Ultrasonic method and apparaus for determination of vessel location and size
First Claim
1. A method of establishing the dimensions and orientation of a vessel which, when subjected to ultrasonic echoscopy examination, is found to be essentially free of substantial internal acoustic discontinuities, said vessel having an axis which is straight in least part of the vessel, said method comprising the steps of(a) obtaining a B-mode ultrasonic echogram image of said vessel or the part thereof in which said axis is straight from a number of A-mode ultrasonic images, each corresponding to a respective A-mode line of sight of a beam of ultrasonic energy which is scanned over said vessel or said part thereof;
- (b) establishing an angle marker in the form of a short line segment within or close to the B-mode image of said vessel or said part thereof;
(c) establishing a plurality of adjacent sub-sectors within the B-mode echogram image of said vessel or part thereof;
each of said sub-sectors being intersected by said angle marker;
each sub-sector receiving substantially the same number of adjacent A-mode lines of sight of said scanning beam;
(d) obtaining an average video-detected A-mode signal for each of said sub-sectors,(e) performing a comparison of said average A-mode signals of the sub-sectors and determining from said comparison the difference between the orientation of the axis of said vessel and said angle marker and the orientation of said axis of said vessel;
(f) combining said average A-mode signals to obtain a composite A-mode signal for said vessel or part thereof; and
(g) performing edge-detection analysis on said composite A-mode signal, to obtain a value of the diameter of said vessel or part thereof.
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Accused Products
Abstract
An improved technique for establishing the position, dimensions and orientation of a vessel which is essentially free of internal acoustic discontinuities involves scanning the vessel with a beam of ultrasonic energy and, from the ultrasonic echoes received in the A-mode lines of sight of the ultrasonic beam, establishing a B-mode image of the vessel. An angle marker, in the form of a short line segment, is established, using the B-mode image, on or near a straight axis of the vessel. The length of the angle marker is divided into a number of sub-sectors, each of which receives approximately the same number of A-mode lines of sight of the ultrasonic beam. An average A-mode signal is obtained for each sub-sector. Comparison of the average A-mode signals provides information about the orientation of the angle marker relative to the axis of the vessel. Combining the average A-mode signals to obtain a composite signal and performing edge-detection analysis of the composite signal enables the edges of the vessel to be established with precision, and the diameter of the vessel to be determined accurately. A single computer can programmed to perform the analysis and re-position the angle markers (if necessary) on to the axis of the vessel. Using information obtained from this technique, accurate values of the flow rate of a fluid moving within the vessel can be obtained when Doppler frequency shift measurements are made.
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Citations
15 Claims
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1. A method of establishing the dimensions and orientation of a vessel which, when subjected to ultrasonic echoscopy examination, is found to be essentially free of substantial internal acoustic discontinuities, said vessel having an axis which is straight in least part of the vessel, said method comprising the steps of
(a) obtaining a B-mode ultrasonic echogram image of said vessel or the part thereof in which said axis is straight from a number of A-mode ultrasonic images, each corresponding to a respective A-mode line of sight of a beam of ultrasonic energy which is scanned over said vessel or said part thereof; -
(b) establishing an angle marker in the form of a short line segment within or close to the B-mode image of said vessel or said part thereof; (c) establishing a plurality of adjacent sub-sectors within the B-mode echogram image of said vessel or part thereof;
each of said sub-sectors being intersected by said angle marker;
each sub-sector receiving substantially the same number of adjacent A-mode lines of sight of said scanning beam;(d) obtaining an average video-detected A-mode signal for each of said sub-sectors, (e) performing a comparison of said average A-mode signals of the sub-sectors and determining from said comparison the difference between the orientation of the axis of said vessel and said angle marker and the orientation of said axis of said vessel; (f) combining said average A-mode signals to obtain a composite A-mode signal for said vessel or part thereof; and (g) performing edge-detection analysis on said composite A-mode signal, to obtain a value of the diameter of said vessel or part thereof. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. Apparatus for establishing the orientation and cross-sectional dimensions of a vessel having an axis, said apparatus comprising:
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(a) conventional apparatus for generating a beam of ultrasonic energy and scanning said beam over at least part of said vessel, to obtain a B-mode ultrasonic echogram image of said vessel or part thereof from a number of A-mode ultrasonic images, each corresponding to a respective A-mode line of sight of said beam; (b) operator-activated means for establishing an angle marker in the form of a short line segment within or close to the B-mode image of said vessel or part thereof; (c) accumulation means for accumulating echoes relating to respective sub-sectors of a plurality of sub-sectors of said B-mode image, said sub-sectors (i) being adjacent to each other, (ii) being intersected by said angle marker, and (iii) containing substantially equal numbers of adjacent A-mode lines of sight of said scanning beam; (d) averaging means for producing a respective average A-mode signal for each of said sub-sectors; (e) comparison means for comparing said average A-mode signals and for obtaining differences between the average A-mode signals, to enable the orientation of said axis relative to said angle marker to be computed; (f) combining means for combining said average A-mode signals to produce a composite A-mode signal; and (g) analytical means to perform edge analysis on said composite A-mode signal and to obtain therefrom a value of the diameter of said vessel or part thereof. - View Dependent Claims (12, 13, 14, 15)
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Specification