 |
Claims  |
|
|
We claim:
1. Ultrasound diagnostic equipment for diagnosing a region of interest of
an organ of a body by using one of a scattering coefficient and an
attenuation slope of the region of interest, said ultrasound diagnostic
equipment comprising:
first ultrasound radiation and receipt means adapted to contact a body
surface over the organ, for radiating an ultrasound beam to blood flowing
inside a blood vessel or heart close to the region of interest and
receiving ultrasound waves scattered from the blood; scattering power
calculation means, connected to said first ultrasound radiation and
receipt means, for calculating a Doppler signal power from said received
ultrasound waves; and
cumulative attenuation slope calculation means, connected to said
scattering power calculation means, for calculating a cumulative
attenuation slope based on the Doppler signal power calculated by said
scattering power calculation means.
2. Ultrasound diagnostic equipment according to claim 1, wherein said
ultrasound diagnostic equipment further comprises a coefficient
calculation unit, connected to said cumulative attenuation slope
calculation means, for calculating an average attenuation slope of the
region of interest by using a plurality of cumulative attenuation slopes
calculated by said cumulative attenuation slope calculation means.
3. Ultrasound diagnostic equipment according to claim 1, wherein said
ultrasound diagnostic equipment further comprises:
scattering coefficient calculation means for calculating a scattering
coefficient of the region of interest using the cumulative attenuation
slope of the blood close to the region of interest; and
second ultrasound radiation and receipt means connected to said scattering
coefficient calculation means for calculating a scattering coefficient of
the region of interest by using said calculated cumulative attenuation
slope of the blood close to said region of interest and contacting said
body surface over the organ, for radiating an ultrasound beam to the
region of interest and receiving an ultrasound wave scattered from the
region of interest.
4. Ultrasound diagnostic equipment according to claim 3, wherein said
second ultrasound radiation and receipt means comprises:
an ultrasound probe, contacted to the body surface of the organ, for
radiating an ultrasound beam to an optional portion in the organ and
receiving an ultrasound wave scattered from said optional portion;
a transmitting amplifier, connected to said ultrasound probe, for driving
said ultrasound probe; and
a receiving amplifier, connected to said ultrasound probe, for amplifying
the ultrasound wave signals received by said ultrasound probe.
5. Ultrasound diagnostic equipment according to claim 4, wherein said
ultrasound diagnostic equipment further comprises:
a B-mode receiving circuit, connected to said receiving amplifier, for
generating a B-mode image by luminance signals corresponding to signal
strength of an output of said receiving amplifier.
6. Ultrasound diagnostic equipment according to claim 3, wherein said
scattering coefficient calculation means comprises:
a scattering spectrum calculation unit;
a read only memory; and
a coefficient calculation unit connected to said scattering spectrum
calculation unit and said read only memory.
7. Ultrasound diagnostic equipment according to claim 6, wherein said
scattering spectrum calculation unit comprises:
an A/D converter, connected to said receiving amplifier, for converting an
output signal of said receiving amplifier into a digital signal;
an operation circuit, connected to said A/D converter, for performing a
high speed operation of a fast Fourier transform of an output signal of
said A/D converter;
a power operation circuit, connected to said operation circuit, for
calculating a real component and an imaginary component of said fast
Fourier transform; and
an accumulator, connected to said power operation circuit, for adding a
power spectrum of a scanning line in the region of interest.
8. Ultrasound diagnostic equipment according to claim 6, wherein said
scattering spectrum calculation unit comprises:
a logarithmic amplifier, connected to said receiving amplifier, for
amplifying the output signal of said receiving amplifier as a logarithmic
compression;
an A/D converter, connected to said logarithmic amplifier, for converting
an output signal of said logarithmic amplifier into a digital signal;
an inverse logarithmic circuit, connected to said A/D converter, for
converting an output signal of said A/D converter into a primary
antilogarithm;
an arithmetic circuit, connected to said inverse logarithmic circuit, for
performing a high speed operation of a fast Fourier transform on an output
signal of said inverse logarithmic circuit;
a power calculation circuit, connected to said arithmetic circuit, for
calculating the sum of a square of a real component and a square of an
imaginary component of the Fourier spectrum; and
an accumulator, connected to said power calculation circuit, for adding a
power spectrum of a scanning line in the region of interest.
9. Ultrasound diagnostic equipment according to claim 1, wherein said first
ultrasound radiation and receipt means comprises:
an ultrasound probe, adapted to contact a body surface over the organ, for
radiating an ultrasound beam to an optional portion in the organ and
receiving ultrasound waves scattered from the optional portion;
a transmitting amplifier, connected to said ultrasound probe, for driving
said ultrasound probe; and
a receiving amplifier, connected to said ultrasound probe, for amplifying
the ultrasound waves received by said ultrasound probe.
10. Ultrasound diagnostic equipment according to claim 1, wherein said
scattering power calculation means comprises:
a Doppler signal calculation circuit, connected to said receiving
amplifier, for calculating a Doppler signal of said receiving amplifier in
a sample volume;
a power calculation circuit, connected to said Doppler signal calculation
circuit, for calculating a power of the Doppler signal and calculating a
sum of a square and averaging in time between and imaginary component and
a real component of the Doppler signal; and
an A/D converter, connected to said power calculation circuit, for
converting the power of the Doppler signal into a digital signal.
11. Ultrasound diagnostic equipment according to claim 1, wherein said
cumulative attenuation slope calculation unit comprises a read only
memory, connected to said scattering power calculation means, wherein
scattering characteristics of said ultrasound beam, transmitting-receiving
characteristics, and a power transfer function including frequency
characteristics of said equipment are stored in said read only memory.
12. Ultrasound diagnostic equipment according to claim 1, wherein said
ultrasound diagnostic equipment further comprises:
a coefficient calculation unit, connected to said cumulative attenuation
slope calculation means, for calculating an average attenuation slope of
an existing section among a plurality of blood positions based on the
cumulative attenuation coefficients corresponding to blood positions
calculated by said cumulative attenuation slope calculation means.
13. Ultrasound diagnostic equipment according to claim 12, wherein said
coefficient calculation means calculates a scattering coefficient and an
attenuation slope of the region of interest based on a calculated power
spectrum of a reflected wave and the cumulative attenuation slope.
14. Ultrasound diagnostic equipment for diagnosing a region of interest of
an organ by using a scattering coefficient and an attenuation slope of the
region of interest, said ultrasound diagnostic equipment comprising:
an ultrasound probe, contacted to a body surface over the organ, for
radiating an ultrasound beam to an optional portion in the organ and
receiving an ultrasound wave scattered from said optional portion;
a transmitting amplifier, connected to said ultrasound probe, for driving
said ultrasound probe;
a receiving amplifier, connected to said ultrasound probe, for amplifying
the ultrasound wave signals received by said ultrasound probe;
a timing control unit, connected to said transmitting amplifier, for
supplying pulse shape electric signals to said transmitting amplifier;
a B-mode receiving circuit, connected to said receiving amplifier, for
generating a B-mode image by luminance signals corresponding to signal
strength of an output of said receiving amplifier;
a scattering spectrum calculation unit, connected to said receiving
amplifier, for calculating a scattering spectrum of said region of
interest by using the output signals of said receiving amplifier;
a scattering power calculation unit, connected to said receiving amplifier
and said timing control unit, for calculating an ultrasound scattering
wave power scattered from the blood close to the region of interest;
a cumulative attenuation slope calculation unit, connected to said
scattering power calculation unit and said timing control unit, for
calculating a cumulative attenuation slope based on the ultrasound
scattering wave power calculated by said scattering power calculation unit
and said timing signal output from said timing control unit;
a read only memory, connected to said timing control unit, for reading out
various data in response to addresses from said timing control unit;
a coefficient calculation unit, connected to said scattering spectrum
calculation unit, said cumulative attenuation slope calculation unit and
said read only memory, for calculating a scattering coefficient and an
attenuation slope of the region of interest; and
a display, connected to said B-mode receiving circuit and said coefficient
calculation unit, for displaying a B-mode image and an image defined by
the scattering coefficient and the attenuation slope of the region of
interest.
15. Ultrasound diagnostic equipment according to claim 14, wherein said
scattering spectrum calculation unit comprises:
an A/D converter, connected to said receiving amplifier, for converting an
output signal of said receiving amplifier into a digital signal;
an arithmetic circuit, connected to said A/D converter, for performing a
high speed operation of a fast Fourier transform of an output signal of
said A/D converter;
a power operation circuit, connected to said arithmetic circuit, for
calculating a real component and an imaginary component of the fast
Fourier transform; and
an accumulator, connected to said power operation circuit, for adding a
power spectrum of a scanning line in the region of interest.
16. Ultrasound diagnostic equipment according to claim 14, wherein said
scattering spectrum calculation unit comprises:
a logarithmic amplifier, connected to said receiving amplifier, for
amplifying the output signal of said receiving amplifier as a logarithmic
compression;
an A/D converter, connected to said logarithmic amplifier, for converting
an output signal of said logarithmic amplifier into a digital signal;
an inverse logarithmic circuit, connected to said A/D converter, for
converting an output signal of said A/D converter to a primary
antilogarithm;
an operation circuit, connected to said inverse logarithmic circuit, for
performing a high speed operation of a fast Fourier transform of an output
signal of said inverse logarithmic circuit;
a power operation circuit, connected to said operation circuit, for
calculating a real component and an imaginary component of the fast
Fourier transform; and
an accumulator, connected to said power operation circuit, for adding a
power spectrum of a scanning line in the region of interest.
17. Ultrasound diagnostic equipment according to claim 14, wherein said
scattering power calculation unit comprises:
a Doppler signal calculation circuit, connected to said receiving amplifier
and said timing control unit, for calculating a Doppler signal of said
receiving amplifier in a sample volume by the timing signal from said
timing control unit;
a power calculation circuit, connected to said Doppler signal calculation
circuit, for calculating a power of the Doppler signal by calculating a
sum of a square and averaging in time between an imaginary component and a
real component of the Doppler signal; and
an A/D converter, connected to said power calculation circuit, for
converting the power of the Doppler signal into a digital signal.
18. Ultrasound diagnostic equipment according to claim 14, wherein said
cumulative attenuation slope calculation unit comprises a read only
memory, connected to said scattering power calculation unit and said
timing control unit, wherein scattering characteristics of said ultrasound
beam, transmitting-receiving characteristics, and a power transfer
function including frequency characteristics of said equipment are stored
in said read only memory. |
|
 |
|
 |
Claims |
|
|
|
Description |
|
|
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to ultrasound diagnostic equipment, more
particularly, to ultrasound diagnostic equipment for diagnosing a region
of interest of an organ by using a scattering coefficient and an
attenuation slope of the region of interest.
2. Description of the Related Art
Recently, in accordance with progress in diagnostic techniques using an
ultrasound wave, it has become necessary that diagnostic accuracy be
improved by using diagnosis of acoustic characteristics of tissues,
instead of a conventional diagnostic method for diagnosing from the shapes
of internal organs or tumors. Now, acoustic characteristics of tissues,
especially an attenuation coefficient (an attenuation slope) and a
scattering coefficient (a differential scattering crosssection per unit
volume), are used to indicate the characteristics of tissues. These
coefficients are useful for detecting a diffuse disease and a cancer in a
liver. The scattering coefficient is particularly useful for detecting a
myocardial infarction. However, it is difficult to measure the above
coefficients with high accuracy and to use these coefficients for
practical diagnosis. Namely, when detecting an attenuation slope of the
region of interest, a scattering coefficient thereof should be supposed to
a specific fixed value, and conversely, when detecting a scattering
coefficient of the region of interest, an attenuation slope thereof should
be supposed to a specific fixed value.
Therefore, an accuracy of measurements of acoustic characteristics by
radiating an ultrasound wave to an organ, receiving a scattered wave and
calculating from the scattered wave, is not sufficient. Namely, it is
difficult to determine the attenuation slope and the scattering
coefficient exactly.
In a manner of speaking, the tissue of an organ is like gelatin including a
plurality of particulates floating therein. Thus a power spectrum, a
center frequency and an amplitude calculated by using a fast Fourier
analysis of ultrasound scattered signals of one scanning line, have large
stochastic variance. Therefore, acoustic characteristics calculated by
using the power spectrum, the center frequency and the amplitude cannot
have sufficient accuracy.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide ultrasound diagnostic
equipment for exactly diagnosing a region of interest of an organ using
the calculated values of scattering coefficient and an attenuation slope
of the region of interest. In the ultrasound diagnostic equipment of the
present invention, flowing blood existing close to the region of interest
is used as a standard reference target which has a specific value, since
the scattering coefficient of blood does not fluctuate with individual
differences.
According to the present invention, there is provided ultrasound diagnostic
equipment for diagnosing a region of interest of an organ by using a
scattering coefficient and/or an attenuation slope of the region of
interest, which comprises a first ultrasound radiation and receipt unit
and a cumulative attenuation slope calculation unit. The first ultrasound
radiation and receipt unit is contacted to a body surface over an organ
and is used for radiating an ultrasound beam to blood close to the region
of interest and receiving an ultrasound wave scattered by the blood. The
cumulative attenuation slope calculation unit is connected to the first
ultrasound radiation and receipt unit and is used for calculating a
cumulative attenuation slope of the intervening tissue between the body
surface and a position of the blood.
The ultrasound diagnostic equipment may further comprise a coefficient
calculation unit connected to the cumulative attenuation slope calculation
unit, for calculating an average attenuation slope of the region of
interest by using a plurality of cumulative attenuation slopes calculated
by the cumulative attenuation slope calculation unit.
The ultrasound diagnostic equipment may further comprise a scattering
coefficient calculation unit and a second ultrasound radiation and receipt
unit. The scattering coefficient calculation unit is connected to the
second ultrasound radiation and receipt unit, for calculating a scattering
coefficient of the region of interest by using the calculated cumulative
attenuation slope of the blood close to the region of interest. The second
ultrasound radiation and receipt unit is contacted to the body surface
over the organ for radiating an ultrasound beam to the region of interest
and receiving an ultrasound wave scattered from the region of interest.
The second ultrasound radiation and receipt unit may comprise an ultrasound
probe, a transmitting amplifier, and a receiving amplifier. The ultrasound
probe is contacted to the body surface of the organ for radiating an
ultrasound beam to an optional portion in the organ and receiving an
ultrasound wave scattered from the optional portion. The transmitting
amplifier is connected to the ultrasound probe for driving the ultrasound
probe.
The receiving amplifier is connected to the ultrasound probe for amplifying
the ultrasound wave signals received by the ultrasound probe. The
scattering coefficient calculation unit may comprise a scattering spectrum
calculation unit, a read only memory, and a coefficient calculation unit.
The scattering spectrum calculation unit may comprise an A/D converter, an
operation circuit, a power operation circuit, and an accumulator. The A/D
converter is connected to the receiving amplifier for converting an output
signal of the receiving amplifier into a digital signal. The operation
circuit is connected to the A/D converter for performing a high speed
operation of a fast Fourier transform of an output signal of the A/D
converter. The power operation circuit is connected to the operation
circuit for calculating a real component and an imaginary component of the
fast Fourier transform. The accumulator is connected to the power
operation circuit for adding a power spectrum of a scanning line in the
region of interest.
The scattering spectrum calculation unit may comprise a logarithmic
amplifier, an A/D converter, an inverse logarithmic circuit, an arithmetic
circuit, a power calculation circuit, and an accumulator. The A/D
converter is connected the receiving amplifier, for amplifying the output
signal of the receiving amplifier as a logarithmic compression. The A/D
converter is connected to the logarithmic amplifier for converting an
output signal of said logarithmic amplifier into a digital signal. The
inverse logarithmic circuit is connected to the A/D converter for
returning to a primary antilogarithm a output signal of the A/D converter.
The arithmetic circuit is connected to the inverse logarithmic circuit for
performing a high speed operation of a fast Fourier transform on an output
signal of the inverse logarithmic circuit. The power calculation circuit
is connected to the operation circuit for calculating a sum of a square of
a real component and square of an imaginary component of the Fourier
spectrum. The accumulator is connected to the power operation circuit, for
adding a power spectrum of a scanning line in the region of interest.
The first ultrasound radiation and receipt unit may comprise an ultrasound
probe contacted to the body surface over the organ and used for radiating
an ultrasound beam to an optional portion in the organ and receiving an
ultrasound wave scattered from the optional portion, a transmitting
amplifier connected to the ultrasound probe and used for driving the
ultrasound probe, and a receiving amplifier connected to the ultrasound
probe and used for amplifying the ultrasound wave signals received by the
ultrasound probe.
The cumulative attenuation slope calculation unit may comprise a scattering
power calculation unit connected to the first ultrasound radiation and
receipt unit and used for calculating an ultrasound scattering wave power
scattered from the blood close to the region of interest by using a
scattering coefficient of blood which is known to be constant, and a
cumulative attenuation slope calculation unit connected to the scattering
power calculation unit and used for calculating a cumulative attenuation
slope based on an ultrasound scattering wave power calculated by the
scattering power calculation unit.
The scattering power calculation unit may comprise a Doppler signal
calculation circuit connected to the receiving amplifier and used for
calculating a Doppler signal of the receiving amplifier in a sample
volume, a power calculation circuit connected to the Doppler signal
calculation circuit and used for calculating a power of the Doppler signal
by calculating a sum and averaging in time the square of an imaginary
component and the square of a real component of the Doppler signal, and an
A/D converter connected to the power calculation circuit and used for
converting the power of the Doppler signal into a digital signal.
The cumulative attenuation slope calculation unit may comprise a read only
memory connected to the scattering power calculation unit, wherein
transfer tables for the scattering power and depth to the cumulative
attenuation slope calculated from the scattering coefficient of blood are
memorized in the read only memory. diffraction characteristics of the
ultrasound beam, transmitting-receiving characteristics, and a power
transfer function including frequency characteristics of the equipment.
Further, the ultrasound diagnostic equipment may comprise a coefficient
calculation unit connected to the cumulative attenuation slope calculation
unit and used for calculating an average attenuation slope of an
intervening tissue section among a plurality of blood positions based on
the cumulative attenuation coefficients corresponding to the blood
positions calculated by the cumulative attenuation slope calculation unit.
The coefficient calculation unit may calculate a scattering coefficient of
the region of interest based on the calculated power spectrum of a
reflected wave and the cumulative attenuation slope.
Furthermore, the ultrasound diagnostic equipment may comprise a B-mode
receiving circuit connected to the receiving amplifier and used for
generating a B-mode image using luminance signals corresponding to the
signal strength of the output of the receiving amplifier.
According to the present invention, there is also provided ultrasound
diagnostic equipment for diagnosing a region of interest of an organ by
using a scattering coefficient and an attenuation slope of the region of
interest, which comprises an ultrasound probe, a transmitting amplifier, a
receiving amplifier, a timing control unit, a B-mode receiving circuit, a
scattering spectrum calculation unit, a scattering power calculation unit,
a cumulative attenuation slope calculation unit, a read only memory, a
coefficient calculation unit, and a display. The ultrasound probe is
contacted to a body surface over an organ and is used for radiating an
ultrasound beam to an optional portion in the organ and receiving an
ultrasound wave scattered from the optional portion. The transmitting
amplifier is connected to the ultrasound probe. The receiving amplifier is
connected to the ultrasound probe and is used for amplifying the
ultrasound wave signal received by the ultrasound probe. The timing
control unit is connected to the transmitting amplifier and is used for
supplying pulse shape electrical signals to the transmitting amplifier.
The B-mode receiving circuit is connected to the receiving amplifier and
is used for generating a B-mode image using luminance signals
corresponding to the signal strength of the output of the receiving
amplifier. The scattering spectrum calculation unit is connected to the
receiving amplifier and is used for calculating a scattering spectrum of
the region of interest based on the output signals of the receiving
amplifier. The scattering power calculation unit is connected to the
receiving amplifier and the timing control unit and is used for
calculating an ultrasound scattering wave power scattered from blood close
to the region of interest and a timing signal output from the timing
control unit. The cumulative attenuation slope calculation unit is
connected to the scattering power calculation unit and the timing control
unit and is used for calculating a cumulative attenuation slope based on a
ultrasound scattering wave power calculated by the scattering power
calculation unit and the timing signal output from the timing control
unit. The read only memory is connected to the timing unit and is used for
reading out various data in response to addresses from the timing control
unit. The coefficient calculation unit is connected to the scattering
spectrum calculation unit, the cumulative attenuation slope calculation
unit and the read only memory and is used for calculating a scattering
coefficient of the region of interest and an attenuation slope of an
intervening tissue between two blood positions. The display is connected
to the B-mode receiving circuit and the coefficient calculation unit and
is used for displaying a B-mode image and an image characterized by the
scattering coefficient of the region of interest and the attenuation slope
of an intervening tissue between blood position.
The scattering spectrum calculation unit may comprise an A/D converter
connected to the receiving amplifier and used for converting an output
signal of the receiving amplifier into a digital signal, an operation
circuit connected to the A/D converter and used for performing a high
speed operation of a fast Fourier transform of an output signal of the A/D
converter, a power operation circuit connected to the operation circuit
and used for calculating a real component and an imaginary component of
the Fourier spectrum, and an accumulator connected to the power operation
circuit and used for adding a power spectrum of a scanning line in the
region of interest.
The scattering spectrum calculation unit may comprise a logarithmic
amplifier connected to the receiving amplifier and used for amplifying the
output signal of the receiving amplifier as a logarithmic compression, an
A/D converter connected to the logarithmic amplifier and used for
converting an output signal of the logarithmic amplifier into a digital
signal, an inverse logarithmic circuit connected to the A/D converter and
used for returning to a primary antilogarithm output signal of the A/D
converter, an operation circuit connected to the inverse logarithmic
circuit and used for performing a high speed operation of a fast Fourier
transform of an output signal of the inverse logarithmic circuit, a power
calculation circuit connected to the operation circuit and used for
calculating a real component and an imaginary component of the Fourier
spectrum, and an accumulator connected to the power operation circuit and
used for adding a power spectrum of a scanning line in the region of
interest.
The scattering power calculation unit may comprise a Doppler signal
calculation circuit connected to the receiving amplifier and the timing
control unit and used for calculating a Doppler signal of the receiving
amplifier in a sample volume by the timing signal from the timing control
unit, a power calculation circuit connected to the Doppler signal
calculation circuit and used for calculating a power of the Doppler signal
by calculating a sum and averaging in time of the square of an imaginary
component and the square of a real component of the Doppler signal, and an
A/D converter connected to the power calculation circuit and used for
converting the power of the Doppler signal into a digital signal.
The cumulative attenuation slope calculation unit may comprise a read only
memory connected to the scattering power calculation unit and the timing
control unit, wherein scattering characteristics of the ultrasound beam,
transmitting-receiving characteristics, and a power transfer function
including frequency characteristics of the equipment are stored in the
read only memory.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be more clearly understood from the description
of the preferred embodiments as set forth below with reference to the
accompanying drawings, wherein:
FIG. 1 is a block diagram showing a construction of an embodiment of
ultrasound diagnostic equipment according to the present invention;
FIG. 2 is a block diagram showing one example of the ultrasound diagnostic
equipment shown in FIG. 1;
FIG. 3 is a block diagram showing another example of the ultrasound
diagnostic equipment shown in FIG. 1;
FIG. 4 is a circuit block diagram showing an example of a scattering power
calculation unit of ultrasound diagnostic equipment according to the
present invention;
FIGS. 5a and 5b are explanatory diagrams for explaining calculation of an
ultrasound scattering wave power scattered from blood;
FIG. 6a is an explanatory diagram of a real component of an quadrature
detection;
FIG. 6b is an explanatory diagram of a real component of a Doppler signal;
FIG. 6c output signal of guad rature detector; and
FIGS. 7a to 7e are explanatory diagrams of a power spectrum of a reflected
wave.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The principle of the present invention will be explained, before
explanation of an embodiment.
Ultrasound diagnostic equipment of the present invention diagnoses a region
of interest ROI of an organ by using a scattering coefficient of the
region of interest ROI and an attenuation slope of the intervening tissue
between two blood portions by an ultrasonic Tissue Characterization (TC).
First, an ultrasound beam UB is radiated from an ultrasound probe through a
body surface BS to blood which is positioned close to the region of
interest ROI. An ultrasound wave scattered from the blood is received by
the ultrasound probe. That is, a region of interest ROI is located close
to a blood vessel where a scattered power spectrum of the received
ultrasound wave signals can be provided. Further, a cumulative attenuation
slope between the body surface BS and the position of the blood is
calculated by using a scattering coefficient of blood. Note, the
scattering coefficient of the blood can be known previously, and does not
fluctuate at each position of a human body or by individual difference.
Next, an ultrasound beam UB is radiated from an ultrasound probe through a
body surface BS to a region of interest ROI. An ultrasound wave scattered
from the region of interest ROI is received by the ultrasound probe.
Further, a scattering coefficient of the region of interest ROI is
calculated by using the cumulative attenuation slope of the intervening
tissue between the body surface and the blood close to the region of
interest ROI. Note, the measurement position of the blood is not only a
position of a blood vessel, but also a position of existing blood, i.e., a
heart, and the like.
Next, an embodiment of ultrasound diagnostic equipment of the present
invention will be explained with reference to the drawings.
FIG. 1 is a block diagram showing a construction of an embodiment of
ultrasound diagnostic equipment according to the present invention. As
shown in FIG. 1, ultrasound diagnostic equipment is used for diagnosing a
region of interest ROI of an organ by using a scattering coefficient of
the region of interest ROI and an attenuation slope of the intervening
tissue. The ultrasound diagnostic equipment comprises an ultrasound probe
1, a transmitting amplifier 2, a receiving amplifier 3, a timing control
unit 4, a B-mode receiving circuit 5, a scattering spectrum calculation
unit 6, a scattering power calculation unit 7, a cumulative attenuation
slope calculation unit 8, a read only memory 9, a coefficient calculation
unit 10, and a display 11.
The ultrasound probe 1 is contacted to a body surface BS over the organ and
used for radiating an ultrasound beam UB to an optional portion in the
organ and receiving an ultrasound wave scattered from the optional
portion. Note, the optional portion is, for example, a position SV.sub.1
of blood in blood vessel BV.sub.1 or a position SV.sub.2 of blood in blood
vessel BV.sub.2. These positions SV.sub.1 and SV.sub.2 are located close
to the region of interest ROI.
The transmitting amplifier 2 is connected to the ultrasound probe 1 and
used for driving the ultrasound probe 1 by inputting pulse shape
electrical signals thereto. The receiving amplifier 3 is connected to the
ultrasound probe 1 and used for amplifying the ultrasound wave signals
received by the ultrasound probe 1.
The timing control unit 4 is connected to the transmitting amplifier 2 and
used for supplying pulse shape electric signals to the transmitting
amplifier 2.
The B-mode receiving circuit 5 is connected to the receiving amplifier 3
and used for generating a B-mode image using luminance signals
corresponding to the signal strength of the output of the receiving
amplifier 3.
The scattering spectrum calculation unit 6 is connected to the receiving
amplifier 3 and used for calculating a scattering spectrum of the region
of interest ROI by the output signals of the receiving amplifier 3.
The scattering power calculation unit 7 is connected to the receiving
amplifier 3 and the timing control unit 4, and used for calculating an
ultrasound scattering wave power P(D.sub.i) scattered from the blood close
to the region of interest ROI and a timing signal output from the timing
control unit 4.
The cumulative attenuation slope calculation unit 8 is connected to the
scattering power calculation unit 7 and the timing control unit 4, and
used for calculating a cumulative attenuation slope based on the
ultrasound scattering wave power P(D.sub.i) calculated by the scattering
power calculation unit 7 and the timing signal output from the timing
control unit 4.
The read only memory (ROM) 9 is connected to the timing control unit 4, and
used for reading out various data in response to addresses from the timing
control unit 4. Note, the data stored in the ROM 9 is, for example,
diffraction characteristics of the ultrasound beam, transmit and receive
characteristics, and power transfer functions including frequency
characteristics of the ultrasound diagnostic equipment.
The coefficient calculation unit 10 is connected to the scattering spectrum
calculation unit 6, the cumulative attenuation slope calculation unit 8
and the read only memory 9, and used for calculating a scattering
coefficient of the region of interest ROI by the power spectrum of
scattered wave from the region of interest ROI 1, and cumulative
attenuation slopes, and used for calculating an attenuation slope of the
region of interest ROI 2 by a plurality of commulative attenuation slopes.
A coefficient calculation unit 10 is used for calculating an average
attenuation coefficient, a scattered coefficient, and the like.
The display 11 is connected to the B-mode receiving circuit 5 and the
coefficient calculation unit 10, and used for displaying a B-mode image
and an image characterized by the scattering coefficient of the region of
interest ROI and the attenuation slope.
As shown in FIG. 1, the scattering power calculation unit 7 calculates an
ultrasound scattering wave power P(D.sub.i) by using received signals
scattered by blood in a blood vessel which has definite scattering
characteristics. The cumulative attenuation slope calculation unit 8
calculates a cumulative attenuation slope by using the ultrasound
scattering wave power (D.sub.i) and an average attenuation slope by using
a plurality of cumulative attenuation coefficients with high accuracy.
Further, the scattering spectrum calculation unit 6 calculates ultrasound
scattering wave power spectrums of a plurality of signals scattered by a
region of interest ROI 1, and the coefficient calculation unit 10
calculates a scattering coefficient and an attenuation slope by using the
ultrasound scattering wave power spectrums of a plurality of signals with
high accuracy.
Therefore, coefficients (a cumulative attenuation slope and an average
attenuation slope) of an organ can be calculated with high accuracy based
on the signals scattered by blood having definite scattering
characteristics. Further, a scattering coefficient of a region of interest
ROI 1 located close to a blood vessel can be calculated with high accuracy
by using the above cumulative attenuation slope of the intervening tissue
between the body surface and the blood.
Next, an operation of the ultrasound diagnostic equipment shown in FIG. 1
will be explained.
First, the ultrasound diagnostic equipment is adjusted so that an
ultrasound scattering wave power of a receiving signal scattered from a
position SV.sub.1 of blood in a blood vessel BV.sub.1 can be calculated.
Next, an ultrasound wave at a position of an ultrasound beam UB is
received many times, and receiving signals scattered from the position
SV.sub.1 are calculated as an average-sum, so that an ultrasound
scattering wave power P(D.sub.i) is calculated by a scattering power
calculation unit 10. Note, scattering characteristics of blood have only
slight deviation in different human bodies, and thus the scattering
characteristics of the blood can be determined as a standard coefficient.
Further, the ultrasound scattering wavepower P(D.sub.i) of blood is
proportional to the 4th power of frequency f.sub..phi., and an attenuation
slope of an organ is equal to the frequency f.sub.0. Below, calculations
of the cumulative attenuation slope, the average attenuation slope, and
the scattering coefficient are explained in detail.
An attenuation slope at a position of a depth z from a body surface BS
.beta. (z) (dB/MHz/cm), a turn around cumulative attenuation slope B.sub.1
(dB/MHz) and a cumulative attenuation (dB) are indicated by the following
equations (1) and (2).
##EQU1##
Assuming that power transfer characteristics including scattering
characteristics and transmit receive characteristics of an ultrasound beam
UB is a distance D.sub.1 from the body surface BS to a measurement point
SV.sub.1 of a scattering power and frequency characteristics of the
equipment, a received power spectrum R(f, D.sub.1) from the measurement
point SV.sub.i of the scattering power is indicated by the following
equation (3).
##EQU2##
Where, B.sub.0 f.sup.4 indicates a scattering coefficient of blood which
value is previously known.
Therefore, an ultrasound scattering wave power (a receiving power)
P(D.sub.1) scattered by a measurement point SV.sub.1 is indicated by the
following equation (4).
##EQU3##
Note, a sensitivity of a standard ultrasound probe has been calibrated by
using a small sphere of tungsten carbide positioned sufficiently far from
the standard ultrasound probe, a scattering coefficient in a floating
solution including fine grains of a dextran have been absolutely measured
by the calibrated standard ultrasound probe, the floating solution of the
fine grains is determined as a standard phantom, and a value of G(f,
D.sub.1) is obtained by measuring a scattering power spectrum from a depth
D.sub.1 using the ultrasound probe and the ultrasound diagnostic
equipment. Therefore, if the cumulative attenuation slope B.sub.1 is
given, a receiving power P(D.sub.1) corresponding to the depth D.sub.1 can
be calculated by using the equation (4). Since the ultrasound scattering
wave power P(D.sub.1) and cumulative attenuation slope B.sub.1 are
single-valued functions the cumulative attenuation slope B.sub.1 can also
be easily calculated by using the depth D.sub.1 and the ultrasound
scattering wave power P(D.sub.1).
Consequently, a cumulative attenuation slope B.sub.1 can be obtained from
an ultrasound scattering wave power P(D.sub.1) by previously stored data
in a ROM 8 in FIG. 1. That is, the cumulative attenuation slope B.sub.1
can be obtained by a scattering power calculation unit 8 in FIG. 1.
Further, a cumulative attenuation slope B.sub.1 can be obtained by
inputting a depth D.sub.1 and an ultrasound scattering wave power
P(D.sub.1) to the equation (4). Similarly, an ultrasound scattering wave
power P(D.sub.2) at a measuring point SV.sub.2 can be obtained. An average
attenuation slope .beta..sub.12 (dB/MHz/cm) of the region of interest
ROI.sub.2 among the measuring points SV.sub.1 and SV.sub.2 is calculated.
That is, the average attenuation slope is calculated by a coefficient
calculation unit 10 in FIG. 1 by the following equation (5).
.beta..sub.12 =(B.sub.1 -B.sub.2) / 2(D.sub.2 -D.sub.1) (5)
Further, an average power spectrum R.sub.ROI(f) of receiving signals from a
region of interest ROI close to the measuring point SV.sub.1 of the
scattering power is obtained by the following equation (6).
R.sub.ROI(f) =G(f, D.sub.1).multidot.S(f).multidot.10.sup.-B
1.sup..vertline.f.vertline./10 (6)
Where, S(f) indicates scattering characteristics of the region of interest
ROI. Note, a value or the cumulative attenuation slope B.sub.1 is
previously obtained, and thus S(f) is calculated by the following equation
(7).
S(f)=R.sub.ROI (f)/(G(f, D.sub.1) .multidot.10.sup.-B
1.sup..vertline.f.vertline./10) (7)
Next, a construction of FIG. 2 will be explained. FIG. 2 is a block diagram
showing one example of the ultrasound diagnostic equipment shown in FIG.
1.
As shown in FIG. 2, the scattering spectrum calculation unit 6 comprises a
logarithmic amplifier 65, an A/D converter 61, an inverse logarithmic
circuit 66, an operation circuit 62, a power operation circuit 63, and an
accumulator 64.
The logarithmic amplifier 65 is connected to the receiving amplifier 3, and
used for amplifying an amplitude of the output signal of the receiving
amplifier 3 as a logarithmic compression. The A/D converter 61 is
connected to the logarithmic amplifier 65, and used for converting an
output signal of the logarithmic amplifier 65 into a digital signal. The
inverse logarithmic circuit 66 is connected to the A/D converter 61, and
used for returning to an output signal of the A/D converter 61 to a
primary antilogarithm. The arithmetic circuit 62 is connected to the
inverse logarithmic circuit 66 and used for performing a high speed
calculation of a Fourier spectrum of an output signal of the inverse
logarithmic circuit 66. The power calculation circuit 63, is connected to
the operation circuit 62, and used for calculating a sum of the square of
a real component and the square of an imaginary component of the fast
Fourier transform. The accumulator 64 is connected to the power operation
circuit 63 and used for adding a power spectrum of a scanning line in the
region of interest ROI.
The scattering power calculation unit 7 comprises a Doppler signal
calculation circuit 71, a power calculation circuit 72, and an A/D
converter 73. The Doppler signal calculation circuit 71 is connected to
the receiving amplifier 3 and the timing control unit 4 and used for
calculating a Doppler signal of the receiving amplifier 3 in a sample
volume by the timing signal from the timing control unit 4. The power
calculation circuit 72 is connected to the Doppler signal calculation
circuit 71, and used for calculating power of the Doppler signal by
calculating a sum of a square and averaging in time between an imaginary
component and a real component of the Doppler signal. The A/D converter 73
is connected to the power calculation circuit 72 and used for converting
the power of the Doppler signal into a digital signal.
The cumulative attenuation slope calculation unit 8 comprises a read only
memory which is connected to the scattering power calculation unit 7 and
the timing control unit 4. Note, transfer tables from the scattering
powder P(D.sub.1) and depth D.sub.1 to the cumulative attenuation slope
are stored in the read only memory 8, which are calculated from the
scattering coefficient of blood, diffraction characteristics of the
ultrasound beam UB, transmitting-receiving characteristics, and a power
transfer function including frequency characteristics of the equipment.
FIG. 3 is a block diagram showing another example of the ultrasound
diagnostic equipment shown in FIG. 1. This ultrasound diagnostic equipment
of FIG. 3 does not include a logarithmic amplifier 65 and an inverse
logarithmic circuit 66 shown in FIG. 2. The logarithmic amplifier 65 and
the inverse logarithmic circuit 66 are used for improving dynamic range of
digital output data, and thus the logarithmic amplifier 65 and inverse
logarithmic circuit 66 are not always necessary.
Next, an operation of the construction of FIG. 2 including the construction
of FIG. 3 will be explained.
In FIG. 2, an ultrasound wave UB is radiated from the ultrasound probe 1 to
an organ by pulse signals output from the transmitting amplifier 2. An
ultrasound wave is scattered and returned from the organ in sequence. An
ultrasound scattering signal received by the ultrasound probe 1 is
amplified by the receiving amplifier 3. The amplified receiving signal is
processed through the logarit | | |
