| Project/Area Number |
18591324
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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 | Hokkaido University |
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Principal Investigator |
TERAE Satoshi Hokkaido University, Hokkaido University Hospital, Associate Professor (40240634)
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| Co-Investigator(Kenkyū-buntansha) |
YAMAMOTO Toru Hokkaido University, Faculty of Health Sciences, School of Medicine, Professor (80261361)
KATOH Chietsugu Hokkaido University, Faculty of Health Sciences, School of Medicine, Associate Professor (10292012)
KURODA Satoshi Hokkaido University, Hokkaido University Hospital, Lecturer (10301904)
KUDO Kohsuke Hokkaido University, Hokkaido University Hospital, Assistant Professor (10374232)
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| Project Period (FY) |
2006 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,790,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥390,000)
Fiscal Year 2007: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2006: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Keywords | MRI / susceptibility-weighted imaging / deoxyhemoglobin |
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| Research Abstract |
Using susceptibility-weighted imaging (SWI) of MRI (magnetic resonance imaging), we tried to develop a method to measure regional oxygen consumption of the brain. We evaluated local inhomogeneity of the magnetic field caused by deoxyhemoglobin (deoxyHb) in the cerebral vein using the phase information of SWI. We found that the local inhomogeneity observed by SWI is strongly affected by an angle between the longitudinal axis of the vein and the direction of the static magnetic field of the MRI unit. Therefore, the angle has to be incorporated to calculate local deoxyHb concentration of the vein.
In normal volunteers, the phase shift increased under hyperventilation and it decreased under breath hold. Changes in oxygen saturation of the veins and in cerebral blood flow, that were calculated by using the difference in phase shift, showed the same results. This indicates that we can measure deoxyHb concentration of the cerebral veins by SWI if we can establish a reference of relationship between the amount of phase shift and deoxyHb concentration in the vein.
In a patient with acute cerebral infarct, the largest local phase shift was observed in the infracted area. The phase shift was the largest immediately after the onset, and it decreased gradually during the first 20 days. In contrast, in another patient with chronically impaired blood flow and increased oxygen extraction fraction (OEF) in left anterior and middle cerebral artery territory that was caused by left internal carotid artery occlusion, there was no difference in the phase shift between the ischemic area and the contralateral healthy area. These results imply that SWI can detect increased deoxyHb in the veins of acute ischemic area, but cannot detect increased OEF in chronic phase.
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