Subjects with <5% pre-test low likelihood for CAD based on Diamond and Forrester criteria will be recruited to undergo both rest/stress dipyridamole PET followed by a rest/stress Lexiscan(TM) PET with 30 days.

Subjects with existing mild-moderate ishemia demonstrated by a recent (< 1 month) rest/stress dipyridamole PET will undergo a rest/stress Lexiscan(TM) PET.

A CT scan will be acquired for attenuation correction of the rest image (9 mA, 120 kVp, 4.24 secs) during end-expiration breath-holding. This will be followed by infusion of approximately 60 mCi of Rb-82, 60 to 100 seconds after which resting images will be acquired with ECG-gating. Following rest imaging, 0.56 mg/kg of dipyridamole will be infused over 4 minutes. Three minutes after the completion of the infusion, approximately 60 mCi of Rb-82 will be infused. Peak stress images will be acquired with ECG-gating, starting 90 seconds after the the beginning of the infusion of Rb-82 and continuing for 5 minutes. A CT scan will be acquired for attenuation correction of the stress image (9 mA, 120 kVp, 4.24 secs) during end-expiration breath-holding.