We propose a single-scan two-injection myocardial perfusion imaging protocol using ammonia. Subjects will undergo single-scan two-injection imaging as well as regular stress single-scan single-injection protocol and the myocardial blood flow of both techniques will be compared.

Healthy Volunteers:

Inclusion Criteria:

• Subjects must be ≥30 and ≤75 years of age;
• Subjects must provide informed consent prior to study procedures;

Exclusion Criteria:

• History of CAD, including:
• Prior abnormal myocardial perfusion study
• History of MI
• History of angina
• Coronary artery obstruction >50% on CTA and/or angiography
• Left ventricular ejection fraction <50%
• Any relative or absolute contraindication to adenosine stress, including:
• 2nd or 3rd degree heart block
• Bradycardia (HR<50 bpm)
• Recent acute coronary syndrome (ACS)
• Unstable angina
• Severe heart failure (left ventricular ejection fraction <15%)
• Ventricular arrhythmia
• Severe asthma and/or chronic obstructive pulmonary disease (COPD)
• Baseline hypotension defined as systolic blood pressure < 90 mmHg
• Caffeine intake within 24 hours prior to imaging
• Current use of theophylline, dipyridamole, or carbamazepine
• Allergy or intolerance to adenosine
• Positive serum and/or urine pregnancy test, or lactating, or possibility of pregnancy cannot be ruled out prior to dosing;

Subjects with CAD:

Inclusion criteria

• Subjects must be ≥30 and ≤75 years of age;
• Subjects must provide informed consent prior to study procedures;
• Abnormal myocardial perfusion study within the past 12 months

Exclusion criteria

• Revascularization (percutaneous coronary intervention and/or coronary artery bypass) following last myocardial perfusion study
• Acute coronary syndrome within 30 days
• Left ventricular ejection fraction <50%
• Any relative or absolute contraindication to adenosine stress, including:
• 2nd or 3rd degree heart block
• Bradycardia (HR<50 bpm)
• Recent acute coronary syndrome (ACS)
• Unstable angina
• Severe heart failure (left ventricular ejection fraction <15%)
• Ventricular arrhythmia
• Severe asthma and/or chronic obstructive pulmonary disease (COPD)
• Baseline hypotension defined as systolic blood pressure < 90 mmHg
• Caffeine intake within 24 hours prior to imaging
• Current use of theophylline, dipyridamole, or carbamazepine
• Allergy or intolerance to adenosine
• Any clinically significant acute or unstable physical or psychological disease, judged by the investigators, to be incompatible with the study;
• Radiation exposure exceeds current Radiology Department guidelines (i.e. 50 mSv in the prior 12 months);
• Female participants only: Positive serum and/or urine pregnancy test, or lactating, or possibility of pregnancy cannot be ruled out prior to dosing;
• Inability to provide written informed consent;

Patients of the Massachusetts General Hospital