Multiparametric MRI (mpMRI) over diagnosis?

Well good info, that is more than I ever got from Decipher. In about three years on AS I must have spoken to 20 doctors at differing places, and each one I gave the decipher result I got originally. Only one doctor (oncologist) at the start was serious about Decipher. But once he ordered he never said a word on the result to me, and what Decipher sent me was basically nothing with some sort of super general pamphlet. So what you wrote is more than I know because the doctors don't know either is what I guess. I am sure in some cases it matters so one checks, but beyond that not exactly sure about it. There may be hundreds of characteristics tumors have, they can't test all of them some of which they don't even know yet, so in some cases the test may present completely wrong info, or in other cases where you do have the exact characteristics that are in the test well then it makes a true difference. It is still a black box basically for perhaps decades to come for some people who have characteristics not tested for, and with what you get from them it won't be much. Luckily I got insurance to finally pay for my decipher test, but even with really top insurance I had a hard time getting it paid for the pamphlet they gave me.

As you wrote, "in most cases" PC is slow-growing; unfortunately, mine was one of the 5% or so which is fast-growing (the kind that often hits in your 50s). If you're relatively younger, I wouldn't sit and wait with any PSA much above 3.

I had more confidence in multiple opinions from doctors and multiple pathologists, through imaging and test results, than just one MRI opinion. I had a 3T MRI and my urologist was careful to pick a doctor that he had confidence in to read the results properly. The contrast technology is changing pretty quickly to provide better images. AI is already starting to show potential in enhancing image data and utilizing large finite data sets to help a doctor read images (in my opinion our future for collaborative diagnosis...man and AI). If I have BCR at some point in the future, the imaging might include something like Pylarify, a radioactive contrast. Anyway, I did not stop with just imaging and biopsy.

I also had the prolaris test and the decipher test. Two different RO's from two different centers of excellence recommended the Decipher test because its sampling size was larger than Prolaris. All five of the RO's I saw definitively used the decipher test as a guideline to treatment. Both my tests indicated single mode of treatment which was encouraging. I also took the Myrisk genetic test which tests about 50 specific genes, including BRCA 1 & 2 in case I needed to alert my sons or daughter (breast cancer).

I am 70 and was treated with a specific narrow margin radiation machine. I had Pirad 4. Gleason 3+4. One RO suggested AS (no guarantees from DR's that every 3 month testing would catch any possible spread outside the prostate in time so not worth the risk of waiting). One suggested radiation with hormone therapy. The other three radiation only since I had ruled out prostate removal. Imaging is important but your more than valid question, which alludes to MRI accuracy, encouraged me to look for answers in many directions and then collaboratively decide on treatment.

Thanks for your well explained reply. It's clear you did a lot of homework (nothing like a PCa diagnosis to provide motivation) and selected the best treatment decision based on your level of risk tolerance. I was curious about your 3T MRI...did you investigate the 1.5T vs 3.0T or was it simply the one your urologist ordered? I'm getting the sense that it's much more important to find a doctor with tons of experience in reading prostate MRI's than the power of the MRI machine that is used. However, I have read that 3T MRI scans are performed more quickly, so it seems to me that the potential for blurred images due to having to stay motionless for longer time in a 1.5T versus a shorter duration 3T would be an inherent advantage for 3T MRI's...if nothing else.

I felt the power level of the MRI was important for the image that was being used for diagnosis and the subsequent report so I confirmed the higher power level with the facility I went to. I had looked up the latest machine available and my Urologist did not discuss it with me other than he wanted a specific doctor to read the image. He said pick whatever facility works for you with no regard to machine type. I am grateful for his work but he was not good at answering a bunch of questions.

Pandora's box. I believe that PSA is not well understood by the medical profession and in many cases leads to numerous tests, which can add confusion. I have no magic answers but in my case I am being very cautious relative to testing with firm understanding of why and what follows. We do the best we can. I have one 7 mm lesion PIRADS4 that has not changed in 13 months. Resisting biopsy.

What really put me off having immediate treatment when my psa hit 12 was a fear of ED and to a lesser degree, incontinence. My fears as it turned out were overblown and I haven’t had any ED issues as yet. No urinary issues either. That may be a function of age (I am 62 and chose proton beam therapy).
Good luck with everything.

Layman question would be why resist the biopsy?
Biopsy is the only way to identify PCa and you can have a more targeted fusion guided biopsy since you have had the MRI.
I resisted seeing a Urologist after my PSA rose, but it was the right thing to do. It allowed me to treat aggressive cancer before it spread further.
IF you have a threatening cancerous lesion after biopsy, then you can decide on treatment or active surveillance, but at least you are making a more informed decision.
Best wishes to you and everyone.

Just found the answer to my question via a YouTube video entitled "Day 2 #ProstateCancer Active Surveillance, Advanced Treatments, Q&A | PCRI 2023 Conference" (between 39:00 - 45:00).

Dr. Matt Cooperberg, MD MPH (Fellow of the American College of Surgeons) explains "Inter Observer Variability", as it relates to radiologists reading mpMRI's. He also explains, in detail, what is being measured during the T2, diffusion weighting and contrast dye portions of the mpMRI.

Bottom Line: Even at the "best" mpMRI reading centers, individual radiologists have a 25% - 75% chance that their PIRAD 5 lesion reading will be a high grade cancer AND the mpMRI reports from different radiologists (at the best centers) will be different when reading the SAME mpMRI.

It seems to me that mpMRI image reading would be a perfect application for AI...to take out the inherent human error associated with reading the extremely complex mpMRI prostate scan. Maybe this has already begun???

Here's where you can find the YouTube video for which I refer: https://www.youtube.com/watch?v=eq9PscmTaSU

Primary reason I have resisted is concern over spread if the lesion is cancer because of invasive nature of the biopsy.....

Literature says to monitor via another MRI in 2 years to check if growing. I had a second MRI at 13 months which showed no growth.

Also most recent PSA Free test suggests that "if" it is cancer it likely is not aggressive. Everything seems to be "if" or "maybe"..

Why was MRI ordered? Because I had a PSA of 4.3.... Later I learned that 4.3 is not high for my age.