Multiparametric MRI examination of the prostate (mpMRI prostate)
Prostate carcinoma is the most common form of cancer in men. However, there is a good chance of a cure if prostate cancer is discovered at an early stage. Nevertheless, many men still shy away from a precautionary examination by a urologist. However, new examination methods can take away the fear of a painful examination for many men.
The usual procedure for the diagnosis of prostate cancer is, first of all, a digital rectal examination by the urologist, followed by determination of the so-called PSA value in the blood. This value can be elevated in the case of a carcinoma, but also in the case of an age-related benign prostate enlargement or inflammation.
If the PSA level is elevated, tissue samples can be taken from the prostate. In routine tissue collection (biopsy), 12-18 samples are usually taken.
Hitherto, taking these tissue samples has been very painful for the patient, and has often produced inaccurate results. The urologist often had to take samples several times from different parts of the prostate. If the prostate carcinoma is not located in one of the areas reached by the biopsy, the tumour can often not be detected. In order to increase the accuracy - i.e. the detection rate - of a tissue sample, MRI examination of the prostate is therefore being increasingly carried out. This means less pain, an accurate diagnosis and thus less stress for the patient.
How does the MRI examination work?
The examination can be performed in a comfortable supine position. A lightweight measuring coil is placed on the patient's pelvis to receive the signals from the prostate. For claustrophobic patients: The head remains outside the MRI tube during the entire examination and the tube aperture is larger than average at 70 cm. In our special centre, no endorectal receiving coil is necessary, thanks to our state-of-the-art 3Tesla MRI device. Various high-resolution images are taken during the examination. All show different tissue characteristics of the prostate. This is called a multiparametric MRI of the prostate. This examination comprises the following components:
- Morphological T2 imaging: The anatomy of the prostate is shown in three different spatial directions. Tumours are characterised by a dark spot in the prostate. Most tumours are located in the so-called peripheral zone of the prostate (area outlined in red in the right image; the tumour is marked in blue in the right image; around 20% of all tumours are to be found within the green-marked central zone of the prostate).
- Diffusion imaging of the prostate: Here, the cell density within the prostate is measured. Tumours have a higher cell density than healthy tissue due to their growth. In the figure shown below, the increased cell density is clearly recognisable by the bright signal in the image.
- Perfusion imaging: With this examination, the blood flow (perfusion) within the prostate is displayed and measured. Tumours are much more strongly supplied with blood than normal prostate tissue. For measuring blood flow, the images are continuously recorded while a contrast agent is administered. In the image, the tumour can be seen as a bright spot in comparison to the surrounding prostate tissue. This is due to the higher blood flow within the tumour.
With the help of multiparametric MRI of the prostate, a prostate carcinoma can be detected in our special centre with an accuracy of approximately 90%. If no tumour is detected in the examination, a relevant prostate carcinoma can be ruled out with a very high degree of probability.
The duration of such a multiparametric prostate MRI examination in our special centre for prostate MRI is approximately 30 minutes.
If a prostate carcinoma is detected, the findings are reported to the treating urologist via a quality-assured and standardised report. This ensures that the urological colleagues can reliably target the tumour when performing a biopsy and that in the best case, patients need to undergo biopsy of the prostate only once.
When is an mpMRI of the prostate useful?
- Unclear elevation in the PSA value
- Differentiation between inflammation and prostate carcinoma
- Exclusion of a significant prostate carcinoma
- Before a planned biopsy of the prostate
- After a negative standard biopsy, but persistent suspicion of a tumour
- Active surveillance in cases of proven low-grade prostate cancer
- Before planned prostate surgery to enable safe surgical planning (TUR of the prostate; radical prostatectomy
Importance of MRI for fusion biopsy:
In conventional prostate biopsies, the urologist takes one or two samples from each area of the prostate under ultrasound guidance. Since prostate tumours cannot be visualised with ultrasound as well as they can with MRI (the tumour tissue is very similar to healthy tissue in the ultrasound image), however, the sample collection with ultrasound guidance is ultimately random. Particularly in the case of small tumours or tumours at an atypical site, this method often fails to detect a tumour, even though cancer is already present.
In a fusion biopsy, the live ultrasound image is overlaid with the mpMRI images as described above, using a special ultrasound device. Suspicious areas are marked beforehand by the radiologist and can now be targeted during the biopsy.
Fusion biopsy is thus a less invasive procedure in which even very small parts of suspected cancerous tissue can be detected at an early stage with a high degree of accuracy and recommendations for further action can then be made.
The mpMRI can also be used to identify the most aggressive part of the tumour, so that your urologist can initiate the correct, individual therapy with a high degree of certainty following the performance of a targeted biopsy.
For the patient, this ultimately means a much clearer statement as to whether prostate cancer is really present and to what extent treatment may be necessary.
