- Exclusionary criteria include age under 18 years and over 85 years, those who are unable to understand the consent process , those who cannot read or speak English, active pregnancy, hypersensitivity to perflutren contrast agents, pulmonary hypertension, active illicit drug use, untreated blood pressure over 160/95, sickle cell disease, or a history of intracardiac shunt. Additional exclusion criteria neurological diseases such as spinal stenosis, unspecified pain disorders, and any uncontrolled medical conditions.