Microvascular Blood Flow in Sickle Cell Anemia

Subjects who are not having a pain crisis receive a 24-hour infusion of regadenoson. Contrast-enhanced ultrasound will be performed four times during the 24 hour regadenoson infusion

Subjects who are not having a pain crisis will have contrast-enhanced ultrasound performed up to four times over a two-day period. Time points will resemble the time course used for the Regadenoson Arm, although no investigational drug will be given.

Contrast-enhanced ultrasound will be performed on adults with sickle cell anemia at baseline who are not having a pain crisis and performed again during a pain crisis

Contrast-enhanced ultrasound will be performed on healthy control subjects at baseline, on the first day of the study and 30 days later

Contrast-enhanced ultrasound will be performed on healthy volunteers (Technique Optimization Controls)