RU2254142C2 - Method for diagnosing lower extremity muscle ischemia in the cases of their chronic arterial insufficiency - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: method involves introducing radioactive preparation of 99^mTc-metoxyisobutylisonitryl or 99^mTc-tetrophosmine. Parameters reflecting arterial blood circulation intensity are analyzed. Standard physical activity is applied not earlier as at the second day. Radiopharmaceutical preparation is immediately introduced at the same dose. Extremity muscle ischemia diagnosis is set on the basis of increased blood circulation intensity after having applied exercise stress.

EFFECT: high reliability of diagnosis.

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Description

The invention relates to medicine, namely to radionuclide research methods, and can be used to diagnose the degree of ischemia of the muscles of the lower extremities in their chronic arterial insufficiency.

An important problem of modern angiology is the ability to accurately determine the degree of ischemia of the muscles of the lower extremities, because it allows you to determine the tactics of treatment of patients with chronic arterial insufficiency of the extremities (HANK), the range of surgical and conservative measures used, evaluate the effectiveness of the treatment and the prognosis of the disease.

From this perspective, clinical methods for assessing the severity of HANK are most convenient, consisting in recording the maximum possible “painless path” at an average speed on a flat surface (about 5 km / h). According to this method, 4 degrees of chronic circulatory disorders of the lower extremities are distinguished (Pokrovsky A.V. Clinical angiology. - M .: Medicine, 1979. - 367 p.).

However, it should be noted that the clinical methods for determining the degree of disorders of the arterial circulation of the lower extremities, despite the convenience of their use, are sufficiently subjective and largely depend on the psychoemotional characteristics of the studied patient. In addition, with their help it is difficult to identify the so-called preclinical stages of the disease, and the emerging pains in the lower extremities may be due to another, not vascular pathology.

To obtain objective information about the degree of organ ischemia, radionuclide research methods are often used. So, there is a method for radionuclide diagnosis of myocardial perfusion disorders in chronic ischemia using radioactive thallium - TL-201 (Britten AJ, Jamali F., Gane JN et al. Motion detection and correction using multi-rotation 180 degrees single-photon emission tomography for thallium myocardial imaging. // Eur. J. Nucl. Med. - 1998. - Nov. - Vol.25 (11). - P.1524-1530). The method is based on determining the rate of excretion of thallium-201 from cardiomyocytes due to standard physical (bicycle ergometer) or pharmacological (dipyridamole) load. At an isotope elimination rate significantly lower than normal, cardiac muscle ischemia is recorded.

However, this method, despite its physiological and informative nature, was developed for the diagnosis of myocardial ischemia and was not used to assess the degree of ischemia of striated muscles, in particular muscles of the lower extremities. In addition, the radiopharmaceutical used is very expensive, and the radiation load on the patient during the study is quite high (the effective equivalent dose is 10-14 Mzv for critical organs), which significantly limits its use in clinical medicine.

In order to increase the information content and obtain more accurate information about the degree of HANK, an instrumental method was proposed, which consists in combining ultrasound dopplerography and a treadmill - treadmill (Zatevakhin II, Tsitsiashvili M.Sh., Zolkin VN and others. A new approach in assessing the severity of HANK in patients with limiting "intermittent claudication." // Angiology and Vascular Surgery. - 1997. - T.2 (Appendix). - S.7-8). This method is adopted as a prototype.

However, the prototype method has significant disadvantages, primarily associated with its subjectivity, as it is mainly based on the patient's pain response in response to physical activity.

In addition, the treadmill test can be performed only in half of patients with chronic obliterating diseases of the arteries of the lower extremities due to the presence of atherosclerotic lesions of other vascular pools and other associated pathology (Koshkin V.M., Nosenko E.M., Dadova L. V. and others. The place of the treadmill test in the diagnosis of the severity of arterial insufficiency in patients with arteriosclerosis obliterans of the lower limb arteries. // Angiology and Vascular Surgery. - 2001. - T.7, No. 2. - P.10-14).

In this regard, there is an urgent need to use in such patients a physiological, on the one hand, and the most specific and informative, on the other, instrumental method for diagnosing the degree of muscle ischemia of the lower extremities.

The objective of the invention is to develop clear scintigraphic criteria for ischemia of the muscles of the lower extremities in their chronic arterial insufficiency.

The task is achieved in that after the introduction of the radioactive drug ^99m Tc-methoxyisobutylisonitrile (technetril) or ^99m Tc-tetrofosmin into the peripheral vein of the patient, its accumulation in the muscles of the lower extremities is assessed at rest and after standard exercise and changes in the studied parameters relative to the norm, the available circulatory disorders of the lower extremities.

Using a radiopharmaceutical, the degree of blood supply to an extremity at rest and the compensatory possibilities of its blood flow during exercise are determined.

The proposed method is as follows.

The study is carried out in two stages (within 2 days). At the first stage, perfusion of the muscles at rest is determined. The patient is placed in front of the gamma-ray detector so that both legs are in the field of view of the device. 370 MBq (10 mki) of radiopharmaceutical ^99m Tc-methoxyisobutylisonitrile (or ^99m Tc-tetrofosmin) is injected into any accessible peripheral vein. Immediately after the injection of the “label”, 60 serial scintigrams are recorded, each lasting 1 s, which makes up the dynamic phase of the study. Then, activity – time curves are plotted and the following parameters are analyzed, which reflect the intensity of arterial blood supply to the extremities:

T arrival - the time from the beginning of the curve to the place of its most active rise;

T plateau - the time from the beginning of the curve to its exit on the plateau.

Then, after 15 minutes, static scintigrams of the muscles of the legs and hips are recorded with a duration of information collection of 2 minutes per frame. In this case, the intensity of radiopharmaceutical accumulation in the limb muscles is determined, which characterizes the state of tissue metabolism of the studied regions.

Not earlier than the next day (after the decay and removal of the radiopharmaceutical from the body), the second stage of the study is performed, also consisting of dynamic and static phases. The second stage is distinguished by conducting standard physical activity, which consists in rhythmic ascent and descent on a special step 25 cm high under the second-second hits of the metronome for 3 minutes or until pain in the lower extremities appears. Immediately after this, the radiopharmaceutical is administered in the same dose and the scintigrams are recorded and processed according to the above protocol. According to the results of studies obtained at rest, as well as the degree of increased blood flow in the limbs after standard physical activity, the existing circulatory disorders are judged.

To identify normal indicators of the dynamic and static phases of the proposed method, a special study was conducted in which these parameters were determined in 16 young patients, aged 18 to 30 years, patients suffering from varicose veins of the lower extremities without clinical and instrumental (ultrasound dopplerography and ultrasonic angioscanning) signs of chronic arterial insufficiency of the limbs. When performing phleboscintigraphy using a standard technique (A.V. Karalkin, V.Yu. Bogachev, S.G. Gavrilov and others. Phleboscintigraphy in the diagnosis of chronic venous insufficiency of the lower extremities // Annals of Surgery. - 1996. - No. 3. - C.63-69) instead of the traditionally used ^99m Tc-pertechnetate, ^99m Tc-methoxyisobutylisonitrile (or ^99m Tc-tetrophosmin) was intravenously administered and muscle perfusion was assessed along with the parameters of venous hemodynamics using the above protocol. Thus, not only did the topical diagnosis of valve failure of perforating veins be carried out, but also the arterial blood supply to the lower extremities was evaluated.

As a result of our observations, we did not reveal a significant difference in the studied parameters on the left and right lower extremities, which allowed us to analyze a total of 32 objects of study. The data obtained are presented in table 1.

The data obtained in this study will allow us to more clearly identify the degree of chronic arterial insufficiency of the lower extremities, determining the treatment tactics of patients with HANK.

Table 1.
Normal indicators of the dynamic and static phases of the proposed method. Options Physiological rest Stand. exercise stress hip shin hip shin T arrival (s) 12.17 ± 1.42 14.50 ± 1.12 7.09 ± 0.66 8.30 ± 0.85 T plateau (s) 39.87 ± 3.12 44.11 ± 3.51 19.56 ± 2.14 22.13 ± 2.08 Specific activity 23.70 ± 2.32 16.30 ± 1.74 35.25 ± 2.56 30.38 ± 2.77

Note:

Specific activity is an indicator reflecting the number of decays of a radionuclide in one cell (4 × 4 mm) in the selected zone of interest during the recording of the scintigram (2 min).

Clinical example

Patient K., 55 years old, no. bol. 1428, upon admission to the clinic complained of pain in the right calf muscle while walking at a distance of about 100 m, cooling of the right foot and lower leg.

The patient underwent direct aorto-arteriography, in which an extended occlusion of the right superficial femoral artery from the mouth to the lower third of the thigh and stenosis of the right common iliac artery were revealed; The diagnosis was made: atherosclerosis obliterans of the arteries of the lower extremities, occlusion of the right superficial femoral artery, stenosis of the right common iliac artery, chronic arterial insufficiency of the extremities PBst.

Performed scintigraphy of the muscles of the lower extremities by the proposed method. The following results were obtained (Table 2):

Table 2.
Indicators of the dynamic and static phases of the proposed method on the right lower limb in patient K. Options Physiological rest Stand. exercise stress hip shin hip shin patient K. counter. Group patient K. counter. Group patient K. counter. Group patient K. counter. Group T arrival (s) 14 12.17 ± 1.42 17 14.50 ± 1.12 nine 7.09 ±
0.66 10 8.30
± 0.85 T plateau (s) 44 39.87 ± 3.12 48 44.11 ± 3.51 32 19.56 ± 2.14 40 22.13
± 2.08 Specific activity 17 23.70 ± 2.32 14 16.30 ± 1.74 thirty 35.25 ± 2.56 25 30.38
± 2.77

As can be seen from the data presented, at rest, the examined patient has no significant changes in either the static or dynamic phases of the study. During physical exertion, there is a slight decrease in the accumulation of the radiopharmaceutical in the muscles of both the thigh and lower leg (static phase of the study) and the elongation of the curve reaching the plateau in the lower leg is almost 2 times, and in the thigh - 1.7 times, which generally indicates pronounced disorders of perfusion of the muscles of the right lower limb and reflects a high degree of severity of ischemia stress. Violation of perfusion of the muscles of the right femur unambiguously indicates a hemodynamically significant stenosis of the right common iliac artery, which excludes the possibility of an individual performing femoral-popliteal bypass surgery without reconstruction of the iliac segment due to the high possibility of thrombotic occlusion of the vascular prosthesis due to insufficient blood flow to it.

This example illustrates the great potential of the proposed method in the topical diagnosis and diagnosis of the degree of ischemia of the muscles of the lower extremities, which contributes to the selection of more appropriate treatment tactics. On the other hand, this method can also be used to assess the effectiveness of both surgical and conservative treatment of patients with chronic arterial insufficiency of the limbs, specifying the prognosis of the disease.

Thus, the proposed method for the diagnosis of chronic lower limb ischemia is highly effective, which allows it to be used both for choosing treatment tactics and for dynamic monitoring after the treatment.

Claims (1)

A method for the diagnosis of ischemia of the muscles of the lower extremities in their chronic arterial insufficiency, characterized in that the radioactive drug ^99m Tc-methoxyisobutylisonitrile or ^99m Tc-tetrophosmin is injected into the patient’s peripheral vein, parameters reflecting the intensity of arterial blood supply to the limb are analyzed, then they are carried out not earlier than the next day standard physical activity and immediately after it a radiopharmaceutical is administered in the same dose and ischemia is diagnosed by the degree of blood flow enhancement after exercise mission of the limb muscles.