Devices and methods for tracking blood flow and determining parameters of blood flow

Abstract

Provided herein is a method for use in medical applications that permits (1) affordable three-dimensional imaging of blood flow using a low-profile easily-attached transducer pad, (2) real-time blood-flow vector velocity, and (3) long-term unattended Doppler-ultrasound monitoring in spite of motion of the patient or pad. The pad and associated processor collects and Doppler processes ultrasound blood velocity data in a three dimensional region through the use of a planar phased array of piezoelectric elements. The invention locks onto and tracks the points in three-dimensional space that produce the locally maximum blood velocity signals. The integrated coordinates of points acquired by the accurate tracking process is used to form a three-dimensional map of blood vessels and provide a display that can be used to select multiple points of interest for expanded data collection and for long term continuous and unattended blood flow monitoring. The three dimensional map allows for the calculation of vector velocity from measured radial Doppler.A thinned array (greater than half-wavelength element spacing of the transducer array) is used to make a device of the present invention inexpensive and allow the pad to have a low profile (fewer connecting cables for a given spatial resolution). The full aperture is used for transmit and receive so that there is no loss of sensitivity (signal-to-noise ratio) or dynamic range. Utilizing more elements (extending the physical array) without increasing the number of active elements increases the angular field of view. A further increase is obtained by utilizing a convex non-planar surface.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of U.S. application Ser. No. 10 / 831,547 filed Apr. 23, 2004, which is a continuation in part of U.S. application Ser. No. 10 / 327,265 filed Dec. 20, 2002, which is a continuation-in-part of U.S. application Ser. No. 09 / 926,666, now U.S. Pat. No. 6,682,483, which is a National Phase Application of International Application No. PCT / US00 / 14691 filed May 26, 2000 and is based upon U.S. Provisional Application Nos. 60 / 136,364, filed 28 May 1999; 60 / 138,793, filed 14 Jun. 1999; and 60 / 152,886, filed Sep. 8, 1999. The above-referenced U.S. application Ser. No. 10 / 327,265 claims priority to U.S. provisional application Ser. No. 60 / 343,061.FIELD OF THE INVENTION[0002]The present invention involves an ultrasound Doppler method that permits non-invasive diagnosis and non-invasive unattended, continuous monitoring of vascular blood flow for medical applications. The invention further relates to a method and a system ...

AI Technical Summary

Benefits of technology

[0052]As explained above, an operator performing a method of the present invention can obtain blood flow parameters from a blood vessel of interest, and even from a particular region of a blood vessel of interest.

[0150]It is yet another object of the present invention to provide a thinned array which does not utilize the number of element transducers as are required with heretofore known Doppler ultrasound devices. As a result, the decreased number of elements in the array decreases size of the array utilized and provides a patient being analyzed with mobility that would not be available if using conventional ultrasound devices to obtain blood flow parameters such as vector velocity, blood flow volume, and Doppler spectral distribution. The parameter being measured can be an instantaneous value, or an average value determined over a heart cycle.

Problems solved by technology

Blood velocity monitoring is not currently practical for intensive care unit (ICU) or surgical applications.

Slight movements cause the probe to lose the blood velocity signal.

However, in order for a two dimensional (2-D) device to provide such imaging normally requires thousands of elements, and must form many thousands of pencil beams every 1 / 30 second.

Sensor cost grows with the number of elements in the array and the number of processing channels.

Thus, such devices are cost prohibitive, as well as impractical.

Moreover, no automated procedure exists in current practice for precisely locating the optimum point at which to measure the Doppler signal.

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