The purpose of this research study is to determine the frequency and severity of iron overload in patients with Sickle Cell Anemia and its relationship to blood vessel function. The investigators hypothesize that intermittent transfusions that these patients receive during hospitalizations produces significant iron overload and impairs blood vessel relaxation.

Patients with sickle cell anemia often require blood transfusion as part of the treatment for their disease. Each teaspoon of transfused blood contains about 5 mg of iron and the levels of iron in sickle cell patients increase rapidly with each transfusion. While iron is necessary for many bodily functions, too much iron damages blood vessels, liver, hormone producing glands (pancreas, pituitary and thyroid) and the heart. It is important to know how iron damages blood vessels because most of the problems experienced by sickle cell anemia patients (stroke, kidney failure, pulmonary hypertension, heart disease) result from blood vessel damage. In this trial, iron in the liver, pancreas, and kidney will be measured noninvasively by MRI while vascular function will be measured by ultrasound and tissue Doppler. Patients will be recruited primarily from the greater Los Angeles area, although patients from greater distances will be allowed to participate.

Inclusion Criteria:

• Age > 13 years
• Documented diagnosis of sickle cell anemia (SS, SC, Sß0, Sß+)
• Transfused no more than 8 times in a year.

Exclusion Criteria:

• Cardiac pacemaker, implantable neurostimulator or other MRI incompatible device.
• History of extreme claustrophobia in MRI machine or other reason for inability to do MRI without sedation.
• Inability to be positioned on the MRI table for sufficient time to complete the MRI exams.
• Any medical or psychological condition that, in the opinion of the local investigator, would make it unsafe or ill-advised for the subject to participate.
• Currently not receiving chronic transfusion therapy, defined as greater than 8 transfusions per year.

Our large and well-established sickle cell Center has strong ties to the SCD community in a large metropolitan area (Los Angeles), placing us in an ideal position to rapidly accrue sufficient subjects to study the prevalence of iron overload and determine the relation between directly measured iron loading, vascular responsiveness and clinically relevant biomarkers of vascular function.