MRI of the brain with contrast

A diagnostic method for studying the internal systems and structures of the body is MRI. Let's consider the features of this procedure, indications for contrast.

MRI is a non-invasive and safe diagnostic method. It is used to detect various disorders and severe pathologies. During the examination, the device takes clear and detailed pictures of the structures being studied, and the introduction of contrast allows the slightest deviations to be visualized.

The main advantages of MRI with contrast are based on its high information content in comparison with standard magnetic resonance imaging:

• Localizes the lesion with high accuracy and shows its size.
• Determines the degree of tumor malignancy and the smallest foci of its metastasis. [ 1 ],
• Allows to identify pathologies at early stages and prevent their further development.

Before the examination, the patient is injected with special substances that highlight and visualize the brain structures. Coloring agents have a minimum of contraindications, do not cause allergic reactions and are quickly eliminated from the body. According to medical statistics, complications after contrast occur in 0.1% of cases.

Today, more than 20% of all MRI examinations are performed using a contrast agent. The need to use a contrast agent is determined by the attending physician. Most often, it is prescribed for suspected oncology, vascular disorders, to detect signs of stroke, complications after injuries. [ 2 ]

Is MRI with contrast of the brain dangerous?

Magnetic resonance imaging of the brain using a contrast agent has a wide range of applications. But many patients are afraid of intravenous/oral administration of contrast due to the risk of complications. In fact, the procedure does not have a negative effect on the body, and the occurrence of side effects is associated with individual intolerance to the chosen agent.

The possibility of using contrast has brought MRI to a new level of non-invasive procedures, allowing for the most reliable establishment of diagnoses and acute conditions. Most often, drugs with intra-complex compounds of gadolinium ion are used for contrast:

• Nasty. [ 3 ]
• Dotarem. [ 4 ]
• Primovist. [ 5 ], [ 6 ]
• Gadolinium. [ 7 ]

These substances have passed all clinical trials, so if the dosage is calculated correctly, they do not pose a threat to the body. The contrast affects the electromagnetic waves of the device, which allows you to get the most accurate image.

At the same time, the isotope used as a marker can become toxic if there are problems with its elimination from the body. Because of this, the procedure is not prescribed for renal failure and hypersensitivity to the substance used. [ 8 ]

Indications for the procedure

Magnetic resonance imaging with contrast allows us to detect many disorders in the functioning of the brain. The main indications for the diagnostic manipulation are:

• Tumor lesions of the pituitary gland and tissues surrounding the sella turcica.
• Brain tumors and metastases. [ 9 ]
• Tumors of the cerebellopontine angle.
• Acute cerebrovascular accidents of hemorrhagic or ischemic type.
• Vascular pathologies of the central nervous system.
• Infectious diseases of the central nervous system.
• Chronic diseases of the nervous system of autoimmune etiology (multiple sclerosis, [ 10 ] leukodystrophy, leukoencephalopathy, etc.).
• Detailed study of the structure of identified neoplasms.
• Assessment of the state of brain structures after operations and injuries.
• Detection of brain metastases.
• Alzheimer's disease.
• Cerebral hemorrhage.

There are also a number of symptoms that are an indication for an MRI of the brain with contrast:

• Migraines and headaches.
• Frequent dizziness and fainting.
• Traumatic brain injury.
• Convulsive and epileptic seizures.
• Tinnitus.
• Progressive deterioration of hearing and vision.
• Impaired sensitivity (tactile, pain, temperature).
• A crawling sensation on the skin.

The method of layer-by-layer examination of organs and tissues using nuclear magnetic resonance allows us to identify the smallest metastases, signs of inflammatory processes and assess the volume of the surgical field before surgery. [ 11 ]

Preparation

One of the advantages of contrast-enhanced MRI of the brain is that the procedure does not require any special preparation. There is no need to follow strict diets, abstain from food for a long time, or follow any other rules.

Preparation for diagnostic manipulation is based on studying the patient's medical history and indications for MRI. To do this, the doctor conducts a survey and clarifies the presence of pathologies, studies the results of previously conducted tests. This is necessary in order to avoid errors during the study and reliably decipher the results obtained.

Before the actual start of the scan, you should remove all metal objects and clothing. Women should remember that it is better not to apply makeup before the diagnostics, as cosmetics may contain microparticles of metal. These precautions are associated with the risk of distorting the results.

Particular attention is paid to the choice of contrast agent. The isotope used as a marker can be hydrophilic complex compounds with a high concentration of gadolinium cations. Preparations from the group of magneto-pharmaceuticals differ from those used in radiography. They are less toxic than the contrast in iodine salt, which is used for fluorography and CT. [ 12 ]

Technique MRI of the brain with contrast

MRI begins with proper preparation for the procedure. If all the rules are followed and a contrast agent is selected, the doctor begins the examination. There are many contrast agents, but they are all divided into the following groups:

• Intravascular – the dye is injected into the vein in full at a rate of 0.2 mg/kg of weight. For these purposes, preparations based on iron oxide or manganese compounds, which have superparamagnetic properties, are used.
• Bolus – intravenous dosed administration through a drip. In this case, the course of the diagnostic procedure is synchronized with the supply of contrast. [ 13 ]
• Oral – used to examine the gastrointestinal tract. Manganese and gadolinium compounds, certain natural products with increased manganese content are used as isotopes.

Using a special syringe or injector (automatically regulates the dose of the drug), the patient is injected with a contrast agent. Then the patient is sent into the tomograph tunnel and the head is fixed to immobilize it. The scanning duration is from 10 to 30 minutes.

Allergic reactions (itching, urticaria) to gadolinium compounds are extremely rare. Improved visualization of the tissues being examined is achieved due to the substance passing through the blood vessels and accumulating in the soft tissues. Gadolinium amplifies the magnetic signal of the tomograph, thereby improving the quality of the images.

The diagnostic manipulation allows to identify the localization and the extent of the affected cells already in the first hours of stroke development. [ 14 ] It determines the size of neoplasms, their structure, location, and the presence of metastases. The isotope penetrates defective cells, highlighting them against the background of healthy ones. [ 15 ]

MRI of the brain with contrast 1.5, 3 Tesla

The method of layer-by-layer examination of organs and tissues using nuclear magnetic resonance and contrast enhancement is one of the most popular and reliable in modern medicine. The basis of MRI is a change in the behavior of hydrogen atom nuclei under the influence of electromagnetic waves in the field of the tomograph, i.e. magnetic resonance. The magnetic field is harmless to the human body, unlike ionizing radiation used in CT.

There is a misconception that contrast significantly affects the overall quality of the resulting image (brightness, contrast, resolution, clarity). But contrast accumulates only in areas of the brain with pathological changes and cannot affect the clarity of the images. In fact, image quality depends entirely on the magnetic field strength.

Conventionally, all tomographs are divided into three groups:

• Low-floor – 0.23-0.35 T.
• Mid-floor – 2 T.
• High-field – 1.5-3 T.
• Ultra-high-field – more than 3 T.

The unit of measurement of magnetic field strength (T) was named after the scientist Nikola Tesla. Most diagnostic centers have tomographs with a power of 1-2 T. Low-field devices are rarely used, since their results are not 100% reliable and accurate. That is, the higher the field strength, the more accurate the examination result. [ 16 ]

The gold standard of MRI is diagnostics on devices with a power of 1.5-3 T. In addition to the quality of the images, the intensity of the tomograph affects the scanning speed. Examination of the brain on a tomograph with 1 T takes about 20 minutes, on a 1.5 T device - 10-15 minutes, and on a 3 T device - up to 10 minutes. In some cases, this is important, for example, when diagnosing patients in serious condition.

Features of MRI of the brain with contrast of 1.5-3 Tesla:

• Increased clarity and detail of images.
• The procedure does not take much time.
• Can be used when there are problems with diagnosis.
• Study of fine tissue structures.
• Effective search for the smallest metastases and disorders.

Despite the effectiveness of high-field tomographs, their use for some patients is limited. Such devices are only of a closed type, so they are not suitable for people with excess body weight, claustrophobia, intolerance to high noise levels. Such devices do not have the ability to monitor the functioning of organs.

Low-field tomography is less expensive in technical terms and is cheaper for the patient. The study can only be prescribed for preliminary diagnostics. Devices with a power of more than 5 T are used exclusively for scientific research purposes.

MRI of the brain vessels with contrast

Scanning of the brain vessels using a contrast agent is called MR angiography. The tomograph emits a specific combination of electromagnetic waves that provoke the oscillation of the nuclei of hydrogen atoms in the molecules of the human body. The introduced contrast improves the quality of the procedure, allowing the visualization of the smallest structures and components of the area being studied. [ 17 ]

Multiple MRIs are safe for the body. The main indications for magnetic resonance imaging of the brain vessels using contrast are:

• Acute cerebrovascular accident.
• Assessment of blood flow through brain tissue.
• Detection of hemorrhages.
• Diagnostics of metabolic disorders.
• Congenital anomalies.
• Assessment of the scope of surgical intervention before surgery.
• Detection of metastases and tumors.
• Mapping the cerebral cortex.
• Traumatic brain injury.
• Atherosclerosis, inflammation of the walls or pathological dilation of blood vessels.
• Headaches of unknown etiology.
• Narrowing of the lumen of the arteries.
• Infectious diseases
• Acute infectious processes.
• Damage to the organs of hearing and vision.
• Increased intracranial pressure.
• Epilepsy and other pathologies.

Tomographs with a power of 0.3 T are used to scan the brain vessels. Before the procedure, it is necessary to remove all metal items, including clothing with metal inserts. The patient is injected with contrast, then placed on a couch, the head is fixed and moved into the tomograph.

The duration of the procedure depends on the power of the device, on average it takes no more than 45 minutes. If in addition to angiography spectroscopy is performed (study of biochemical processes inside cells), then this requires additional time. After completing the diagnosis, the radiologist deciphers the images obtained and gives his conclusion. [ 18 ]

MR angiography has a number of contraindications. The procedure is prohibited in case of hypersensitivity to the contrast agent, during pregnancy, for patients with pacemakers, electronic or metal implants and even braces. [ 19 ]

MRI of the pituitary gland with contrast

The pituitary gland is an appendage of the brain. The gland is located in a bony pocket (sella turcica). Its dimensions are 5-13 mm in length, 3-5 mm in width and about 6-8 mm in height. But despite such tiny dimensions, the pituitary gland is the central organ of the endocrine system. It produces hormones that are responsible for regulating the functioning of the entire body.

The main functions of the pituitary gland:

• Production of hormones of the thyroid gland, sex glands, and adrenal glands.
• Production of somatostatin (growth hormone).
• Regulation of the central nervous system (psychoemotional state, stress level, appetite).
• Affects the endocrine, genitourinary and reproductive systems.
• Regulates blood pressure.
• Responsible for pigmentation.
• Regulates the functioning of the cardiovascular system and kidneys.
• Responsible for maternal instincts.
• Stimulates the lactation process.

The method of layer-by-layer examination of the pituitary gland using nuclear magnetic resonance and contrast enhancement is performed to visualize the gland itself and its location - the sella turcica of the sphenoid bone.

Most often, diagnostic manipulation is prescribed for regular hormonal disorders caused by congenital pathologies, injuries, tumors. Scanning is indicated for patients with various endocrine disorders. [ 20 ]

The main indications for MRI of the pituitary gland with contrast are:

• Headaches of unknown etiology.
• Dizziness.
• Visual impairment.
• Metabolic disorders.
• Menstrual dysfunction in women and erectile dysfunction in men.
• Hormonal pathologies (Itsenko-Cushing syndrome, acromegaly).
• Changes in the concentration of pituitary hormones in the blood (thyrotropin, prolactin, somatropin).

To improve the quality of the procedure, contrast agents are used. Contrast makes it possible to verify the presence of microadenomas and other pathologies that are not visible in standard MRI.

For these purposes, paramagnetic contrast agents are used, which are administered immediately before the procedure. The dosage is calculated individually for each patient. In this case, iodine-containing contrast agents are not used. If the patient has chronic kidney or urinary system diseases, then a set of tests should be taken before the diagnosis. This is necessary to determine the rate of contrast removal from the body. [ 21 ]

But, like any diagnostic procedure, MRI has a number of contraindications. They are usually divided into absolute and relative.

Absolute contraindications:

• The patient has a pacemaker.
• Metal implants, fragments and other metal objects in the patient's body.
• Dental braces.

Relative:

• First trimesters of pregnancy.
• Claustrophobia (an open-type tomograph is required for diagnosis).
• Epilepsy.
• Inability of the patient to remain still during the examination.
• The patient's condition is serious.
• Allergy to the contrast used.
• Severe renal failure.

No special preparation is required for MRI of the pituitary gland. It is recommended not to eat for 5-6 hours before the procedure. It is better to administer the contrast on an empty stomach to minimize the risk of side effects. Before entering the office, the patient removes all metal objects. Scanning is performed in a supine position. In order to ensure maximum immobility of the head, it is fixed to the couch. The duration of the procedure is 30-60 minutes.

The results are deciphered by a radiologist, who also writes out a conclusion. Normally, on a section in the frontal plane, the shape of the pituitary gland is similar to a rectangle. On a frontal section, the pituitary gland is symmetrical, but slight asymmetry is also a normal variant.

Pathologies revealed during the research:

1. Empty sella syndrome - the images show the pituitary gland spread out along the bottom of the sella turcica. The optic chiasm cistern prolapses into the cavity of the bone formation. In the images with the anterior-posterior direction, the pituitary gland resembles a sickle, and its thickness is 2-3 mm.

Tumors in the sella turcica are differentiated by size. Up to 10 mm in diameter is a microadenoma, more than 10 mm is a macroadenoma. Tumors larger than 22 mm are mesoadenoma, and larger than 30 mm are giant adenomas. Tumors in the chiasmal-sellar region can also be diagnosed.

Tumors can grow into the cavernous sinuses, ventricles of the brain, sphenoid sinus, nasal passages and other structures.

2. Diabetes insipidus – develops due to a lack of the hormone vasopressin, which is produced by the cells of the hypothalamus, enters the pituitary gland, and from there into the blood. Hormone deficiency provokes inflammatory processes in the hypothalamic-pituitary system and the appearance of neoplasms.
3. Somatotropic hormone deficiency – during tomography, ectopia of the neurohypophysis, hypoplasia of the adenohypophysis, hypoplasia/aplasia of the pituitary stalk may be detected. STH deficiency also manifests itself as empty sella syndrome.

Diagnostic manipulation with contrast enhancement is the most informative method in diagnosing pituitary pathologies. MRI allows to detect the smallest tumors and deviations from the norm. [ 22 ] It has a minimum of contraindications and side effects, does not require special preparation. Allows to make a timely correct diagnosis, which is the key to the success of the prescribed therapy.

MRI of the brain with contrast for a child

Children are predisposed to the development of various pathologies that are directly related to age-related changes in the functioning of the brain. For reliable diagnosis of any disorders, MRI is performed. This study allows us to identify the smallest deviations in the tissue structure of the organ.

The use of nuclear magnetic resonance for children has a wide range of indications. Brain examination is necessary in the following cases:

• Frequent dizziness and headaches.
• Loss of consciousness.
• Deterioration of hearing and vision.
• Impaired sensitivity.
• Convulsions.
• Retardation of mental development.
• Head injuries.
• Emotional lability.

The above symptoms are a reason to undergo tomography. Timely diagnostics allows to identify such diseases and disorders:

• Brain hemorrhages.
• Vascular pathologies.
  Pituitary gland lesions.
• Epilepsy.
• Hypoxia.
• Sclerosis.
• Cystic and tumor neoplasms.

The procedure does not require any special preparation. All metal objects are removed from the patient and a contrast agent is injected. But the most difficult task is to keep the baby still for the entire duration of the scan. In addition, the tomograph is quite noisy, which is a challenge for children under 5 years old. Anesthesia is recommended for a quality examination.

The main purpose of anesthesia is to turn off the child's consciousness. The type of anesthesia and the method of its administration are determined by the anesthesiologist after studying the information about the baby's health. Anesthesia can be administered parenterally or by inhalation. During the procedure, doctors monitor the patient's breathing and cardiac activity. And after the procedure, they observe the child until he or she regains consciousness. [ 23 ]

MRI is not harmful to children. To date, no cases of negative effects of nuclear resonance on a child's body have been established. As for the disadvantages of the method, they include fear of prolonged stay in a confined space and allergic reactions to contrast agents. An absolute contraindication to diagnostics is electronic devices implanted in the body.

Contraindications to the procedure

MRI is an advanced diagnostic procedure. However, despite this, examination using a contrast agent has a number of contraindications:

• Metal implants and other foreign objects in the body.
• Hypersensitivity to the components of the contrast agent.
• Renal failure.
• Low blood pressure.
• Thickening of the skin.
• Pathologies of the urinary system.
• Blood diseases, anemia.
• First trimester of pregnancy.
• Breast-feeding.
• Different types of asthma.

Most often, gadolinium is used as a contrast agent. It contains a safe metal that minimizes the risk of side effects. But 2% of patients may experience skin irritation and itching, and a decrease in blood pressure. As the contrast agent is eliminated from the body, the patient's well-being returns to normal.

You cannot come to the examination with a full stomach or after drinking a lot of water. Also, you will not be allowed to undergo a tomography if you are intoxicated.

Normal performance

MRI is a method of layer-by-layer examination of organs and tissues using nuclear magnetic resonance. To increase the accuracy of the procedure, it is possible to introduce contrast enhancement. In fact, such diagnostics allows you to see any disturbances in the tissue structure, neoplasms, pathological processes, vascular deformations, physical and chemical disturbances. [ 24 ]

MRI with tissue contrast enhancement reveals the following brain disorders:

• Pathologies of cerebral vessels.
• Internal bleeding.
• Brain injuries and contusions.
• Tumor neoplasms.
• Tumors of the cerebellopontine ganglion.
• Signs of infectious diseases of the central nervous system.
• Praxismal states.
• Abnormal development of blood vessels in the head.
• Pituitary tumors.
• Neurodegenerative and other diseases.

Preparations with gadolinium are used as a contrast agent. When entering the intercellular space, the substance forms weak bonds with the hydrogen of water molecules. The preparation does not penetrate the blood-brain barrier and does not affect tissue contrast. However, inflammatory and infectious processes, hemorrhages, necrosis of brain cells, neoplasms and metastases provoke a violation of the blood-brain barrier, due to which gadolinium freely enters pathologically altered tissues, staining them. [ 25 ]

Particular attention is paid to the values of the rate and degree of accumulation of contrast in the tissues of neoplasms. Benign tumors slowly absorb and release a small amount of contrast. Malignant neoplasms have a developed vascular network, so they capture a large amount of contrast and quickly release it. This allows us to make preliminary conclusions about the nature of the tumor. [ 26 ]

Complications after the procedure

Despite the uniqueness, safety and diagnostic value of magnetic resonance imaging, there are still patients who are convinced that scanning is dangerous due to serious complications for the body.

• Radiation – during the procedure it is 5 times lower than during a conversation on a mobile phone.
• Pregnancy – there is currently no reliable data on the negative impact of MRI on the fetus. The procedure is performed for expectant mothers. The only warning concerns lactation. When introducing contrast, breastfeeding should be interrupted for 24 hours.
• Exacerbation of chronic diseases - magnetic resonance does not affect chronic diseases.
• Negative impact on the central nervous system – the device does not affect the psyche. But there are restrictions for the procedure for people with an unstable nervous system. During the scan, it is necessary to lie still, so drug-induced sleep is recommended for such patients.
• Adverse effects on the kidneys and urinary system. It is not the MRI that is dangerous to the kidneys, but the contrast used. Due to problems with excretion, it can cause adverse reactions or provoke an exacerbation of the disease. For this reason, contrast scanning is not performed on patients with chronic renal failure.

Diagnostic manipulation can cause complications, but in most cases they are associated with failure to follow medical recommendations. For example, the introduction of contrast can provoke a number of allergic reactions, so before the procedure the patient undergoes a sensitivity test to the selected drug. [ 27 ]

Some patients complain of headaches after the procedure. An unpleasant symptom occurs if there were objects with metal parts on the body or clothes during the scan. Because of this, some medical centers issue disposable sets of clothes for the examination.

Another possible complication is an unpleasant metallic taste in the mouth. This problem is encountered by patients who have dental fillings and fonts. After a while, the taste goes away on its own. [ 28 ]

Consequences after the procedure

In most cases, the only possible consequences of contrast MRI include allergic reactions. However, incorrect administration of contrast is also dangerous and can cause the following problems:

• Air blockage of blood vessels.
• Infectious contamination (phlebitis, shock, sepsis).
• Local inflammation when the drug is administered outside the vein.

The most problematic and severe side effect of contrast use is nephrogenic systemic fibrosis. This pathology involves damage to the skin and parenchymatous tissue of internal organs. Active proliferation of fibrous tissue is observed. [ 29 ]

The occurrence of this disease is associated with a hereditary predisposition, renal failure, and MRI with contrast. To prevent fibrosis due to diagnostic scanning, before the procedure, the doctor evaluates the condition of the kidneys and conducts an analysis of the glomerular filtration rate. [ 30 ], [ 31 ]

Particular attention is paid to calculating the contrast dosage for each specific study.

Care after the procedure

MRI of the brain with contrast does not have any post-procedure restrictions. Immediately after scanning, the patient can return to normal life. The only caveat is patients with allergic reactions to contrast. To alleviate the unpleasant condition, it is recommended to take antihistamines and drink plenty of fluids. If headaches appear after scanning, you can take a painkiller and be sure to report the unpleasant symptom to the doctor.

According to numerous reviews, the method of layer-by-layer examination of organs and tissues using nuclear magnetic resonance and contrast enhancement is one of the most informative diagnostic procedures today.

Non-invasive visualization of the brain finds the slightest changes in the structure of its tissues. Scanning reveals malignant neoplasms and their metastases, the consequences of injuries, ischemia, hemorrhages, various developmental anomalies and much more. The procedure is painless and poses no danger to the patient.

Which is better? MRI of the brain with or without contrast?

Magnetic resonance imaging is a highly effective diagnostic method. It is used to detect pathologies such as:

• Malignant/benign neoplasms.
• Infectious and inflammatory processes in the body.
• Cystic formations.
• Metastases.
• Vascular pathologies.
• Traumatic injuries.
• Hemorrhages.
• Congenital developmental anomalies.

But in some cases, a regular MRI is not enough, so contrast enhancement is indicated. Most often, contrast is used to examine the brain and its vessels. Preparations based on gadolinium salts are used as a contrast. The substance introduced into the body acts as a kind of indicator, as it accumulates in the altered tissues.

The use of contrast is painless and harmless to the body. The only contraindication to its use is individual intolerance. Contrast enhancement allows to detect the smallest neoplasms in the brain structures, determines early signs of Alzheimer's, stroke and many other pathologies. Very often, contrast is prescribed to assess the condition of the pituitary gland.

MRI of the brain with contrast and the procedure without dye differ in that in the first case, a clearer visualization of the organ being examined is possible. The decision on the choice of one or another method is made by the attending physician, assessing the indications and all possible complications.