1986 Fiscal Year Final Research Report Summary
Fundamental Research on Acoustic Diagnosis of Intracranial Aneurysms
| Project/Area Number |
60440068
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
Cerebral neurosurgery
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
IKEBE Jun Tokyo Institute of Technology, Professor, 精密工学研究所, 教授 (70016749)
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| Co-Investigator(Kenkyū-buntansha) |
KOSUGI Yukio Tokyo Institute of Technology, Associate Professor, 大学院総合理工学研究科, 助教授 (30108237)
TAKAKURA Kintomo University of Tokyo, Professor, 医学部, 教授 (90109984)
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| Project Period (FY) |
1985 – 1986
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| Keywords | Aneurysm / AVM / Blood-flow / Turbulence / Sound / Acoustic-Diagnosis |
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| Research Abstract |
Intracranial aneurysm and arteriovenous malformation (AVM) are potentially dangerous diseases because they often cause fatal hemorrhage without any warning signs or symptoms. In the normal cerebrovascular system, the blood flow is laminar and no sound is audible, whereas in the abnormal arteries, turbulent flow sometimes generate an acoustically detectable noise; this sound is called a cranial bruit.
In this research, methods of detecting the cranial bruit are investigated. For successful detection of the sound, sensitive detectors must be applied close to the head since the sound is very weak, and, as in cerebrovascular diseases, the sound source is usually concealed deep inside the hard shelter of the skull. For this purpose , we designed new detectors that are acoustically matched to the head by making measurements of the mechanical impedance of the heads of normal subjects. The detection system used had a gain of 40 to 50 dB greater than that of an ordinary stethoscope. In our experiments on the patients suffering from intracranial aneurysm and AVM , the sound usually started about 160 msec after the ventricular contraction and lasted for 100 to 400 msec. Its frequency component mostly ranged from 200 Hz to 2 kHz, but the spectrum profile changed according to the detector position and the degree of abnormality. These results showed the possibility of noninvasive diagnosis of intracranial vascular lesions, especially for detecting aneurysms in health care examinations.
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