Hippocampus MRI is a targeted study of the paired structure located in the temporal lobes of the brain, which involves receiving and digitally processing radio signals from hydrogen atoms when they are in a constant magnetic field of high intensity. It can be performed separately or as part of a comprehensive study of the brain. Allows to make a morphometric assessment of this intracerebral structure responsible for the formation of memory and emotions. MRI can detect changes in the size of the hippocampus (hyperplasia, atrophy, sclerosis). The study is informative in the diagnosis of epilepsy, Alzheimer’s disease, and the causes of amnesia.
As we study the functions of the hippocampus, which is actively continuing at the present time, the list of indications for the diagnostic study of this organ is constantly being updated. Historically, the first indication for MRI of the hippocampus is various memory disorders, especially short-term memory, since it is this organ that is responsible for memorizing, encoding and filtering information entering the brain. Quite often, such a study is prescribed for Korsakov syndrome – a type of amnesia characterized by the inability to remember current events, disorientation, paramnesia.
Often, MRI of the hippocampus is performed in the presence of convulsive seizures (epilepsy) of various origins. Researchers have identified a relationship between the frequency of seizures, their severity and the degree of changes in this area of the brain. In some cases, the presence of sclerosis sites detected on tomograms confirms the diagnosis of epilepsy and allows you to adjust anticonvulsant therapy. In recent years, this study has been used for early diagnosis of Alzheimer’s disease, since a change in the size of the hippocampus is the very first manifestation of this condition.
In recent years, MRI of the hippocampus is carried out in the process of diagnosing depressive states. It has been established that relapses of depression lead to a decrease in the physical size of the hippocampus and, as a consequence, a decrease in its function. Therefore, magnetic resonance imaging allows you to determine how often a patient suffers from such a condition and choose more active antidepressants. In addition, the indication of the examination may be traumatic brain injuries accompanied by memory loss, as well as disorientation, suspicion of tumors of this organ and other conditions. In case of suspicion of the presence of neoplastic processes in the hippocampus, an MRI with contrast is performed to more accurately assess the size and spread of the tumor.
There are few contraindications to MRI, since this study has practically no effect on the human body. An absolute contraindication is the presence of metal implants (pins, orthopedic or dental elements, artificial heart valves) and electronic devices (pacemakers, insulin pumps). Neglect of this rule can have fatal consequences due to the influence of the strongest magnetic field of the device. For the same reason, a contraindication is the presence of metal fragments in the body (for example, after wounds). Relative contraindications are considered to be excessive obesity (due to the parameters of the equipment), claustrophobia, hyperkinesis, expressed in involuntary movements of the head. If there is a need to use contrast, then the list of contraindications additionally includes kidney failure, pregnancy, diabetes mellitus and other endocrine disorders.
Specific preparation for MRI of the hippocampus is not required, except in cases when it is necessary to use contrast – while on the eve of the procedure it is better to refrain from eating and maintain an optimal water regime. Immediately before the MRI, it is necessary to take off all metal objects (jewelry, watches, etc.), and clothes with metal elements. In some medical centers, before the diagnostic procedure, the subject is dressed in a bathrobe or special underwear.
Methodology of conducting
MRI of the hippocampus is performed on specialized equipment that creates a strong magnetic field to excite hydrogen atoms in the tissues under study. During the study, it is very important to keep the head stationary, since any movement can “blur” the picture and reduce the value of the diagnostic study. Scanning takes several minutes, after which an image of the hippocampus and other elements of the brain in any plane is formed on a computer by mathematical data processing. Hippocampal MRI results can be stored on digital media (disk) or record on a special tape. The interpretation of the results is handled by a radiologist, the diagnosis is made by a specialist who sent for the study.
Interpretation of results
MRI of the hippocampus provides information about the relative size of this organ, its symmetry, structure, on the basis of which conclusions are drawn about the presence of certain diseases. Thus, a decrease in the relative size of the hippocampus at a young age indicates frequent recurrent bouts of depression, sometimes such results occur against the background of drug addiction. Organ reduction at the age of 40-50 years is most often the first sign of Alzheimer’s disease, taking into account this circumstance, MRI is considered almost the only method of early diagnosis of this condition. The unequal sizes of the right and left hippocampus indicate the possibility of the development of a neoplastic process (tumor).
With epilepsy and epileptic status in the structure of this organ, areas of sclerosis are detected on tomograms. At the same time, there is a pattern – the more damaged the hippocampus, the more frequent and more severe seizures occur. Contrasting during the study can reveal tumors (both originating from brain tissue and being metastases from other foci). MRI of the hippocampus in Korsakov syndrome or memory disorders confirms hemorrhages, dystrophy, neoplasms or other damage to this brain structure.