] The studies of the brain function using MRI have been done with the T2^* weighted images, on that the origin of the signal intensity changes is the oxygenation of the hemoglobin. Recently the diffusion weighted images-(DWI) is expected as a new method to investigate brain function because this method can estimate movement of the water molecules in some physiological changes. But few studies were reported about the diffusion weighted functional MRI.The purpose of this study is to evaluate the ability of application of DWI to the functional image.
[Materials and Methods] 1. The photic stimulation that was an objective and easy method of neural activation was applied in this study. The usual functional images and the diffusion weighted functional images of normal volunteers were scanned by the 1 .5T MRI system with and without looking at the images on the screen. 2. The differences of the signal intensities between images with stimulation and without stimulation were examined.
[Results] The changes of signal intensity in the visual field of cerebral cortex were observed in accordance with the stimulation on the usual functional image but were not observed on the diffusion weighted functional images.
[Discussion] Nevertheless the increase of diffusion with the nerve stimulation was speculated in the literature, the signal changes were not observed in this study. The increase of focal blood flow and oxyhemoglobin caused by the nerve stimulation raise the signal intensity but increase of diffusion caused by the nerve stimulation lower the signal intensity. So these two factors would be cancelled out.
[Conclusion] Diffusion weighted images could not detect focal signal changes with the nerve stimulation. The new diffusion weighted technique that raise the signal intensity with the increase of diffusion was thought to be necessary in the application of functional MRI.
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