CT Pulmonary Angiography
-When performing a CT Pulmonary Angiography exam, the goal is to image the pulmonary arteries during peak opacification. Patients are instructed to either perform shallow breathing or simply stop breathing for a short period of time during the acquisition.
-This technique is utilized because, if the patient takes in a breath and holds it during the acquisition, it may cause non opacified blood to be pulled into the pulmonary arteries, which will dilute the contrast.
-It is common for this exam to be scanned in the caudocranial direction, as this can reduce motion artifacts from the patient breathing and helps to reduce artifact from the contrast as it is being administered.
-Contrast media should be injected at a rate of at least 4mL/second, and there are several methods that could be used to achieve peak opacification of the pulmonary arteries. Primarily, these include:
A test bolus can be performed to determine actual time until peak enhancement
Bolus tracking can be utilized to monitor and automatically begin scanning at peak enhancement
– Utilizing a saline flush immediately post contrast administration may help to reduce streak artifact in the superior vena cava.
-Arms above head
-IV in the antecubital
-Suspension of breathing
-From above lung apices through the lung bases