Functional, Dynamic, and Anatomic MR Urography

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)