U.S. patent application number 10/224666 was filed with the patent office on 2003-09-04 for examination method of vascular endothelium function.
Invention is credited to Dohi, Takeyoshi, Ouchi, Yasuyoshi, Sakuma, Ichiro, Yoshizumi, Masao.
Application Number | 20030167005 10/224666 |
Document ID | / |
Family ID | 27800014 |
Filed Date | 2003-09-04 |
United States Patent
Application |
20030167005 |
Kind Code |
A1 |
Sakuma, Ichiro ; et
al. |
September 4, 2003 |
EXAMINATION METHOD OF VASCULAR ENDOTHELIUM FUNCTION
Abstract
A rapid vascular endothelium function examining method with
improved reproducibility is provided. An apparatus for the method
comprises systems for acquiring ultrasound images by an ultrasound
probe, processing the acquired images and moving/rotating the
ultrasound probe. The method comprises: a first step where the
acquired image is processed so that the center of a blood vessel is
laid on the center of the image; a second step where a series of
operations for acquiring an image, processing the acquired image
and moving the probe based on the processed result, are repeated so
that the probe is moved in parallel to the blood vessel; a third
step where the similar operations to the second step are executed
so that the probe is moved in parallel to and immediately above the
blood vessel; a fourth step for determining a blood vessel diameter
from the finally acquired image at the third step.
Inventors: |
Sakuma, Ichiro;
(Yokohama-shi, JP) ; Dohi, Takeyoshi; (Tokyo,
JP) ; Ouchi, Yasuyoshi; (Tokyo, JP) ;
Yoshizumi, Masao; (Tokyo, JP) |
Correspondence
Address: |
William Suire, Esq.
CARELLA, BYRNE, BAIN, GILFILLAN, CECCHI,
STEWART & OLSTEIN
6 Becker Farm Road
Roseland
NJ
07068
US
|
Family ID: |
27800014 |
Appl. No.: |
10/224666 |
Filed: |
August 21, 2002 |
Current U.S.
Class: |
600/443 |
Current CPC
Class: |
A61B 5/489 20130101;
A61B 8/08 20130101; A61B 5/1075 20130101; A61B 5/02007 20130101;
A61B 8/54 20130101 |
Class at
Publication: |
600/443 |
International
Class: |
A61B 008/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 25, 2002 |
JP |
2002-48057 |
Claims
What is claimed is:
1. A method of examining a vascular endothelium function by an
automatic measurement system comprising: a measuring system
comprising an ultrasound diagnostic device and an ultrasound probe
attached to said ultrasound diagnostic device for acquiring an
ultrasound image; an image processing and calculating system
comprising a computer and an image processing board for processing
the acquired ultrasound image by said measuring system; and a
navigation system comprising a robot arm for moving and rotating
said ultrasound probe, wherein said method comprises steps of: a
first step wherein an ultrasound image is acquired after said
ultrasound probe is moved to a subject portion for probing its
vascular endothelium function and said acquired image is processed
for calculating and controlling a position of said ultrasound probe
so that the center of a blood vessel to be probed is laid on the
center of said image; a second step wherein a series of operations
comprising an operation for acquiring ultrasound image, an
operation for processing and calculating the acquired ultrasound
image and an operation for moving said robot arm based on the
calculated result, are repeated starting from the finally acquired
ultrasound image at said first step so that said ultrasound probe
is moved to in a parallel position to the center line of the blood
vessel; a third step wherein a series of operations comprising an
operation for acquiring ultrasound image, an operation for
processing and calculating the acquired ultrasound image and an
operation for moving said robot arm based on the calculated result,
are repeated starting from the finally acquired ultrasound image at
said second step so that said ultrasound probe is moved to a
position where said ultrasound probe is in parallel to and
immediately above the center line of the blood vessel; and a fourth
step wherein a blood vessel diameter is determined from the finally
acquired ultrasound image at said third step.
2. The method according to claim 1, wherein: the center of gravity
of a color Doppler signal area in the acquired ultrasound image is
recognized as the center of the blood vessel.
3. The method according to claim 1, wherein: a distance between two
boundaries determined such that a certain width along X-axis of the
acquired ultrasound image is extracted, in the extracted width
gradient of image energy defined as accumulated brightness in the
perpendicular direction to the X-axis, is examined and two maximum
point in said gradient are determined as said boundaries and said
determined distance is determined as the blood vessel diameter.
4. The method according to claim 1, wherein: said robot arm is
controlled by two moving degrees of freedom and one rotating degree
of freedom.
5. The method according to claim 1, wherein: said robot arm is
moved and controlled along the X-axis direction in said first
step.
6. The method according to claim 1, wherein: said robot arm is
rotated and controlled around the Z-axis in said second step.
7. The method according to claim 1, wherein: said robot arm is
moved and controlled along the X-axis direction in said third
step.
8. The method according to claim 1, wherein said second and third
steps respectively further comprise steps of: any one of the
ultrasound images acquired during a series of operations is divided
by a predetermined width in the X-axis direction into a plurality
of segments; a blood vessel diameter in each divided segment is
determined; a median value is selected among determined blood
vessel diameters; the number of determined blood vessel diameters
which fall into a certain range centered by said median value, is
calculated; a score value is calculated by dividing said calculated
number by the total number of the divided segments; score values
calculated from respective series of acquired ultrasound images are
compared; and a position having a maximum score value is judged as
an optimum position of said ultrasound probe in said second step or
third step.
9. The method according to claim 1, wherein: a changing passage
after the blood vessel is dilated, is tracked on a real-time basis.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a probing system of
vascular endothelium functions, particularly relates to a probing
method where a positioning operation with the aid of a robot arm
and an image processing operation are combined.
[0003] 2. Brief Description of the Related Art
[0004] Arterial scleroses, a main cause of a cerebrovascular
disease infarction and a myocardial infarction among three major
causes of death in the Japanese, have been increasing as diets of
the Japanese have been westernized. Consequently, noninvasive and
simple probing methods to detect such arterial scleroses at their
early stages, have been required.
[0005] An Examination method of a vascular endothelium function is
used as one of such examination methods. In this method, a function
of the vascular endothelium (i.e. inner most cell layers of a
vascular wall which regulate vasodilation/vasoconstriction by
releasing a vasodilator) is measured. In an examination procedure
of the vascular endothelium function, after a blood vessel diameter
at rest is determined, a lower portion of the arm is avascularized
for 5 minutes by applying 250 mmHg of pressure with a cuff around
the arm and released so as to generate a vascular dilating reaction
caused by blood flow. An increased rate of a blood vessel diameter
due to flow mediated vasodilation against the blood vessel diameter
at rest is used as an index to evaluate arterial sclerosis.
Hashimoto et al. reported in a Japanese medical journal
(Rinsho-i(1998): 24(5) pp789-791) that a dilated degree in a
subject with a slight arterial sclerosis is ca. 10% while a dilated
degree in a subject with a grave arterial sclerosis is lowered to
ca. 2%.
[0006] They determined blood vessel diameters in such a manner that
after an ultrasound probe was applied to an arm of a subject and a
appropriate blood vessel image along its longitudinal direction is
acquired and stored for determining blood vessel diameters. They
recognized the blood vessel walls in the acquired image by their
naked eyes and the blood vessel diameters are determined based on
the recognized walls.
[0007] Fan et al. determined the blood vessel diameters by
processing images acquired by medical doctors (IEEE Transaction on
Medical Imaging: Vol.19, No.16, June 2000, pp621-631).
[0008] However, in the method by Hashimoto et al., it takes a
fairly long time to acquire images and reproducibility of the
determined blood vessel diameters is poor because walls are
recognized by naked eyes. Further, it is reported that in the
method by Fan et al. determined results largely depend on images
even when images are selected from the same subject.
SUMMARY OF THE INVENTION
[0009] The present invention is carried out to solve the problems
mentioned above and to provide an examination method of the
vascular endothelium function by combining a positioning operation
with the aid of a robot arm and an image processing operation. The
present invention attains a more rapid examination method with
improved reproducibility when determining blood vessel
diameters.
[0010] More specifically, the present invention having the
following arrangements (1) to (9) solve the problems mentioned
above.
[0011] (1) A method of examining a vascular endothelium function by
an automatic measurement system comprising: a measuring system
comprising an ultrasound diagnostic device and an ultrasound probe
attached to the ultrasound diagnostic device for acquiring an
ultrasound image; an image processing and calculating system
comprising a computer and an image processing board for processing
the acquired ultrasound image by the measuring system; and a
navigation system comprising a robot arm for moving and rotating
the ultrasound probe, wherein the method comprises steps of: a
first step wherein an ultrasound image is acquired after the
ultrasound probe is moved to a subject portion for probing its
vascular endothelium function and the acquired image is processed
for calculating and controlling a position of the ultrasound probe
so that the center of a blood vessel to be probed is laid on the
center of the image; a second step wherein a series of operations
comprising an operation for acquiring ultrasound image, an
operation for processing and calculating the acquired ultrasound
image and an operation for moving the robot arm based on the
calculated result, are repeated starting from the finally acquired
ultrasound image at the first step so that the ultrasound probe is
moved to in a parallel position to the center line of the blood
vessel; a third step wherein a series of operations comprising an
operation for acquiring ultrasound image, an operation for
processing and calculating the acquired ultrasound image and an
operation for moving the robot arm based on the calculated result,
are repeated starting from the finally acquired ultrasound image at
the second step so that the ultrasound probe is moved to a position
where the ultrasound probe is in parallel to and immediately above
the center line of the blood vessel; and a fourth step wherein a
blood vessel diameter is determined from the finally acquired
ultrasound image at the third step.
[0012] (2) The method according to (1), wherein: the center of
gravity of a color Doppler signal area in the acquired ultrasound
image is recognized as the center of the blood vessel.
[0013] (3) The method according to (1), wherein: a distance between
two boundaries determined such that a certain width along X-axis of
the acquired ultrasound image is extracted, in the extracted width
gradient of image energy defined as accumulated brightness in the
perpendicular direction to the X-axis, is examined and two maximum
point in the gradient are determined as the boundaries and the
determined distance is determined as the blood vessel diameter.
[0014] (4) The method according to (1), wherein: the robot arm is
controlled by two moving degrees of freedom and one rotating degree
of freedom.
[0015] (5) The method according to (1), wherein: the robot arm is
moved and controlled along the X-axis direction in the first
step.
[0016] (6) The method according to (1), wherein: the robot arm is
rotated and controlled around the Z-axis in the second step.
[0017] (7) The method according to (1), wherein: the robot arm is
moved and controlled along the X-axis direction in the third
step.
[0018] (8) The method according to (1), wherein the second and the
steps respectively further comprise steps of: any one of the
ultrasound images acquired during a series of operations is divided
by a predetermined width in the X-axis direction into a plurality
of segments; a blood vessel diameter in each divided segment is
determined; a median value is selected among determined blood
vessel diameters; the number of determined blood vessel diameters
which fall into a certain range centered by the median value, is
calculated; a score value is calculated by dividing the calculated
number by the total number of the divided segments; score values
calculated from respective series of acquired ultrasound images are
compared; and a position having a maximum score value is judged as
an optimum position of the ultrasound probe in the second step or
the third step.
[0019] (9) The method according to (1), wherein: a changing passage
after the blood vessel is dilated, is tracked on a real-time
basis.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a block diagram illustrating a rough arrangement
of an automatic examination system for measuring the vascular
endothelium function.
[0021] FIG. 2 is a schematic view illustrating functions of a robot
arm for holding, moving and rotating an ultrasound probe.
[0022] FIG. 3 is an ultrasound image for explaining a determining
method of a blood vessel diameter.
[0023] FIG. 4 is an ultrasound image together with determined blood
vessel diameters.
[0024] FIG. 5 is a schematic diagram illustrating relations between
positions of the ultrasound probe and corresponding acquired images
by the ultrasound probe.
[0025] FIGS. 6A to 6C are schematic diagrams illustrating a series
of navigating procedures of the ultrasound probe, where FIG. 6A
shows a procedure for determining the center line of the blood
vessel, FIG. 6B shows a procedure for positioning the ultrasound
probe in parallel to the center line of the blood vessel and FIG.
6C shows a procedure for positioning the ultrasound probe in
parallel to and immediately above the center line of the blood
vessel.
[0026] FIG. 7 is a diagram illustrating relations between revolving
angles of the ultrasound probe around Z-axis and corresponding
score values for positioning depicted in FIG. 6B.
[0027] FIG. 8 is a diagram illustrating relations between positions
of the ultrasound probe along X-axis and corresponding score values
for positioning depicted in FIG. 6C.
[0028] FIG. 9 is a diagram for comparing manual and automatic
dilations in respect to blood vessel diameter changes as the
passage of time.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0029] Hereinafter an embodiment according to the present invention
is explained in detail by referring to drawings.
[0030] FIG. 1 is the block diagram illustrating the rough
arrangement of the automatic examination system for measuring the
vascular endothelium function, where the measuring system comprises
three sub-systems, namely, a measuring system, an image processing
and calculating system and a navigating system. The measuring
system comprising an ultrasound diagnostic apparatus, an ultrasound
probe attached to the ultrasound diagnostic apparatus, acquires
ultrasound images. The image processing and calculating system
comprising a computer, an image processing board, processes the
acquired images by the measuring system, and calculates values to
control a motor for driving the robot arm (which will be described
hereinafter) based on the processed results. The navigating system
comprises the robot arm which holds the ultrasound probe for
scanning and for determining positions of the ultrasound probe.
[0031] FIG. 2 schematically illustrates an arrangement of the robot
arm. The robot arm has two degrees of rotating freedom and two
degrees of parallel moving freedom as shown in Table 1 so as to
scan and hold the ultrasound probe at optimum positions for
acquiring ultrasound images to determine blood vessel diameters,
which will be explained below. More specifically, the robot arm
equipped with the ultrasound probe is brought to a subject portion
to be probed (an arm of the subject) and adjusted its position by
controlling within the following four degrees of rotating/moving
freedom: a degree of rotating freedom around Y-axis
(.quadrature.45.degree..quadrature..quadrature.45.degree.) for
determining a rough position of the ultrasound probe manually; a
degree of moving freedom along Z-axis for laying the center of an
ultrasound image on the center of a blood vessel and a degree of
moving freedom along X-axis and a degree of rotating freedom around
Z-axis for guiding the ultrasound probe to the optimum position to
acquire a proper image for determining the blood vessel diameter.
Automatically controlled degrees of moving freedom along X-axis and
Z-axis are set between .quadrature.20 mm and .quadrature.20 mm,
since the ultrasound probe is scanned in an image frame having a
range of 40 mm by 40 mm. The automatically controlled degree of
rotating freedom around Z-axis is set from 70.degree. to
110.degree. in accordance with the other degrees of freedom. Since
the size of a pixel of the acquired ultrasound image is enlarged up
to 0.05 mm, respective spatial resolutions of moving freedom along
X-axis and Z-axis are set {fraction (1/20)} of the size of the
pixel, namely 0.002 mm. A resolution of the rotating freedom around
Z-axis is set 0.1.degree. in accordance with the above-mentioned
resolutions of moving freedom.
[0032] Ranges of strokes of the robot arm shown in Table 1 are one
of examples and not limited in these ranges.
1TABLE 1 Specification of Robot Arm Degree of Stroke Controlled
Freedom Range Resolution Manually Y-axis .quadrature.45.degree.
Rotation .quadrature. .quadrature.45.degree. -- Automatically
X-axis .quadrature.20 mm .quadrature. Movement .quadrature.
.quadrature.20 mm 0.002 mm Z-axis .quadrature.20 mm .quadrature.
Movement .quadrature. .quadrature.20 mm 0.002 mm Z-axis 70.degree.
.quadrature. Rotation .quadrature.110.degree. 0.1.degree.
[0033] Further, a 6-axe force sensor is arranged in the robot arm
for sensing a contact pressure of the ultrasound probe against a
subject (an arm) so as to keep the contact pressure at a constant
level.
[0034] Hereinafter a procedure to determine the blood vessel
diameters by processing acquired images with the aid of a computer
is described.
[0035] A distance between two boundaries formed by a upper/lower
vascular wall and a upper/lower vascular lumen is determined from
the acquired ultrasound image of the blood vessel in the
longitudinal direction as the blood vessel diameter. However, it
has been well known that reproducibility of the determined results
is poor when extracted boundaries are processed by an ordinarily
used edge detecting algorithm, since in the acquired ultrasound
image, density of the recognized vascular wall along the
longitudinal direction fluctuates irregularly. In the present
invention, based on our observed fact that a vascular wall image
shows a gradual curve approximating to a straight line, a method
for approximating the vascular walls to a plurality of line
segments having a predetermined width (line segment method) is
employed. In this method, accumulated brightness of pixels existing
in a line segment of width "d" along X-axis is defined as image
energy and gradient of the image energy is examined in a direction
from the center of the vascular lumen to the vascular wall as shown
in FIG. 3. A position where the image energy reaches to a threshold
value, is defied as a boundary between a vascular lumen and a
vascular wall. In FIG. 3, two image energy peaks (which are seen
near scale marks 100 and 200 on Y coordinate) are determined as the
boundaries. A processed ultrasound image by utilizing the line
segment method is depicted in FIG. 4.
[0036] Numerals in square (.quadrature.) at upper portion of FIG. 4
indicate respective vascular diameters expressed in the number of
pixels in respective areas 1 to 10 surrounded by circle
(.smallcircle.). These numerals (the number of pixels) distribute
around 64. Since some numerals (which are apparently considered to
be error) apart from other remaining numerals are sometimes
recognized, a median numeral is selected as a determined blood
vessel diameter so as to avoid influences owing to the
above-mentioned numerals considered to be error. The selected
median numeral "65" is shown in the square (.quadrature.) at the
lower portion of FIG. 4.
[0037] In order to acquire an ultrasound image showing vivid
vascular walls proper for determining the blood vessel diameter,
the ultrasound probe and the blood vessel should be set at proper
positions each other. For that purpose, the ultrasound probe is
finally brought to an optimum position starting from rough
positioning to fine positioning based on determined blood vessel
diameters in the above-mentioned way by processing ultrasound
images acquired stepwise by moving/rotating the robot arm within
the above-described degrees of moving/rotating freedom.
Hereinafter, a positioning procedure for determining the optimum
position of the ultrasound probe is described.
[0038] Case 1 in FIG. 5 shows a state where the ultrasound probe is
properly positioned, namely the probe is positioned parallel to and
immediately above the center line of a blood vessel. In this case,
an accurate blood vessel diameter D.sub.0 is observed as shown in
FIG. 5. In case 2 where the ultrasound probe is rotated in a
certain angle from the center line of the blood vessel, the
accurate value D.sub.0 is observed only at a portion which is
immediately above the center line. And observed diameters of other
portions indicate the smaller than the accurate diameter, the
further apart from the center line. In case 3 where the ultrasound
probe is positioned parallel to but not immediately above the
center line, the observed diameter D.sub.1 is smaller than the
accurate value D.sub.0. From the observed facts mentioned above,
only when the ultrasound probe is positioned parallel to and
immediately above the center line of the blood vessel, observed
diameters indicate maximum value D.sub.0, which can be employed as
the accurate diameter.
[0039] The ultrasound probe is led to an optimum position
corresponding to case 1 in FIG. 5 via three steps of automatic
navigating procedures, depicted in FIGS. 6A, 6B and 6C.
[0040] Before executing the above-mentioned automatic navigating
procedures, the ultrasound probe is moved manually to a position
where an ultrasound image in the minor axis direction (namely a
cross-sectional image perpendicular to the center line) can be
acquired. After the ultrasound image is acquired in the
above-mentioned way, the ultrasound prove is moved automatically
along X-axis such that the center of the blood vessel is brought to
the center of the ultrasound image in accordance with the automatic
navigation procedure depicted in FIG. 6A. Here the center of
gravity of a color Doppler signal area corresponding to a blood
flowing area is recognized as the center of the blood vessel.
[0041] After the center of the blood vessel is brought to the
center of the ultrasound image, the robot arm is rotated angle by
angle with a predetermined pitch around Z-axis as shown in FIG. 6B
and ultrasound images at respective rotated angles are acquired.
The acquired ultrasound images are examined after processed, and a
position where a most suitable ultrasound image in the major axis
(namely in the parallel direction to the center axis of the blood
vessel) for obtaining the blood vessel diameter, is determined.
[0042] Whether the ultrasound probe is moved to the optimum
position or not is judged by the facts explained in cases 2 and 3
of FIG. 5 that the observed blood vessel diameter indicates smaller
value than the accurate diameter when the ultrasound probe deviated
from the center of the blood vessel. Based on acquired ultrasound
images, a score value for each rotated angle is calculated
according to the following equation and a rotated angle having a
maximum score value is determined as the optimum position.
Score value (%)=n/N.times.100.
[0043] In the above equation, n is the number of blood vessel
diameters having pixel number falling into a range of the median
value .+-.1 at a certain rotated angle. In the example shown in
FIG. 4, n, namely the number of blood vessel diameters having pixel
number 65.+-.1, happened to be 7. N is the total number of blood
vessel diameters (line segments) at the same rotated angle and
happens to be 10 in the example of FIG. 4. Therefore the score
value of this example is determined as {fraction (7/10)}, namely
70%.
[0044] In the above mentioned way score values are calculated and
an example of a relation between the score value and the rotated
angle is depicted in FIG. 7. In this example a score value at a
rotated angle of 12.degree. indicates a maximum value, which is
judged as the optimum position of the ultrasound probe.
[0045] The ultrasound probe is moved to a parallel position to the
center line of the blood vessel by the navigating procedure shown
in FIG. 6B, but the ultrasound probe is positioned not always
immediately above the center line. Accordingly, the robot arm is
moved pitch by pitch with a predetermined distance along X-axis as
shown in FIG. 6C and an ultrasound image at each moved angle is
acquired. The optimum position of the ultrasound probe is
determined in the same way as in the case of procedure depicted in
FIG. 6B.
[0046] FIG. 8 shows an example of a relation between calculated
score values and displacements from a reference point, when the
ultrasound probe is moved pitch by pitch with a distance of 0.05
mm. In this example a score value at a displacement value of
.quadrature.0.05 indicates a maximum value, which is determined as
the optimum point of the ultrasound probe.
[0047] The blood vessel diameters and FMD (Flow Mediated Dilation)
values are determined by applying the above-described procedures to
three subjects (A, B and C; each is healthy person in their
twenties).
[0048] [Determination of Blood Vessel Diameter]
[0049] In order to prove reproducibility of the above-mentioned
determining procedure, 10 determining procedures are carried out in
one subject. In each determining procedure, an initial position and
an initial angle of the ultrasound probe are varied. Manual
determining procedures are also carried out in subject B in order
to compare with automatic procedures by the present invention. An
average blood vessel diameter (in mm), a score value (in %), a
maximum error (in mm) and a standard deviation (in mm) calculated
from 10 determining procedures for each subject, and corresponding
data by the manual procedure are shown in Table 2.
2TABLE 2 Determined Blood Vessel Diameter Manual Automatic
Procedure Procedure A B C B Average 3.53 3.42 3.87 3.71 Diameter
(mm) Average 77.8 55.9 44.0 38 Score Value (%) Maximum 0.06 0.06
0.08 0.2 Error (mm) Standard 0.04 0.03 0.04 0.14 Deviation (mm)
[0050] From Table 2, it is evident that a determining precision of
the automatic procedure is much improved compared with that of the
manual procedure, since maximum errors and standard deviations of
the automatic procedure are reduced to a large extent.
[0051] [Determination of FMD Value]
[0052] In an examination procedure of the vascular endothelium
function, after a blood vessel diameter "d" at rest is determined,
a lower portion of the arm is avascularized for 5 minutes by
applying 250 mmHg of pressure with a cuff around the arm and
released so as to generate a vascular dilating reaction caused by
blood flow. During a recovering period of the avascularized arm, a
maximum blood vessel diameter d.sub.max is determined and the FMD
value defined in the following equation is calculated so as to
employ as an index for the arterial sclerosis.
FMD value(%)=(d.sub.max.quadrature.d).times.100/d
[0053] In FIG. 9, blood vessel diameters during the recovering
period determined by the automatic procedure are plotted in
relation the passage of time together with diameters determined by
manual procedure. The FMD value is determined in about 2 minute by
the automatic procedure on the real time basis in the case shown in
FIG. 9. On the other hand, in the manual procedure, it takes about
30 minutes for even a skilled person to determine the FMD value.
Consequently, it is obvious that rapid determination of the FMD
value is attained by employing the automatic procedure according to
the present invention. Determined blood vessel diameters at rest,
maximum blood vessel diameters and FMD values of respective
subjects A, B and C are shown in Table 3.
3TABLE 3 Probed Results of Vascular Endothelium Subject Subject
Subject A B C Diameter at 3.48 3.31 3.87 rest (mm) Diameter in 3.86
3.64 4.23 Dilation (mm) FMD value 11.0 10.1 9.4 (%)
[0054] Since two FMD values of out of three subjects in TABLE 3
fall into a range from 9.8 to 11.5%, which Hashimoto et al. (the
same people referred in the section of "Brief Description of the
Related Art") of the medical department of the university of Tokyo,
obtained manually from 17 subjects in their twenties. Therefore the
automatically determined FMD values mentioned above are considered
to be medically proper compared with manually determined
values.
[0055] As described above, when the examination method of vascular
endothelium function by the present invention is employed, the FMD
value for employing as the index of the arterial sclerosis can be
determined more accurately and rapidly, which were not attained by
conventional manual methods. Consequently, the examination method
by the present invention can detect the arterial sclerosis (which
has been increasing as diets among Japanese people have been
varied) much earlier than conventional manual methods.
[0056] As explained above, the optimum ultrasound image is obtained
and the blood vessel diameter is determined rapidly with good
reproducibility by the present invention such that the acquired
ultrasound images by the ultrasound probe are analyzed by the
computer and then the robot arm which holds the ultrasound probe is
controlled by the analyzed results of the ultrasound images. The
arterial sclerosis can be detected much earlier when the rapid
determining procedure of the blood vessel diameter by the present
invention is employed.
* * * * *