Method and apparatus for removing artifacts from an ultrasonically generated image of a small cavity

A method of imaging a cross section of a small cavity such as a coronary vessel, the method employing an imaging apparatus including a transducer, wherein the transducer flexes in response to a received electrical pulse so as to emit ultrasonic waves in an ambient environment of the transducer within the small cavity, the method comprising the steps of:

• a. positioning the transducer within a reference collection environment;
• b. emitting ultrasonic waves into the reference collection environment by exciting the transducer in response to an electrical pulse;
• c. detecting a ringdown signal generated by a damped oscillation of the transducer in response to the electrical pulse;
• d. storing the ringdown signal as a linear reference waveform;
• e. inserting the transducer into a small cavity to be imaged;
• f. emitting ultrasonic waves into the small cavity by exciting the transducer in response to an electrical pulse;
• g. detecting an echo waveform generated by echoes of the ultrasonic waves as they are reflected off surfaces of the small cavity and impinge upon the transducer;
• h. subtracting the reference waveform from the echo waveform so as to generate an imaging waveform;
• i. amplifying the imaging waveform such that the entire waveform remains linear;
• and
• j. processing the linear imaging waveform with other linear imaging waveforms in order to create a visual image of the small cavity.

An apparatus for imaging a cross section of a small cavity such as a coronary vessel, the apparatus including in combination:

• a probe having a transducer element;
• a source of an electrical pulse for exciting the transducer element to emit ultrasonic waves in an ambient environment of the transducer element within the small cavity;
• a receiver for detecting electrical signals generated by mechanical oscillations of the transducer element after excitation of the transducer element by the electrical pulse;
• a first buffer for storing the electrical signals as an echo waveform, comprising N bytes;
• a second buffer for storing the electrical signals as a reference waveform, comprising M bytes of non-zero data, where N>M;
• means for subtracting the reference waveform from the echo waveform in order to provide an imaging waveform stripped of any repeatable noise patterns;
• and
• an imaging device responsive to the imaging waveform for generating a visual image.

An apparatus for imaging a cross section of a small cavity such as a coronary vessel, the apparatus including in combination:

• a prove having a transducer element;
• a source of an electrical pulse for exciting the transducer element to emit ultrasonic waves in an ambient environment of the transducer element within the small cavity;
• a receiver for detecting electrical signals generated by the mechanical flexing of the transducer element after excitation of the transducer element by the electrical pulse;
• a first buffer for storing as a reference waveform electrical signals which are free of signals caused by echoes of the ultrasonic waves, where the reference waveform is substantially entirely linear;
• means for subtracting the reference waveform from electrical signals that include signals caused by echoes of the ultrasonic waves in order to generate an echo waveform;
• a second buffer for storing the echo waveform;
• means responsive to the second buffer for generating visual images.