An MRI is not 100 percent, therefore, not definitive. When using a dye (myelogram) it enhances the accuracy, but only then to about 85-90%. I had surgery done for a torn rotator cuff and detached labrum about 5 years back. After I had extensive physical therapy for months, I was still having quite a bit of pain and discomfort. I had an ensuing MRI with dye/contrast that came back negative, and was advised by my orthopedic surgeon that it was probably scar tissue, and, that he could go back in and perform a cleaning or, in medical terms, a debridement...I had this performed, only to reveal that my labrum was still torn...and had to reconstruct again...