Diagnosis of osteoarthritis: radioisotope scintigraphy and thermography

Radioisotope scintigraphy of joints is carried out with the help of osteotropic radiopharmaceuticals (pyrophosphate, phosphon, labeled ^{99т Тс} ). These drugs actively accumulate in places of active bone and collagen metabolism. Especially intensively, they accumulate in the inflamed tissues of the joints, which is reflected in the scintigram of the joints.

The method of radioisotope scintigraphy is used for early diagnosis of arthritis, detection of subclinical phases of joint damage, differential diagnosis of inflammatory and dystrophic lesions.

For early diagnosis of pathological changes in the joints, the detection of reactive inflammation can be used scintigraphy of the skeleton with pyrophosphate labeled ^99m Tc. Hyperfixation with a diffuse distribution of the radioisotope is noted in the presence of a reactive synovitis. In the hypovascular parts of the epiphyses of bones on scintigrams in the ischemic zones, a decrease in the accumulation of the radiopharmaceutical is determined, whereas in places of increased blood supply, which corresponds to the sites of bone restructuring, its accumulation is uniformly increased. When comparing the scintigraphy data with the results of intraosseous phlebography and intraosseous pressure measurement, it was noted that venous stasis and increased pressure in the medullary canal are combined with abnormally high absorption of the radiopharmaceutical. The degree of absorption is directly proportional to the stage of the degenerative-dystrophic process. Analysis of radionuclide distribution in coxarthrosis revealed increased accumulation of the labeled compound in the zones of increased load, mainly in the walls of cysts and osteoids, as well as in the areas of new bone formation.

In the broad sense of the word, thermography is a graphical registration of the thermal field of objects produced by various methods, i.e. Fields of their infrared radiation. A thermogram is a fixed two-dimensional image of the temperature field of a part or the whole body of the subject.

Thermography is an auxiliary diagnostic test, which must be deciphered in a single connection with clinical, laboratory, anamnestic data obtained in accordance with the diagnostic algorithm. According to L.G. Rosenfeld and co-authors (1988), the main advantages of thermography are:

1. Absolute security. The human body does not undergo irradiation or damage. Multiple investigation of the same subject is possible.
2. Speed of research. Depending on the type of thermograph, it takes from 1 min to 4 min. The time required to balance the temperature of the patient's skin and the surrounding air (15 min) can be significantly reduced with the appropriate equipment of the thermography cabinet.
3. High accuracy. The minimum recorded temperature gradient between two points at a distance of one millimeter is 0.1 C. This accuracy allows for a preliminary topical diagnosis of the lesion.
4. The choice of a sequence of safe research procedures for pregnant women and children.
5. The possibility of simultaneous evaluation of the functional state of several body systems (with survey thermography).

An important point in the accurate performance of thermography is the proper equipment of the room, as well as preparing the patient for the study. In the office, conditions should be created to stabilize the effect of environmental factors on the thermodiagnostic equipment and the patient. For this, doors and windows are covered with dense light-protecting curtains. Possible sources of infrared radiation (central heating batteries) are screened. In the observation room it is recommended to maintain the temperature of 22 + 1 C, as at a higher contrast the thermogram is reduced, and at a lower temperature, the patients develop vasoconstriction, which sharply reduces the informative value of the method. Relative air humidity in the rooms of the cabinet should be within 40-70%. The speed of air flow in the room should not exceed 0.15-0.2 m / s. These requirements are met by a closed room equipped with air conditioning.

When diseases of joints of different locations should adhere to the following rules for preparing a patient for thermographic examination:

A. Upper limbs:

• Hands should be clean, remove nail polish.
• During the day before the examination, do not apply creams, do not take physioprocedures, vasodilators or vasoconstrictors.
• During the examination, hands are released from clothing and placed on a table-stand.

B. Lower limbs:

• The legs are released from any bandages, compresses and uncovered to adapt the skin to the room temperature.
• During the day before the examination, do not take medicines and do not perform physiotherapy.
• The night before, you need to make a foot bath to remove sebum and exfoliated epidermis; varnish with nails to remove.
• Examination of the patient is performed in the supine position, less often in the standing position.

The study should be preceded by a period of temperature adaptation, which in an adult is 10-15 minutes. Due to the fact that the temperature indices of the human body change within 3-4 hours with fluctuations of 0.2-0.4 ° C, comparative (dynamic) studies are recommended at the same time. It must also be taken into account that the maximum body temperature in healthy people is noted at 15-16 hours.

Correct interpretation of thermograms requires knowledge of general physiology, anatomy and special fields of medicine. Normally, in a healthy person, there are zones of hyper- and hypothermia, caused by a number of reasons. The appearance of hyperthermia zones can be caused by:

• increased metabolism in a given organ or tissue in a certain period of time (for example, mammary glands during lactation),
• "Cavity effect" (areas of orbits, navel, interannual folds, axillary, inguinal areas, interdigital spaces, medial surfaces of the lower limbs or upper extremities that are compressed together tightly pressed to the body).

[1], [2], [3], [4], [5], [6], [7], [8], [9]

Topographical features of normal thermograms

The back and spine on the thermograms are represented by homogeneous thermotopography with slight hyperthermia in the middle part of the lumbar region. Sometimes there is moderate hyperthermia of the interscapular space.

On the thermogram of the back, four permanent hyperthermia zones can be distinguished:

1. in the projection of spinous processes, beginning with the level of the middle thoracic spine; the width of the first zone is somewhat larger in the lower thoracic and upper lumbar regions than in the lower lumbar region,
2. in the projection of the interannual fold,
3. two symmetrical zones in the projection of the sacroiliac joints (lateral and slightly higher than the interannual fold);
4. in the projection of the kidneys (symmetrically located areas of hyperthermia of uneven intensity).

Lumbosacral radicular syndrome leads to a decrease in the temperature of the skin of the leg in the innervation zone of this root by 0.7-0.9 ° C with simultaneous mild hyperthermia of the segment at the level of the corresponding connecting branches of the sympathetic trunk. Novocain blockade of the affected root normalizes the surface temperature of an adequate limb dermatome and lowers the segment temperature in the lumbar-sacral region by 0.2-0.3 ° C. After 10-12 min after completion of novocaine or trimecaine blockade of the lumbar sympathetic nodes, the temperature of the skin of the foot and shin of the corresponding side increases by 0.7-0.9 ° C, which persists for 2-3 min.

The average temperature of the skin in the back and spine is 33.5-34.2 ° C.

Upper limbs

The thermographic image of both upper extremities is characterized by symmetry, although according to the data of GM Frolov and co-authors (1979), insignificant thermal asymmetry of the upper extremities is noted, caused by the predominant development of the right or left limb or the difference in blood pressure.

Hyperthermia zones on thermographs of the upper extremities are normally defined in the area of passage of the vascular bundles - the inner surface of the shoulder, elbow joint, forearm, axillary region. Relative hypothermia is characteristic for the outer surface of the shoulder and forearm, fingers (compared to the palms). In the region of the finger of the hand, interdigital spaces, moderate hyperthermia is observed along the veins on the back of the hand. The average temperature of the skin in the upper limbs (except for the fingers) is 31.2-32.6 С, and the fingers of the hands are 27.2-28.6 С.

Lower limbs

The thermographic image of both lower limbs is also symmetrical. In the upper and middle thirds of the shins, zones of pronounced hyperthermia are defined, while areas of hypothermia are noted in the region of the knee joint, lower third of the shin and foot.

On the thermograms of the rear surface of the feet, a heterogeneous pattern is recorded with a tendency to reduce hyperthermia from the top down - the hypothermia zone is determined in the region of the fingers. On the plantar surface of the foot, the intensity of hyperthermia is more pronounced along the medial margin, especially in the projection of the arch of the foot. Hypothermia zones are recorded on the lateral margin and in the region of the fingers.

On the posterior surface of the thighs, there is a zone of pronounced hypothermia in the projection of the buttocks and a zone of hyperthermia in the upper third of the thighs, popliteal fossa, upper third of the shins. For the shins, the tendency is to decrease the intensity of hyperthermia in the distal direction. Above the Achilles tendon, the hypothermia zone is determined. The average value of the temperature of the skin in the lower limbs (except for the toes) is 32.1-32.4 ° C, the toes are 23.3-23.9 ° C.

Analysis and processing of thermograms is carried out according to the following thermographic features:

• detection of thermal asymmetry,
• the study of the area of an asymmetric site (zones of hypo- or hyperthermia): dimensions, degree of homogeneity, characteristic boundaries, etc.,
• the determination of the temperature gradient and the calculation of its coefficient expressing the ratio of the temperature difference between the points and the distance between them,
• Determination of the maximum, minimum and average absolute temperature of symmetric sections,
• Determination of the thermographic index (TI), which is the ratio of the sum of the temperatures corresponding to each isothermal field, to the total area of the zone of pathological thermosymmetry.

Normally, the thermographic index ranged from 4.62 to 4.94, averaging 4.87.

According to the data of NK Ternovoy and co-authors (1988), in the case of osteoarthritis of the first X-ray stage according to N.S. Kosinskaya observed thermal asymmetry of the joints, a zone of hypothermia over the joint area, gradually turning into the hyperthermia zone above and below the lying segments of the limb. The temperature gradient in the hypothermia zone is 0.6 ± 0.2 ° C.

Thermograms of patients with osteoarthrosis of stages II-III show thermosymmetry, a zone of hyperthermia over the affected joint of different relief and degree of severity, which indicates joint hypervascularization and aseptic inflammation in the synovial membrane of the joint and paraarticular fiber. The temperature gradient of the pathologically altered joint is 1 ± 0.2 ° C.

In case of effective treatment, the thermogram is characterized by a decrease in the temperature asymmetry, a decrease in the intensity of hyperthermia, the temperature gradient drops to 0.4-0.8 ° C.

In the Ukrainian rheumatological center, a study was made of the relationship between data from remote computer thermography (VCT), radiography and ultrasound of knee joints affected by osteoarthrosis.

The study involved 62 patients with knee osteoarthritis meeting the ACR classification criteria (1986), 43 (69.4%) women, 19 (30.6%) men aged 47 to 69 (mean 57.4 +6.2 years), who were ill for 1.5 years - 12 years (an average of 5.6 ± 2.6 years). Monoarticular injury of knee joints was detected in 44 (71%) patients, bilateral - in 18 (29%), thus, in total 80 knee joints were examined in patients of the main group. 1 X-ray stage according to Kellgren and Lawrence was diagnosed in 23 (28,8%), II - in 32 (40%), III - in 19 (23,8%) and IV - in 6 (7,4%) patients. For comparison, 54 radiographs of knee joints were used in 27 persons who made up the control group, who had no history of traumatic or any other lesions of the knee joints, as well as vessels, soft tissues, bones and other joints of the lower limbs. Among the 27 people in the control group, 18 (66.7%) women and 9 (33.3%) men aged 31 to 53 years (an average of 41.5 + 4.9 years) were women.

Radiography of the knee joints was performed in the anteroposterior projection using standard techniques. Graduation of x-ray criteria for osteoarthritis from 0 to 3 degrees (decrease in joint height and osteophytes) was carried out using Atlas of grading of knee osteoarthrosis of Y. Nagaosa and co-authors (2000).

When carrying out VCT with the help of a thermal imager "Raduga-1" the recommendations of LG were used. Rosenfeld (1988). A two-symmetrical 35x35 mm section was chosen for the knee joints in the thermogram, which corresponded to the medial and lateral parts of the tibiofemoral section of the knee (TPS), where the mean temperature was determined. For mathematical processing of the VCT results, the temperature gradient was determined by the formula:

ATm = Tm - Trm and ATl = Tl - Tril,

Where AT is the temperature gradient, Tm and Tl are the temperatures of the sections in the projection of the medial and lateral regions of TPS, Trm and Trp are the reference values of the temperature of the sections in the projection of the medial and lateral regions of TPSC obtained in the examination of healthy controls.

All the examined persons underwent ultrasound of knee joints using SONOLINE Omnia (Siemens) with a linear sensor 7.5L70 (frequency 7.5 MHz) in ortho mode in standard positions. The condition of the bony articular surfaces (including the presence of "loosening" of the cortical layer and its defects), joint cracks, periarticular soft tissues, the presence of effusion, changes in the ligamentous apparatus, and some other parameters were assessed.

The patients of the main group also studied the clinical signs of the joint syndrome. For this purpose, the algofunctional Leken index (AFI) of the severity of gonarthrosis was used, which was determined by the nature of the pain syndrome (time of onset, maximum walking distance without pain), duration of morning stiffness, etc. The degree of gonatrosis was coded in points (1-4 - weak, 5 -7 - medium, 8-10 - pronounced, 11-13 - significant, more than 14 - pronounced). The intensity of the pain syndrome was assessed using a visual analog pain scale (VAS), where the absence of pain corresponds to 0 mm, and the maximum pain is 100 mm.

Statistical analysis of the results was carried out using the computer program STATGRAPHICS plus v.3. When performing the correlation analysis, the correlation coefficient r <0.37 indicated the presence of a weak, 0.37 0.9 - very strong coupling. The value of p <0.05 was considered reliable.

Clinical examination of patients revealed a weak degree of gonarthrosis in 8 (12.9%), middle - in 13 (20.9%), severe - in 21 (33.9%), significantly expressed - in 15 (24.2%) , sharply expressed - in 5 (8.1%) patients. Nine (14.5%) patients did not complain of pain in the affected joints, the other 53 (85.5%) - assessed the intensity of pain by VAS from 5 to 85 mm. Limitation of the volume of motion from 75 to 125 ° was found in 38 (61.2%), an increase in the extension from 5 to 20 ° in 19 (30.6%) patients.

Clinical characteristics of articular syndrome in patients with osteoarthritis

Index	M ± cr
AFI Leken	8.87 ± 3.9
YOUR pain, mm	35.48 ± 23.3
The amount of bending, ° (in the norm 130-150 °)	128.15 + 20
Extension volume, ° (in norm 0 ")	3.23 ± 5.7

The study of thermograms of knee joints in the examined patients with osteoarthritis showed that on average, DTM was 0.69 ± 0.2 ° C, and DTT was 0.63 + 0.26 ° C (p = 0.061). The correlation analysis revealed a statistically significant relationship between DTM and all the clinical indicators studied, as well as between DTL and LEHEN, the pain and the flexion volume.

When performing the correlation analysis, a statistically significant direct relationship was found between the temperature gradient in medial TPSA and the decrease in the height of the joint gap in the medial region, as well as osteophytosis in the medial and lateral regions, while the temperature gradient of lateral TPS correlated with a decrease in the height of the joint gap and osteophytosis only in the lateral TPS.

According to the data of ultrasound in patients with osteoarthritis, narrowing of the joint gap due to a decrease in the height of the articular cartilage (transverse position of the sensor), bone growths (osteophytes) and / or defects of the joint surface of the bones, change of the synovial membrane and the presence of effusion in the joint, change of pararticular soft tissues all positions). Changes in the surfaces of the cortical layer of the articular surface of bones (unevenness, formation of surface defects) were recorded already in the initial stages of the disease (stage I) and reached the maximum extent in the III-IV stage.

Exudation in the joint was recorded in 28 (45.16%) patients, mainly in the II and III stages of osteoarthritis, which was mainly localized in the upper turn (32.3% of patients in the lateral part of the joint space (17.7%), less often in median (9.7%) and in the back turn (3.2%) .The effusion had a homogeneous anechoic echostructure provided that the clinical symptomatology lasted up to 1 month, and in patients with clinical signs of persistent inflammation it was inhomogeneous with inclusions of different sizes and echomolarities. Synovium was increased 24 (38.7%) patients, and uneven thickening was recorded in 14. The average duration of the disease in this group was greater than in the whole (6.7 ± 2.4 years), and in patients with uneven thickening of the synovium she was even greater (7.1 +/- 1.9 years.) Thus, the synovitis features reflected the duration of the disease and the severity of the current at the time of the survey.The comparison of the results of VCT and ultrasound is worthy of note.

A strong or very strong direct correlation is observed between the temperature gradient in the medial and lateral TPSS, on the one hand, and the effusion to the joint and the thickening of the synovial membrane, according to the data of the ultrasound, on the other. A weaker relationship was found between the presence of bone growths in the medial TSCS region (ultrasound data) and the temperature gradient in all the sites of the joint examined.

There was a correlation between the VCT data, on the one hand, and the clinical characteristics of the joint syndrome in the patients with osteoarthritis, the x-ray stage of the disease and ultrasound results on the other. The obtained data testify to the advisability of using a complex of instrumental diagnostic methods, including radiography, VCT and ultrasound, which provides more information about the condition of not only intraarticular, but also extraarticular tissues.