What are the typical CTA and MRA pulmonary vascular imaging protocols?
On modern multidetector computed tomography (MDCT) scanners, CTA for pulmonary arterial evaluation utilizes a high rate of iodinated contrast material injection (4 to 6 ml/sec) via a peripheral vein. Scanning is timed to obtain optimal contrast opacification of the pulmonary arteries. Thin-section axial and multiplanar CT images of 1 mm thickness are then reconstructed through the chest. With the latest generation CT scanners, image acquisition times can be less than 5 seconds, providing high-quality images even in patients who are unable to breath hold.
Bright blood MRA utilizing steady state free precession (SSFP) gradient echo sequences and 2D time of flight (TOF) techniques may be performed without gadolinium-based intravenous contrast material. 3D contrast-enhanced MRA is an additional technique used to image the pulmonary vasculature with greater detail. Similar to CTA, the image data can be reformatted on a computer workstation to obtain multiplanar views for optimal evaluation.