 This will be accomplished by imaging transplant recipients in three distinct cohorts; those with good allograft function but coming in for routine protocol biopsy, with stable renal function, and with unstable renal function due to post-transplant complications. These patient populations will receive protocol biopsies i.e. scheduled repeat biopsies as standard of care; therefore pathologic results will be available for correlation with MRI measures. The investigators hypothesize that MRI methods can be a non-invasive surrogate marker of renal tissue properties and functional changes induced by renal post-transplant dysfunction e.g. renal rejection currently only obtained through biopsy. 