Magnetic resonance imaging (MRI, colloquially “nuclear spin”) is the most important diagnostic measure for multiple sclerosis, both for diagnosis and during the course of the disease. Metal parts such as piercings must be removed before an MRI examination.How does an MRI work? In simplified terms, the images in an MRI examination are generated by stimulating water molecules in a strong magnetic field. Unlike X-ray procedures like computed tomography, this is not associated with radiation exposure. However, an MRI examination is not recommended during pregnancy, even though no harmful effects have been detected so far. Another limitation: MRI machines are very narrow and the examination is very loud, so patients with “claustrophobia” may have problems. Here, pre-medication with a sedative (benzodiazepine) is often helpful. An alternative are so-called open MRI scanners, although their image quality is worse compared to the image quality of closed devices.
A thousand times stronger magnetic field than that of the earth
In order to create images using magnetic fields, very strong magnetic fields are necessary. The flux density of a magnetic field is given in Tesla (T). Named after the brilliant physicist and electrical engineer Nikola Tesla, who lived from 1856 – 1943 and to whom numerous inventions in the field of electrical engineering can be traced. Standard MRI devices in clinics and practices usually have field strengths from 1.5 T to 3 T. This means that the magnetic field of a nuclear spin tomograph is about 30,000 – 60,000 times stronger than the magnetic field of the earth. Accordingly, such considerable magnetic forces act that even heavy metal objects can inevitably be drawn into the magnetic field. In fact, careless handling has already caused serious damage to the equipment and in the worst case personal injury.
Against this background, it is clear that an MRI examination should not be performed if patients have metal parts, including piercings, in their bodies. This restriction no longer applies to joint implants – they have been made from MRI-capable materials since the late 80s. However, the restriction still applies to patients with pacemakers or implantable cardio defibrillators, cochlear implants or permanently implanted medication pumps. While modern devices are also MRI-compatible, an examination always needs to be clarified with the responsible specialist beforehand. Because even the MRI-compatible devices have to be switched off before the examination and reprogrammed after the examination. So it means a considerable effort. Also, metal splinters in the eye or a magnetically fixed denture represent a contraindication for performing an MRI.
Metal parts in the body during MRI
Accordingly, it is clear that for safety reasons any body jewelry made of metal, i.e. any piercing, must be removed before an MRI examination. Because not only can artifacts be caused, but there is also the possibility that parts heat up and cause burns. This is problematic with non-removable or hard-to-remove piercings (dermal anchor, genital piercing). Here the radiologist can refuse the examination, or a careful benefit-risk assessment would have to take place. The question whether a piercing can be left in place if the MRI examination takes place in another part of the body (e.g. question about removal of a belly button piercing for head MRI) is understandable, but for safety reasons the piercing should actually always be removed. Ultimately, it also depends on how relaxed the radiology practice/hospital department views the topic of body jewelry/piercing.
In any case, MS patients should consider the MRI when deciding where and in which places to get what type of piercing. Regular MRI recordings are an indispensable part of the course control and provide important clues with regard to the therapy response.
