JP3283375B2 - Evaluation device for osteoporosis by ultrasound - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Industrial applications]

The present invention relates to an apparatus for evaluating the progress of osteoporosis using ultrasound.

[0002]

2. Description of the Related Art With the increase in the aging population, the rapid increase in the number of illnesses called osteoporosis, which tend to cause fractures in ordinary daily life, has become a major problem in the medical field. Osteoporosis is a disease in which components such as bone calcium decrease and bone loss occurs, and cracks and breakage due to reduced strength are likely to occur.
It is said that about 30% of those aged 0 and over, and about 10% of men, fall under this category. If osteoporosis is discovered early, various treatments can effectively prevent the progression of osteoporosis, so early detection by periodic examination is important. For this reason, conventionally, bone mineral content (BMC) by radiography (X-ray) radiation or gamma radiation
The measurement predicted and evaluated the degree of osteoporosis progression.

[0003] However, radiation is extremely harmful to living organisms, and is intended for people aged 50 to 60 years or older, who are expected to have a high possibility of osteoporosis, and women who have closed their diameters. The evaluation took risks.
Therefore, an apparatus for evaluating osteoporosis using ultrasound which is harmless to the human body has been proposed.

For example, it has been proposed to determine the sound velocity and attenuation rate inside a bone from a received signal transmitted by transmitting an ultrasonic wave to a patient (subject) and use these as evaluation indexes for a bone disease state. (For example, JP-A-1-503199, JP-A-2-1-1)
04337, Tokuyohei 4-541519, etc.). However, as shown in FIG. 15, the ordinate takes an index called stiffness calculated by computer from information obtained by transmission of ultrasonic waves, while the abscissa takes age. Draw an average curve of a healthy person, and plot the measurement results of the patient (subject) on the average curve, and how far the patient (subject) is from the healthy person As a result, it was determined whether the patient (subject) was in a normal condition, a condition requiring caution, or a condition in which treatment had to be started immediately.

[0005]

However, from the viewpoint of the patient (subject), what is displayed on the computer screen is exactly how far away from the reference curve shown by a healthy person is. Even though they could understand whether or not the condition was linked to the degree of progression of the osteoporosis disease, they could not easily understand the explanations given by doctors and public health nurses. Therefore, the present invention enables a patient (subject) himself to recognize the progress of osteoporosis at a glance from his / her computer screen. Subject)
In contrast, an object of the present invention is to provide an osteoporosis evaluation device provided with a computer screen displaying bone internal information which makes it easy to easily explain the progress of osteoporosis.

[0006]

Means for Solving the Problems The present invention utilizes the fact that the speed at which ultrasonic waves propagate between bone (solid) and bone marrow (liquid) in hard tissue differs greatly, and the length ratio of solid and liquid The area ratio of the portion occupied by the bone is determined from the measurement in at least two perpendicular directions, or the measurement at two or more positions on the same surface (the position has been moved as when ironing). (Cancellous bone) An equivalent cancellous bone shape is displayed based on a quantification (trabecular area area ratio) parameter representing a feature of the shape. That is, when osteoporosis is evaluated using ultrasonic waves, the ultrasonic waves are transmitted to the calcaneus or patella of the subject, and the transmission propagation speed inside the bones is determined. Next, the trabecular area ratio is calculated from the trabecular density of the cancellous bone inside the bone by a predetermined calculation formula from the obtained propagation velocity. Next, using the fractal dimension corresponding to the trabecular bone density, a drawing is performed to satisfy the trabecular area ratio using a predetermined drawing program by a computer. The progress of osteoporosis is evaluated by comparing the drawn image with images of at least the cancellous bone of healthy subjects of at least the same sex and age of males and females. To explain the above in more detail, the present invention
It has the following first to fifth features. First, use ultrasound
Ultrasound to assess the progress of osteoporosis
Is transmitted to the subject's calcaneus or patella,
The seeding speed is determined, and then from the determined propagation speed,
From the trabecular density of the cancellous bone inside the bone,
Calculate the trabecular area ratio and use a computer
Use a drawing program to create a plot that meets this trabecular area ratio.
Perform a diagram, and at least the gender of the gender,
Compare the image of the cancellous bone of a healthy person with almost the same age.
The progress of osteoporosis was evaluated by comparison.

(Equation 1) Eu (trabecular bone linear density) = (1 / Vb-1 / Vc) / (1 /
Va-1 / Vc) --- (Formula 1) Here, Vb: ultrasonic propagation speed in bone Va: Ultrasonic bone marrow propagation velocity (1500 m / s) Vc: Ultrasonic bone material propagation velocity (3000 m / s)

(Equation 2) Au (trabecular area ratio) = Eu × Eu (2nd formula) Second, when evaluating osteoporosis using ultrasound
Ultrasound is transmitted to the subject's calcaneus or patella,
The transmission propagation velocity of the part is determined and then the determined propagation
From the speed, the trabecular bone of the cancellous bone inside the bone by the following formula
The trabecular area ratio is calculated from the linear density
Using the fractal dimension corresponding to
This trabecular area ratio is calculated using a predetermined drawing program
Make a satisfactory drawing and at least a man with this drawn image
The bone and cancellous bone of a healthy person whose female gender and age are almost the same
I will evaluate the progress of osteoporosis by comparing with the image
Caught.

(Equation 3) Eu (trabecular bone linear density) = (1 / Vb-1 / Vc) / (1 /
Va-1 / Vc) --- (Formula 1) Here, Vb: ultrasonic propagation speed in bone Va: Ultrasonic bone marrow propagation velocity (1500 m / s) Vc: Ultrasonic bone material propagation velocity (3000 m / s)

(Equation 4) Au (trabecular area ratio) = Eu × Eu (2nd formula) Third, when evaluating osteoporosis using ultrasound
Ultrasound is transmitted to the subject's calcaneus or patella,
The transmission propagation velocity of the part is determined and then the determined propagation
From the speed, the trabecular bone of the cancellous bone inside the bone by the following formula
Calculate trabecular area ratio from linear density and computer
This trabecular area ratio is calculated using a predetermined drawing program
Perform a satisfactory drawing, and use the fractal dimension
, On the other hand, the trabecular bone of natural bone (human bone)
Find the relationship between the area ratio and the fractal dimension, and
Engagement, trabecular area ratio and fractal dimension of the subject
Check that both the trabecular area ratio and the fractal dimension are almost the same.
If they match, a predetermined drawing program by the computer
The image displayed using the ram is a picture of the cancellous bone of the subject's bone.
Statue, and this certified image and at least gender sex
Separately, images of cancellous bones of healthy subjects with almost the same age
To evaluate the progress of osteoporosis
Was.

(Equation 5) Eu (trabecular bone linear density) = (1 / Vb-1 / Vc) / (1 /
Va-1 / Vc) --- (Formula 1) Here, Vb: ultrasonic propagation speed in bone Va: Ultrasonic bone marrow propagation velocity (1500 m / s) Vc: Ultrasonic bone material propagation velocity (3000 m / s)

(Equation 6) Au (trabecular area ratio) = Eu × Eu (2nd formula) Fourth, when evaluating osteoporosis using ultrasound
The ultrasound is transmitted to the subject's calcaneus and transmitted through the bone.
The seeding speed is determined, and then from the determined propagation speed,
Use the following formula to calculate the trabecular density of the cancellous bone inside the bone.
And calculate the trabecular line density
The trabecular area ratio is determined, and then the equivalent trabecular area ratio is calculated.
Computer image and display this image at least for both men and women.
Compared to the bone image of a healthy subject with almost the same gender and age.
The part where the trabecular bone of the subject is reduced is displayed in different colors.
Was.

(Equation 7) Eu (trabecular bone linear density) = (1 / Vb-1 / Vc) / (1 /
Va-1 / Vc) --- (Formula 1) Fifth, when evaluating osteoporosis using ultrasound
Ultrasound is applied to the subject's patella approximately horizontally and
Transmitting in two directions that are almost perpendicular to each other,
Respectively, and then from this determined propagation velocity,
Use the following formula to calculate the trabecular density of the cancellous bone inside the bone.
And calculate the calculated trabecular density
To calculate the trabecular area ratio, and then
Display valuable computer images and at least
Gender images of healthy men and women with almost the same gender and age
In comparison, the part where the trabecular bone of the subject is reduced
Indicated.

(Equation 8) Eu (trabecular bone linear density) = (1 / Vb-1 / Vc) / (1 /
Va-1 / Vc) --- (Formula 1)

[0007]

First, when evaluating the progress of osteoporosis in a human, for example, an ultrasonic probe composed of a pair of transmitting and receiving heels is applied to the calcaneus, and the propagation time transmitted through the inside of the bone is measured. Next, a propagation velocity is calculated from the measured propagation time, and a computer processing is performed by a predetermined calculation formula based on the data of the ultrasonic propagation velocity, and a graphic equivalent to the shape of the cancellous bone in the calcaneus is displayed on the computer display screen. To This display image is displayed in a different color from that of an average healthy person, for example, by turning only the thinned bones red. On the other hand, when the treatment is started after being evaluated as osteoporosis, and the effect of the treatment gradually appears, only the increased portion of the trabecular bone is changed to blue by color coding. By visually recognizing the color-coded region, the patient (subject) can specifically grasp the progress of the disease and, conversely, the effect of the treatment.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an example of an apparatus for carrying out the present invention.
OM, computer body including RAM, 2 is CRT as display, 3 is printer, 4 is KEY for input
A board 5 is a measuring unit provided with a footrest on which a subject's foot is placed and an ultrasonic probe connected to an ultrasonic transmitter / receiver, and 6 is an FD device of an external storage device.

FIG. 2 shows an electric circuit diagram of a connection relationship between a measuring unit including an ultrasonic probe connected to an ultrasonic transmitter / receiver and a computer. The ultrasonic probes 5a and 5b are relays, respectively. It is connected to an ultrasonic transceiver 8 via a substrate 7. The electric pulse signal from the ultrasonic probe 5a is converted into an ultrasonic signal by the piezoelectric element and transmitted to the ultrasonic probe 5b. The ultrasonic probe 5b converts the ultrasonic signal into an electric signal again by the piezoelectric element. The ultrasonic transceiver 8 is connected to an A / D converter 11 via a filter 9 and an amplifier 10. The filter 9 removes a low frequency component and a high frequency component from an RF signal of the ultrasonic transceiver 8, and an amplifier. The A / D converter 11 converts the signal from the amplifier 10 into a digital signal and sends the data to the CPU of the computer 1. Further, the CPU of the computer main body 1 performs arithmetic processing based on the signal from the ultrasonic transceiver 8 to estimate the trabecular area ratio and the trabecular shape of the cancellous bone. Furthermore, the ultrasonic transceiver 8 is connected to a CPU of the computer main body 1, while the CPU is connected to the CRT 2, the printer 3, and the FDD.
It is also connected to the device 6, and outputs the result of the arithmetic processing to these devices, and stores and holds the result.

FIG. 3 shows the appearance of a main part of the measuring section 5 having an ultrasonic probe connected to an ultrasonic transceiver. The footrest 21 is bent in a substantially right angle direction and includes a surface 21a for supporting the sole and a surface 21b for supporting the leg, and is fixed to the base 22. The ultrasonic probe 5a is fixed to the side of the base 22, while the other ultrasonic probe 5b
Is loosely attached to a groove 22a provided in the base 22, and a handle 23
Is mounted so as to be movable in the horizontal direction along the groove 22a. In FIG. 4, a thin cylindrical cylindrical cassette 30 is loaded with water and gel-like liquid in a synthetic resin film-like storage bag 31 and fixed in a laterally protruding spherical state. Have been. The cassette 30 is screwed to the outer peripheral surface of the head of the ultrasonic probes 5a and 5b.
Note that a pad made of silicon may be attached instead of the bag 31 containing water or the like.

Now, when measuring by ultrasonic waves to evaluate osteoporosis, first, as shown in FIG. 5, when the subject's foot is placed on the footrest 21 of the measuring section 5, the heel becomes extremely high. It hits the side surface of the storage bag 31 of the cassette 30 screwed to the acoustic probe 5a. Next, the other ultrasonic probe 5b is
When it is moved in the lateral direction by the operation of 3, the storage bag 31 of the cassette 30 screwed to the ultrasonic probe 5b hits the other side surface of the heel, and the heel is just sandwiched. Here, ultrasonic waves are transmitted from the ultrasonic probe 5a and received by the other ultrasonic probe 5b. The signal of the ultrasonic probe 5b is sent to the ultrasonic transmitter / receiver 8 via the relay board 7 as shown in FIG. 2, and here, the time during which the ultrasonic wave passes through the inside of the bone is measured. Next, the signal from the ultrasonic transceiver 8 is transmitted to the filter 9, the amplifier 10, and the A / D converter 11.
It is sent to the computer main body 1 through the. In the computer main body 1, since the distance between the ultrasonic probes 5a and 5b is known in advance, the propagation speed of the ultrasonic wave transmitting through the inside of the bone is calculated from the measured transmission time of the ultrasonic wave.

The trabecular bone density is calculated from the calculated propagation velocity by the following equation.

## EQU9 ## Eu (trabecular bone linear density) = (1 / Vb-1 / Vc) / (1 /
Va-1 / Vc) --- (Formula 1) where Vb: Ultrasonic bone bone velocity Va: Ultrasonic bone marrow propagation velocity (1500 m / s) Vc: Ultrasonic bone bone propagation velocity (3000 m / s) The trabecular bone density refers to the ratio of a portion containing bone (solid) to bone marrow (liquid) and bone (solid) in a one-dimensional (longitudinal) direction. That is, in general, the heel and knee are composed of soft tissue (skin and flesh) and hard tissue (bone), and the hard tissue (bone) is composed of cortical bone and cancellous bone (trabecular bone). And bone marrow) and bone marrow (liquid)
People. Since the ultrasonic waves are actually transmitted through the entire heel (the solid part and the liquid part), the ultrasonic velocity means the average velocity of the ultrasonic waves. By the way, the heel bone because cancellous bone accounts for the almost 95%, osteoporosis from the first place that appears in the cancellous bone, is in the evaluation is the site of the optimum. Next, the trabecular area ratio is determined from the determined trabecular linear density. Au (trabecular area ratio) = Eu × Eu (2nd expression) Here, the trabecular area ratio includes the bone (solid) portion of bone (solid) and bone marrow (liquid) in a certain area. Say percentage. This is for calculating the data measured by the ultrasonic wave using a computer and displaying the data as internal information of a bone in a two-dimensional (planar) image.

FIG. 6 shows an example in which the ultrasonic measuring unit is a knee instead of the heel shown in FIG.
In this case, the measurement is performed by applying the pair of ultrasonic probes 5a and 5b in a horizontal direction (XX direction) and a vertical direction (YY direction) perpendicular to the horizontal direction. From the obtained ultrasonic wave propagation velocity, the trabecular bone density (Eu) is obtained in the X direction and the Y direction, respectively, by the above-described first calculation formula. Next, the trabecular bone area ratio (trabecular bone surface density) is calculated from the trabecular bone density. Au (trabecular area ratio) = Eux * Euy (3rd formula)

Next, a drawing that satisfies the above trabecular area ratio is performed using a predetermined drawing program by a computer, and a fractal dimension is obtained from the drawn image. That is, the geometric pattern of the cancellous bone inside the bone is two-dimensional (planar).
In the following, a method for artificially drawing the shape will be described.
First, the first square to be based (eg, 240 * 240
Pixel), and P * Q elliptical pilot holes are made in it.
Here, the center coordinates of the prepared hole were points on a staggered lattice as shown in FIG. This is to eliminate extreme trabecular thickness variations in the final cancellous bone image. next,
By generating n osteoclasts grown in m stages on the surface of the bone, the shape of the cancellous bone is considered to be approximated. That is, it is assumed that an elliptical hole smaller than the base pilot hole is drilled around a position slightly eccentric from the center coordinate of the pilot hole, and the black portion is broken as shown in FIG. In FIG. 8, the hatched portion represents the trabecular bone portion). At this time, the size and number of pilot holes, or m, n
The fractal dimension is affected by the value of. FIG. 9 shows the trabecular shape of the cancellous bone that has been artificially processed in this manner (in this figure, the hatched portion represents the bone marrow, while the white portion represents the trabecular bone). Next, the relationship between the trabecular area ratio (apparent density) of cancellous bone and the fractal dimension obtained by the artificial construction diagram is shown in FIG.
A.

[0015] On the other hand, our Ku seeking the relationship between the trabecular bone area ratio and the fractal dimension of cancellous bone of separately beforehand natural bone (human bones). That is, when the geometric pattern of the cancellous bone of natural bone (human bone) is viewed two-dimensionally (in a plane) and the trabecular area ratio is arranged in fractal dimension, the fractal dimension is taken on the vertical axis, while the horizontal direction is taken. Taking the trabecular area ratio on the axis, all the cancellous bones overlap on one curve as shown in FIG. 10B. As a result, the following approximate expression could be expressed between the trabecular area ratio S and the fractal dimension D. D = 1 + S to the power of 0.4 (where S: trabecular area ratio) --- (Formula 4)

The fractal dimension and the trabecular area ratio obtained by this relational expression are compared with the trabecular area ratio and the fractal dimension of the subject, and if both the trabecular area ratio and the fractal dimension substantially match. Then, the image displayed using the predetermined drawing program by the computer (see FIG. 9) is recognized as the image of the cancellous bone of the subject. That is, comparing the actual shape of the cancellous bone and the shape of the cancellous bone by drawing, when the trabecular area ratio and the fractal dimension are almost the same,
This is because the two figures are very similar figures. Therefore, considering that the shape of the trabecular bone drawn by a computer represents one of the shapes of the trabecular bone that represents this trabecular bone area ratio, the trabecular bone area ratio is determined by ultrasonic measurement or the like. By obtaining the fractal dimension, a figure representing the shape of the cancellous bone at that trabecular area ratio can be derived.

The progress of osteoporosis was evaluated by comparing the images identified as described above with images of cancellous bones of bones of healthy subjects having at least substantially the same sex and age of men and women. That is, information on cancellous bone according to the age of healthy men and women is prepared in advance as standard data, and this data is stored in the ROM of the computer body 1 (FIG. 1).
1). Here, instead of the data for each age, information indicating the ratio of the trabecular area ratio stepwise may be prepared as standard data (see FIG. 12). 11 and FIG.
2, the white part represents the bone marrow, while the black part represents the trabecular bone.

Evaluation Example 1 The subject is a 65-year-old woman, and the measured ultrasonic propagation velocity is 1
It was 680 m / s. The trabecular area ratio at this time is calculated by the above-described first and second formulas by the computer main body 1 to be 21.5%, and the fractal dimension at this time is 1.54 by the fourth formula. Was. On the other hand, the ultrasonic propagation velocity and trabecular area ratio of a 65-year-old healthy woman were 1790 m / s and 27%, respectively, and the fractal dimension was 1.59. A computer image of the cancellous bone of the subject's calcaneus is shown in FIG. 13A, while that of a healthy person is shown in FIG. 13B. The images of both the subject and the healthy subject are displayed on the same display screen, and the image of the subject is compared with the image of the healthy subject, in which the portion where the trabecular bone is reduced is color-coded (in the figure, Part painted black)
This subject was evaluated as having advanced osteoporosis (in FIG. 13, the white portion represents trabecular bone and the hatched portion represents bone marrow). Evaluation Example 2 FIG. 14 shows an example in which a patient evaluated as osteoporosis has started treatment for one year. FIG. 14A shows the result of one year ago, FIG. 14B shows the result of six months ago, and FIG. 14C shows an example of the case of the current measurement. Compared to the first one, the increased portion of the trabecular bone is color-coded (in the figure, the portion painted black), so that the effect of the treatment can be immediately determined (FIG. 14).
The white part represents the trabecular bone and the shaded part represents the bone marrow.)

As described above, according to the present invention, ultrasonic waves are transmitted to the calcaneus or patella to determine the permeation propagation speed inside the bone, and based on this propagation speed information, the computer is operated to process the sponge inside the bone. Although the example of the image of the bone is displayed, the present invention is not limited to this example. Instead of the propagation speed of the ultrasonic wave, the present invention uses a computer to calculate the transmission attenuation rate information of the amplitude of the ultrasonic wave. Display the image of the cancellous bone inside the bone by processing, or perform a computer operation based on the information considering both the transmission speed of the ultrasonic wave and the attenuation rate of the transmitted amplitude, and perform the calculation processing by the computer. Of course, it can also be applied to the image display of cancellous bone.

[0020]

As described above, according to the present invention, a subject can display an image displaying the state of the geometrical pattern of the cancellous bone of his own bone, which has been processed by a computer from data obtained by ultrasonic measurement, and a healthy subject. Compared with the bone image of the osteoporosis, the trabecular bone reduction is displayed in different colors, so you can grasp the progress of osteoporosis with your own eyes, and evaluate the osteoporosis However, since the treatment is started and the portion where the trabecular bone has increased due to the temporal change is displayed in different colors, the effect of the treatment can be recognized at a glance.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of an apparatus for evaluating osteoporosis embodying the present invention.

FIG. 2 is an explanatory diagram showing a configuration of an electric circuit of the device shown in FIG.

FIG. 3 is a schematic perspective view of a measuring unit provided with an ultrasonic probe.

FIG. 4 is a cross-sectional view of a main part showing a relationship between an ultrasonic probe and a storage bag.

FIG. 5 is an explanatory diagram of a case where ultrasonic waves are transmitted to the calcaneus for measurement.

FIG. 6 is an explanatory diagram of a case where ultrasonic waves are transmitted to the patella for measurement.

FIG. 7 is an explanatory diagram in the case of drawing a shape of cancellous bone with computer assistance.

FIG. 8 is an explanatory diagram in the case of drawing a shape of cancellous bone with computer assistance.

FIG. 9 is an explanatory diagram showing the shape of cancellous bone artificially drawn by computer assistance.

FIG. 10 is a graph showing the relationship between the trabecular area ratio of cancellous bone and the fractal dimension.

FIG. 11 is an explanatory view showing a planar shape of cancellous bone according to the age of a healthy person.

FIG. 12 is an explanatory diagram showing the ratio of the trabecular bone area ratio of cancellous bone in a stepwise manner.

FIG. 13 is an explanatory diagram showing a trabecular area ratio of cancellous bone of a subject and a trabecular area ratio of cancellous bone of a healthy subject.

FIG. 14 is an explanatory diagram showing a change over time in the trabecular area ratio of cancellous bone of the same person.

FIG. 15 is an explanatory diagram of evaluation results used for conventional ultrasonic evaluation.

[Description of Signs] 1 Computer main body 2 CRT 5 Ultrasonic measuring unit 5a, 5b Ultrasonic probe 8 Ultrasonic transceiver

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) A61B 8/00-8/15 JICST file (JOIS)

Claims (1)

(57) [Claims] An ultrasonic transmitting / receiving means for transmitting ultrasonic waves to a calcaneus or a patella of a subject, and information on the propagation speed of ultrasonic waves transmitted through the inside of the bone by the ultrasonic transmitting / receiving means is used to determine the cancellous bone inside the bone. Means for calculating the trabecular area ratio, drawing an image equivalent to the trabecular area ratio of the subject obtained by the calculating means, and displaying the drawing image on a display;
Separately, from the standard data of trabecular area ratio of trabecular bone of the calcaneus or patella based on gender and age of healthy men and women prepared in advance, data of trabecular area ratio of the same gender and age as the subject Means for extracting the images of the subject and the healthy subject on the same screen as the display for displaying the drawing image of the trabecular area ratio of the subject, and displaying different parts of the subject by color coding. An ultrasonic evaluation apparatus for osteoporosis, comprising: