Introduction
Magnetic resonance imaging is one of the leading procedures for screening, diagnosis and therapy planning and implementation in relation to prostate diseases – especially prostate cancer: 85% of all prostate cancer cases can be detected with the help of MRI. If, on the other hand, no specific changes in the prostate are present in the MRI, these can be excluded with a 90% certainty. MRI of the prostate is considered the most reliable diagnostic tool, even before ultrasound, elastography and punch biopsy. Other advantages of MRI imaging are its non-invasive, painless nature and the absence of radiation exposure (in contrast to CT or conventional X-rays). However, not every prostate disease is also an indication for an MRI examination, precisely because it is a very expensive procedure.
Indications for an MRT of the prostate
In contrast to CT or X-rays, MRI is particularly well suited for imaging soft tissue and thus the prostate. The sectional images generated by means of a magnetic field make it possible to draw conclusions regarding the morphology, blood flow (and possible bleeding), calcifications and ultimately also benign or malignant changes in the prostate. This includes, on the one hand, the early detection procedure: if elevated PSA levels are detected or if the physician detects an abnormal palpation during the physical examination, the MRI can be used to detect or rule out a malignant change so that an unnecessary biopsy can possibly be avoided.
On the other hand, the MRI can enable specific planning for a possibly necessary punch biopsy in the event that the PSA level continues to rise despite previous biopsies without cancer detection. If, however, prostate cancer has already been detected, the MRI then serves to assess the exact extent and progress of the disease in the pelvic area and to further plan and monitor the course of treatment. Finally, it can also be used in the search for a possible recurrence of a prostate cancer that has already been treated.
MRI imaging, on the other hand, is less useful if prostate inflammation (prostatitis) is predominant, as it makes it more difficult to detect any malignant changes that may be present. Even a simple, benign prostate enlargement (benign prostatic hyperplasia; BPH) is not an indication. In preparation for the MRI examination of the prostate, the patient is usually advised not to eat any food for about 4 hours before the examination begins.
However, small amounts of water and possibly necessary tablets can be taken as usual before the examination. Shortly before the examination begins, the patient is asked to remove all metallic objects (jewelry, watches, piercings, dentures, hair clips, etc.) and to remove any clothing with metallic components (e.g. underwired bra, buttons, zipper, etc.).
The underwear and usually also a (metal-free) T-shirt, can remain dressed. Next, the patient is asked to empty the bladder completely in order to achieve the best possible imaging. After the patient has placed himself in a supine position on the examination couch, on which he will later be pushed into the MRI tube for imaging, headphones are placed against the loud knocking sounds of the device and an emergency bell. As a rule, an indwelling cannula is also placed in the antecubital vein to allow for the administration of contrast medium that may be necessary for MRI of the prostate before or during the examination. In order to avoid image disturbances and to improve the image quality, it may also be necessary to administer an additional medication that relaxes and calms the intestinal movements (e.g. Buscopan®).
