Magnetic resonance imaging (MRI) of the skull (synonyms: cranial MRI; cMRI; brain MRI) – or also called magnetic resonance imaging or NMR (nuclear magnetic resonance imaging) of the skull – refers to a radiological examination procedure in which a magnetic field is used to examine primarily the brain, but also bony portions, vessels, cerebral ventricles with cerebrospinal fluid (cerebral ventricles with cerebrospinal fluid), and the remaining soft tissues inside the skull. MRI is now routinely used for many different indications, as it is a very informative diagnostic method.
Indications (areas of application)
- Cerebral hemorrhage
- Brain tumors
- Cerebral infarction
- Meningitis (meningitis)
- Encephalitis (inflammation of the brain) or other inflammatory changes in the area of the brain and facial skull.
- Craniocerebral trauma (TBI)
- Changes in blood vessels such as atherosclerosis (arteriosclerosis, arteriosclerosis), vascular anomalies angiomas, aneurysm formation).
- Representation of the orbit (eye socket), representation of the inner ear with the representation of the auditory ossicles, representation of the internal auditory canals.
- Injuries to the eye or ear
- Cranial nerve injuries
- Malformations in the area of the skull
- Diagnosis of tumorous, cystic and inflammatory dental, oral and maxillofacial diseases.
- Joint pain, noise and movement restrictions in craniomandibular dysfunction (CMD).
Contraindications
The usual contraindications apply to cranial MRI as they do to any MRI examination:
- Cardiac pacemakers (with exceptions).
- Mechanical artificial heart valves (with exceptions).
- ICD (implanted defibrillator)
- Metallic foreign body in dangerous localization (e.g., in close proximity to vessels or eyeball)
- Other implants such as: Cochlear/ocular implant, implanted infusion pumps, vascular clips, Swan-Ganz catheters, epicardial wires, neurostimulators, etc.
Contrast administration should be avoided in cases of severe renal insufficiency (renal impairment) and existing pregnancy.
The procedure
Magnetic resonance imaging is one of the non-invasive imaging procedures, meaning that it does not penetrate the body. By using the magnetic field, protons (mainly hydrogen) are excited in the body to produce nuclear magnetic resonance. This is a change in the orientation of the particle due to a magnetic field. This is picked up as a signal by the coils placed around the body during the examination and sent to the computer, which calculates the exact image of the body region from the many measurements that take place during an examination. In these images, the differences in the shades of gray are thus caused by the distribution of hydrogen ions. In MRI, one can distinguish between different imaging techniques, such as T1-weighted and T2-weighted sequences. MRI provides very good visualization of soft tissue structures. A contrast agent can be administered for even better differentiation of tissue types. Thus, the radiologist can obtain even more detailed information about any disease processes that may be present through this examination. The examination usually takes about half an hour and is performed with the patient lying down. During the examination, the patient is in a closed room in which there is a strong magnetic field. Since the MRI machine is relatively loud, the patient is fitted with headphones. Claustrophobia (fear of space) can occur, especially during examinations of the head, since the head is then in a coil. Magnetic resonance imaging of the skull, including the brain and brain-supplying vessels, as well as the eyes and ears, is a very precise diagnostic procedure that is used today for many diseases and complaints.
Possible complications
Ferromagnetic metal bodies (including metallic makeup or tattoos) can lead to local heat generation and possibly cause paresthesia-like sensations (tingling).
Incidental findings on MRI examinations of the brain
- In a prospective population-based cohort study in the Netherlands, incidental findings occurred in 9.5% of patients during MRI examinations of the brain. The most common were meningiomas (meningeal tumors; usually benign) and cerebral aneurysms (arterial dilation).Less common were arachnoid cysts (congenital benign cavities in the brain) and changes in the pituitary gland.
