Prostate Cancer

[healthylife]

Hi,
My father last Novermber had an acute prostatitis which was cured by the antibiotic. But My father's PSA is high(maybe 19), and the Ultrasonography shows prostate enlargement with prostate stone. the digital rectal exam shows prostate normal. The doctor ordered MRI for him, the MRI shows some shadow. So, the doctor asked him to do a biopsy. I am wondering can MRI detect the prostate cancer? How high the false positive??
Thanks a lot