This is a clinical feasibility study to assess the value of MR imaging for obtaining functional, dynamic and anatomical information in a comprehensive imaging protocol in subjects having obstructive uropathy.

Inclusion Criteria:

• Males or females 18 years of age or older.
• All female patients of childbearing potential must agree to use a medically accepted method of contraception at the time of the study.
• Patients must have the ability to understand the requirements of the study, provide written and informed consent to participate, and agree to abide by the study requirements.
• Patients who have known or suspected hydronephrosis or patients with solitary kidneys.

Exclusion Criteria:

• Patients with known or suspected hypersensitivity to gadolinium-based agents.
• Patients who are pregnant or lactating.
• Patients with a condition that is a contraindication to MRI (e.g., cardiac pacemaker, epicardial pacemaker leads, cochlear implants, ferromagnetic aneurysm clip, ferromagnetic halo device, or other conditions that would preclude patient proximity to a strong external magnetic field).
• Patients with a recent history of hemolytic anemia, sickle cell anemia or other hemoglobinopathy.
• Patients with a history of significant claustrophobia.
• Patients with impaired renal function based on 24-hr urine collection (creatinine clearance <10 ml/min or serum creatinine >1.8 mg/dl)

Patients who have been diagnosed with obstructive uropathy