VITUS Privatklinik

VITUS DIAGNOSTICS Prostate MRI

How does it work and for whom is it suitable?

Previous prostate cancer
provision

According to experts useless to dangerous

Palpation of the prostate, digital rectal examination, or DRU, is useless. That’s according to Patric Walsh, chief of urology at Johns Hopkins University. In Germany it is still standard! And the PSA test has been eliminated as a screening test in many countries because an elevated PSA level triggers an often unnecessary biopsy, but a low PSA level does not rule out carcinoma.

So what should men do if they want to protect themselves from prostate cancer. The answer has been clear and scientifically proven for years:

Magnetic resonance imaging (MRI) of the prostate can detect or rule out carcinoma with a high degree of certainty.

Also find out about the alternatives or contact us.
We will be happy to advise you.

Prostate-MRI

The new quality standard in prostate diagnostics

Palpation of the prostate, digital rectal examination, or DRU, is useless. That’s according to Patric Walsh, chief of urology at Johns Hopkins University. In Germany, it is still the standard As with female breast cancer, magnetic resonance imaging (MRI) of the prostate has become by far the best method for detecting and/or ruling out prostate cancer in recent years. This has since been proven in several scientific studies.

Already, the 2017 PROMIS multicenter study from England1 of 576 men demonstrated that prostate MRI had nearly twice the sensitivity of detection for clinically relevant prostate cancer (93%) compared with prostate biopsy (TRUS biopsy), which achieved a sensitivity of only 48%.

These data were confirmed by the results of a large multicenter interdisciplinary study in the USA, which included a total of 1500 patients over several years2.

Clinically relevant carcinomas

MRI detects clinically relevant carcinomas with almost 100% certainty

The researchers demonstrated that multiparametric MRI (mpMRI) of the prostate has a sensitivity for prostate cancer of 94-95%. Of note, MRI was able to exclude clinically relevant carcinomas (Gleason score ≥ 7) with a certainty of 93-97%. If the difficult to detect, almost benign Gleason 6 carcinomas were also taken into account, the negative predictive value was still 87% – much better than with the punch biopsy.

The size and extent of carcinomas in the prostate are also better detected by mpMRI than by punch biopsy, with a sensitivity of 84%. Infiltration of the seminal vesicles and tumor growth exceeding the prostate can be detected with a specificity of 97-98% (Gleason score ≥ 7).

MRI helps avoid unnecessary biopsies

That magnetic resonance imaging (MRI) can avoid unnecessary biopsies of the prostate has been suspected for years. In 2018, a study by the University of Mainz also provided scientific evidence of this in Germany3. They were able to show that among the 651 men in the study, nearly 40% of biopsies could have been avoided by MRI without missing relevant cancer foci.

In summary, it can be said today that the informative value of prostate MRI is so superior to other procedures that prostate MRI should be performed whenever prostate cancer is suspected.

Endorectal coil: Necessary or dispensable

Magnetic resonance imaging uses strong magnetic fields (B0) to magnetize protons – hydrogen nuclei – in the human body. Roughly speaking, the protons align themselves parallel to the magnetic field. This magnetization is twice as large at 3 Tesla as at 1.5 Tesla.

To generate a signal from which the MRI image can then be calculated, the magnetized protons must be “excited,” which is done with radio frequency waves of the appropriate frequency: about 64 MHz at 1.5 Tesla, about 128 MHz at 3 Tesla.

The MR signal, more precisely the signal-to-noise (SNR) ratio – increases approximately with the square of the field strength at low field strengths (SNR ~ B07/4), at higher field strengths only linearly (SNR ~ B0).

However, the radio frequency energy required to fully excite the protons and thus achieve full signal for imaging increases with the square of the field strength: SAR ~ B02α2, where α is the strength of the radiofrequency pulse (the “flip angle”). Thus, it is four times higher at 3 Tesla than at 1.5 Tesla!

The absorption of radio frequency (RF) energy heats the body. Therefore, the maximum usable RF energy in commercial MRI scanners used in medicine is strictly limited. If the magnetic field strength B0 increases, the strength of the radio frequency pulses α used for imaging must be decreased.

This only leads to the fact that the higher signal theoretically available at 3 Tesla cannot be used, since it is to be avoided that the patient is damaged by heating.

These restrictions do not apply to the radio frequency coils, antennas that receive the signal needed for imaging. The smaller the so-called RF coil and the closer it is placed to the object to be imaged, the higher the received signal. Since the prostate is posteriorly adjacent to the rectum, a small endorectal coil can be placed directly behind the prostate and doubles4 the signal available for imaging.

In general, therefore, it can be said:

Recommendation: Have 3 Tesla MRIs of your prostate performed only with an endorectal coil or at least after emptying the rectum by laxative and/or filling the rectum with a susceptibility-neutral fluid – so that you were not “in the tube” for nothing.

1.5 Tesla with endorectal coil
3 Tesla without endorectal coil

First and second image: MRI images of the prostate taken with a 3 Tesla scanner WITHOUT endorectal coil. The images have a high noise content. The carcinoma (arrow) is not well visualized on either the morphologic T2 images (left) or the functional ADC maps (right).
Third and fourth image: 1.5 Tesla images WITH endorectal coil: The carcinoma is now clearly shown on all images.

Air in the rectum – prostate gone:

The problem of susceptibility artifacts at 3 Tesla

3 Tesla MRI scanners pose challenges to users that few experts have mastered. It requires a sound knowledge of physics, which most physicians do not have.

For example, most MRI scans of the prostate do not look to see if there is air in the rectum. This is because magnetic fields are sensitive to the different magnetic conductivity (susceptibility) of air and water-containing tissues – as occurs at the interface of the air-filled intestine and the prostate directly in front of it. These so-called susceptibility differences lead to a distortion of the magnetic field and thus to signal cancellations, which particularly affect the outer zone of the prostate near the rectum – where 70 to 80% of all carcinomas are located!

Figure 2: A case from practice: The prostate (green border) is located directly in front of the air-filled rectum (*) – right image. In the left image, the prostate is shown only as a crescent-shaped structure (yellow border); the posterior, rectal portion of the prostate is obliterated by a susceptibility artifact (red area). The air in the rectum appears to extend to above the outer zone of the prostate. An evaluation of whether a carcinoma is present is no longer possible here.

Diagnostics – Frequently Asked Questions (FAQ)

What is the Gleason score and how do you evaluate the aggressiveness of prostate cancer?

The so-called Gleason score is a measure of the aggressiveness of prostate cancer. It results from the microscopic sections that the pathologist prepares from the biopsy specimens. The Gleason score is an elementary component of the so-called grading (classification into differentiation grades) of prostate carcinoma. In addition to grading, staging (staging, TNM classification) is always required, preferably by MRI.
Somewhat simplified, we can summarize:
Gleason score 3+3 = 6
Rarely, prostate cancer with this Gleason score is high risk.
The 10-year survival probability is over 99%.
If this Gleason score is exclusively present, Active Surveillance, Watchful Waiting, or sparing focal therapy with IRE/NanoKnife should be considered. Radical therapies bring no survival benefit here, but many unnecessary side effects. Let us advise you.
Gleason score 3+4 = 7a
The most common Gleason score. Prostate cancer with this Gleason score is intermediate risk.
Mortality risk here is strongly dependent on PSA level and spread.
Therapy should be considered here. Both focal and radical therapies make sense here.
This makes perfect diagnosis and counseling all the more important for this Gleason score.
Statistically, radical therapies are most effective at the intermediate Gleason score (= reduction of prostate cancer specific mortality). Let us advise you.
Gleason score 4+3 = 7b
Similar to Gleason score 7a, but with predominant load to the riskier 4 pattern.
Often the evaluation between 7b and already 8 is difficult and very pathologist-subjective.
Propagation estimation (also by MRI) is very important here.
Gleason score 4+4 = 8
From here on, one always speaks of a high-risk prostate carcinoma (regardless of age or PSA value).
Although the probability of survival over 10 years is still high (compared to other cancers), this prostate cancer usually has a high impact on the patient’s life expectancy.
In particular, the risk of recurrence after successful prostate cancer treatment is high here.
Anti-hormonal therapy may be necessary/recommended.
Gleason score 4+5 = 9 and 5+5 = 10
These highest Gleason scores are typically found in advanced carcinomas.
The probability that the carcinoma has already formed (micro-)metastases is significantly higher.
Good advice is also absolutely essential here.
Adjuvant (=supportive) therapies in addition to primary therapy are not unlikely here. E.g. anti-hormonal therapy or more recently immunotherapies.
In the following document we explain in more detail:
How does the risk of dying from prostate cancer relate to the Gleason score?
How does the likelihood of developing a recurrence relate to the Gleason score?
Prostate cancer information on treatment efficacy, cure rate and survival probability.
Important for the patient:
The Gleason score is a subjective evaluation. As such, this is subject to intrinsic imprecision. Therefore, while it is a good approximation, it is never an exact measure that can accurately predict a patient’s individual risk.
In addition to the Gleason score, it is equally important how many samples were positive and, most importantly, what spread the MRI of the prostate shows. This dispersion estimation is called staging. Grading and staging together are the first necessary steps before any therapy for any carcinoma.

What information does an MRI scan provide?

An MRI is a non-invasive, painless method of medical imaging. Examinations can thus be performed without radiation exposure. An MRI allows 3D images to be taken as well as a variety of physical diagnostic parameters to be collected. Combined, these parameters allow exceptionally reliable statements to be made about the tissue properties at a specific site within the prostate – for example, in the case of carcinoma. An MRI is an effective method of medical imaging for prostate examination and should be performed as soon as possible in the case of suspected prostate cancer.
An MRI scan also shows the extent of the prostate cancer and provides information on whether the tumor is limited to the prostate or has already spread to surrounding structures (staging). This is a very important factor when weighing the various treatment options. MRI is considered superior to other methods such as ultrasound, histoscanning, elastography, CT (computed tomography), and PET/CT (positron emission tomography with CT). For optimal results, an MRI scan of the prostate should be performed at 1.5 or 3.0 Tesla using an endorectal coil.
Advances in the development of MRI examinations have meant that the procedure can now be performed as a whole-body examination. Thus, MRI replaces both bone scintigraphy and CT scans as staging tools for secondary metastases and affected lymph nodes. Completely free of exposure to ionizing radiation, MRI offers increased accuracy and reduces the examination time from four to six hours for bone scintigraphy to about one hour.
Contact us.

My PSA levels continue to rise. I have had several rectal biopsies. What can I do?

First, we would recommend an MRI scan of the prostate, followed by either an MRI-guided biopsy or a 3D biopsy, depending on whether one or more abnormal sites were detected.
Contact us.

Can any radiology practice perform an MRI scan?

For best results, an endorectal coil should be used during the MRI scan (even at 3 Tesla). However, often the results of an investigation at 3 Tesla are worse than at 1.5 Tesla. This is because the stronger magnetic field leads to an increase in susceptibility artifacts (image distortions) and higher energy deposition (SAR – specific absorption rate).
The endorectal coil must be filled with a susceptibility-neutral substance. Furthermore, the calculation and interpretation of many parameters, such as diffusion, perfusion, and MR spectroscopy, is highly complex. There are only a few specialists who have the necessary expertise to do this.
Contact us.

MRI shows a suspicious area. What now?

We recommend a transperineal 3D (histology mapping) biopsy instead of a transrectal punch biopsy. Because this method significantly reduces the risk of infection. This is because samples are obtained under sterile conditions through the skin of the perineum and not through the wall of the rectum. The examination is performed under general anesthesia.

3D biopsy has an accuracy of 80 to 100 percent in detecting carcinoma. With a conventional transrectal punch biopsy, the figure is only 30 to 35 percent. The 3D biopsy also provides a reliable Gleason score and an accurate map of how the cancer is distributed within the prostate. It is very rarely necessary to repeat this type of examination.
Contact us.

Can an MRI replace a biopsy?

For the exclusion and localization of clinically relevant prostate carcinoma: yes.
When determining the tissue (carcinoma type/grade): only conditionally.
Both diffusion and 1H MR spectroscopy can provide clues to the aggressiveness of a carcinoma. Only histopathological analysis of tissue samples obtained by biopsy can confirm this evidence. The findings obtained from this are documented as a Gleason score.
However, biopsy alone cannot replace MRI examination. MRI allows the detection and localization of cancerous tissue so that it can then be selectively biopsied to obtain cancerous tissue for histopathologic examination. This allows the degree and size (staging and grading) of the tumor to be determined.
In some cases, after an MRI, the biopsy can be skipped and therapy can be started directly. However, these are isolated cases which can only be discussed after a thorough anamnesis in the tumor board.
Contact us.

Why are transrectal biopsies insufficient?

Transrectal biopsies involve taking between six and twelve samples through the rectum, either blindly or with the aid of ultrasound. The accuracy of a transrectal biopsy is 30 to 35 percent, even when the number of samples taken is increased to a maximum of 24. Considering the respective sample size (< 1 millimeter in diameter, 10 to 25 millimeters in length), it becomes clear that in fact only tissue is taken from a small area of the prostate. If the tumor is not in the biopsied areas, no cancerous tissue is collected.
Transrectal biopsies are performed by inserting a biopsy needle into a predetermined area of the prostate. The exact origin of the sample cannot be determined in this process (accuracy of only five to 10 cubic centimeters), since no coordinate system is used during tissue sampling. In addition, not all areas of the prostate can be easily biopsied due to the narrow conditions in the rectum and the angle of insertion required by the biopsy needle. In addition, during the transrectal procedure, each biopsy needle carries fecal matter into the prostate. The associated increasing risk of prostatitis (inflammation of the prostate) limits the number of biopsies that can be performed. Whether the samples taken with this technique contain cancer cells ultimately depends on chance.
Transperineal biopsy, on the other hand, uses a more anatomically precise method to obtain specimens and comes to an accuracy of origin of 0.5 to 1 cubic centimeter. With this method, samples can be localized five to twenty times more precisely than with a transrectal biopsy. It also allows access to all areas of the prostate. There is also no risk of contamination with feces here.
Despite these statistics, transrectal biopsy still has its place in the diagnosis of large carcinomas (tumors). Prior to radical prostatectomy, it is sufficient to confirm carcinoma based on a positive specimen before surgically removing the prostate. However, gentler, focal therapy requires a great deal of site information that a traditional biopsy cannot provide. This information is obtained by 3D histology mapping biopsy. A 3D histological model of the prostate then helps in treatment planning and allows for precise treatment in which only the cancer cells are targeted and destroyed.
Contact us.

What are the advantages and disadvantages of transperineal or 3D mapping biopsy?

Advantages:
Precise
No risk of infection
Minimal postoperative pain and bleeding
Performed under general anesthesia
3D model of the prostate
Disadvantages:
Due to the complex planning and precise execution, this diagnostic technique is more expensive than regular biopsies.
It is also possible to perform targeted MRI biopsies (MRI-targeted biopsies or fusion biopsies). However, these serve a different purpose: it involves confirming a carcinoma for subsequent radical therapy rather than planning focal therapy.
Contact us.

After a biopsy, cancer was diagnosed. How should I proceed now?

In order to select the best treatment, the spread and type of carcinoma (tumor) should be known precisely. This is called staging and grading.
Staging:
Distribution of carcinoma within the prostate.
Spread of carcinoma outside the prostate to other organs in the pelvis (seminal vesicles, pelvic floor, etc.)
Spread of carcinoma to other organs, lymph nodes, and/or bone.
Grading:
Histological appearance of the carcinoma
Carcinoma type
Aggressiveness of the tumor
Person-related factors are also taken into account:
Patient age
General health
Sexual and general activity
Prostate size
PSA values
Once all these parameters have been identified, they can be used to select the most appropriate treatment from a wide range of options:
Watch and wait – active surveillance (Active Surveillance)
Focal therapy: NanoKnife, HIFU, laser, RFA, etc.
Partial or radical prostatectomy
Brachytherapy, afterloading, CyberKnife, proton radiotherapy, conventional radiotherapy, etc.
Hormone blockade
Chemotherapy
Immunotherapy
We will be happy to advise you on both conventional and modern therapy methods.
Don’t worry: Because the prostate, and therefore prostate cancer, typically grows slowly, you have plenty of time to gather comprehensive information and expert opinions. The goal of any therapy should be to control prostate cancer while avoiding complications such as impotence, incontinence, or radiation damage.
Together, we can develop a strategy that provides the optimal diagnosis and treatment for your prostate cancer.
Contact us

Does my health insurance cover the costs of diagnostics and treatment?

You should clarify the question of which costs are covered directly with your statutory health insurance. However, the cost of endorectal MRI and 3D biopsy is not covered by health insurance.

Even if you have private health insurance, we recommend that you clarify exactly which costs for diagnostics and therapy your health insurance will cover before you have a procedure performed. We will be happy to provide you with information on this.
Contact us.

If I decide to pay myself, what costs can I expect?

The cost of both multiparameter MRI and 3D biopsy is highly dependent on the individual case.
Contact us to get an accurate assessment for your specific case.

References
  1. Ahmed HU, El-Shater Bosaily A, Brown LC, et al. Diagnostic accuracy of multi-parametric MRI and TRUS biopsy in prostate cancer (PROMIS): a paired validating confirmatory study. Lancet. 2017 Feb 25;389(10071):815-822. doi: 10.1016/S0140-6736(16)32401-1
  2. Gaunay G, Patel V, Shah P, et al. Role of multi-parametric MRI of the prostate for screening and staging: Experience with over 1500 cases. Asian Journal of Urology (2017) 4, 68e74
  3. Mehralivand S, Shih JH, Rais-Bahrami S, et al. A Magnetic Resonance Imaging–Based Prediction Model for Prostate Biopsy Risk Stratification. JAMA Oncol. 2018;4(5):678-685. doi:10.1001/jamaoncol.2017.5667
  4. Abschätzung bei 1 – 2 cm Eindringtiefe, abhängig von der RF-Spule und meheren anderen Parametern.
  5. Yuan Q, Xi Y, Rofsky NM, et al. Comparison of prostate cancer detection at 3-T MRI with and without an endorectal coil: A prospective, paired-patient study
  6. Epstein JI: Pathology of prostatic neoplasia. In: Campbell's Urology, 8th ed, Walsh PC (Ed), Saunders, Philadelphia 2002