Magnetic resonance imaging ( MRT ) is an imaging procedure that is used in medical diagnostics, especially for the visualization of soft tissue and organs. With the help of magnetic resonance tomography, the finest sectional images of the body can be made.
Due to the particularly high-resolution images, which are generated by MRI, individual changes in organs and the soft tissue can be reproduced accurately.
The mode of operation of the MRI is based on a very strong magnetic field generated within the device, which excites certain atomic nuclei (especially hydrogen nuclei / protons ) in the human body.
The use of a magnetic field to represent tissues and organs offers tremendous advantages compared to conventional imaging techniques.
One advantage of MRI over imaging techniques (such as x-rays) is the ability to achieve significantly better soft tissue contrasts. The differences in the presentation of different types of fabric based on their specific fat and water content.
In addition, the images can be generated by an MRI, in contrast to conventional radiography, without harmful ionizing radiation ( X-rays ). This has the consequence that it does not come to a radiation exposure even with repeated production of MRI images.
Furthermore, an improvement in the diagnostic possibilities results from the fact that two different acquisition series can be obtained with the magnetic resonance tomograph. In this connection, a distinction must be made between contrast-free and contrast-enhanced MRI. With the help of contrast-enhanced MRI, for example, inflammatory processes or vital tumor tissue can be better visualized by intensified whitening.
In addition to the usual MRI, in which the preparation of the sectional images takes a longer period of time, the medical diagnostics are now so-called " real-time MRI " available. With this form of imaging, individual slices can be scanned in a fraction of a second.
With the help of this method, for example, movements of organs can be displayed in real time. In addition, real-time MRI can be used during surgery to show the exact position of medical instruments.
Thus, although magnetic resonance imaging offers a variety of advantages, this form of imaging can not be performed on every patient. Patients who wear a pacemaker or implanted defibrillator usually can not have MRI. The reason for this is the fact that both the pacemaker and the implanted defibrillator could be damaged during the examination. In addition, interactions between these medical devices and the MRI scanner can significantly damage the health of the patient.
In addition, persons who have metal fragments and / or vascular clips made of magnetic materials in an unfavorable position (for example in the area of the eye or on the brain) can not be diagnosed with the aid of MRI.
An early pregnancy (1st trimester, 1st to 13th week) is considered a contraindication for the performance of a magnetic resonance tomography. However, in women who are in early pregnancy, it must be decided individually whether there is a risk to the unborn child.
In addition, performing an MRI scan on people who are claustrophobic can be problematic. The reason for this is the fact that the patient must be completely placed in a closed tube for some MRI indications (for example, MRI from the head or MRI of the cervical spine). Especially in these patients, the enormous benefits offered by MRI have so far been limited or used with sedatives.
For some time, however, several radiological institutes have been offering examinations in a so-called open MRI. Patients with claustrophobia can finally take full advantage of magnetic resonance imaging thanks to this new form of imaging.
The new open MRI equipment is not a tube with an opening at the top and bottom, as has been used in some radiology institutes since the 1990's. Due to the novel design, which requires only a single buttress, access to the patient to be examined over 320 degrees is now possible.
Especially for people who suffer from severe claustrophobia, the almost unrestricted view from the magnetic resonance tomograph offers enormous advantages.
An open MRI can therefore be used in almost every patient. In direct comparison to conventional closed MRI devices, however, an open MRI can only produce a significantly lower magnetic field strength. While the magnetic field strength in a tunnel system is about 1.5 to 3 Tesla, in open MRI only 0.4 to 1.0 Tesla can be generated. At first glance, this may seem to be a disadvantage of the open magnetic resonance tomograph. In fact, lowering the magnetic field strength has a major impact on the ability of the device to excite hydrogen atoms ( protons ) in the human body. This in turn can have a negative effect on the resolution of the individual sectional images. For this reason one could assume that the images produced in an open MRI are much blurred and less detailed.
According to some studies, the reduction of the magnetic field strength can be compensated almost completely by a longer recording time. An open MRI is even, if it concerns a device of newer year of construction, by increasing measuring times able to produce equivalent or even better quality sectional images.
In addition, eccentric body portions, such as the shoulder, elbow and wrist, due to the variety of storage options, can be examined in much more comfortable positions. In this way, motion artifacts that adversely affect image quality can be avoided. This is not readily possible in most of the conventional magnetic resonance imaging (MRI) scanners.
An open MRI offers many advantages over the conventional closed MRI tube.
The main advantages of this novel diagnostic procedure include the fact that open MRI:
Although an open MRI can only produce lower magnetic field strength compared to a closed tube, all adjustments can be made by adjusting the acquisition time.
An open MRI can produce sectional images of the joints, internal organs, nerves and vessels and the female breast in particularly high image quality. Without exposure to radiation, as is the case with conventional x-ray images or computed tomography, for example, the patient's internal tissue can be visualized and even the smallest changes made visible.
In addition, an open MRI, compared to the closed magnetic resonance imaging, has a much wider lying surface. For this reason, the open MRI offers patients much more comfort. Especially for people who suffer from severe claustrophobia, the examinations can be carried out by the 360-degree all-round view without anxiety attacks. The use of a tranquilizer prior to examination is usually not necessary in these patients. For this reason, it is no longer necessary to bring an accompanying person to the MRT appointment.
An open MRI also provides enormous benefits for the examination of small children. If the positioning of the child alone in the device should not be possible, a parent can go to the examination couch. In this way, even in infants, high-resolution sectional images without movement artifacts can be generated. The examination in open MRI is much more relaxed and less stressful for the child.
Due to the extensive design of an open MRI with a 360 degree panoramic view, even older patients are much more comfortable in the examination device. This advantage can also be used for people with limited range of motion.
Stark obese patients could be examined in the conventional magnetic resonance tomographs so far only limited or not at all. Due to the expansion of the space on the bed, these patients can now be examined with an open MRI easily.
In addition, the quality of the sectional images can be positively influenced by the possibility of being able to move the patient to be examined in all directions on the examination couch. The reason for this is the fact that the resolving power of each magnetic resonance tomograph is centrally highest. If, for example, the liver is to be displayed, then the patient to be examined can be positioned so that the liver is in the center of the MRI.
Even with techniques that are getting better and better, the lower field strength of the magnetic field can not make up for the reduced quality to closed MRI.
The costs for an examination in an open MRI are not covered by the insurance carriers in all cases (especially in the statutory health insurance (SHI)).
Patients who are privately insured may have the total cost of performing an open MRI exam charged by the insurance.
The statutory health insurance companies, however, reimburse the costs only in selected cases. Prerequisite for the assumption of the costs in open MRT is the so-called cost- acceptance declaration .
This is granted only under certain conditions and should be obtained prior to the conduct of the investigation. In order to be able to decide on the special situation of the patient, the health insurance company needs a justification for the choice of the open MRI procedure, as well as a cost estimate. This estimate can be obtained from the radiology institute where the examination is to be carried out.
It is therefore essential to apply for reimbursement prior to the start of the investigation. As a rule, the statutory health insurance fund gives this application to small children without any problems. Even with seriously overweight patients, who can not be examined in a closed MRI, a reimbursement by the health insurance is generally not a problem. Persons who are prone to clawing open MRI due to claustrophobia must, ideally, be able to demonstrate this by medical examination. For this reason, it is recommended that (if this attempt has already been made) documented by the attending radiologist anxiety attacks in a closed tube system and forwarded to the health insurance.
If an open MRI can not be performed due to the reimbursement of the health insurance company, you can read here how an MRI can be performed in case of claustrophobia.
If the reimbursement of costs is not granted by the statutory insurance, the patient must fully pay for the examination by open MRI.
As a self-payer, the patient receives an invoice in which all costs are listed on the basis of the fee schedule for physicians (in short: GOÄ). The actual costs depend on the organ to be examined and the effort of the examination.
Depending on the organ system, an open MRI can cost between 140 and 1200 euros in Germany.
The costs vary depending on the imaging performed (location of the MRI), additional sections, reconstruction of the images, administration of contrast medium and radiology.
For privately insured costs between 500 - 1000 € can be expected.
Read more on this topic under: Cost of an MRI
An open MRI is able to display almost any body region in high-resolution tomograms. For this reason, images of the head ( skull ) in an open MRI can be easily generated. In direct comparison to closed head (or cranial) magnetic resonance tomography, no differences in quality can be detected in open MRI.
In the MRI examination of the skull, images without contrast media must be taken first both in the closed tube and in open MRI. Only then can special structures be more clearly imaged using a contrast agent.
An open MRI offers the advantage when creating the sectional images of the head (skull) that the comparatively long examination time can be spent in a much more pleasant position. In addition, the MRI examination of the head (skull) in a closed device presents a major challenge especially for patients suffering from claustrophobia. An open MRI, however, provides an all-round view and also in the preparation of sectional images of the head (skull) thus also allows for claustrophobia patients a pleasant study atmosphere.
Also read the appropriate topic: MRI from the head
In addition to the visualization of soft tissue and internal organs, open MRI is also used for diagnostic imaging of joints. Especially the pelvis, the shoulder and the knees can be imaged with high resolution using the open MRI.
When using the closed tube, it can often be observed that the images cause the development of motion artifacts. The reason for this is usually the fact that the position in which the shoulder to be examined or the knee to be imaged must be kept during the examination is very unpleasant for the patients.
An open MRI offers the advantage when taking pictures of the shoulder or the knee that the joint to be examined can be gently positioned. In this way, motion artifacts on the shoulder and knee slices can be reduced.
Restricting a lower magnetic field strength has the advantages over that usually the image quality in an open system is worse than in a closed MRI.
An open MRI of the spine provides overlay-free, high-resolution cross-sectional images, which can be made without radiation exposure. In addition, the MRI scan of the spine can be performed in a comfortable position. Only in MRI, whether it is a closed tube or an open MRI, cartilage, ligament and spinal cord structures of the spine can be imaged in sufficiently high quality and resolution.
When examining the spine in an open MRI, the patient is pushed into the device, either lying on his stomach or on his back. Examination of the spine in open MRI usually takes between 15 and 30 minutes.
Among the most common suspected diagnoses, which make the preparation of MRI images of the spine necessary, include:
By administering a contrast agent while performing an open MRI, an artificial density difference between different structures can be generated. A contrast agent is always necessary when very similar body tissues, such as muscles and blood vessels, are to be delimited from each other.
Also in open MRI, two types of contrast agents must be distinguished: iodine and barium sulfate-containing contrast agents. A contrast medium for carrying out an examination in open MRI, which contains an amount of iodine, is used primarily to sharply contrast kidneys, vessels and internal organs.
In contrast, a contrast medium with a barium sulfate content is particularly suitable for sharpening the appearance of the gastrointestinal tract.