Introduction
MRI imaging of the brain is used for many different problems and, in addition to CT imaging, it is another way to obtain a detailed view of the skull and brain tissue. MRI is particularly well suited for imaging soft tissues, whereas CT imaging is better for imaging bone. Indications for an MRI examination of the brain include the diagnosis of a stroke or precursors of a stroke, spatial masses such as benign or malignant brain tumors, water retention, etc. so-called demyelinating brain diseases, such as multiple sclerosis, so-called degenerative brain diseases, such as the various forms of dementia or Parkinson’s disease, severe headaches (e.g. migraine), epilepsies or birth defects. The MRI can be used for the initial diagnosis, for monitoring the course of the disease, for therapy planning or for therapy monitoring.
Do I need contrast medium?
Whether a contrast medium is required or used in an MRI examination depends on the problem – i.e. on the structures that are to be examined with special attention. Since MRI images are shown in black and white and the range of gray scales is limited, it may be difficult to distinguish between different structures or tissues. If a contrast medium is administered – usually via the arm vein – it can make it easier to distinguish specific tissues from the surrounding area.
The reason for this is that the contrast medium used in MRI is particularly distributed in the blood vessel system and is more likely to flood into tissues such as tumors or metastases as well as into tissues that are inflammatory. This means that, for example, brain aneurysms, bleeding, centres of inflammation or brain tumours/metastases can be better visualised and highlighted by administering contrast medium. Whether a contrast medium is used is decided by the examining radiologist before or during the examination.
MRI of the brain in MS
In the context of multiple sclerosis (MS), magnetic resonance imaging (MRI) is used to make a diagnosis on suspicion and to monitor the course of the disease if the diagnosis is already established. What the MRI image of the brain can show in relation to MS disease is in particular the centres of inflammation that are characteristic of this neurological disease of the central nervous system. The centres of inflammation are caused by the body’s own immune system mistakenly recognizing certain structures of the nerves or nerve cells as foreign and fighting them (so-called autoimmune reaction), so that an inflammatory reaction occurs (also called “centres of inflammation”). These centres of inflammation are mainly located in the lateral cerebral ventricles (periventricular) and in the so-called “bar“, a part of the brain that connects both halves of the brain. In the MRI they usually appear brighter than the surrounding tissue, especially when contrast medium is given as part of the MRI diagnosis.
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