Prostate MRI

Definition: What is Prostate MRI?

Magnetic resonance imaging, also known as MRI, is a medical imaging technique that is used primarily to show the structure and function of tissues and organs. The specialists for MRIs are radiologists and radiotherapists. A more recent procedure is the possibility of examining the prostate using magnetic resonance imaging, where the prostate gland is examined for changes in tissue consistency, organ structure, and size.

Prostate carcinoma (cancer of the prostate gland) is the most common cancer in men in Germany, with 25.4% of all diagnosed cancers. Every year, about 60,000 men in Germany are newly diagnosed with this tumor. The average age of the patients is 69 years. Thanks to the more precise diagnosis, tumors are now being detected at earlier stages of the disease and are therefore usually still well treatable. Especially, men with affected family members (brother, father) have a more than double increased risk of prostate cancer.

As of the age of 45 years, routine screening for early detection by determining the PSA level and digital rectal examination is recommended. The PSA value (prostate-specific antigen) can, especially in the case of changes or very high levels, indicate growth and transformation processes of the prostate gland and provide an indication of malignant growth in prostate tissue.

During the MRI examination, sectional images of the body are generated. The images are mainly created with the help of a large magnetic field that interacts with the body. The reactions of the individual cells and tissues to this field vary due to different compositions (water content, density, etc.), which makes it possible to differentiate between diverse tissue areas. There are various forms of MRI, which differ, for example, in their so-called weighting (e.g., T1-, T2-, proton-weighted images). Depending on the type of organ or tissue to be examined, the weighting is decisive in image evaluation.

Indications: When is Prostate Magnetic Resonance Imaging Used?

If there is a high degree of suspicion of prostate carcinoma despite a negative biopsy, an MRI examination of the prostate is a way of confirming the diagnosis. Prostate MRI is a more recent procedure, already shows good results in terms of its diagnostic reliability. In the T2-weighting of the MRI, the prostate tumor is a circumscribed dark region with a relatively bright surrounding zone.

The suspected carcinoma foci detected in the prostate MRI should be explicitly biopsied since the diagnosis of prostate carcinoma must be confirmed by a tissue sample. In addition to the targeted biopsy, a systematic biopsy should be carried out. In the systematic biopsy, 10-12 tissue punches are taken from the prostate gland under local anesthesia according to the standard scheme. The tissue sample is decisive for the assessment of the tumor disease and further therapy steps.

Types of Prostate-MRI

The MRI examination of the prostate is carried out as a so-called multiparametric MRI. The MRI of the prostate gland is made up of 3 different magnetic resonance sequences. The three different examination parts include:

• One T2-weighted MRI sequence to assess the organ structure (prostate, seminal vesicles, surrounding organs): This examination section can be used to evaluate whether, in the case of tumor disease, there has already been organ-crossing growth or further metastases (tumor metastases) in the surrounding area.
• One diffusion-weighted MR sequence (DWI) for assessing cell density: tumor tissue is altered due to a higher number of cells in the same space (cell density). This sequence is important for the detection and characterization of prostate carcinoma.
• One dynamic contrast-enhanced MR sequence (dynamic contrast-enhanced MRI, DCE) for the imaging tissue with increased blood flow or new vessel formation (tumor suspicious). In this examination, a gadolinium-containing contrast medium is injected. Increased blood flow is characteristic of tumors, but can also occur in cases of inflammation (prostatitis) or benign prostatic hyperplasia.

In combination, these sequences provide exact information on the localization and spread of a possible tumor without having to enter the body from outside and without exposing the body to radioactive radiation.

Procedure and duration: Procedure of MRI examination

The length of the MRI examination depends on the area of the body being examined, the diagnostic task, and the equipment used. The higher the desired detail resolution, the longer the examination time has to be estimated. Prostate MRI usually takes about 30 minutes. Often two series of images are made, initially without contrast agent, then with contrast agent.

Recent developments promise to significantly shorten the examination time by recording the MR signal in parallel with numerous receiving coils, which means, in extreme cases, recording times of less than one second are possible.

Advantages of prostate MRI

MRI examination of the prostate belongs to the gold standard in primary diagnosis or further observation (active monitoring) of prostate cancer meanwhile. MRI should be carried out in case of a negative biopsy but a highly suspected tumor disease, among other things, due to high PSA values.

MRI examination has the great advantage of being radiation-free, associated with excellent tissue imaging. The reliability of the prognosis will probably continue to increase due to further improvements in technology and the increasing experience of radiologists.

Recent studies (see the source of "The New England Journal of Medicine") show that prostate MRI is superior to previous examinations using PSA levels, palpation, and systematic biopsy when it comes to clarifying abnormal changes. MRI allows the diagnosis of prostate carcinoma with an approximately 80% certainty.

Thanks to non-existing radiation exposure, MRI can also be used for follow-up examinations after therapy.

Disadvantages of Prostate MRI

Untreated, prostate cancer usually progresses rather slowly, so only men with a life expectancy of more than 10-15 years benefit from therapy. Early detection by MRI sometimes reveals tumors that would probably never have been problematic for patients.

Even an inconspicuous MRI carries a residual risk for small tumors, which is why a PSA-supported check-up, as well as a systematic biopsy, should also be offered in the case of negative MRI findings.

Prostate MRI has proven to be approximately equivalent to transrectal ultrasound but is much more complex and cost-intensive. Besides, the costs of prostate MRI have not yet been covered by statutory health insurance companies.

If the patient is unable to lie still for a more extended period of time (approx. 30 minutes), the image quality may be limited.

Despite permanently improving technology, magnetic resonance imaging of the prostate also leads to errors. For example, approx. 10% of prostate tumors are not recognized during the MRI examination and approx. 10% of patients are classified as falsely positive (suspected cancer) and unnecessarily biopsied.

Since contrast agents are usually also used in prostate MRI, this can lead to allergic reactions, including anaphylactic shock with cardiac arrest. If you have an increased risk of allergies or known allergies, please contact our specialists in confidence!

Prostate MRI: Costs and Coverage by Health Insurance Companies

According to the current status, the costs of this complex examination are typically not covered by the statutory health insurance companies. Private health insurance companies usually completely reimburse the costs. The fees are about 400€ for the examination. If you have any questions, please contact our specialists that have many years of experience!

Which Doctors and Clinics are Specialists for Prostate MRI?

The following doctors are specialists for prostate MRI:

• Prof. Dr. med. Christoph M. Bamberger (Hamburg)
• Dr. Beat Porcellini (Zurich)

Sources:

• Supplement: Perspektiven der Onkologie, Multiparametrische Prostata-MRI: Vorzüge und Grenzen, Dtsch Arztebl 2018; 115(47), DOI: 10.3238/PersOnko.2018.11.23.01, Schlemmer, Heinz-Peter
• www.die-radiologie.de/kompetenzzentren/prostatadiagnostik.html
• Interdisziplinäre Leitlinie der Qualität S3 zur Früherkennung, Diagnose und Therapie der verschiedenen Stadien des Prostatakarzinoms: Version 5.1–Mai 2019
• de.wikipedia.org/wiki/Prostatakrebs
• de.wikipedia.org/wiki/Magnetresonanztomographie
• www.nejm.org/doi/pdf/10.1056/NEJMoa1801993