Ultrasonic diagnostic equipment

• US 5,840,028 A
• Filed: 01/21/1997
• Issued: 11/24/1998
• Est. Priority Date: 06/24/1996
• Status: Expired due to Term

• Current Assignee: Japan Science And Technology Corpration
• Original Assignee: Japan Science And Technology Corpration
• Inventors: Chubachi, Noriyoshi, Kanai, Hiroshi, Koiwa, Yoshiro
• Primary Examiner(s): JAWORSKI, FRANCIS J
• Application Number:
  US08/786,797
• Time in Patent Office: 672 Days
• Field of Search: 128/660.01, 128/660.02, 128/661.03-661.04, 128/661.07-661.1, 600/437, 600/438, 600/449-450, 600/454-457, 600/402, 600/300, 600/305
• US Class Current: 600/437
• CPC Class Codes: A61B 8/0858 involving measuring tissue layers, e.g. skin, interfaces
• CPC Class Codes: A61B 8/0883 for diagnosis of the heart
• CPC Class Codes: A61B 8/485 involving measuring strain or elastic properties
• CPC Class Codes: A61B 8/488 involving Doppler signals
• CPC Class Codes: A61B 8/5223 for extracting a diagnostic or physiological parameter from medical diagnostic data for algorithms to analyse biomedical images G06T7/0012
• CPC Class Codes: G01S 15/582 using transmission of interrupted pulse-modulated waves and based upon the Doppler effect resulting from movement of targets
• CPC Class Codes: G01S 7/52042 determining elastic properties of the propagation medium or of the reflective target diagnostic techniques involving the measurement of strain A61B8/485
• CPC Class Codes: G16H 50/30 for calculating health indices; for individual health risk assessment

Abstract

This invention relates to an ultrasonic diagnostic equipment usable to measure small vibrations in myocardial tissues superimposed on a large amplitude vibration of heartbeat. And it comprises a large amplitude motion analyzing means for deciding the an instantaneous position of the object by using the amplitude and phase of the detected signal and tracking a large amplitude of motion of the object, and a small vibration analyzing means for detecting a small vibration superimposed on the large amplitude motion by analyzing, succeeding positions of the large amplitude motion obtained from the large amplitude motion analyzing means. By using this invention, a local elasticity of width of 1-2 mm in myocardium and arterial wall can be evaluated noninvasively.

Claims

1. Ultrasonic diagnostic apparatus for measuring the position of an object having a vibratory motion of a large amplitude and having a small vibration which is superimposed on the large amplitude vibratory motion in a living body by transmitting an ultrasonic wave to the object, detecting a reflected ultrasonic wave from the object, and analyzing the reflected ultrasonic wave, the apparatus comprising:

a large amplitude motion analyzing means for deciding an instantaneous position of the object based on a detected amplitude and phase of the reflected wave, said large amplitude motion analyzing means tracking a reflected position of the object; and

a small vibration analyzing means for measuring the small vibration of the object by calculating a changing distance of the object'"'"'s position based on succeeding reflected positions of the object.

2. Ultrasonic diagnostic apparatus of claim 1, wherein:

said large amplitude motion analyzing means comprises a phase detecting means and detects a phase shift ∠

β

(t+Δ

T/2) during Δ

T by the detected reflected signal y(x;

t) at a reflecting position of the object x and a time t, and by a detected reflected signal y(x;

t+Δ

T) at a reflected position x and at time (t+Δ

T), under a constraint that an amplitude does not change and only a phase and the reflecting position change between signals of time t and time (t+Δ

T), and obtains a moving distance of the object during Δ

T.

3. Ultrasonic diagnostic apparatus of claim 1, wherein:

a phase detecting means and an object tracking means calculates a phase shift by a method minimizing a squared difference between signals at time t and (t+Δ

T), and obtains a moving velocity of the object by the following equation, ##EQU4## where β

is a phase shift ∠

β

(t+Δ

T/2) and Δ

T is a ultrasonic wave pulse transmission interval, ω

₀ is an angular frequency of the ultrasonic wave and C₀ is a propagation velocity of the ultrasonic wave, said phase detecting means and said object tracking means obtains an object displacement Δ

x (t+Δ

T/2) during Δ

T by the following equation,

space="preserve" listing-type="equation">Δ

x(t+Δ

T/2)=v(t+Δ

T/2)×

Δ

T

and obtains a trace of the object according to the following equation,

space="preserve" listing-type="equation">x(t+Δ

T/2)=x(t)+Δ

x(t+Δ

T/2).

4. Ultrasonic diagnostic apparatus of claim 1, wherein:

the object is a heart and the vibratory motion of large amplitude is a heartbeat motion, a frequency range of the small vibration is up to several hundred Hz.

5. Ultrasonic diagnostic apparatus of claim 1, wherein:

said small vibration analyzing means comprises a spectrum analyzing means and analyzes a spectrum of the small vibration.

6. A method for measuring a position of an object having a vibratory motion of a large amplitude and having a small vibration which is superimposed on the large amplitude vibratory motion in a living body, the method comprising the steps of:

transmitting an ultrasonic wave to the object;

detecting a reflected ultrasonic wave from the object;

analyzing the reflected ultrasonic wave to determine an instantaneous position of a large amplitude vibration of the object based on an amplitude and phase of the reflected ultrasonic wave;

tracking a reflecting position of the object;

measuring the small vibration by calculating a distance of the object position based on succeeding reflecting positions of the object.

7. A method in accordance with claim 6, further comprising;

detecting a phase shift ∠

β

(t+Δ

T/2) during Δ

T by the detected reflected signal y(x;

t) at a reflecting position of the object x and at time t, and from the detected reflected signal y(x;

t+Δ

T) at a reflecting position of the object x and at time (t+Δ

T), under a constraint that an amplitude does not change and only a phase and the reflecting position change between signals of time t and time (t+Δ

T);

obtaining a moving distance of the object during Δ

T.

8. A method in accordance with claim 6, further comprising;

calculating a phase shift between signals at time t and (t+Δ

T) by minimizing a squared difference;

obtaining a moving velocity of the object by the following equation, ##EQU5## where β

is a phase shift ∠

β

(t+Δ

T/2) and Δ

T is a ultrasonic wave pulse transmission interval, ω

₀ is an angular frequency of the ultrasonic wave and C₀ is a propagation velocity of the ultrasonic wave;

obtaining an object displacement Δ

x(t+Δ

T/2) during Δ

T by the following equation,

space="preserve" listing-type="equation">Δ

x(t+Δ

T/2)=v(t+Δ

T/2)×

Δ

T;

obtaining a trace of the object according to the following equation,

space="preserve" listing-type="equation">x(t+Δ

T/2)=x(t)+Δ

x(t+Δ

T/2).

9. A method in accordance with claim 6, wherein:

the object is a heart and the large amplitude vibratory motion is a heartbeat motion;

a frequency range of the small vibration is up to several hundred Hz.

10. A method in accordance with claim 6, further comprising;

analyzing a spectrum of the small vibration with a spectrum analyzing means.