Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
2002-03-20
2004-01-27
Imam, Ali M. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S443000, C128S916000
Reexamination Certificate
active
06682483
ABSTRACT:
FIELD OF THE INVENTION
The present invention involves an ultrasound Doppler method that permits noninvasive diagnosis and non-invasive unattended, continuous monitoring of vascular blood flow for medical applications.
BACKGROUND OF THE INVENTION
Blood velocity monitoring is not currently practical for intensive care unit (ICU) or surgical applications. For non-invasive brain blood velocity monitoring, for example, a transcranial Doppler (TCD) probe must be mounted in a ball joint that is attached to the head by a helmet. The probe must be carefully aimed and fastened in place by an experienced person who knows how to locate the middle cerebral artery. Slight movements cause the probe to lose the blood velocity signal. Moreover, conventional Doppler ultrasound probes used in these devices scan (either mechanically or by using an acoustic phased array) in only one angle (which we will call azimuth), and will map only a single slice of the object being imaged.
Efforts have been made to modify such devices to provide real-time three dimensional (3-D) imaging. 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 ⅓0 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. Conventional ultrasound Doppler-imaging devices can only measure radial velocity in blood vessels, and not the vector velocity or magnitude of the velocity of the blood.
Accordingly, what is needed is a new and useful Doppler ultrasound device and method that can automatically locate the optimum point at which to measure the Doppler signal, and thus provide medical providers with parameters such as vector velocity, the volume of blood passing through the blood vessel and the Doppler spectral distribution of the blood flow.
What is also needed is a new and useful Doppler ultrasound device and method that does not require it be placed on a patient with precision, and will enable a patient wearing the device to move freely.
The citation of any reference herein should not be construed as an admission that such reference is available as “Prior Art” to the instant application.
SUMMARY OF THE INVENTION
There is provided, in accordance with the present invention, a new, useful, and unobvious method of determining parameters of blood flow, such as vector velocity, blood flow volume, and Doppler spectral distribution, using sonic energy (ultrasound) and a novel thinned array. Also provided is a novel method of tracking blood flow and generating a three dimensional image of a blood vessel of interest that has much greater resolution than images produced using heretofore known ultrasound devices and methods.
Broadly, the present invention extends to a method for determining a parameter of blood flow in a blood vessel of interest, comprising the steps of:
a) providing an array of sonic transducer elements, wherein the element spacing in the array is greater than, equal or less than a half wavelength of the sonic energy produced by the elements, wherein at least one element transmits sonic energy, and a portion of the elements receive sonic energy;
b) directing sonic energy produced by the at least one element of the array into a volume of the subject's body having the blood vessel of interest,
c) receiving echoes of the sonic energy from the volume of the subject's body having the blood vessel of interest;
d) reporting the echoes to a processor programmed to
i) Doppler process the echoes to determine radial velocity of the blood flowing in the blood vessel of interest;
ii) calculate a three dimensional position of blood flow in the vessel of interest; and
iii) calculate the parameter of blood flow in the blood vessel at the three dimensional position calculated in step (ii); and
(e) displaying the parameter on a display monitor that is electrically connected to the processor.
Moreover, a method of the present invention permits an operator examining a subject to obtain information on blood flow in a particular region of the blood vessel of interest.
As used herein, the phrases “element spacing” and “distance between the elements” can be used interchangeably and refer to the distance between the center of elements of an array.
Various methods can be used to determine the three dimensional position of blood flow. In a particular embodiment, the method comprises the steps of having the processor programmed to:
i) determine a sum beam, an azimuth difference beam and an elevation difference beam from the echoes received from the blood vessel of interest;
ii) modulate the directions of the transmitted and received sonic energy based upon the sum, azimuth difference and elevation difference beams in order to lock on to the highest Doppler energy calculated from echoes from the flow of blood in the blood vessel of interest, and
iii) calculate the three dimensional position of the highest Doppler energy from the blood flow in the vessel of interest.
Optionally, the processor can also be programmed to determine at least one additional beam having an angle between the azimuth difference beam and the elevation difference beam prior to modulating the directions of the transmitted and received sonic energy, wherein the at least one additional beam is used to modulate the directions of the transmitted and received sonic energy. Naturally, the angle of the at least one additional beam can vary. In a particular embodiment, the at least one additional beam is at an angle that is orthogonal to the blood vessel of interest.
Moreover, the present invention extends to a method as described above, wherein steps (b) through (e) are periodically repeated so that the three dimensional position of blood flow in the vessel of interest is tracked, and the parameter of blood flow is periodically calculated and displayed on the display monitor. In a particular embodiment, the period of time between repeating steps (b) through (e) is sufficiently short so that the parameter being measured remains constant, e.g., 20 milliseconds.
The present invention further extends to a method for determining a parameter of blood flow in a particular region of a blood vessel of interest, comprising the steps of:
a) providing an array of sonic transducer elements, wherein the element spacing in the array is greater than, equal or less than a half wavelength of the sonic energy produced by the elements, wherein at least one element transmits sonic energy, and a portion of the elements receive sonic energy;
b) directing sonic energy produced by the at least one element of the array into a volume of the subject's body having the particular region of the blood vessel of interest,
c) receiving echoes of the sonic energy from the volume of the subject's body having the particular region of the blood vessel of interest;
d) reporting the echoes to a processor programmed to
i) Doppler process the echoes to determine radial velocity of the blood flowing in the particular region of the blood vessel of interest;
ii) calculate a three dimensional position of blood flow in the particular region of the blood vessel of interest; and
iii) calculate the parameter of blood flow in the particular region of the blood vessel of interest at the three dimensional position calculated in step (ii); and
(e) displaying the parameter on a display monitor that is electrically connected to the processor.
A particular method of calculating the three dimensional position of blow flow in such a method of the present invention comprises having the processor programmed to:
i) determine a sum beam, an azimuth difference beam and an elevation difference beam from the echoes received from the particular region of the blood vessel of interest;
ii) modulate the directions of the transmitted and received sonic energy based upo
Abend Kenneth
Attia Elsayed H.
Fallow, Esq. Charles W.
Friedman, Esq. Allen N.
McCarter & English LLP
VueSonix Sensors Inc.
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