Inclusion Criteria:

• * Between ages 40 and 80 years old.
• * Patients with hypertension (BP\>140/90 mmHg) and/or requirement for two or more antihypertensive medications for more than 4 weeks.
• * Serum creatinine under 2.2 and 2.0 mg/dL for men and women, respectively (Caucasians). Values for African-American subjects are slightly higher (2.4 mg/dL, males; 2.1 mg/dL females).
• * No contraindications to angiography: severe contrast allergy.
• * No contraindications to no-contrast MR evaluations: e.g. pacemaker or magnetically active metal fragments, claustrophobia.
• * Patients have the ability to comply with protocol
• * Patients are competent and able to provide written informed consent

Exclusion Criteria:

• * Patient has serum creatinine \>2.2 mg/dL for men and \>2.0 mg/dL for women (Caucasians); \>2.4 mg/dL for men and \>2.1 mg/dL for women (African American).
• * RVD in a solitary kidney
• * Patients have clinically significant medical conditions within the prior six months: e.g. myocardial infarction, congestive heart failure, stroke, that would, in the opinion of the investigators, compromise the safety of the patient.
• * Uncontrolled hypertension (Systolic BP \>180 mmHg despite therapy).
• * Diabetes requiring insulin or oral hypoglycemic medications.
• * Evidence of hepatitis B or C, or HIV infection.
• * Requirement for potentially nephrotoxic drugs; e.g., non-steroidal anti-inflammatory drugs.
• * Cardiac ejection fraction less than 30%.
• * History of deep venous thrombosis within 3 months of enrollment.
• * Kidney transplant.
• * Pacemaker, implantable defibrillator or other contraindication to MRI
• * Inability to comply with breath-hold for 20 seconds
• * Any active malignancy and undergoing therapy
• * Patients are pregnant.
• * Kidney or ureteric stone
• * Another known acute or chronic kidney disease
• * Federal medical center inmates.
• * Latex allergy