To share my experience: I had an MRI to investigate a fluctuating PSA and the MRI showed a PIRADS 4 lesion. I had a trans-perineal biopsy with 4 cores targeted at the suspect lesion and 12 other cores in the usual sampling pattern. Finding from the biopsy was no cancer - just inflammation attributed to BPH.

18 months later I had an ExoDx urine based screening test which indicated a 36% likelihood of prostate cancer. My urologist recommended an MRI which was completely clear; they carefully checked the location of the previous PIRADS 4 lesion and nothing was seen. Despite the clear MRI, my urologist recommended a biopsy 'just to be sure' and I had a saturation biopsy - 24 cores. Two of the cores showed a very low percentage of prostate cancer which I had a prostatectomy to treat.

So my experience has shown that MRI's are not a 100% certain diagnostic tool for prostate cancer especially in cases where there is only a single lesion confined to the prostate. It's important to have a biopsy to follow up on a finding of a PIRADS 4 or 5 lesion to make a complete diagnosis. If your biopsy turns out to show no cancer, it might be good to use one of the newly developed diagnostic tests that go beyond the PSA to look for other biomarkers of cancer. I had the ExoDx; I think another test is the IsoPSA. One of the other members on this forum has a chart that summarizes these tests and shows their accuracy - maybe he will see this post and repost his chart for your reference.

All the best to you as you go through the biopsy and any follow that is needed. This forum is a really great place to get information for the journey - it has been extremely beneficial to me.