Densitometry types. Densitometry of the spine. How to complete the study
Bone densitometry is a modern non-invasive method for determining bone density, which is performed to diagnose osteoporosis. With this disease, the mineral content of the bones (mainly calcium) is reduced, causing them to become more fragile. Osteoporosis poses the greatest danger to the spine and femoral neck, since fractures in these places are fraught with the most severe consequences.
Description of the procedure
What is this procedure? densitometry, every postmenopausal woman should know, since during this period the likelihood of developing osteoporosis is highest. Such a study makes it possible to detect it effectively and absolutely painlessly at the earliest stages.
Densitometry refers to instrumental diagnostic methods, and allows you to determine the density of bone tissue, more precisely, to do its quantitative and qualitative analysis.
There are densitometry ultrasonic And X-ray. The two methods are based on different operating principles and use different equipment. Sensors are used to read indicators, after which the data is transferred to a computer for calculation:
- relative bone density;
- thickness of the cortical layer;
- architectonics (spatial structure) and other parameters.
Equipment for densitometric examination can be stationary, with a table and sleeves. It is usually used to examine the spine, as well as the bones and joints of the pelvis.
Monobloc equipment is also used in the form of a small device that allows scanning hands, feet and other individual joints and bones.
X-ray densitometry
X-ray bone densitometry is based on the ability of X-rays to pass through soft tissue, being retained in the dense structure of bones, which are characterized by a high concentration of calcium salts and other minerals. Based on the rate of absorption of X-rays by bone tissue, specialists calculate the degree of mineralization of its various sections.
X-ray densitometry considered more accurate than ultrasonic. It is carried out on a stationary table with a “sleeve”, where the patient is placed for 10-30 minutes.
During the procedure, the spine or its parts, hip and wrist joints, or the entire skeleton are examined. The technique is very accurate, but it cannot be used in all cases: for example, pregnancy is a contraindication for it.
The cost of the procedure ranges from 1,300 to 3,000 rubles, it is determined by the scope of the study and the type of clinic. If there is a need to conduct combined densitometry using a computed tomograph (CT densitometry), then the cost will be about 5,000 rubles.
This densinometry method is similar to X-ray, but its accuracy is lower. considered an indirect method for determining bone density. Ultrasound waves travel at different speeds through areas of bone tissue that have different densities. The process is recorded by a sensor, processed and provided in the form of data to a specialist for analysis.
The cost of this type of examination ranges from 700-2000 rubles.
Despite the lower accuracy of the results, this method is also used quite widely, due to its absolute safety, speed and ability to be performed without additional examinations. The procedure lasts from 5 to 15 minutes and can be performed for pregnant and lactating women.
Indications
Densinometry is performed when osteoporosis is suspected, as well as as a preventive examination associated with this disease.
This type of examination is used to determine:
- The amounts of minerals in any one of the bones or in the entire skeleton.
- General condition of the spine.
- The presence of osteoporosis or osteopenia (a disease characterized by a slight decrease in calcium content in bone tissue), the degree of development of the pathology.
- Fractures of bones and vertebrae.
That is, undergoing densitometry makes sense for any person who is at risk of developing osteoporosis. This is especially true for people exposed to risk factors.
The list of these factors is presented:
- Metabolic disorders.
- Pregnancy, especially multiple pregnancies.
- Diseases of the spine (spondylolisthesis, osteochondrosis), injuries.
- Endocrine diseases - hypothyroidism, diabetes, pathologies of the parathyroid gland.
- Long-term use of hormonal and other drugs that remove calcium.
- Some neurological disorders.
- Recurrent fractures.
- Rheumatism.
- Poor nutrition, frequent adherence to strict diets.
- Low body weight, alcohol abuse and smoking.
Densitometry of the lumbar spine And femoral neck can give a 10-year prognosis for a fracture, and can also be used to evaluate the effectiveness of the treatment used.
When conducting such an examination on a child, it is possible to determine whether there is enough calcium and phosphorus in his body so that the child’s body can cope with intensive bone growth.
Amount of calcium in bones after 30 years begins to decrease over time, so approximately from 40 years old you need to control this indicator.
How often can densitometry be done? It should be carried out once every 2 years. Thanks to screening examinations, osteoporosis can be detected and treated in a timely manner. This examination regimen is recommended for women over 30 years of age who have close relatives susceptible to osteoporosis. Men should be screened for prevention starting at age 60.
How to prepare for the procedure
Preparing for densitometry involves following simple rules:
- The day before the procedure, you should stop taking medications containing calcium and phosphorus, as well as eating calcium-rich foods (cheese, cottage cheese).
- A week before the procedure, MRI or CT with contrast, as well as isotope scanning, should not be performed.
- You should not come to the examination wearing clothes with metal elements (zippers, rivets, buttons), which may affect the information content of the results.
- When starting the procedure, you need to take off your watch and hide your mobile phone in your bag.
How is densitometry done?
When performing X-ray densitometry, the patient is placed on a table equipped with a stationary device, after which the specialist leaves the room. When examining the spine, a special stand is used to support the legs.
When examining the pelvic bones, the legs are placed in a brace. After this, the arm of the device moves, during which a series of photographs are taken, and the data is transferred to a computer.
Movement during the procedure is prohibited unless such a command is given by the doctor. He may also ask the patient to hold his breath.
How is ultrasound densitometry performed? In this case, the patient lies on a medical couch, and the doctor performs an ultrasound procedure using a special attachment with a sensor. Both types of examination are absolutely painless and are performed fairly quickly.
In this way, you can examine any area: the lumbosacral spine, femoral region, heel bone, etc.
Ultrasound densitometry has no contraindications. X-ray It is strictly prohibited for pregnant and lactating women, and for children it is done in case of urgent need.
How to interpret densitometry results
Of all the results that densinometry shows, the most important are:
- Bone density (T-score), compared with the norm for young people in points. The norm is considered to be 1 point or higher; at 1-2.5 they speak of osteopenia, less than -2.5 - osteoporosis is diagnosed.
- Bone density compared to the norm for a specific age group (Z score). This indicator must be within the specified age limits.
Fluoroscopy, as a research method, became outdated in the last century. It has been replaced by new diagnostic methods. Densitometry began to be used for the structural study and diagnosis of bone tissue pathologies. This effective technique is indispensable for diseases that result in loosening of bone tissue. It allows you to identify the degree of loss of its density and detect the slightest structural anomalies.
Densitometry is not inconvenient, painless, safe and harmless. In addition, it does not take much time and does not require preliminary preparation. At the same time, the method is many times more effective than other instrumental methods, especially when working with the tissue structure of bones.
By the way. When diagnosing the spine, the procedure is performed most often in the lumbar area, as well as in the hip and shoulder joints. If there is such a need, densitometry of the entire skeleton can be performed.
The purpose of the study is to identify indicators of bone loss, decreased bone density, and impaired mineralization. An x-ray shows the same thing, but only in the case when the bone mass has decreased by a quarter, that is, its loss is 25% or more. With densitometry, a loss of even two percent can be seen. Of course, this is a very big breakthrough in diagnostics, because the earlier the disease is recognized and identified, the more effective the treatment will be.
Important! If similar diseases, which result in demineralization and loss of bone mass at the onset of the process, are diagnosed, it is possible to stop their development, increase mineralization and minimize the likelihood of fractures and bone damage.
Densitometry can be carried out either by X-ray or ultrasound, depending on the type of device used.
At the first stage of diagnosis, ultrasonic densitometers are often chosen. With their use, it is possible to detect osteoporosis at the zero stage with maximum safety for patients.
Ultrasound is an accurate and absolutely safe diagnostic method.
By the way. Ultrasound densitometry is not dangerous for both pregnant women and newborns. In addition, this method is cheaper than radiographic, and there is no need for a specially adapted and technically equipped room.
The indicator that determines the density of bone tissue is studied on the radius bones, which are found in the hand, as well as on the bones of the feet and tibia. The device measures the speed at which ultrasonic waves are transmitted through bone tissue. Then the readings are analyzed by the device, in comparison with the standard ones, and displayed on the monitor in the form of a graph. The diagnosis can be made immediately.
For indicators that deviate greatly from the norm, additional studies are required, which are carried out using an X-ray densitometer or a DXA machine (the method is called dual-energy absorptiometry - this is its abbreviation). This device carefully examines the shoulders, hips, spine and, if necessary, the entire skeleton.
Important! When examined with this device, the patient receives an incomparably lower dose of radiation than with a conventional X-ray machine. It is almost equal to the value of natural and non-hazardous radiological background.
The DXA densitometer allows you to examine:
- mineral composition of bone tissue;
- its density and strength;
- bone elasticity;
- the size of the cortical layers;
- thickness of the structure.
In addition to initial diagnosis, both devices are used to monitor the treatment process in order to record changes in the composition of bone tissue. It is also recommended to undergo the study once every few years for preventive purposes for people who are at risk for possible bone diseases.
By the way. There is another option for densitometry called quantitative computer tomography. This is an improved CT scan (CT) that allows you to obtain a three-dimensional projection of bone structures. The method is effective, but gives the highest radiation load of all, so it is used infrequently and only in justified cases.
Examination of the spine with a densitometer lasts no more than ten minutes, and can be prescribed by a doctor if the patient experiences back pain, osteoporosis or related diseases.
How does the procedure work?
There is no preparation, no need to follow a diet or regimen the day before. The only caveat is that if you are constantly taking medications in which the main substance is calcium or its content is high, it must be interrupted a day before the procedure, since calcium can affect the bone structure, changing parameters.
It is advisable to wear loose clothing that does not have metal parts. The patient will also be asked to remove jewelry, watches, glasses, and other accessories. And if there is metal in the patient’s body (prosthesis, pacemaker, etc.), you need to warn the doctor.
Important! If shortly before the scheduled densitometry (five days or less) you had a computed tomography scan using contrast fluid, you must also inform your doctor about this before the study.
During the X-ray procedure, the patient is placed on a couch. Above it there is a sensor, which, having passed the desired zone, begins to read readings from the emitter placed under the patient’s bed.
The patient's legs are bent at the knees and placed on a stand. The body is fixed so that it is motionless. The back at the base should be pressed tightly to the plane. It is recommended to hold your breath even while passing the device so that the readings are as clear as possible. Most often the spine is examined at the level of segments L4, L5. Here the results will be most revealing.
Important! The procedure is contraindicated for pregnant and breastfeeding women. Also, you should not undergo it if radioisotope diagnostics were carried out two days before.
As for the ultrasound form of the study, it is performed like a regular ultrasound, using a portable probe using gel. The information is transferred to a computer for processing.
How to understand the results
The densitometric apparatus already contains standards for the indicators and characteristics of human bones. They are different for each area of the body, age, ethnicity of the patient and other factors taken into account. Based on these standards, analytical calculations are carried out by the device.
Main parameters:
- BMC, which measures mineral content (how many grams of minerals are in bone tissue);
- BMD, which shows the mineral density of the tissue (in g/cm²).
Main analysis criteria:
Table. Criteria and their meaning
| Criterion | What does it show | Meaning |
|---|---|---|
| T | How does the patient’s bone density compare with the density of a universal, absolutely healthy person of the same age and gender. | If the chart shows indicators in the range of +2... -0.9, this is the norm. When the result is from -1 to -2.5, the initial stage of osteopenia is diagnosed, which means that bone density begins to decrease. Below -2.5 – this is developing osteoporosis. |
| Z | How does this density indicator compare with the statistical average inherent in a group of people of the same age and gender? | Z-score indicators are more variable. If they go negative from zero and are too low, an additional study may be prescribed to clarify all the parameters. |
For whom is densitometry indicated?
- If there are two or more risk factors for osteoporosis.
- Women during natural menopause.
- Women with artificial menopause, which occurred after surgical removal of the ovaries.
- Women taking hormonal contraceptives for a long time.
Hormonal contraceptives, for example, the drug "Rigevidon", lead to a decrease in bone density with long-term use
- Men over sixty years of age.
- Patients who have undergone treatment with glucocorticoids, since they promote intensive removal of calcium from the body.
- People of both sexes are over forty if they have had fractures due to falls, accidents, sports and work injuries, and so on.
- In the presence of rheumatic or endocrine disease.
- If a person is up to one and a half meters tall, while his parents are not short.
- If a person's body weight is below normal.
- When an x-ray taken for another reason revealed osteoporosis.
- Age from thirty years, if there is a hereditary predisposition to osteoporosis.
- If you have any of the spinal diseases: hernia, kyphosis, osteochondrosis, scoliosis.
- Taking tranquilizers, diuretics, non-steroids and anticonvulsants for a long time.
- Fragile asthenic physique.
- Diets lasting several months.
- Constant physical activity that is excessive.
- When treatment control is required.
- Bad habits such as excess alcohol, smoking, for a long time.
Advice. Today, densitometry can be done in almost any medical center and medical institution. This should be used, since early detection of bone mineralization disorders will prevent fractures.
What factors cause osteoporosis?
Why is osteoporosis dangerous and should be diagnosed as early as possible? This is a skeletal pathology that progresses and causes many complications. Bone mass decreases, tissue structure is disrupted, bones become fragile and break.
If you want to learn in more detail how, as well as consider the best remedies and treatment methods, you can read an article about this on our portal.
By the way. In this case, the disease develops gradually, almost asymptomatically. Height may decrease slightly (by 1-2 cm), the back may become rounded, and occasional aching pain in the back may occur, especially when walking for a long time or carrying heavy objects, as well as in a static position.
There is a list of factors that cause the disease or increase the risk of its development.
- Vitamin D deficiency.
- Calcium deficiency due to insufficient intake.
- Impaired calcium absorption if a person eats too much plant foods.
- Lack of hormones that are involved in bone formation.
- If there is an excess of phosphorus and salt, calcium is excreted in the urine.
- With alcoholism, there is an accumulation of toxins in the body and loss of bone mass.
- Decreased bone mass due to low physical activity.
- Nicotine addiction.
If at least two factors from this list are present, regular densitometry is necessary. The ultrasound procedure is used more often for initial diagnosis because it is safer. There are no contraindications to it. The X-ray method is used specifically to clarify suspicions of osteoporosis or to monitor treatment.
If you want to know in more detail what it shows, and also consider the dangers of x-rays, indications and contraindications, you can read an article about this on our portal.
The following are considered contraindications:
Densitometry of the spine is today the most popular and most frequently used method for diagnosing osteoporosis, which helps determine the presence of not only the disease in development, but also at the initial stage, when treatment is still highly effective.
Video: Densitometry (measuring bone density)
Diagnostics - clinics in Moscow
Choose among the best clinics and make an appointment
Diagnostics - specialists in Moscow
Choose among the best specialists and make an appointment
Densitometry is a medical test that measures bone mineral density and predicts the possibility of fractures. This is a non-invasive research method, as a result of which it is possible to obtain data on the content of calcium in bone tissues - the main structural element, which in turn makes it possible to diagnose the development of osteoporosis in the early stages. Most often, densitometry is performed in the lumbar spine, hip bones, and sometimes in the forearm area. In some cases, examination of the entire skeleton is required.
Bone densitometry is prescribed for people who are at risk of developing osteoporosis. This group includes:
- women after 50 years, men after 60 years;
- women during menopause;
- people with frequent bone fractures;
- people suffering from endocrine and rheumatic diseases;
- persons of mature age, less than 1.5 meters tall;
- women who have been taking hormonal medications for a long period of time;
- people suffering from diseases such as scoliosis and osteochondrosis, as well as those who have intervertebral hernias;
- persons with low weight (below 18 units);
- people leading a sedentary lifestyle, smokers and coffee drinkers.
Doctors recommend that people who are not at risk undergo preventive densitometric studies once every two years in order to be able to timely assess the dynamics of changes in bone mineral density.
What happens?
Densitometry of the spine in the clinic, which gives the most accurate idea of its condition
There are three types of examinations, which differ in the apparatus used to carry them out: X-ray, ultrasound and DXL densitometer.
Densitometry using X-rays is a very accurate examination method. But it has one very significant drawback - it cannot be repeated several times, since X-rays in large quantities cause harm to the body. It also cannot be performed on people who are contraindicated for X-ray exposure.
DXL densitometers are more advanced devices, the principle of which is also used in the study of X-ray irradiation, but they are distinguished by greater accuracy of the results obtained.
In most cases, portable densitometers that measure the density of the heel bone. This method is a quick and fairly accurate way to find out the bone density of the spine and hip, since they are composed of the same type (trabecular bone). Ultrasound densitometry is carried out without the use of X-rays, therefore it is absolutely harmless to the human body and can be repeated as many times as necessary for accurate diagnosis and treatment of the disease. In addition, ultrasound densitometry is allowed for pregnant women and children. The essence of an ultrasound study is that bone with normal density reflects ultrasound, and with reduced density, partial absorption of ultrasound by tissue occurs and, as a result, the wave reflection rate decreases.
Ultrasound densitometry of the hand bone. Such densitometers are portable in the form of a small suitcase. How is densitometry performed?
This procedure is completely painless and is carried out quite quickly. To conduct the examination, you must adhere to several rules:
- no later than one day before the procedure, you need to stop taking calcium supplements;
- Tell your doctor about recent x-rays, if any;
- tell your doctor if there is even the slightest chance of pregnancy;
- Do not move during the examination so that the image is clear.
There is no need to remove clothing during the examination (if there are no metal elements on it). The patient lies down on the table and a sensor is slowly passed over the area of the body being examined for 10 to 30 minutes. The resulting image is displayed on the computer screen.
results
After the examination, the radiologist issues a conclusion based on its results.
The result of densitometry is the receipt of two criteria: T-score and Z-score.
T-score is a comparison of the density of the studied bone tissue with the reference one. The normal indicator is - +2 - (-0.9). If the T-score is within the range of -1 - (-2.5), low mineral density is stated (called “osteopenia”). If the T-score is lower – 2.5 – osteoporosis is diagnosed with a high risk of fractures.
The Z-score compares the density of the bones being tested to the average for that age group. If this indicator is extremely high or low, the doctor refers the patient for additional studies.
Where can I get densitometry?
You can undergo densitometry in public clinics, as well as private medical centers.
Price.
The price depends on the research method, as well as on the number of body areas that need to be checked.
The price for examining one area of the body (“one zone”) is:
- for X-ray densitometry – from 5 dollars;
- for ultrasonic densitometry – from 8 dollars.
The most expensive is full body densitometry, although it lasts only a few minutes, it costs more than $70.
For the treatment of bone pathologies, early diagnosis of the disease is important. In this regard, the question: how densitometry is carried out is of interest to more and more people who have learned about the existence of such a research method. Bone densitometry makes it possible to accurately detect signs of osteoporosis in the early stages, and preventive studies using this technology will eliminate the development of the disease in people at high risk, especially the elderly.
Densitometry is a non-destructive method for determining bone mineral density; mainly based on measuring the level of calcium in bone composition, which largely determines bone strength. The most important areas of study are the spine and the neck of the femur, pathologies of which often lead to the loss of a person’s motor ability. Densitometry of the spine is especially important for older people, since the level of bone calcium begins to decrease after 35 years and can drop to critical values by the age of 52-55 years.
The main objectives of the study: identification of two main bone pathologies - osteoporosis and osteomalacia. Osteoporosis is characterized by a decrease in tissue density as a result of a decrease in the amount of bone substance per unit volume - a quantitative change in bone mass. Osteomalacia is caused by a deficiency of a mineral ingredient in normal volume - a qualitative change in bone composition. If osteoporosis most often develops against the background of age-related tissue degeneration, then osteomalacia can be observed in pregnant and postpartum women as a result of calcium loss (for example, through breast milk).
Numerous studies have proven that the problem of osteoporosis begins in childhood, and this bone disease is based on genetic, hormonal, nutritional, and mechanical reasons; chronic diseases and metabolic syndromes. If children do not develop optimal bone mass, the risk of osteoporosis and bone fractures in the future is quite high. Monitoring the development of children's bone structure is one of the areas of densitometry.
The danger of osteoporosis varies in different parts of the human skeleton, so when determining the localization of the densitometry zone, it is important to determine the optimal site of exposure. In general, bone tissue contains two important layers: compact (cortical) substance, which contributes to the greatest extent to bone strength, but has a low rate of metabolic processes, and spongy (trabecular) substance, which is actively involved in metabolism.
Different types of pathology affect these layers differently. Postmenopausal, hypogonadal and steroid osteoporosis mainly destroy trabecular substance. Damage to the cortical substance occurs in senile, hyperthyroid, hyperparathyroid and diabetic types of the disease. If the pathology affects the growing skeleton (before the age of 18 years), then systemic bone damage is often established with disturbances in both layers.
Currently, there are many ways to determine bone density.
The following technologies have found practical application:
- Dual-energy X-ray densitometry (absorptiometry) is based on the transmission of two X-rays. The main purpose is to study the spine and hip. The principle is based on the fact that increasing tissue density reduces the permeability of such rays. The results of the passage of both rays (through bone and soft tissue) are analyzed and compared. The accuracy of the method is estimated to be about 2% of the change in bone mass per year.
- Peripheral bone densitometry is similar to the previous technique, but is intended to study the bones of the extremities, but cannot be used to study the spine and hip. Small portable X-ray sources are used. The accuracy of the method is not high enough, so it is often used not for diagnosis, but for monitoring the treatment process and conducting screening studies.
- Two-photon absorptiometry involves the use of radioactive isotopes as sources. Radioactive radiation makes it possible to determine the density of bone matter in the hip and spinal regions.
- Quantitative computed tomography is based on obtaining a three-dimensional picture of bone structure using X-rays. The method is rarely used due to the increased radiation concentration.
- The ultrasound technique is based on determining the speed of propagation of the ultrasonic wave and its dispersion in bone tissue. The method is widespread. It has a lower informative capacity compared to the x-ray method, but is absolutely safe and accessible.
Densitometry is prescribed by a doctor and should be taken by people who are at increased risk of developing bone pathologies, twice a year. The risk group consists of the following people: women aged 42-45 years and men over 55 years old; women during menopause, if it occurs prematurely; women after adnexectomy; people after bone fractures; patients with pathology of the parathyroid glands; people over 35 years of age who have close relatives with osteoporosis; persons taking medications with the effect of leaching calcium (glucocorticosteroids, anticoagulants, oral hormonal contraceptives, tranquilizers, diuretics, anticonvulsants and psychotropic drugs); with alcohol and smoking abuse; people with a sedentary lifestyle and poor diet; after systemic fasting; people exposed to significant long-term physical overload; patients with endocrine and rheumatic diseases, diseases of the spine.
It is especially important to conduct research when the slightest signs of osteoporosis appear. Densitometry using x-ray methods is contraindicated in pregnant women and nursing mothers. The procedure should not be performed after the administration of a contrast agent during a previous CT or MRI, if 6-7 days have not passed. When using radioisotope diagnostics, it is necessary to maintain an appropriate interval. Ultrasonic waves are considered absolutely safe.
X-ray densitometry methods are carried out using three types of devices: axial X-ray densitometers; peripheral portable densitometers and peripheral ultrasonometers. Stationary axial devices are used to implement dual-energy absobtiometry and can perform 4 research programs; portable - for examining the forearm, limbs (especially the heel bone).
This technology allows the following research:
- densitometry of the lumbar spine;
- examination of the proximal femur: the condition of the entire department and its parts is subject to analysis - the neck (especially Ward’s triangle), greater trochanter, diaphysis, intertrochanteric zone;
- assessment of the condition of the entire skeleton and its parts - spine, pelvis, limbs;
- examination of the distal and ultradistal areas of the forearm;
- examination of the calcaneus.
As a result of radiography, surface mineral density is determined - the number of minerals in the area traversed by the beam. The study is carried out using fan-type and point-type devices.
Ultrasound densitometry is based on the use of a portable densimeter. The technique is approved for examining pregnant and lactating women. The device's sensor records the speed of the wave, which depends on bone density. In addition, wide-band attenuation of the signal as a result of its absorption by bone tissue is determined.
The results obtained are sent to a computer, which analyzes them. Research is most often carried out in peripheral areas of the skeleton. The calcaneus, tibia, phalanges, and patella are subjected to ultrasound densitometry.
Study criteria
Densitometric diagnostic methods are based on bone density standards, which differ in different areas of the skeleton.
Analysis of the obtained data (transcription) is carried out taking into account established standard indicators, gender, age and individual characteristics of the person.
The main research indicators are:
- Navy. An indicator of the mineral composition of bone tissue, measured in grams.
- BMD. Tissue mineral density indicator; determined in g/cm².
The analysis of indicators is carried out according to two main criteria:
- T-test. The ratio of the resulting bone density to density is normal (the value of the indicator for an absolutely healthy person of the same age and gender).
- Z-score. The ratio of the resulting bone density to the average of a group of people of the same age and gender.
The T-criterion norm is set in the range from -0.9 to +2, which indicates the normal state of the bone tissue. When the first signs of bone pathology (osteopenia) appear, the T-criterion value drops to (-1) - (-2.5). When the criterion drops below -2.5, we can talk about the development of osteoporosis.
Technique and preparation
Preparation for densitometry does not require any special procedures. To exclude incorrect influences, only a few restrictions are recommended:
- stop taking medications with calcium supplements 24 hours before the test;
- it is necessary to notify the doctor about the following circumstances: undergoing procedures with the administration of barium or other contrast agent; presence of pregnancy; undergoing examinations using x-rays, tomography or radioactive isotopes; presence of pacemakers or metal implants;
- maintaining stillness during the procedure.
The position in which the beam or wave is applied is selected depending on which area of the skeleton is being examined. A sensor slowly moves over the area under study, the signal from which is projected onto a computer monitor. The duration of the procedure is from 15 to 35 minutes, and a few minutes are enough for peripheral examination. The obtained research result is entered into the radiologist’s report for subsequent decoding.
During densitometry, the patient remains clothed if the clothing is loose enough and does not have metal elements. Repeated densitometry is recommended to be performed once every two years to determine the dynamics of changes in bone tissue density.
Osteoporosis is a disease that develops against the background of disruption of the structure of bone tissue and a decrease in its mass. As a result, bone fragility increases and the risk of fractures increases significantly. In the world, among non-infectious diseases in terms of mortality and disability, this disease ranks fourth after cardiovascular diseases, cancer pathologies and diabetes mellitus.
With the advent of menopause, one third of women worldwide face bone problems. In addition, osteoporosis is diagnosed in every second person who has reached the age of seventy. Bone densitometry is widely used to diagnose this disease. Early diagnosis is indispensable for starting timely treatment. But the purpose of this procedure raises a number of questions in patients: densitometry - what is it? What are its types? How is densitometry performed and what does it show?
Types of procedure
Densitometry or osteodensitometry is an instrumental diagnostic method that allows you to assess how much and in what quantity the demineralization of bone tissue is. To do this, pay attention to a number of indicators, including relative density, spatial structure and thickness of cortical bone mass.
The mechanism and principles of manipulation can vary greatly, so studies are divided into 3 types:
- ultrasonic densitometry;
- X-ray densitometry;
- photon absorptiometry.
As a rule, if osteoporosis is suspected, ultrasound diagnostics are first prescribed, and if the suspicion is justified and some clarification is necessary, then X-rays or radioisotopes are used.
To confirm osteoporosis, the T-score in the transcript must be below 2.5
Ultrasound densitometry
Ultrasound densitometry is an indirect determination of bone mineralization. An ultrasonic wave, passing through tissues of different densities, differs in speed. The densitometer device produces ultrasound of a certain frequency, which is passed through the bones in a given area and is captured at the output by a recording sensor. Ultrasound densitometry, despite its lower information capabilities, is used quite often. This is due to its complete safety, speed of execution and the ability to carry out such diagnostics without a doctor’s referral and additional examinations.
X-ray densitometry
Bone mineralization is calculated using a developed algorithm on the examined area, which was exposed to x-rays. There are several types of X-ray densitometry:
- Dual energy densitometry. This method involves passing a pair of x-rays. One passes through bone tissue, the other through soft tissue, and their results are compared. The measurement is made based on the fact that the higher the mineralization of the bones, the lower the permeability of X-rays. This method is used to examine the spine and femur.
- Densitometry peripheral. The principle of density measurement is no different, as in the case of the dual-energy technique, but with lower radiation doses. This method is suitable for assessing the bone tissue of the extremities, but is weak for studying the condition of the spinal column and femur. It is used primarily to control the therapeutic process.
- Quantitative computed tomography method is also carried out under the influence of ionizing radiation and allows you to obtain a three-dimensional image of the bone structure. It is used extremely rarely, due to the high degree of ionizing radiation to which the patient is exposed and the price category of the procedure.
Due to increased radiation exposure, X-ray densitometry is not performed on pregnant and lactating women, and is used with great caution in pediatric practice.
Densitometry can be done in most public clinics or diagnostic centers
Photon absorptiometry
This method is based on photon beams. They are passed through the bone tissue and, depending on how many photons were absorbed, bone mineralization is calculated. The process uses low doses of radiation. There are 2 types of photon absortiometry:
- Monochrome densitometry - this method is used exclusively for diagnosing peripheral bone mineralization.
- The dichrome method is used to diagnose the mineral density of the bones of the spine and hip.
If we compare X-ray densitometry and photon absorcimetry, the former has a significantly higher resolution due to the use of more powerful radiation. In addition, this method is more accurate and scanning is much faster.
Indications for use
Diagnosis of osteoporosis even before the onset of its symptoms is the main indication for densitometry. This procedure is recommended to be carried out at least once every 2 years for the following groups of people:
- for the purpose of prevention for everyone who has reached the age of 50;
- poor heredity (close relatives suffer from osteoporosis);
- female representatives after the onset of menopause;
- against the background of long-term hormone replacement therapy;
- patients seen by an endocrinologist (diabetes mellitus, hypothyroidism, adrenal insufficiency);
- after a hip fracture at the age of 40 years;
- when primary symptoms of osteoporosis appear;
- improper diet for a long time.
Indications for this procedure in children can be determined by an endocrinologist, rheumatologist or traumatologist. Most often, the following pathological conditions can serve as a reason for such an examination:
- long-term use of hormonal drugs;
- chronic inflammatory diseases of the digestive tract, pulmonary intestinal form of cystic fibrosis;
- diseases affecting connective tissue and blood vessels;
- severe pulmonary and renal failure;
- dwarfism (pituitary dwarfism);
- a syndrome accompanied by insufficiency of the functions of the gonads and impaired synthesis of sex hormones;
- keeping the child immobile for a long time;
- pathologies of the musculoskeletal system caused by genetic factors;
- history of fractures.
Dwarfism - indications for diagnosis
Bone densitometry allows a specialist to determine the decrease in bone mass in the initial stages, when only about 2% is still lost. This is a very good indicator for early diagnosis against the background of standard x-rays, which reveal pathology if a third (or more) of the total bone mass is already affected. And this already indicates the irreversibility of the processes and a high risk of developing serious complications.
Areas of study
Today, densitometric analysis is the “gold” standard, and is recommended by WHO to confirm osteoporosis in a patient. Densitometry of the entire body or individual parts of the musculoskeletal system can be performed.
Osteodensitometry of the axial skeleton (spine) is examined from the first to fourth lumbar vertebrae using a special sensor that measures the degree of absorption of passing x-rays and builds a graph. Sometimes it is not possible to measure all 4 vertebrae, so they are content with three or two.
The femurs are examined as follows. X-rays can be used to scan the hip joint area. Most often, measurements are taken on the left thigh, but the right thigh also gives an equivalent result. 5 parts of the hip joint are examined: its neck, the upper end of the body of the femur, the intertrochanteric region, Ward's triangle and the upper part of the femur.
Forearm bones - bone mineral density measurements are performed on the passive arm, since the radius bone of the dominant arm has approximately 3% higher bone mineral density. Of particular importance is the indicator obtained at the point that corresponds to 1/3 of the length of the radius. If the procedure is performed on a child or adolescent, then preference is given to examining the vertebrae in the lumbar region.
At the same time, they try to perform the procedures as quickly as possible and with a minimum dose of ionizing radiation. After computer processing, the bones are assigned different scores.
Preparation and methodology
Ultrasound densitometry requires absolutely no special preparation. In the case of a radiation procedure, the doctor will explain to the patient how to properly prepare. 24 hours before the scheduled procedure, you should stop taking medications that contain calcium. It is imperative to inform the diagnostician if this patient has recently undergone radiation examinations using a contrast agent. You need to be determined to be as motionless as possible during the procedure and maintain the position specified by the doctor.
It is important to avoid calcium-based medications
The examination usually takes 30-40 minutes. The subject is asked to position himself correctly on the diagnostic table, under which there is a radiation source, and above it a device that records the result. During a stationary examination, a special sensor is moved along the body, it measures radiation levels, transfers it to computer equipment, analyzes and displays the result.
If equipment consisting of one block is used, then the part of the body being examined is placed in a special apparatus, and the result is given after processing by a computer program. To improve image quality, the limb may be immobilized or the patient may be asked not to breathe for a period of time. Having understood what densitometry is, it becomes obvious that this examination should be seriously considered by all those who are exposed to factors that increase the likelihood of developing osteoporosis at any age.
