Optimization of contrast delivery for pulmonary CT angiography

Pulmonary CT angiography is becoming an increasingly important tool for diagnosing Pulmonary Emboli. An important aspect in optimizing the quality of these studies is achieving maximum levels of enhancement of the pulmonary arteries. In this study we reviewed the current literature to see if there was any standardization of protocols to achieve this purpose, and found that there was no consensus. Using well described techniques for determining blood flow we were able to demonstrate the proper time delays to achieve the highest levels of enhancement. As contrast flows into the pulmonary arteries, the degree of enhancement rapidly reaches a plateau phase. This is then followed by a recirculation phase where enhancement starts to increase again. The proper time delays between scan time and start of contrast infusion should allow for enhancement to be within this recirculation phase. An experimental model was developed to demonstrate the principles.