Maybe a stupid question on my part since we are talking about Mayo here, but are you sure that it was a 3T multi-parametric MRI, and did they use intravenous contrast?
Sometimes they can't use the 3T because of a small amount of metal somewhere inside the patient's body, and so they have to use the 1.5T instead.
But I think that the commenter who suggested that perhaps the radiologist just missed some suspicious nodules that the urologist picked up on the MRI images makes sense as a possible explanation, assuming the biopsy was an MRI fusion biopsy.