Inclusion Criteria:  ≥18yrs Acute kidney injury stage 1-3 by KDIGO criteria At least one previous serum creatinine result available for determining baseline renal function Able to give informed consent  Exclusion Criteria:  Unable to give consent or understand written information Obstructive uropathy Renal transplant Patient receiving palliative care Patient with AKI due to recent nephrectomy Patients with known or suspected acute vasculitis or glomerulonephritis requiring immunosuppression End-stage kidney disease (CKD stage G5 or already on RRT) Serum creatinine changes that do not meet the KDIGO definition of AKI  MRI cohort:  Contraindications to MRI e.g. claustrophobia, cardiac pacemaker, metallic fragments or implants Age < 50years old