Blood vessel state evaluating device, blood vessel state evaluating method, and computer-readable recording medium storing blood vessel state evaluating program
First Claim
1. A blood vessel state evaluation device comprising:
- a storage unit for storing a circulatory system model in which a blood vessel located in a living body is divided into a plurality of zones and modeled, the circulatory system model including a shape value representing each of the plurality of zones;
a first measurement unit, adapted for attachment to a first measurement site of the living body, for measuring a time waveform of a first biological signal;
a second measurement unit, adapted for attachment to a second measurement site of the living body, for measuring a time waveform of a second biological signal in synchronization with the first measurement unit;
a first calculating unit for calculating phase difference characteristics of actual measurement based on a phase difference on each frequency component between the first biological signal and the second biological signal,wherein the first calculating unit is configured to calculate the phase difference characteristics of actual measurement using a frequency component in which a coherence value, which is an index indicating a correlation at a frequency region, between the first biological signal and the second biological signal is higher than a threshold value defined in advance;
a second calculating unit for calculating phase difference characteristics between a first transfer function defined based on the circulatory system model in correspondence to a blood vessel passage to the first measurement site and a second transfer function defined based on the circulatory system model in correspondence to a blood vessel passage to the second measurement site, the first transfer function and the second transfer function including an elasticity variable indicating a degree of elasticity of the blood vessel; and
a search unit for determining an optimum elasticity variable by sequentially changing the elasticity variable from an initial value until the phase difference characteristics calculated by the second calculating unit substantially match the phase difference characteristics of actual measurement calculated by the first calculating unit,wherein the elasticity variable indicates a degree of arterial sclerosis of the blood vessel located in the living body.
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Accused Products
Abstract
A phase line tilt calculating unit (actual measurement) receives phase characteristics Pa(f) and Pb(f) outputted from frequency conversion units, and calculates phase difference characteristics of actual measurement based on a phase difference on each frequency component between the phase characteristics. A phase line tilt calculating unit (model) calculates phase difference characteristics between a transfer function Ga(f) and a transfer function Gb(f) calculated by a transfer function calculating unit, and outputs the calculated phase difference characteristics to a search unit. The search unit fits a variable k and determines a variable kopt (optimum solution) in which a tilt g(k) and a tilt gexp substantially match each other. The variable kopt is an index indicating a degree of arterial sclerosis of a subject.
9 Citations
14 Claims
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1. A blood vessel state evaluation device comprising:
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a storage unit for storing a circulatory system model in which a blood vessel located in a living body is divided into a plurality of zones and modeled, the circulatory system model including a shape value representing each of the plurality of zones; a first measurement unit, adapted for attachment to a first measurement site of the living body, for measuring a time waveform of a first biological signal; a second measurement unit, adapted for attachment to a second measurement site of the living body, for measuring a time waveform of a second biological signal in synchronization with the first measurement unit; a first calculating unit for calculating phase difference characteristics of actual measurement based on a phase difference on each frequency component between the first biological signal and the second biological signal, wherein the first calculating unit is configured to calculate the phase difference characteristics of actual measurement using a frequency component in which a coherence value, which is an index indicating a correlation at a frequency region, between the first biological signal and the second biological signal is higher than a threshold value defined in advance; a second calculating unit for calculating phase difference characteristics between a first transfer function defined based on the circulatory system model in correspondence to a blood vessel passage to the first measurement site and a second transfer function defined based on the circulatory system model in correspondence to a blood vessel passage to the second measurement site, the first transfer function and the second transfer function including an elasticity variable indicating a degree of elasticity of the blood vessel; and a search unit for determining an optimum elasticity variable by sequentially changing the elasticity variable from an initial value until the phase difference characteristics calculated by the second calculating unit substantially match the phase difference characteristics of actual measurement calculated by the first calculating unit, wherein the elasticity variable indicates a degree of arterial sclerosis of the blood vessel located in the living body. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A blood vessel state evaluation method for evaluating a state of a blood vessel located in a living body, the blood vessel state evaluation method comprising the steps of:
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storing a circulatory system model, in which the blood vessel located in the living body is divided into a plurality of zones and modeled, in a storage unit, wherein the circulatory system model includes a shape value representing each of the plurality of zones; measuring a time waveform of a first biological signal from a first measurement site of the living body and measuring a time waveform of a second biological signal from a second measurement site of the living body; calculating phase difference characteristics of actual measurement based on a phase difference on each frequency component between the first biological signal and the second biological signal, wherein in the step of calculating the phase difference characteristics of actual measurement, the phase difference characteristics of actual measurement are calculated using a frequency component in which a coherence value, which is an index indicating a correlation at a frequency region, between the first biological signal and the second biological signal is higher than a threshold value defined in advance; calculating phase difference characteristics between a first transfer function defined based on the circulatory system model in correspondence to a blood vessel passage to the first measurement site and a second transfer function defined based on the circulatory system model in correspondence to a blood vessel passage to the second measurement site, the first transfer function and the second transfer function including an elasticity variable indicating a degree of elasticity of the blood vessel; and determining an optimum elasticity variable by sequentially changing the elasticity variable from an initial value until the phase difference characteristics between the first transfer function and the second transfer function substantially match the phase difference characteristics of actual measurement, wherein the elasticity variable indicates a degree of arterial sclerosis of the blood vessel located in the living body.
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14. A blood vessel state evaluation program stored on a non-transitory computer readable recording medium for evaluating a state of a blood vessel located in a living body using a circulatory system model in which a blood vessel located in the living body is divided into a plurality of zones and modeled, wherein
the circulatory system model includes a shape value representing each of the plurality of zones; -
a calculation processing unit performing, in response to a command from the program, the steps of; acquiring a time waveform of a first biological signal at a first measurement site of the living body and acquiring a time waveform of a second biological signal at a second measurement site of the living body; calculating phase difference characteristics of actual measurement based on a phase difference on each frequency component between the first biological signal and the second biological signal, wherein in the step of calculating the phase difference characteristics of actual measurement, the phase difference characteristics of actual measurement are calculated using a frequency component in which a coherence value, which is an index indicating a correlation at a frequency region, between the first biological signal and the second biological signal is higher than a threshold value defined in advance; calculating phase difference characteristics between a first transfer function defined based on the circulatory system model in correspondence to a blood vessel passage to the first measurement site and a second transfer function defined based on the circulatory system model in correspondence to a blood vessel passage to the second measurement site, the first transfer function and the second transfer function including an elasticity variable indicating a degree of elasticity of the blood vessel; and determining an optimum elasticity variable by sequentially changing the elasticity variable from an initial value until the phase difference characteristics between the first transfer function and the second transfer function substantially match the phase difference characteristics of actual measurement, wherein the elasticity variable indicates a degree of arterial sclerosis of the blood vessel located in the living body.
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Specification