Device and method for measuring the elasticity of an artery by ultrasonic echography
First Claim
1. A device for measuring physiological parameters of an artery containing flowing blood having an instantaneous pressure P(t), said device comprising, in an ultrasonic echograph used in profilometer mode (M mode) and provided with transmission/receiving means including a device for forming channels in a receiving mode, a first assembly for measuring and forming at outputs of the first assembly a first set of signals representing an instantaneous blood flow rate Q(t) within the artery, an instantaneous radius variation Δ
- r(t) of the artery, and a mean radius r0 of the artery along a first excitation line A, characterized in that it also comprises, for the determination of elasticity γ
(t) of said artery and the pressure P(t) of the flowing blood within the artery, a second assembly for measuring, by ultrasonic echography, and forming at its outputs a second set of signals representing an instantaneous blood flow rate Q'"'"'(t) and an instantaneous radius variation Δ
r'"'"'(t) along a second excitation line B neighbouring the first excitation line A, the second excitation line B being situated at a distance e from the first excitation line A, which distance is small in comparison with the systolic propogation wavelength λ
along the artery, the two excitation lines A and B traversing the artery according to one of its meridian planes, the distance e being taken in the direction of the axis of the artery, first and second storage means connected to the respective outputs of said first and second assemblies for storing digital samples of said respective first and second sets of signals and calculation means coupled to said first and second storage means for operating on said stored digital samples to calculate physiological parameters of said artery.
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Abstract
An ultrasonic echograph is used as a profilometer for the measurement of the instantaneous blood flow rate Q(t) and the instantaneous radius variation Δr(t) and the mean radius r0 of the artery along a first excitation line A. In accordance with the invention, the profilometer is conceived to supply also Q'"'"'(t) and Δr'"'"'(t) along a second excitation line B which is situated at a distance e, of the order of magnitude of millimeters, from the first line. This collection of data enables, by calculation, determination of the elasticity or compliance γ(t) of the artery and its internal pressure P(t) at the area of measurement.
56 Citations
9 Claims
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1. A device for measuring physiological parameters of an artery containing flowing blood having an instantaneous pressure P(t), said device comprising, in an ultrasonic echograph used in profilometer mode (M mode) and provided with transmission/receiving means including a device for forming channels in a receiving mode, a first assembly for measuring and forming at outputs of the first assembly a first set of signals representing an instantaneous blood flow rate Q(t) within the artery, an instantaneous radius variation Δ
- r(t) of the artery, and a mean radius r0 of the artery along a first excitation line A, characterized in that it also comprises, for the determination of elasticity γ
(t) of said artery and the pressure P(t) of the flowing blood within the artery, a second assembly for measuring, by ultrasonic echography, and forming at its outputs a second set of signals representing an instantaneous blood flow rate Q'"'"'(t) and an instantaneous radius variation Δ
r'"'"'(t) along a second excitation line B neighbouring the first excitation line A, the second excitation line B being situated at a distance e from the first excitation line A, which distance is small in comparison with the systolic propogation wavelength λ
along the artery, the two excitation lines A and B traversing the artery according to one of its meridian planes, the distance e being taken in the direction of the axis of the artery, first and second storage means connected to the respective outputs of said first and second assemblies for storing digital samples of said respective first and second sets of signals and calculation means coupled to said first and second storage means for operating on said stored digital samples to calculate physiological parameters of said artery. - View Dependent Claims (2, 3, 4, 5, 6, 9)
- r(t) of the artery, and a mean radius r0 of the artery along a first excitation line A, characterized in that it also comprises, for the determination of elasticity γ
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7. A method for measuring an elasticity parameter γ
- of an artery within a living subject containing flowing blood having a blood pressure P by irradiating the living subject with ultrasonic radiation along two neighboring, parallel excitation lines traversing the artery according to one of its meridian planes, collecting samples of echo signals returned from said subject and producing from said collected samples, and storing, instantaneous blood flow rates Q(t), Q'"'"'(t), and instantaneous radius variations Δ
r(t), Δ
r'"'"'(t) for the two neighbouring parallel excitation lines respectively, and a mean radius r0 for the artery, said producing comprising the following steps;i calculating, on the basis of one of the two functions Q(t), Q'"'"'(t), a mean value Q0 and a derivative ##EQU37## of the one function, ii calculating, on the basis of the instantaneous values Δ
r(t), Δ
r'"'"'(t) for the lines A and B, the instantaneous value;
space="preserve" listing-type="equation">δ
r(t)=Δ
r(t)-≢
r'"'"'(t)iii determining mean values of the elasticity parameter γ
, a hydrodynamic resistance parameter R and a pressure gradient Δ
P/Δ
x, i.e. γ
0, R0 and R0 Q0, respectively, on the basis of the least squares method applied, over a cardiac cycle, to the relation;
##EQU38## in which the identification;
##EQU39## is made. - View Dependent Claims (8)
- of an artery within a living subject containing flowing blood having a blood pressure P by irradiating the living subject with ultrasonic radiation along two neighboring, parallel excitation lines traversing the artery according to one of its meridian planes, collecting samples of echo signals returned from said subject and producing from said collected samples, and storing, instantaneous blood flow rates Q(t), Q'"'"'(t), and instantaneous radius variations Δ
Specification