KR20050040545A - Method for measuring a bone density using a body impedance - Google Patents

Abstract

An object of the present invention is to provide a method for measuring bone density using a chamber impedance, which can determine bone adequacy by analyzing the measured bone density as well as measuring bone density simply and quickly using the chamber impedance. To this end, the present invention, in the bone density measurement method using the body impedance applied to the bone density measurement device using the body impedance, by using the chamber impedance and bone density information obtained from a plurality of users to define and store the formula for the correlation A first step of making; A second step of supplying current at different frequencies to the local body impedance measurement device (120, 121) attached to a patient who wants to measure bone density; A third step of calculating a body impedance for each frequency using information transmitted from the body impedance measuring apparatus (120, 121); And a fourth step of calculating the bone density by calculating the calculated body impedance for each frequency into the formula of the first step.

Description

Method for Measuring Bone Density Using Body Impedance {Method For Measuring A Bone Density Using A Body Impedance}

The present invention relates to a method for measuring bone density for diagnosing osteoporosis and osteopenia.

First, brief description of osteoporosis is as follows.

In other words, osteoporosis refers to a condition in which bones become weak due to abnormal decrease in bone mass due to various causes and thus are easily broken. In addition, the state before osteoporosis is called osteopenia (osteopenia), and the bone is thinned and lightened until the hole is opened. In general, young people have a balance in the absorption of bone production, but older people have lower estrogen secretion, which decreases bone absorption, and in postmenopausal women, the incidence of osteoporosis increases. This osteoporosis rarely exhibits any apparent external symptoms, especially bone loss once reduced is very difficult to recover. Therefore, prevention and early diagnosis are very important, and periodic inspections are necessary after at least 50s.

According to the report, more than 2 million osteoporosis patients in Korea are estimated to have osteoporosis fractures, more than 100,000 (5%). Bone density increases gradually during the growth process, but rapidly increases through puberty until the maximum bone density is reached at about 25 years of age, maintained until 35-40 years, and thereafter 0.3 ~ 0.5% of bone loss continues every year.

On the other hand, BMD can be used to test for osteoporosis because BMD represents 60-80% of bone strength and is closely related to the occurrence of fracture and is non-invasive. In other words, the bone density test is a test for diagnosing osteoporosis, which does not change the chemical composition of the bone and causes a decrease in the amount of bone in the unit volume and easily fractures even with a slight impact.

Conventional bone density measurement methods include the following methods.

First of all, as a simple radiography method, this method has a problem in that it is difficult to diagnose early, and it is difficult to diagnose when a bone mineral matter is lost more than 30%.

Next, the dual energy X-ray absorptiometry (DEXA) method is currently known as the best method for measuring bone density, which can be measured with only 1% bone loss. The dual-energy X-ray absorptiometry is a measuring instrument that replaces the Gd-153 source of DPA with X-rays. The X-rays have a higher photon flux than Gd-153 and exhibit excellent resolution due to the advantages of beam collimation. In addition, the absorption meter can shorten the scan time, less radioactive exposure (vertebral bone density measurement is less radiation exposure about 1/10 of the chest image), precision error is also reduced (exact error is 2-4% forearm, 6-10% of the spine and femur) is known as a device that can be. However, the method using the dual energy X-ray absorptiometry has a problem in that it is necessary to equip the equipment accordingly because it handles the inconvenience and the radiation that the size of the equipment is very large. In other words, since it is necessary to measure by a professional operator who has a license to handle radiation, there is a limit to being able to receive medical treatment only in a large hospital at a general hospital level, and because the equipment is very expensive and the cost of one-time measurement is high, it is necessary to periodically measure There is a problem that it causes an economic burden in the measurement.

Next, quantitative computed tomography (QCT) is useful for the measurement of cortical and subocular bones of the spine, but has a problem that the precision is lower than DEXA, the price is high, and the radiation exposure is high.

In addition, there are radiation absorption (RA), single photon gamma-ray / X-ray single energy absorption meter (SPA / SXA), photon gamma-ray (DPA) and quantitative ultrasound (QUS) methods. There is a problem that a complex process to measure the bone density.

On the other hand, when the voltage (E) is applied to the biological tissue, the current (I) flows through the biological tissue, wherein the complex ratio of voltage and current is called the impedance, the characteristics of the biological tissue such as subcutaneous fat using such impedance The method of measuring is called the impedance method. That is, all the components in the body have different electrical characteristics, and among those characteristics, the components have different resistivity and dielectric constant. Table 1 below shows an example of the resistivity value of the biological tissue, Table 2 shows an example of the dielectric constant value of the biological tissue.

The chamber impedance was published by Fricke and Cool-Cool, respectively, and modeled the change in the frequency of the chamber impedance.

A representative of medical devices using these characteristics is a lean body mass measurement device using body impedance. In the case of the lean body mass measurement device using the body impedance, the lean body mass component is measured through the association between fat free mass and the body impedance.

On the other hand, as described above, the body impedance method is used to measure the characteristics of various biological tissues, but has not yet been used in the method for measuring bone density.

An object of the present invention for solving the above problems, not only to measure the bone density simply and quickly using the body impedance, but also to determine the adequacy of the bone density by analyzing the measured bone density, bone density using the chamber impedance It is to provide a measuring method.

The present invention for achieving the above object, in the bone density measurement method using the body impedance applied to the bone density measurement device using the body impedance, using the body impedance and bone density information obtained from a plurality of users for the correlation A first step in defining and storing a formula; A second step of supplying current at different frequencies to the local body impedance measurement device (120, 121) attached to a patient who wants to measure bone density; A third step of calculating a body impedance for each frequency using information transmitted from the body impedance measuring apparatus (120, 121); And a fourth step of calculating bone density by calculating the calculated body impedance for each frequency into the formula of the first step, wherein the local body impedance measurement device 120 or 121 includes two pairs of ring-shaped electrodes. It is characterized in that attached to both sides of the body portion to be measured, respectively.

As described in the prior art, the degree of change and quantitative measurement of each component is possible by using the electrical characteristics of the body tissue using the body impedance method. In particular, the present invention provides a method for quantitatively measuring bone density in bone using the relationship between bone density and impedance based on electrical studies and experiments of bone in body tissues.

On the other hand, the bone density measurement method using the body impedance used in the present invention not only can measure the whole body and partial bone minerals (Bone Mineral) using the partial body impedance of the limbs, but also the local site using the local site body impedance. It is a method that can measure the bone density.

That is, in the present invention, after measuring the body impedance of the patient to measure the bone density, the bone impedance of the patient is easily measured by substituting the body impedance into an equation obtained from the data between the body impedance and the bone density obtained from a plurality of patients. It relates to a method for doing so. Hereinafter, first, a process for mathematically expressing the correlation between the chamber impedance and the bone density will be described with reference to FIGS. 1A to 1C, and then a patient who intends to substantially measure the bone density with reference to FIGS. 2A to 2D will be described. As a result, the process of estimating bone density through the measurement of the impedance will be described.

Figure 1a is an illustration of a method of measuring the frequency of each body part impedance value of each part of the body using the partial body impedance applied to the present invention, Figure 1b is a volume corresponding to the volume of lean fat component applied to the present invention One example showing the principle of the method for calculating the value, Figure 1c is an exemplary view of the anatomical division of the body to be applied to the present invention.

That is, by using the partial impedance method, as shown in FIG. 1A, the impedance values for the frequencies of the arms, the legs, and the trunk are measured. In addition, as shown in FIG. 1B, the previously reported information, that is, the height divided by the square of the measured resistance, has a very high effectiveness with the volume of the body's lean body mass. Volume can be calculated. In addition, the same principle can be measured by the amount of bone in each part of the body (because bone mass is one of the fat-free components).

On the other hand, Figure 1c is a full-body scan using the DEXA (Lunar, GE, USA) to divide the body by anatomical criteria, through the analysis can obtain the results shown in Table 3 below In addition, the acquired data includes information on partial bone mass (BMC).

Bone density can be estimated using the body volume, the bone mass, and the volume of each body obtained as a result of the measurement and analysis as described above.

That is, the first step of the present invention, while measuring the bone density in a plurality of patients using a conventional apparatus and method, while measuring the body impedance in the plurality of patients, the measured bone density Analyze the relationship between the body impedance and the body impedance to calculate the bone density estimation equation as shown in Equation 1 below.

Bone Mineral Density = A (Chefence value measured using x frequency) + B (y frequency

         Measured impedance value) + C (constant)

As described above, based on the clinical experiments of a large number of patients, if the equation for estimating bone density using the body impedance value is established, the actual impedance is measured for the patient who wants to measure the bone density. The second step of estimating bone density is performed by substituting the value into [Equation 1].

Figure 2a is an exemplary view of a local body impedance measurement device applied to the present invention. In addition, Figure 2b and Figure 2c is an illustration of a body part for measuring the body impedance applied to the present invention, a body part that can measure the body impedance by attaching a local body impedance measurement device shown in Figure 2a Will be shown respectively. In addition, Figure 2d is an example of the bone density measurement device using the body impedance applied to the present invention, the bone density of the patient in the state attached to the body region measurement device of the local body impedance shown in Figure 2a It shows the internal configuration of the device for measuring bone density using the body impedance for measurement.

First, the reason for using the local site impedance measurement device as shown in FIG. 2A is as follows. In other words, from the pathological symptoms and characteristics of osteoporosis, it can be seen that the bone density of a specific clinically significant site is very important.In the hospital, the bone density is measured mainly in the spine, thigh, wrist, etc. Achieve. The reason for this is that there is a difference in the composition of the specific part, for example, in the spine, 66% of the sponges are made of cortical bone, while in the femoral neck of 75%.

In addition, there are major causes of changes in bone density in certain areas.For example, postmenopausal osteoporosis is caused by a marked change in cavernous bone, Cushing's disease is caused by loss of the osseous bone of the spine, and hyperthyroidism is a change in cortical bone. Is the main cause. Therefore, in order to evaluate the amount of bone density associated with a particular disease, it is necessary to measure the bone density of a specific site.

However, this is not possible with only the partial impedance measurement method described above. Therefore, the following local site impedance measurement method should be added to determine local site. In other words, it is difficult to measure the bone density of sub-regions such as the spine, thigh, wrist, etc. by using the partial body impedance measurement method shown in FIG. 1A. The bone density at the localized site should be determined by measurement.

That is, as shown in FIG. 2A, two rings are placed adjacent to each other, and the positions of the source current and the voltage measuring electrode are positioned adjacent to each other. It can be measured. Impedance value according to the electrical characteristics of the bone by frequency measured in this electrode arrangement state by substituting [Equation 1], which is a clinical data equation obtained through the experimental group mentioned in the description of FIGS. 1A to 1C The condition of the bones in the site can be determined.

This is explained once again. If bone tissue has the same density as a normal person, it will have a corresponding body impedance. According to the literature, the typical Tibia EC has a value of 0.2 mS / Cm, and the EC of skeletal muscle, a major member of soft tissue, Is known to have an average value of 4.1 mS / cm (Duck FA (1990) Physical properties of tissue: A comprehensive reference book.Academic Press: London). But if this density changes, that is, osteoporosis progresses, the electrical resistance of the bone will decrease. Therefore, if you measure the body impedance of the clinically interested area using the electrode as described above, you can observe the change in the chamber impedance according to the bone decrease, and measure the bone density by using the correlation between bone density and body impedance. You can do it. In this case, the body impedance measurement is preferably measured for each of a plurality of different frequencies.

Next, Figures 2b and 2c is an example of a body part for measuring the body impedance applied to the present invention, using the DEXA equipment used in the clinical bone density of the femur (Fig. 2b) and spine bone density (Fig. The state of measuring 2c) is shown. That is, the present invention measures the body impedance by attaching an electrode as shown in FIG. 2a at an anatomical position as shown in FIGS. 2b and 2c, and then using the correlation between the body impedance and bone density of the site. A method for calculating bone density.

Next, Figure 2d is an example of the bone density measurement apparatus using the body impedance applied to the present invention, the current generating unit 111 for generating an alternating current, the voltage for measuring the voltage generated by the current supply Measurement unit 112, bone density calculation DB management unit 114 for storing the information about the chamber impedance and bone density collected through the Fig. 1a to 1c, input the patient's basic information necessary for bone density calculation, or the chamber impedance An input unit 116 for inputting various options related to the measurement or inputting various control signals, a storage unit 115 for storing necessary information among the inputted information, and a local site impedance measurement device shown in FIG. 2A Electrode interface 110 for connecting to (120, 121), the body impedance value transmitted through the electrode interface and information stored in the bone density calculation DB management unit Using a bone density calculator 118 for calculating the bone density of the patient, an output unit 117 for outputting information on the bone density calculated by the bone density calculator, and a controller 113 for controlling the respective units. It is configured to include.

That is, the controller 113 drives the current generating unit 111 and the voltage measuring unit 112 according to a control signal input through the input unit 116 to supply current to the local body impedance measuring devices 120 and 121. While generating and measuring the voltage, the body impedance information transmitted from the local body impedance measurement device (120, 121) is transmitted to the bone density calculator 118 to calculate the bone density. In this case, the body impedance value is a value measured for each of a plurality of frequencies are used. In addition, the bone density calculation unit 118 calculates the bone density of the patient by substituting the body impedance value transmitted by the above process into the bone density calculation formula obtained through the data stored in the bone density calculation DB manager 114. do.

To this end, the bone density measurement apparatus 100 using the body impedance includes an AC constant current source and an AC current measuring and analyzing circuit capable of measuring the body impedance, a digital circuit for analyzing the body impedance, and a body impedance for each part automatically. A selector circuit for selecting a source and a measuring part that can be measured by the present invention, and a circuit for measuring two symmetrical ring electrodes 120 and 121 for measuring a specially designed local part are provided.

In this case, as shown in FIG. 2D, in the local body impedance measurement device 120 or 121, two round electrode pairs are formed. That is, another pair of electrodes 121 is positioned on the opposite surface of the pair of electrodes 120 (in the case of FIG. 2D, a pair of electrodes is placed on the front and back of the body to measure the bone density of the spine). Electrode is attached). Therefore, when the current is drawn from one side, the current flows to the opposite electrode, and if the inner electrode is symmetrical, the impedance is read by reading the voltage therebetween. At this time, the reason for using the ring electrode is to measure the impedance value in the vertical direction by drawing a current in a straight direction as shown in Figure 2a.

In addition, the pair of ring electrodes 120 and 121 are mounted on the pelvis or ankle as well as the spinal region as shown in FIG. 2D to measure the body impedance of the corresponding portion.

That is, in the method of measuring bone density using the body impedance according to the present invention, as mentioned in the description of FIGS. 1A to 1C, first, the correlation between the body impedance and the bone density is summarized as an equation (first step), and FIG. As mentioned in the description of 2a to 2d, the patient's bone impedance is measured by substituting the above equation and the bone density of the patient (second step).

On the other hand, the expression of simple bone density calculated through the above process is not complete data for clinicians to utilize directly. Therefore, a third step is needed to convert the bone density calculated in the process into a new result in association with other indices.

Hereinafter, by analyzing the bone density measured through the above process, it will be described how to determine whether the value of the measured bone density is normal or abnormal.

Bone density is shown in various values according to age, sex, and race, and is analyzed as follows in comparison with the normal mean value for each condition.

First, a method of displaying bone density by Z-score is a method of dividing the numerical value representing the difference between the actual measured value and the theoretical normal value according to each age by dividing the standard deviation as shown in [Equation 2] below. .

Z-score = (measured value-mean value of the same population) / standard deviation

This method is useful for bone mineral density because normal value decreases with age.

Next, a method of displaying bone density by T-score is as shown in Equation 3 below. This method is a method recently used, and it is an age-independent method that expresses the difference between the average value of the measured bone density and the theoretical maximum bone mass divided by the standard deviation.

T-score = (measured value-young population mean) / standard deviation

At this time, there is no significant difference between the two scores before menopause, and T-score is a useful concept for evaluating the risk of fracture.

On the other hand, the value for the Z-score or T-score, may be calculated directly in the bone density measuring apparatus 100 using the body impedance shown in Figure 2d (FIG. 2d is configured for calculating the score value Is not shown), it may be calculated by transmitting the information on the bone density to a separate device.

That is, the present invention as described above, after defining the correlation between the body impedance and bone density, and measuring the bone density by applying the body impedance value obtained as a result of the body impedance measurement for the patient to the correlation, while the measured It relates to a method of converting bone density into data that can be used practically by clinicians using methods such as Z-score or T-score.

The present invention is not limited to the embodiments described above, and various modifications and changes can be made by those skilled in the art, which are included in the spirit and scope of the present invention as defined in the appended claims.

As described above, the present invention allows the user to easily calculate the bone density of the user using the chamber impedance, and by comparing and analyzing the measured bone density with the bone density in the normal state, an excellent effect of allowing the easy determination of the appropriateness of the bone density for each patient have.

Figure 1a is an exemplary view of a method of measuring the frequency impedance by each frequency of each part of the body using the partial body impedance applied to the present invention.

Figure 1b is an exemplary view showing the principle of the method for calculating the value corresponding to the volume of the lean body component applied to the present invention.

Figure 1c is an illustration of an anatomical segmentation of the body applied to the present invention.

Figure 2a is an exemplary view of a local body impedance measurement device applied to the present invention.

2B and 2C are exemplary views of body parts for measuring body impedance applied to the present invention.

Figure 2d is an illustration of an apparatus for measuring bone density using the body impedance applied to the present invention.

Claims (2)

In the bone density measurement method using the body impedance applied to the bone density measurement device using the body impedance, A first step of defining and storing a formula for the correlation using the chamber impedance and bone density information obtained from a plurality of users; A second step of supplying current at different frequencies to the local body impedance measurement device (120, 121) attached to a patient who wants to measure bone density; A third step of calculating a body impedance for each frequency using information transmitted from the body impedance measuring apparatus (120, 121); And Comprising a fourth step of calculating the bone density by calculating the calculated body impedance for each frequency in the formula of the first step, The local body impedance measurement device (120, 121) is a pair of two electrodes in the form of a ring, a bone density measurement method using the body impedance, characterized in that attached to both sides of the body portion to be measured, respectively. The method of claim 1, A fifth step of outputting the calculated bone density in the form of a standard deviation by comparing with the normal value considering the age and sex of the patient Bone density measurement method using a chamber impedance further comprising.