Myocardial Perfusion Imaging: Mechanism

Functions on the premise of mismatch in coronary perfusion after a vasodilator (e.g dipyridamole) is administered. 

HOW? The coronary vessels with disease burden are already maximally dilated, hence after the addition of the vasodilator, perfusion mismatch occurs as the healthier vessels dilate further.

False NEGATIVES:

• Caffeine or theophylline can interact with dipyridamole.
• Severe flow limiting triple vessel disease or LEFT main diseae (may both cause a balanced defect). 

CONTRAINDICATIONS:

• Severe airway disease (COPD or Asthma)

BONUS: reversal agent to dipyridamole is amiophylline.

REFERENCES

1. Driessen, Roel S et al. “Myocardial perfusion imaging with PET.” The international journal of cardiovascular imaging vol. 33,7 (2017): 1021-1031. doi:10.1007/s10554-017-1084-4
2. Burrell S, MacDonald A. Artifacts and pitfalls in myocardial perfusion imaging. J Nucl Med Technol. 2006 Dec;34(4):193-211; quiz 212-4.