Method and apparatus for determining and displaying the absolute value of quantitative backscatter

Claim 2

An ultrasonic scanning system for receiving backscatter from an ultrasonic signal transmitted towards a first point (22) in a subject's body (24) and determining the absolute, quantitative value of the backscatter, the system being characterised in that it comprises; means (12) for detecting the quantitative value of the backscatter, means for determining the backscatter attenuation for moving blood at a second point (26) close to the first point, and means for utilising the backscatter attenuation data to perform an attenuation correction on the detected backscatter to determine its absolute quantitative value.

Claim 3

A system according to claim 1 wherein the transmitted ultrasonic signal has a given voltage, wherein there is a predetermined blood scattering efficiency for the subject, and wherein said means for determining the backscatter attenuation of the moving blood comprises; means for determining the Doppler voltage spectrum of moving blood at said second point (26), means for integrating said Doppler voltage spectrum over a selected frequency range; means for utilizing the output of the integrating means, said blood scattering efficiency and said given voltage to determine the blood backscatter attenuation for the second point.

Claim 4

A system according to claim 2, further comprising means (52) for removing selected low frequency portions of the Doppler spectrum prior to application to said means for integrating; and wherein said selected frequency range is from the positive Nyquist frequency to the negative Nyquist frequency; and wherein said blood backscatter attenuation is calculated utilizing the equation where: A T (d o ) = blood backscatter attenuation at distance d o G(d o ) = beam scanner gain for depth (distance) d o D g = additional Doppler gain B s = blood scattering efficiency V T (t) = the transmitted voltage at time (t) H T (t) = the transducer impulse response S(w) = voltage spectrum of Doppler signal t1 = the beginning of the ultrasonic transmission t2 = the end of ultrasonic transmission Nq = the Nyquist frequency

Claim 9

A system according to claim 7 including a display means (48); and wherein said colour mapping means includes control means responsive to said determined absolute value for controlling at least the colour and intensity of at least a selected portion of the display on said display means.

Claim 10

A system according to claim 8 wherein said control means comprises memory means (56) for storing a table of absolute values and corresponding colour and intensity information, and means responsive to a detected absolute value of quantitative backscatter for reading out the corresponding colour and intensity information to control the display (48).

Claim 11

A system according to claim 8 or 9, for use for diagnostic purposes, wherein first absolute values of quantitative backscatter for certain portions of the body are regarded as healthy and second absolute values are regarded as unhealthy, and wherein said control means is operative in response to said determined absolute value being equal to a first absolute value for causing the at least selected portion of the display (48) to be of a first colour and of a first selected intensity, is operative in response to said determined absolute value being equal to a second absolute value for causing the selected portion of the display to be of a second different colour and a second intensity, which second intensity may be the same as the first intensity, and is operative in response to the determined absolute value being between the first and second absolute values for controlling at least the colour or intensity of the display portion in a predetermined manner.

Claim 12

A system according to claim 10 wherein the control means is operative when the detected absolute value is between the first and second absolute values to control the colour of the display portion to be a colour between the first and second colour, the displayed colour varying as a function of the difference between the detected absolute value and the first and second absolute values respectively.

Claim 13

A system according to claim 8 or 9, for use for diagnostic purposes, wherein first absolute values of quantitative backscatter for certain portions of the body are regarded as healthy and second absolute values are regarded as unhealthy, and wherein said means for controlling is operative to control the intensity of the display such that the intensity varies substantially uniformly as the detected absolute value varies from the first absolute value to the second absolute value.

Claim 16

A method according to claim 13 wherein said selected frequency range is from the positive Nyquist frequency to the negative Nyquist frequency with selected low frequencies removed; and wherein said blood backscatter attenuation is calculated utilizing the equation where: A T (d o ) = blood backscatter attenuation at distance d o G(d o ) = beam scanner gain for depth (distance) d o D g = additional Doppler gain B s = blood scattering efficiency V T (t) = the transmitted voltage at time (t) H T (t) = the transducer impulse response S(w) = voltage spectrum of Doppler signal t1 = the beginning of the ultrasonic transmission t2 = the end of ultrasonic transmission Nq = the Nyquist frequency

Claim 17

A method according to claim 13 and 14 wherein said utilizing step includes the step of adjusting the determined blood backscatter attenuation to compensate for the distance between the selected and predetermined points in the direction of the ultrasonic signal.

Claim 19

A method according to claim 16 including the step of automatically selecting the second point (26) to be used for each first point.

Claim 20

A method according to claim 16 or 17, including the step of colour mapping the determined absolute value of quantitative backscatter.

Claim 21

A method according to claim 18 wherein the system is being used fo diagnostic purposes, wherein first absolute values of quantitative backscatter for certain portions of the body are regarded as healthy and second absolute values are regarded as unhealthy; and including the steps of imaging the scanned portion of the subject's body on a display means; causing the portion of the displayed image corresponding to the selected point to be of a first colour and intensity in response to the absolute value of quantitative backscatter for the point being equal to the first absolute value; causing the portion of the displayed image corresponding to the selected point to be of a second colour and intensity in response to the absolute value of quantitative backscatter for the point being equal to the second absolute value; and causing the colour and/or intensity of the displayed image at the selected point to be between the first and second colour and/or intensity in response to the absolute value of quantitative backscatter at the selected point being between the first and second values.

Claim 22

In an ultrasonic scanning system of the type wherein an ultrasonic signal is transmitted towards selected points of a subject's body and backscatter from the selected points is detected and measured, apparatus for generating a colour map image, at least the colour or intensity of which conveys diagnostic information concerning the subject, comprising: means for determining the absolute value of the quantitative backscatter signal received from a selected point; a display means; memory means storing a table of absolute values and corresponding colour and intensity information; means responsive to a determined absolute value of quantitative backscatter for reading out the corresponding colour and intensity information to control the display; first absolute values of quantitative backscatter for certain portions of the body being regarded as healthy and second absolute values being regarded as unhealthy; means responsive to the determined value being equal to the first absolute value for reading out corresponding first colour and intensity values to control at least a portion of the display at said display means, whereby the display indicates that the subject is healthy, responsive to the determined value being equal to the second absolute value for reading out corresponding second colour and intensity values to control said display, whereby the display indicates that the subject has a particular health problem, and responsive to the determined value being between the first and second values for reading out corresponding colour and intensity values to control the display to indicate in a predetermined manner the relative health of the subject.

Claim 23

In an ultrasonic scanning system of the type wherein an ultrasonic signal is transmitted towards selected points of a subject's body and backscatter from the selected points is detected and measured, apparatus for generating a colour map image, at least the colour or intensity of which conveys diagnostic information concerning the subject, comprising: means for determining the absolute value of the quantitative backscatter signal received from a selected point; a display means; memory means storing a table of absolute values and corresponding colour and intensity information; means responsive to a determined absolute value of quantitative backscatter for reading out the corresponding colour and intensity information to control the display; first absolute values of quantitative backscatter for certain portions of the body being regarded as healthy and second absolute values being regarded as unhealthy; means responsive to the determined value being equal to the first absolute value for reading out corresponding first colour and intensity values to control at least a portion of the display at said display means, whereby the display indicates that the subject is healthy, responsive to the determined value being equal to the second absolute value for reading out corresponding second colour and intensity values to control said display, whereby the display indicates that the subject has a particular health problem, and responsive to the determined value being between the first and second values for reading out corresponding colour and intensity values to control the display to indicate in a predetermined manner the relative health of the subject.