| Project/Area Number |
17206043
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Measurement engineering
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| Research Institution | Tohoku University |
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Principal Investigator |
KANAI Hiroshi Tohoku University, Graduate School of Engineering, Professor (10185895)
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| Co-Investigator(Kenkyū-buntansha) |
HASEGAWA Hideyuki Graduate School of Engineering, 大学院・工学研究科, Associate Professor (00344698)
SAIJO Yoshifumi Institute of Development, Aging and Cancer, Associate Professor (00292277)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥50,700,000 (Direct Cost: ¥39,000,000、Indirect Cost: ¥11,700,000)
Fiscal Year 2007: ¥9,230,000 (Direct Cost: ¥7,100,000、Indirect Cost: ¥2,130,000)
Fiscal Year 2006: ¥10,270,000 (Direct Cost: ¥7,900,000、Indirect Cost: ¥2,370,000)
Fiscal Year 2005: ¥31,200,000 (Direct Cost: ¥24,000,000、Indirect Cost: ¥7,200,000)
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| Keywords | Heart diseases / Medical ultrasonics / Myocardial elasticity / Phased tracking method / Noninvasive measurement / Tissue characterization / Myocardial viscosity / Lamb wave propagation / 動脈硬化症 / 動脈壁弾性特性 / 心臓壁粘性特性 / 心臓疾患 / 心臓壁弾性特性 |
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| Research Abstract |
By ultrasonic measurement of the myocardial motion, we have already found that pulsive waves are spontaneously excited by aortic-valve closure at end-systole. Since myocardial viscoelasticity is essential in the evaluation of heart diastolic properties, this study makes the physiological phenomenon to be measured noninvasively measured in vivo as follows:
1 Using a sparse sector scan, the pulsive waves were measured almost simultaneously at several thousand points set along the heart wall at a sufficiently high frame rate. The consecutive spatial phase distributions clearly revealed wave propagation along the heart wall. The phase velocity of the wave is determined for each frequency component. By comparing the dispersion of the phase velocity with the theoretical one of the Lamb wave, which propagates along the viscoelastic plate immersed in blood, the instantaneous viscoelasticity is determined noninvasively.
2 We realized the principle of the measurement in a clinical ultrasonic diagn
… More
ostic system.
3 By actuating a small pulse in an elastic spherical shell, which was made as a model of the heart, we confirmed that the viscoelasticity of the spherical shell can be measured with an error less than 10% of the viscoelasticity measured by the mechanical test.
4 By applying the developed method to 5 healthy subjects, we confirmed the sufficient reproducibility of the propagation velocity of the pulsive wave among the consecutive cardiac cycles.
5 We confirmed that the difference among the viscoelasticity values estimated from the 5 subjects is less than 20% and the transient of the viscoelasticity just after the aortic valve closure is similar. The viscoelasticity estimates are similar to those measured for the canine heart wall in literature.
6 By applying the method to 10 patients with old myocardial infarction, we found that the amplitude and the propagation speed were decreased in each of the diseased areas. These results correspond to that obtained by using the longitudinal waves in literature.
7 In conclusion, based on the new findings, we developed a means to measure the myocardial viscoelasticity in vivo. These clinical results indicate that the method has a potential for noninvasively revealing myocardial heterogeneity. Less
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