Inclusion Criteria:  Written informed consent Age > 18 years Patients wishing to close the fistula and planned for surgical fistula closure eGFR CKD EPI ≥ 45 ml/min/1.73m2 at one year post transplantation Stable eGFR within the past 6 months Controlled blood pressure  Exclusion Criteria:  Kidney Transplantation < 12 months before fistula closure Proteinuria > 500mg/d Presence of donor specific antibodies Rejection within the past 6 months BK virus replication within the past 3 months Cardiac pacemaker, which is not compatible with MRI Claustrophobia