EP0226044A2 — Display of a stream line of an inhomogeneous flow…

Claim 1

Independent Claim 123 words

A method of detecting a stream line of a flow of an inhomogeneous medium, and displaying a representation of the stream line in real time, comprising:- (a) sending out ultrasonic signals to the object within which the flow occurs, to scan the object along a plurality of scanning lines, covering a scanning field, so that points within the object are scanned a plurality of times; (b) detecting echoes of the ultrasonic signals from the object; (c) forming an image representing differences between echoes received from similar points within the object but arising from ultrasonic signals sent out at different times, thereby to detect and display the locus of movement of features which move with the flow, as a representation of the stream line.

Claim 2

Independent Claim 123 words

A method of detecting a stream line of a flow of an inhomogeneous medium, and displaying a representation of the stream line in real time, comprising:- (a) sending out ultrasonic signals to the object within which the flow occurs, to scan the object along a plurality of scanning lines, covering a scanning field, so that points within the object are scanned a plurality of times; (b) detecting echoes of the ultrasonic signals from the object; (c) forming an image representing differences between echoes received from similar points within the object but arising from ultrasonic signals sent out at different times, thereby to detect and display the locus of movement of features which move with the flow, as a representation of the stream line.

Claim 3

Dependent Claim 13 words

A method as claimed in claim 1, wherein the said features are speckles.

Claim 4

Dependent Claim 19 words

A method as claimed in claim 1, wherein the said features are bubbles or particles introduced into the flow.

Claim 5

Dependent Claim 38 words

A method as claimed in claim 1, 2 or 3, wherein steps (a) to (c) are carried out in respect of each of a plurality of different scanning fields forming respective sub-fields of an overall composite scanning field.

Claim 6

Independent Claim 51 words

A method as claimed in any preceding claim, wherein the or each step (a) comprises completing at least two scanning frames of the scanning field, and wherein step (c) comprises taking differences between echoes relating to the same scanning line but arising from ultrasonic signals sent out in different scanning frames.

Claim 7

Independent Claim 53 words

A method as claimed in any preceding claim, wherein the or each step (a) comprises scanning each line of the scanning field at least twice in a scanning frame, and wherein step (c) comprises taking the differences between echoes relating to different scannings of the same scanning line in the same scanning frame.

Claim 8

Dependent Claim 72 words

A method as claimed in claim 2, or any one of claims 4 to 6 read as appended to claim 2, wherein the time interval T between first and last times at which ultrasonic signals are sent out, echoes arising from which contribute to provision of the imaging of the same point in the object is less than D/V where D is mean speckle diameter and V a maximum (anticipated) flow speed.

Claim 9

Independent Claim 19 words

A method as claimed in any preceding claim, wherein the medium is blood and the object is the heart.

Claim 10

Dependent Claim 22 words

A method as claimed in claim 9, wherein steps (a) to (c) are repeated in synchrony with successive beats of the heart.

Claim 11

Independent Claim 37 words

A method as claimed in any preceding claim, wherein the differences are compared with a threshold value, and quantized to a predetermined maximum or a predetermined minimum depending on whether or not they exceed the threshold value.

Claim 12

Independent Claim 225 words

A device for detecting a stream line of a flow of an inhomogeneous medium, and displaying a representation of the stream line in real time, by scanning the object in which the flow occurs with ultrasonic signals and processing echoes of those signals:- ultrasonic transducer means operable to send out and to receive the said ultrasonic signals and their echoes; transmission circuitry operable to excite the transducer means to cause the ultrasonic transducer means to send out the said ultrasonic signals so that points in the object are scanned a plurality of times; receiving circuitry operable to receive electrical signals provided by the ultrasonic transducer means in response to echoes of the said ultrasonic signals from the object; an echo signal generator operable to process electrical signals from the receiving circuitry to provide echo signals in a digital form suitable for image processing; a plurality of sub-frame memory means operable to store echo signals; a stream line processor (SLP) operable to process data stored in the sub-frame memory means to obtain data representing segments of stream lines; an image memory means for storing data relating to segments of stream lines; and a display circuit operable on the basis of data stored in the image memory means and to generate image signals for representing segments of the stream line on a CRT (cathode ray tube) display.

Claim 13

Independent Claim 225 words

A device for detecting a stream line of a flow of an inhomogeneous medium, and displaying a representation of the stream line in real time, by scanning the object in which the flow occurs with ultrasonic signals and processing echoes of those signals:- ultrasonic transducer means operable to send out and to receive the said ultrasonic signals and their echoes; transmission circuitry operable to excite the transducer means to cause the ultrasonic transducer means to send out the said ultrasonic signals so that points in the object are scanned a plurality of times; receiving circuitry operable to receive electrical signals provided by the ultrasonic transducer means in response to echoes of the said ultrasonic signals from the object; an echo signal generator operable to process electrical signals from the receiving circuitry to provide echo signals in a digital form suitable for image processing; a plurality of sub-frame memory means operable to store echo signals; a stream line processor (SLP) operable to process data stored in the sub-frame memory means to obtain data representing segments of stream lines; an image memory means for storing data relating to segments of stream lines; and a display circuit operable on the basis of data stored in the image memory means and to generate image signals for representing segments of the stream line on a CRT (cathode ray tube) display.

Claim 14

Dependent Claim 26 words

A device as claimed in claim 11, wherein the sub-frame memory means stores echo signals in a plurality of memory planes in accordance with address signals.

Claim 15

Dependent Claim 102 words

A device as claimed in claim 11 or 12, wherein the stream line processor comprises: a digital scan converter which provides an input echo signal with an address signal for use in storage in the sub-frame memory means; a digital signal processor which takes differences between echo signals relating to the same point in the object to obtain data representing images of speckles in the flow and takes differences representing speckle movement in the flow; and a plurality of switches for controlling flow of data and address signals between the digital scan converter, the digital signal processor and the sub-frame memory means.

Claim 16

Dependent Claim 55 words

A device as claimed in claim 13, wherein the medium is blood and the time interval T between first and last echo signals relating to the same point in the object, and between which a difference is taken, is less than D/V, where D is mean speckle diameter and V a maximum (anticipated) flow speed.

Claim 17

Independent Claim 49 words

A device as claimed in any one of claims 13 or 14, wherein the digital signal processor (DSP) is operable to compare the value of a difference representing speckle movement in the flow with a threshold value, and to quantize the difference to a predetermined maximum or minimum value.

Display of a stream line of an inhomogeneous flowing medium

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