Can we trust the scans?
The trustworthyness of the MRI is only as good as the equipment, the image quality, and the expertise of the practitioner who analyzes the images. The differences in tissue appearance, based on which conclusions are drawn, are subtle at best. Prostate MRI analysis is a relatively new undertaking, with many rookies.
I am Gleason 9. I flew 2500 miles to seek out a practitioner who I concluded was one of the few legitimate experts. I don't know what options you have in Canada. Unfortunately, it falls to you to assess the expertise of your practitioners.
You have already indicated that you know the limitations of the pelvic/abdominal CT scan and bone scan.
Unfortunately for all of us, there is no test available anywhere in the world that is able to detect the earliest bundles of spreading prostate cancer, which are microscopically small.
There are experimental scans with better detection capabilities that can sometimes be obtained with sufficient research/persistence/payment, but as said above, there is no scan for which a finding of "clear" guarantees you are actually clear.
That is why some practitioners make use of Gleason score and PSA score to guide treatment decisions. By studying results of treatment over long periods of time, they have observed that certain combinations of Gleason score and PSA score have highly elevated risk of local, regional, and distant metastasis at the time of diagnosis, even when the scans return findings of "clear".
For this reason, some recommend against surgery when Gleason scores and PSA scores reach certain thresholds, even when cancer outside the prostate is not proven. It is assumed.
At the current state of technology, choices of treatment are, at best, educated guesses.