JP3182558B2 - Evaluation of bone mineral density by ultrasonic measurement - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an ultrasonic
The present invention relates to a device capable of evaluating the amount of bone mineral.

[0002]

2. Description of the Related Art In Japan, the population is aging at a considerable speed. It is presumed that this trend will continue in the future, and it is predicted that a super-aged society will arrive in 2020, where the ratio of the population aged 65 and over is 25.5% and one in four people is the elderly. . For this reason, a rapid increase in osteoporosis patients whose incidence increases with aging becomes a serious problem in the medical field. Osteoporosis is a disease in which components such as calcium in bones decrease, resulting in a decrease in bone mass, and tend to cause cracking and breakage due to a decrease in strength. About 30% of women over 60 years old and about 10% of men. It is said that% of people correspond.

In recent years, dual energy X-ray absorption (DX)
With the spread of A) and the like, it has become possible to measure the amount of bone mineral in most parts of the body. However, radiation is very harmful to living organisms, and it poses a risk to radiation for people aged approximately 50 to 60 years or older and women who have been closed, who are predicted to have a high possibility of osteoporosis. It was a good evaluation.

[0004] Therefore, a method of evaluating osteoporosis using ultrasound which is harmless to the human body has been proposed. For example, a method has been proposed in which ultrasonic waves are transmitted to a patient (subject) and the sound velocity and attenuation rate inside the bone are determined from a received signal transmitted therethrough, and these are used as evaluation indexes for bone symptoms (eg, JP-A-6-339478, JP-A-6-47044, JP-A-8-280677, Japanese Patent Application No. 9-142887, etc.).

[0005]

It is estimated that osteoporosis patients and their treatment costs increase year by year. However, although there is no effective treatment for osteoporosis yet, it is important to diagnose and discover early to assess the loss of bone mass and strength and prevent fractures. Therefore, from the knowledge of preventive medicine, it is desired to evaluate bone mineral density (BMD) as a regular checkup avoiding X-ray exposure. Therefore, an object of the present invention is to provide an apparatus that measures the progress of osteoporosis by ultrasound, determines the amount of bone mineral, and can evaluate the amount of bone and the strength of bone.

[0006]

SUMMARY OF THE INVENTION According to the present invention, information (bone mineral content) inside the bones of a patient (examinee) can be measured using ultrasonic waves which are harmless to the human body. Specifically, the trabecular bone density is determined by measuring the transmission propagation speed inside the bone (calcaneus) using ultrasonic waves. Next, the trabecular area ratio is determined from the trabecular linear density. Further, by obtaining a correlation between the trabecular area ratio and DXA, the amount of bone mineral can be evaluated by ultrasonic measurement.

[0007]

[Action] By measuring the inside of the bone with ultrasound, calculating the amount of bone mineral, and evaluating the bone mass and bone strength, the bone mineral evaluation and bone strength evaluation method as a regular checkup avoiding X-ray exposure We can expect establishment. Specifically, by diagnosing and discovering the progress of osteoporosis at an early stage, it is possible to evaluate a decrease in bone mass and bone strength and prevent the occurrence of a fracture.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A system example of an apparatus for evaluating the progress of osteoporosis embodying the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes a computer main body (CPU) having an evaluation program incorporated therein; Display (CR
T), 3 is a printer, 4 is a key board for input, 5
Is a measuring unit provided with a footrest on which the foot of a patient (subject) is placed and an ultrasonic probe connected to an ultrasonic transceiver.

FIG. 2 shows an electric circuit diagram of a connection relationship between a measuring unit including an ultrasonic probe connected to the ultrasonic transceiver 7 and a computer, and the ultrasonic probes 5a and 5b are respectively shown. It is connected to an ultrasonic transceiver 7 via a relay board 6. The electric pulse signal from the ultrasonic probe 5a is converted into an ultrasonic signal by a piezoelectric element, and the ultrasonic probe 5b
Is transmitted toward. The ultrasonic probe 5b converts the ultrasonic signal into an electric signal again by the piezoelectric element. The ultrasonic transceiver 7 is connected to an A / D converter 10 via a filter 8 and an amplifier 9. The filter 8 removes low frequency and high frequency components from the RF signal of the ultrasonic transceiver 7, and 9 while the A / D converter 10 converts the signal from the amplifier 9 to a digital signal,
This is for sending data to PU1. The CPU 1
Estimates the bone density and elastic modulus of cancellous bone by performing arithmetic processing based on the signal from the ultrasonic transceiver 7. Further, the ultrasonic transceiver 7 is connected to the CPU 1 while the CPU 1
Numeral 1 is also connected to the CRT 2 and the printer 3, and outputs the result of the arithmetic processing to these devices and stores and holds the result.

When measuring by ultrasonic waves, a pair of ultrasonic probes 5a and 5b are applied in a horizontal direction to measure a measuring part (calcaneus). In the CPU 1, since the distance between the transmitting and receiving ultrasonic probes 5a and 5b is known in advance, the propagation speed at which the ultrasonic wave passes through the inside of the bone is calculated from the measured transmission time of the ultrasonic wave.

From the obtained ultrasonic propagation velocity, the trabecular bone density Cu is calculated in the X direction (the ultrasonic probes 5a, 5b
In the horizontal direction). Here, the trabecular bone density Cu refers to the ratio of a portion containing bone (solid) to bone marrow (liquid) and bone (solid) in a one-dimensional (longitudinal) direction. The calcaneus is the optimal site for evaluating osteoporosis (cancellous bone accounts for about 95%). This is because the loss of bone mass that causes a fracture first appears in cancellous bone.

[0012]

(Equation 1) Vb: Ultrasonic bone bone propagation velocity Va: Ultrasonic bone marrow propagation velocity (1500 m / s) Vc: Ultrasonic bone substance propagation velocity (3000 m / s)

By the way, in the bone mass structure of the human body, no directionality is observed on the medial and lateral sides of the calcaneus. That is, x, y
The trabecular linear density Cu in the direction does not change (Cux = Cu
y). Therefore, by measuring the measurement part (calcaneus) by applying the pair of ultrasonic probes 5a and 5b in the horizontal direction, the bone mass and the trabecular shape can be handled two-dimensionally.

In view of the above, the bone density of natural bone (human bone) previously measured by ultrasonic wave, Cu, is removed from the bone marrow, and then cut to take a photograph of the cross-sectional trabecular shape. By performing image processing, the cross-sectional area As of the cancellous bone and the area Ab of the trabecular bone are respectively calculated, and the trabecular area ratio Ai is obtained from the following equation.

[0015]

(Equation 2)

Next, the trabecular area ratio Ai is determined for the patient (subject).
As a preparation for transmitting the ultrasonic wave to the measuring unit (calcaneus), a trabecular bone density Ci obtained from the image processing is defined as shown in the following equation. Here, trabecular area ratio A
i is bone material (solid) and bone marrow (liquid) in a certain area
And the ratio of bone (solid) to the total. This is for two-dimensionally expressing the information (bone mass, trabecular shape) inside the bone.

[0017]

(Equation 3)

FIG. 3 shows the relationship between the trabecular bone density Cu measured by ultrasonic waves and the trabecular bone density Ci obtained by image processing. As can be seen from the figure, there is a substantially unique relationship between the trabecular bone density Cu measured by the ultrasonic wave and the trabecular bone density Ci obtained from the image processing. It can be obtained by an approximate expression.

[0019]

(Equation 4)

At this time, from the definition of the trabecular bone density Cu measured by ultrasonic waves and the trabecular bone density Ci obtained by the image processing, the relationship between the two was determined as passing through the origin and (1, 1). That is, by transmitting ultrasonic waves to the inside of the bone of the patient (subject), the trabecular bone density Cu is determined, and the trabecular bone density Ci obtained from the image processing by the above approximate expression is calculated as
The trabecular area ratio Ai can be calculated by equation (3).

Next, the bone mineral density BMD is evaluated from the trabecular area ratio Ai calculated previously. For the patient (subject) whose trabecular area ratio Ai was measured, the bone mineral density BMD of the calcaneus and spine was measured by DXA, and the trabecular area ratio Ai and the bone mineral density of the same patient (subject) were measured. The correlation of BMD was investigated.
FIG. 4 shows trabecular area ratio Ai and DXA measured by ultrasonic waves.
1 shows the relationship between the calcaneus and the bone mineral density BMD of the spine measured by the above method. As can be seen from the figure, there is a correlation between the trabecular bone area ratio Ai measured by the ultrasonic wave and the bone mineral density BMD of the calcaneus and the vertebra measured by the DXA. Relationship between area ratio Ai and bone mineral density BMD of calcaneus), sixth
It is obtained by an approximate expression such as an expression (the relationship between the trabecular area ratio Ai and the amount of bone mineral BMD in the spine).

[0022]

(Equation 5)

[0023]

(Equation 6)

As described above, by calculating the trabecular area ratio Ai measured by ultrasonic waves, it is possible to evaluate (predict) the bone mineral density BMD of the calcaneus and spine of the patient (subject). In this way, the trabecular area ratio Ai is regularly examined and its value is managed (a monitoring sheet based on the bone elastic modulus is created).
By doing so, it becomes possible to diagnose osteoporosis while avoiding X-ray exposure, and it is expected that a method for mechanically evaluating bones will be established (FIG. 5).

[0025]

As described above, the present invention is an apparatus for evaluating the amount of bone mineral by means of a programmed computer, which measures the inside of bone by ultrasonic waves, finds the amount of bone mineral, and calculates the amount of bone and bone strength. The evaluation of bone mineral density and the establishment of a bone strength evaluation method can be expected as a regular checkup avoiding X-ray exposure. Specifically, by diagnosing and discovering the progress of osteoporosis at an early stage, it is possible to evaluate a decrease in bone mass and bone strength and prevent the occurrence of a fracture.

In addition, by performing regular medical examinations avoiding X-ray exposure, doctors and public health nurses can grasp the temporal health of patients (examinees). In addition, doctors and public health nurses can understand the progress of osteoporosis in patients (subjects) and can provide appropriate advice and treatment for daily, dietary, exercise, etc. To play.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram showing a configuration of an electric circuit of the system device of the present invention.

FIG. 3 is an explanatory diagram showing a relationship between a trabecular bone density Cu measured by ultrasonic waves and a trabecular bone density Ci obtained by image processing.

FIG. 4 shows trabecular area ratio Ai and DXA measured by ultrasonic waves.
FIG. 5 is an explanatory diagram showing a relationship between the calcaneus and the bone mineral amount BMD of the spine measured by the method.

FIG. 5 is an explanatory diagram of a monitoring sheet in which the results of a regular examination are described.

Claims (2)

(57) [Claims] 1. An apparatus for evaluating bone mineral density by a programmed computer, comprising: means for measuring a transmission propagation velocity inside a bone by ultrasonic waves to obtain a trabecular bone density; Means for calculating the trabecular bone density obtained from the actual image of the inside of the bone by the relationship between the trabecular linear density measured and the trabecular linear density measured from the ultrasound, and calculating the trabecular area percentage based on this, And a means for calculating a bone mineral density BMD value based on a relationship between a trabecular bone area ratio and a bone mineral density measured by X-rays. 2. A recording medium on which a program for evaluating a bone mineral content is recorded by a computer, wherein a penetration propagation velocity in a bone is measured by an ultrasonic wave to calculate a trabecular bone density.
The trabecular line density obtained from the actual image inside the bone was obtained from the relationship between the trabecular line density obtained from the actual image inside the bone and the trabecular line density measured by ultrasound, and the trabecular area was determined based on this. A recording medium on which a bone mineral density evaluation program is recorded, wherein a bone mineral density evaluation program is calculated based on a relationship between a trabecular bone area rate and a bone mineral density measured by X-rays.