Contents
The adrenal glands are small paired glandular organs located above the upper poles of the kidneys. They produce hormones (adrenaline, norepinephrine, aldosterone, cortisol, hydrocortisone, and partly sex steroids). Adrenal hormones support the body during stress, mobilize defenses, participate in mineral and water metabolism.
Modern living conditions, physical inactivity, abuse of alcohol, drugs, nicotine lead to the development of various pathologies in these small but important organs. There are organic and functional adrenal diseases. Research that visualizes the adrenal glands helps to identify organic pathologies.
Magnetic resonance imaging (MRI) is by far one of the most informative methods for assessing the state of the adrenal glands. In some cases, to clarify the localization and characteristics of neoplasms, MRI is performed with an additional option – the introduction of a contrast agent.
Method principle
The method of magnetic resonance imaging is based on such a phenomenon as nuclear magnetic resonance. The essence of this resonance lies in the fact that the nuclei of atoms placed in a magnetic field begin to emit energy in the form of a special signal, which is captured by the highly sensitive sensors of the apparatus and in a special way is transformed into a slice in the form of a snapshot.
In the cut image, those areas in the tissues that emit a lot of energy look brighter, denser, and more contrast, and those areas that transmit little signal are practically not visualized. The slice that is performed by the tomograph has a thickness of 1-5 mm.
At the same time, all tissues that are located in the human body above and below the cut are not displayed in the image, which gives a clear image. By superimposing several sections, a three-dimensional image of the organ is formed.
A modern MRI tomograph is a horizontal table for a patient moving along a tunnel with special magnets built into its walls that create a magnetic field with a strength of 0,9 to 3 Tesla, and sensors that receive the finest signals from the nuclei of atoms.
Pros and cons of research
MRI of the adrenal glands has many advantages over other methods of examining these organs:
- the procedure is painless, non-invasive (except for contrast) and does not require special preparation;
- does not emit harmful rays, therefore it does not carry an X-ray load for the patient (unlike computed tomography – CT);
- can be carried out several times in a row;
- has a minimum number of contraindications;
- gives a clear image of the tissue of the adrenal glands;
- detection of the earliest manifestations of ischemic disorders in organs.
Contrast-enhanced MRI may be performed to increase the contrast of images and conduct differential diagnosis of various neoplasms in the adrenal glands.
Despite the large number of advantages, the technique still has disadvantages, which partially limit the use of MRI for diagnosing adrenal pathologies. These include:
- the duration of the study (it can last 15 minutes or more), which in some cases, for example, in restless children, requires sedation (introduction of sedatives);
- low diagnostic ability to detect hemorrhages in the adrenal glands;
- does not reflect the hormonal activity of organs;
- the impossibility of carrying out in those patients who have metal objects in the body (valves, plates, pacemakers);
- the difficulty of carrying out in patients on mechanical ventilation, for example, in acute adrenal insufficiency;
- distortion of results at the slightest movement of the patient;
- difficulties in examining patients with claustrophobia;
- high cost of examination.
In some cases, MRI of the adrenal glands is the only method for non-invasive rapid detection of adrenal pathology, for example, in case of tumors of the medulla.
Tomographs are very expensive, so they are not available for many medical institutions, especially provincial ones. Patients from the outback are often forced to undergo MRI examinations in large cities (for example, in Moscow, St. Petersburg, Rostov, Yekaterinburg).
Indications and contraindications
Magnetic resonance imaging is prescribed for patients with inflammatory pathologies of the adrenal glands, with impaired blood supply to organs, with suspected neoplasms or metastases in the adrenal glands, to determine the tactics of patient management, the volume of surgical interventions, and the effectiveness of antitumor treatment (surgical, chemotherapy, radiation therapy).
The diagnostic procedure should be carried out if the patient is found during clinical and / or laboratory examination:
- sustained increase in blood pressure;
- attacks of tachycardia, arrhythmias;
- severe weakness;
- causeless sudden increase in body weight;
- swelling of the face, limbs and body;
- stretch marks (cyanotic stretch marks) on the abdomen, thighs;
- coarsening of the voice and the appearance of hair on the face in women;
- manifestations of osteoporosis.
The method also has its own contraindications, in the presence of which the procedure can be temporarily postponed (relative) or cannot be performed at all (absolute).
Relative contraindications include severe heart disease, kidney or liver disease in the decompensated stage, early pregnancy, breastfeeding, obesity over 150 kg (when examined on closed-type MRI), mental illness in the acute stage.
Absolute contraindications for MRI of the adrenal glands are the presence of metal-containing devices or elements in the patient’s body, epilepsy, allergy to a contrast agent (in the case of MRI with contrast).
Preparing and conducting a survey
No special preparation for an MRI examination of the adrenal glands is required. A few days before the procedure, it is advisable to stop eating gas-producing foods (beans, peas, fast food, chocolate, sweets) and not to drink alcoholic and carbonated drinks so as not to provoke increased flatulence: the slightest movement of the tissues surrounding the adrenal glands can lead to the appearance of artifacts in the pictures.
Substances based on gadolinium salts are used to contrast the adrenal glands. The contrast agent is injected directly during the procedure by intravenous bolus after a preliminary scan without a contrast agent. A person undergoing an MRI with contrast may have an allergic reaction to it.
Before the procedure, the subject must remove all metal jewelry, belts, cufflinks. If the clothing itself has metal buttons, zippers, or fasteners, then these items of clothing should also be removed. The patient lies on the movable table of the tomograph, which during the procedure moves along the tunnel with magnetic emitters and signal sensors.
A patient lying on the couch of a tomograph should not worry that he is left alone in the room where the MRI machine is installed: a means of communication with the doctor conducting the diagnosis is built into the equipment.
If suddenly the patient becomes ill during the procedure (from worries, as a result of an allergy to contrast), the study will be immediately stopped, and the necessary assistance will be provided to him.
MRI examination of the kidneys and adrenal glands is safe and painless, so it can be performed in almost all patients.
MRI of the adrenal glands lasts from 10-15 minutes, during which a person only hears a hum and a special crackling coming from the walls of the apparatus. When using the contrast stage, the study will take longer – approximately 25-30 minutes. The result of the examination is given to the patient immediately after the procedure, together with the conclusion of the diagnostician.
Deciphering the results of MRI of the adrenal glands
The conclusion based on the results of the examination is made by the doctor of MRI diagnostics. In the examination protocol, he assesses the location, shape, size, structure of the adrenal glands, describes the neoplasms and cysts present in them.
The picture of MRI diagnostics of healthy adrenal glands in an adult should correspond (in most cases) to the following description:
- dimensions: 2,4-2,8 cm x 1,9-2,9 cm x 0,2-0,8 cm;
- the size of the right adrenal gland may slightly exceed the size of the left;
- the adrenal glands should be clearly defined among the tissues surrounding them, have even and clear contours, smooth edges;
- the density of the adrenal glands on the Hounsfield scale ranges from 17,42 to 20,70 units;
- the structure of the organs is homogeneous, homogeneous, without inclusions or seals.
MRI of the adrenal glands with contrast
Magnetic resonance imaging with contrast can help in the differential diagnosis between benign and malignant neoplasms in the adrenal glands, but only a histological examination taken during a biopsy or during surgery can give a reliable result.
Benign tumors, as a rule, are small in size (no more than 3 cm), the shape of the neoplasm is round or oval, with clear edges and even contours, the structure of the formation is homogeneous.
Malignant (oncological) tumors are usually large (more than 5 cm), irregular in shape with “torn” edges and uneven contours. The structure of the neoplasm is heterogeneous, nodal.
These signs are indirect and do not allow the diagnosis of oncological pathology to be made to the patient. They are needed in order to determine the program for further examination and treatment of the patient.
Magnetic resonance imaging in diseases of the adrenal glands provides valuable and highly accurate results, but in itself it does not have 100% diagnostic value.
To make a correct diagnosis, an integrated approach is needed, which includes a survey, examination and objective examination, consultations of related specialist doctors, laboratory tests, hardware and functional examination methods, and, if necessary, diagnostic operations.
Only after receiving the results of all studies, you can get a complete picture of the disease, which will make it possible to determine the tactics of managing the patient.
Engaging in self-diagnosis and self-treatment is fraught with the loss of precious time and the occurrence of life-threatening complications.