An MRI scan of the prostate is now a standard step for men with a raised PSA, before any biopsy. It is around 85% accurate, which is very good but not perfect. That raises an important question. What should happen if PSA remains raised, or the prostate feels abnormal, even though the MRI looks normal or a previous biopsy found no cancer? This article looks at research on a raised PSA after a normal MRI and what it means for patients.
The role of MRI
MRI has changed how prostate cancer is diagnosed. It shows areas within the prostate that look suspicious, so that biopsies can be targeted, and it allows some men with a reassuring scan to avoid an immediate biopsy altogether. MRI is used once a urine infection, which can also raise PSA, has been ruled out. Our overview of prostate cancer explains the diagnostic pathway.
However, no scan picks up every cancer. A small proportion of significant cancers do not show clearly on MRI, either because of their size, their position in the gland or the way they grow.
What the FUTURE trial found
Researchers studied a group of more than 400 men from the FUTURE trial. These men had a non-suspicious MRI and underwent thorough systematic biopsies of the prostate through the rectum, known as TRUS biopsies.
Clinically significant prostate cancer was found in 3% of men whose MRI was not suspicious. This means the risk of significant cancer in this group is low. Even so, it remains higher than in the general population, so continued follow-up is recommended. The findings were published in the British Journal of Urology International.
Why the biopsy method matters
In Professor Dasgupta's practice, prostate biopsies are performed through the perineum, the skin between the scrotum and the back passage, rather than through the rectum. This approach has two advantages.
First, it allows the team to target any suspicious areas on MRI and also take systematic samples from other parts of the prostate, so that cancers invisible on MRI are less likely to be missed. As a result, the detection rate is higher than with TRUS biopsies.
Second, avoiding the rectum lowers the risk of serious infection, known as sepsis. Prostate Cancer UK explains the different types of biopsy and what to expect.
The future role of PSMA PET
Professor Dasgupta expects PSMA PET scanning to play a greater role in finding significant cancers. Used alongside MRI, it can increase the chance of detecting cancer that MRI alone might miss. Our article on combining MRI and PSMA PET scans describes the evidence in more detail.
What this means if your MRI was normal
If your MRI did not show anything suspicious but your PSA remains raised, it is reasonable to:
- continue regular PSA tests, as advised by your specialist
- ask whether a repeat MRI or a biopsy might be helpful
- mention any new urinary symptoms or changes promptly
- discuss your family history, which may affect your risk
A normal MRI is reassuring, and most men in this situation do not have significant cancer. Follow-up simply ensures that the small number who do are not missed. The frequency of PSA checks, and whether further scans are needed, should be agreed with your specialist based on your own risk. Other causes of a raised PSA, such as benign prostatic enlargement, are also worth considering.
Structured checks
For men who want a thorough assessment, our article on smart screening for prostate cancer describes a combined approach using PSA, MRI and other tests.
If you have a persistently raised PSA despite a normal MRI or biopsy, please contact the clinic to arrange a review with Professor Dasgupta.