Ultrasonic frequency-domain system and method for sensing fluid flow

Claim 1

A method for measuring blood flow within a blood vessel or organ comprising the following steps: A. repeatedly applying to each of a plurality of piezoelectric transducer elements a corresponding pulsed electrical transmit signal; B. in the transducer elements, sensing a receive signal that is back-scattered from blood within the blood vessel or organ; C. electrically shaping and phasing the transmit and receive signals to generate a substantially spherical and isotropic interrogation region within which blood flow is to be measured; D. for each application of the pulsed electrical excitation signals, sensing an ultrasonic return signal that is back-scattered from particles within the interrogation region; E. converting the sensed ultrasonic return signals into a corresponding composite electrical return signal; F. measuring Doppler shift of the composite electrical return signal and generating a corresponding detected Doppler signal; G. measuring the bandwidth of the detected Doppler signal; H. determining a proportionality factor that is proportional to a beam width of the interrogation region; and I. outputting a representation of a magnitude of flow velocity as a predetermined function of the measured bandwidth of the detected Doppler signal, the predetermined function comprising scaling the beam width by the proportionality factor.

Claim 2

A method for measuring blood flow within a blood vessel or organ comprising the following steps: A. repeatedly applying to each of a plurality of piezoelectric transducer elements a corresponding pulsed electrical transmit signal; B. in the transducer elements, sensing a receive signal that is back-scattered from blood within the blood vessel or organ; C. electrically shaping and phasing the transmit and receive signals to generate a substantially spherical and isotropic interrogation region within which blood flow is to be measured; D. for each application of the pulsed electrical excitation signals, sensing an ultrasonic return signal that is back-scattered from particles within the interrogation region; E. converting the sensed ultrasonic return signals into a corresponding composite electrical return signal; F. measuring Doppler shift of the composite electrical return signal and generating a corresponding detected Doppler signal; G. measuring the bandwidth of the detected Doppler signal; H. determining a proportionality factor that is proportional to a beam width of the interrogation region; and I. outputting a representation of a magnitude of flow velocity as a predetermined function of the measured bandwidth of the detected Doppler signal, the predetermined function comprising scaling the beam width by the proportionality factor.

Claim 6

A method for measuring the magnitude of velocity of blood flow in a blood vessel or organ comprising the following steps: A. repeatedly applying to each of a plurality of piezoelectric transducer elements a corresponding pulsed electrical transmit signal; B. in the transducer elements, sensing a receive signal that is back-scattered from blood within the blood vessel or organ; C. electrically shaping and phasing the transmit and receive signals to generate a substantially spherical and isotropic interrogation region within which blood flow is to be measured, with a range dimension of an interrogation region substantially equal to an elevational dimension and an azimuthal dimension; D. for each application of the pulsed electrical transmit and receive signals, sensing an ultrasonic return signal that is back-scattered from particles within the interrogation region; E. converting the sensed ultrasonic return signals into a corresponding composite electrical return signal; F. determining a proportionality factor that is proportional to a beam width of the interrogation region; G. measuring Doppler shift of the composite electrical return signal and generating a corresponding detected Doppler signal; H. measuring the bandwidth of the detected Doppler signal; and I. outputting a representation of a predetermined blood flow characteristic as a predetermined function of the measured bandwidth of the detected Doppler signal.

Claim 7

A method for measuring the magnitude of velocity of blood flow in a blood vessel or organ comprising the following steps: A. repeatedly applying to each of a plurality of piezoelectric transducer elements a corresponding pulsed electrical transmit signal; B. in the transducer elements, sensing a receive signal that is back-scattered from blood within the blood vessel or organ; C. electrically shaping and phasing the transmit and receive signals to generate a substantially spherical and isotropic interrogation region within which blood flow is to be measured, with a range dimension of an interrogation region substantially equal to an elevational dimension and an azimuthal dimension; D. for each application of the pulsed electrical transmit and receive signals, sensing an ultrasonic return signal that is back-scattered from particles within the interrogation region; E. converting the sensed ultrasonic return signals into a corresponding composite electrical return signal; F. determining a proportionality factor that is proportional to a beam width of the interrogation region; G. measuring Doppler shift of the composite electrical return signal and generating a corresponding detected Doppler signal; H. measuring the bandwidth of the detected Doppler signal; and I. outputting a representation of a predetermined blood flow characteristic as a predetermined function of the measured bandwidth of the detected Doppler signal.

Claim 8

A system for measuring blood flow within a blood vessel or organ comprising: A. an ultrasonic transducer with a plurality of piezoelectric transducer elements forming transducer means for generating a substantially spherical and isotropic ultrasonic interrogation region within which the blood flows; B. timing and signal excitation and sensing means for repeatedly applying to each of the transducer elements a corresponding pulsed electrical transmit signal, for sensing a receive signal that is back-scattered to the transducer elements from blood within the blood vessel or organ, and for electrically shaping and phasing the transmit and receive signals to generate the interrogation region; C. Doppler bandwidth detection means for detecting a bandwidth of a composite Doppler return signal corresponding to back-scattered return signals that have been back-scattered by particles in the blood; and D. processing means for generating a representation of a a magnitude of flow velocity as a predetermined function of the measured bandwidth of the detected Doppler signal, and for generating the representation of the magnitude of velocity by scaling the measured bandwidth by a proportionality factor, which is proportional to a beam width of the interrogation region.

Claim 9

A system for measuring blood flow within a blood vessel or organ comprising: A. an ultrasonic transducer with a plurality of piezoelectric transducer elements forming transducer means for generating a substantially spherical and isotropic ultrasonic interrogation region within which the blood flows; B. timing and signal excitation and sensing means for repeatedly applying to each of the transducer elements a corresponding pulsed electrical transmit signal, for sensing a receive signal that is back-scattered to the transducer elements from blood within the blood vessel or organ, and for electrically shaping and phasing the transmit and receive signals to generate the interrogation region; C. Doppler bandwidth detection means for detecting a bandwidth of a composite Doppler return signal corresponding to back-scattered return signals that have been back-scattered by particles in the blood; and D. processing means for generating a representation of a a magnitude of flow velocity as a predetermined function of the measured bandwidth of the detected Doppler signal, and for generating the representation of the magnitude of velocity by scaling the measured bandwidth by a proportionality factor, which is proportional to a beam width of the interrogation region.

Claim 10

A system for measuring blood flow within a blood vessel or organ comprising: A. an ultrasonic transducer with a plurality of piezoelectric transducer elements forming transducer means for generating an ultrasonic interrogation region within which the blood flows, in which the interrogation region is substantially ellipsoidal with a long axis; B. timing and signal excitation and sensing means for repeatedly applying to each of the transducer elements a corresponding pulsed electrical transmit signal, for sensing a receive signal that is back-scattered to the transducer elements from blood within the blood vessel or organ, and for electrically shaping and phasing the transmit and receive signals to generate the interrogation region; C. Doppler bandwidth detection means for detecting a bandwidth of a composite Doppler return signal corresponding to back-scattered return signals that have been back-scattered by particles in the blood; and D. processing means: 1) for generating a representation of the direction of blood flow as a predetermined function of the measured bandwidth of the detected Doppler signal; 2) for controlling the timing and signal excitation and sensing means for generating a plurality of the ellipsoidal interrogation regions with different directions of their respective long axes; and 3) for outputting as the representation of the flow direction the direction of the long axis of the ellipsoidal interrogation region for which the measured bandwidth is a minimum.

Claim 11

A system for measuring blood flow within a blood vessel or organ comprising: A. an ultrasonic transducer with a plurality of piezoelectric transducer elements forming transducer means for generating an ultrasonic interrogation region within which the blood flows, in which the interrogation region is substantially ellipsoidal with a long axis; B. timing and signal excitation and sensing means for repeatedly applying to each of the transducer elements a corresponding pulsed electrical transmit signal, for sensing a receive signal that is back-scattered to the transducer elements from blood within the blood vessel or organ, and for electrically shaping and phasing the transmit and receive signals to generate the interrogation region; C. Doppler bandwidth detection means for detecting a bandwidth of a composite Doppler return signal corresponding to back-scattered return signals that have been back-scattered by particles in the blood; and D. processing means: 1) for generating a representation of the direction of blood flow as a predetermined function of the measured bandwidth of the detected Doppler signal; 2) for controlling the timing and signal excitation and sensing means for generating a plurality of the ellipsoidal interrogation regions with different directions of their respective long axes; and 3) for outputting as the representation of the flow direction the direction of the long axis of the ellipsoidal interrogation region for which the measured bandwidth is a minimum.