MEMRI and Kidney Disease

Inclusion Criteria: All subjects to be entered must: Be able to provide written informed consent after having received oral and written information about the study. \>18 years of age Availability to complete study visits If female, be non-pregnant as evidenced by a negative pregnancy test or be post-menopausal or surgically sterile. Additionally, cohort specific inclusion criteria are as follows: Cohort 1; Acute kidney injury- A diagnosis of AKI will be made based on the following criteria (based on the definition used in the Kidney Precision Medicine Project www.kpmp.org): Previous (within 3 years) eGFR \>45 ml/min/1.73m2 OR no history of kidney disease if no blood results available AND Elevated creatinine \>1.5x previous result OR \>150 μmol/L if no previous value AND Increasing creatinine within 48 hours OR requirement for dialysis. Cohort 2; Chronic kidney disease- Stable CKD for at least 6 months (monitored by eGFR), matched to AKI cohort at follow up based on renal function. Cohort 3: Matched controls- Matched to AKI cohort participants at baseline for age, sex, cardiovascular disease risk and cardiovascular medication. Cohort 4; Vasculitis- A new diagnosis of vasculitis or an existing diagnosis with relapsing disease, and kidney involvement. Cohort 5; Kidney transplantation- Has kidney failure and has received a kidney transplant in the preceding 1 month. Cohort 6: Kidney transplant rejection- Biopsy proven episode of transplant rejection. Exclusion Criteria: The following criteria apply to all patients: 1. Unable to give informed consent. 2. Have any contraindications to standard MRI safety criteria, including implanted devices. 3. Subjects under the age of 18 years old. 4. Pregnancy/positive pregnancy test. 5. Current breastfeeding. 6. Have a diagnosis of kidney disease due to polycystic kidney disease. 7. Patients in critical care or on surgical wards will be excluded. 8. Patients taking calcium channel antagonists or digoxin. Additionally, cohort specific exclusion criteria are as follow: Cohort 1- Excluded if they have a diagnosis of diabetes. Cohort 2- Excluded if receiving dialysis or those with a functional kidney transplant, multi-system disorders (e.g., systemic vasculitis), or any patients receiving immunosuppression.