Heart examination by means of ultrasound waves

Abstract

An examination of the human heart is carried out by means of ultrasound waves emitted by piezo-electric crystals. The crystals are inserted in a holder adapted to be placed on the body of a patient; they are arranged in a row and have parallel axes of radiation. The crystals are cyclically excited at a high scanning frequency, and the echo signals reflected by the heart walls and received by the crystals are displayed on the screen of a cathode ray tube to obtain a cross-sectional picture of the heart. In a modification of the invention, the holder comprises two or more rows of crystals radiating at different angles; in this case the echo signals related to a common point of the heart wall are superposed on the screen of the cathode ray tube by means of a coordinate transformation.

I claim: .[.1. Apparatus for heart examination by means of ultrasound waves, comprising: 
     
        said cathode ray tube..]. 2. Apparatus as claimed in claim 1, comprising a clock generator for controlling the cyclic excitation of the said crystals; an amplifier controlled by said clock generator and having a time dependent gain; means for supplying said echo signals to said amplifier; and means for supplying an output signal of said amplifier to said cathode ray tube for modulating the intensity of the electron beam, the gain variation of said amplifier being selected in such manner so as to compensate for the intensity difference between the echo signals 
     
     
        reflected by the front wall and the back wall of the heart. 3. .[.Apparatus as claimed in claim 1, comprising.]. .Iadd.Apparatus for heart examination by means of ultrasound waves, comprising: A. a crystal holder adapted to be externally placed on the body of a patient;   B. a first group of piezo-electric crystals supported in said holder, said crystals being arranged in a row and having an active surface lying in a common plane on the outside of the holder, said crystals having parallel axes of radiation lying in a plane adapted to intersect the heart being examined along a predetermined cross-section and forming both a transmitter and receiver of ultrasound waves;   c. a cathode ray tube;   d. means for displaying echo signals reflected by the heart walls at predetermined cross-section and received by said crystals on the screen of said cathode ray tube in a coordinate system wherein one coordinate represents the position of each of the crystals in said holder, and another coordinate represents the time of reception of said echo signals, and   e. means for repeatedly and rapidly cyclically exciting certain ones of said crystals in a predetermined order and at such a frequency that an instantaneous image of said cross-section is displayed on the screen of said cathode ray tube, .Iaddend.a second and third group of piezo-electric crystals arranged in two rows, said rows of first, second and third group of said crystals being juxtaposed in said holders; means for exciting the crystals of one group subsequent to the crystals of the other two groups; and means for superposing the echo signals received by the crystals of said second and third groups on the echo signals received by the crystals of said first group when said echo signals are displayed on the screen of said cathode ray tube, said groups being arranged in a manner so that, when said holder is placed on the body surface of a patient, the axes of radiation of the crystals of said first group are perpendicular to said body surface, and the axes of radiation of the crystals of said second and third groups are inclined with respect to said body surface at equal and   
     
     
        opposite angles. 4. Apparatus as claimed in claim 3, comprising a first generator producing a step function indicating the position of each of said crystals in said holder, a second generator producing a saw tooth signal, a first amplifier for multiplying said saw tooth signal by a factor proportional to the .[.sinus.]. .Iadd.sine .Iaddend.of the angle of radiation; a second amplifier for multiplying said saw tooth signal by a factor proportional to the .[.cosinus.]. .Iadd.cosine .Iaddend.of the angle of radiation; an adding member for adding the output signal of said first amplifier to said step function; means for activating said first and second amplifiers and said adding member during the display of the echo signal received by the crystals of said second and third groups; means activated during the display of the echo signals received by the crystals of said first group for supplying said step function to said cathode ray tube as a vertical deflecting signal and for supplying said saw tooth signal to said cathode ray tube as a horizontal deflecting signal; and means activated during the display of the echo signals received by the crystals of said second and third groups for supplying the output signal of said adding member to said cathode ray tube as a vertical deflecting signal, and for supplying the output signal of said second amplifier to 
     
     
        said cathode ray tube as a horizontal deflecting signal. 5. Apparatus as claimed in claim 4, the crystals of said three groups being displaced with respect to each other in said holder in the row direction; and means for supplying to said adding member a signal compensating for the mutual 
     
     
        displacement of the groups of crystals. .Iadd.6.  Apparatus for heart examination by means of ultrasound waves, comprising: a. a crystal holder adapted to be externally placed on the body of a patient;   b. a first group of piezo-electric crystals supported in said holder, said crystals being arranged in a row and having parallel axes of radiation lying in a plane adapted to intersect the heart being examined along a predetermined cross-section and forming both a transmitter and receiver of ultrasound waves;   c. a cathode ray tube;   d. means for displaying echo signals reflected by the heart walls at the predetermined cross-section and received by said crystals on the screen of said cathode ray tube in a coordinate system wherein one coordinate represents the position of each of the crystals in said holder, and another coordinate represents the time of reception of said echo signals,   e. means for repeatedly and rapidly cyclically exciting certain ones of said crystals in a predetermined order and at such a frequency that an instantaneous image of said cross-section is displayed on the screen of said cathode ray tube, and   f. means for producing additional ultrasound radiation along axes inclined with respect to the parallel axes of radiation produced by said first group of crystals and for producing echo signals superimposed on the echo signals of said first group of crystals for providing an image on said screen of the entire outline of the heart including not only the front and back walls thereof but also the top and bottom walls as well. .Iaddend. .Iadd.7. Apparatus as claimed in claim 6 wherein said means for producing additional ultrasound radiation includes at least one further group of crystals having parallel axes of radiation which are inclined with respect to the axes of radiation of the first group of crystals. .Iaddend. .Iadd.8. Apparatus as claimed in claim 6 wherein said first and further   
     
     
        group of crystals are arranged in parallel rows. .Iaddend. .Iadd.9. Apparatus as claimed in claim 6 wherein said first and further group of crystals are arranged in a common row. .Iaddend. .Iadd.10. Apparatus as claimed in claim 6 wherein said means for producing additional ultrasound radiation includes two further groups of crystals having axes of radiation inclined with respect to said first group. .Iaddend. .Iadd.11. Apparatus as claimed in claim 10 wherein the axes of radiation of the two further groups of crystals are inclined with respect to the first group at equal 
     
     
        and opposite angles. .Iaddend. .Iadd.12.  Apparatus as claimed in claim 6, comprising a clock generator for controlling the cyclic excitation of the said crystals; an amplifier controlled by said clock generator and having a time dependent gain; means for supplying said echo signals to said amplifier; and means for supplying an output signal of said amplifier to said cathode ray tube for modulating the intensity of the electron beam, the gain variation of said amplifier being selected in such manner so as to compensate for the intensity difference between the echo signals reflected by the front wall and the back wall of the heart. .Iaddend.