MRT – Examination of the spine

Introduction

Magnetic resonance tomography is a medical imaging examination method in which longitudinal and/or cross-sectional sectional images of the back or spinal column can be generated. For this purpose, a very strong magnetic field is used and not, as in X-ray or computed tomography, straining X-rays. The images are based on the fact that certain atomic nuclei in the body (preferably hydrogen or protons) are excited by the magnetic field, so that the MRI receiver device registers an electrical signal and converts it into an image.

Indication

The MRI examination of the back is always indicated when the physicians’ focus is particularly on the soft tissues in the context of spinal disorders, such as the back muscles, spinal cord and spinal nerves and intervertebral discs. Accordingly, MRI imaging is the preferred method of choice for questions regarding herniated discs or protrusions, inflammatory processes in the intervertebral discs/spinal muscles/spinal nerves/vertebral bodies or the spinal cord, injuries to the spinal cord(s), constrictions in the spinal canal (spinal canal stenoses), circulatory disorders or after tumors or metastases of the spinal cord / spinal column. Scar tissue (e.g. after operations) can also be visualized particularly well by means of an MRI examination. Fractures in the spinal column or vertebral bodies can also be detected by MRI, but CT is preferred as the imaging method of choice due to its better representation in the context of this question.

Procedure and implementation

Due to the strong magnetic force field generated during an MRI examination, it is important to remove all metallic objects (jewelry, watches, hair clips, piercings, belts, etc.) before starting the procedure, as these could otherwise be attracted by the magnetic field and therefore show potential for injury and/or damage. Pacemakers implanted in the body can also be damaged during an MRI examination and can lead to a possibly life-threatening failure, which is why it is all the more important to mention this before performing the examination (an MRI may then not be possible).

At the beginning, the patient to be examined lies in a supine position on a mobile or movable couch in front of the MRI tube. If the patient suffers from severe pain, so that it will be difficult for him to lie still during the entire examination period, an analgesic can be administered beforehand. If contrast medium is required during the examination, an indwelling cannula is also placed in the arm vein in the crook of the elbow before the examination begins, through which it can be administered later.

Before the examination begins, the patient is also given a bell in his hand, with which he can make himself noticed during the examination in the MRI tube in case of problems or complaints. Once all preparations have been made, the patient is pushed into the MRI tube with the mobile couch. In the case of back images, the patient must remain as motionless and breathing calmly as possible for about 20 minutes to achieve good image quality.

Because the MRI tube is very narrow, discomfort up to claustrophobia can occur in some cases, which may make it necessary to give an additional sedative beforehand. In addition, during the examination, loud tapping noises are produced by the MRI machine, so that earplugs or headphones (possibly with music) are usually provided as noise protection or as a distraction. During an MRI examination, the affected patients do not have to undress completely. However, it is important that all items of clothing that (could) have metallic parts are taken off. This usually includes the bra (underwire) and pants, but also all other items of clothing that have buttons and/or zippers.