Inclusion Criteria:

Stratum 1:

1. Able to provide written informed consent
2. Low (less than 10%) pre-test probability of CAD (Appendix D)
3. Scheduled for clinically indicated stress echocardiography or stress SPECT within the 14 days prior to or following Study Day 1 (prior to coronary angiography) or coronary angiography within the 7 days following Study Day 1
4. Technically adequate unreconstructed stress SPECT data or scheduled for clinically indicated stress SPECT within 14 days of Study Day 1 and prior to coronary angiography
5. Adequate visualization of all myocardial segments in at least one view during non-contrast echocardiography (See Section 5.3.1)
6. No evidence of a right-to-left shunt during non-contrast echocardiography

Stratum 2:

1. Able to provide written informed consent
2. Intermediate (10% to 90%) pre-test probability of CAD (Appendix D)
3. Scheduled for clinically indicated coronary angiography within the 7 days following Study Day 1
4. Technically adequate unreconstructed stress SPECT data or scheduled for stress SPECT within 14 days of Study Day 1 and prior to coronary angiography
5. Adequate visualization of all myocardial segments in at least one view during non-contrast echocardiography (See Section 5.3.1)
6. No evidence of a right-to-left shunt during non-contrast echocardiography

Stratum 3:

1. Able to provide written informed consent
2. High (greater than 90%) pre-test probability of CAD (Appendix D)
3. Scheduled for clinically indicated coronary angiography within the 7 days following Study Day 1
4. Technically adequate unreconstructed stress SPECT data or scheduled for stress SPECT within 14 days of Study Day 1 and prior to coronary angiography
5. Adequate visualization of all myocardial segments in at least one view during non-contrast echocardiography (See Section 5.3.1)
6. No evidence of a right-to-left shunt during non-contrast echocardiography

Exclusion Criteria:

1. Women who are pregnant or lactating

2. Known hypersensitivity or known contraindication to:

   1. Dipyridamole
   2. Ultrasound contrast agents (including PB127 and excipients)
   3. Blood, blood products, albumin, egg, or protein
3. Use of caffeine or xanthine containing products within the 24 hours prior to PB127 MCE
4. Previous exposure to PB127 Ultrasound Contrast Agent
5. Heart transplant
6. Known right-to-left shunt including atrial septal defect
7. Current or history of uncontrolled ventricular tachycardia
8. Current atrial fibrillation, atrial tachycardia, or atrial flutter
9. Pacemaker or defibrillator

10. Unstable cardiac status

    1. Unstable angina grade CCS Class IV severity with ongoing symptoms and/or ongoing infusion of intravenous nitroglycerin (See Appendix F)
    2. Second-degree or greater heart block
    3. Frequent (>60/hour) or symptomatic ventricular ectopics at baseline
    4. Hypertension (SPB >200 and/or DBP >110 mmHg on two consecutive readings within one hour of PB127 MCE)
    5. Hypotension (SPB <90 mmHg)
    6. Severe aortic stenosis (>100 mmHg peak transvalvar gradient or <0.6 cm2 estimated valve area)
    7. Pulmonary edema within the 7 days prior to Study Day 1
    8. Resting oxygen saturation of less than 90%
    9. Q-wave myocardial infarction within the 7 days prior to Study Day 1
    10. PTCA or CABG within the 7 days prior to Study Day 1
11. Chronic Obstructive Pulmonary Disease (COPD) or bronchospastic airway disease which, in the opinion of the Investigator, is significant enough to contraindicate dipyridamole
12. Known history of severe pulmonary hypertension characterized by estimated pulmonary artery systolic pressure of >50 mmHg
13. Use of intravenous or intracoronary contrast agent other than thallium or technetium within the 24 hours prior to Study Day 1

14. Liver disease (i.e., current or previous hepatic viral infection, chronic hepatitis) characterized by one or more of the following

    1. Current jaundice
    2. Elevated bilirubin > upper limit of normal
    3. Currently elevated hepatic enzymes > 2X upper limit of normal
15. Medical conditions or other circumstances that would significantly decrease the chances of obtaining reliable data or achieving the study objectives (i.e., drug dependence, psychiatric disorder, dementia, or associated illness), extenuating circumstances, medical conditions that make it unlikely that a patient can complete the clinical trial or follow-up evaluations, or other reasons for expected poor compliance with the Investigator's instructions