Low radiation dose ECG-gated chest CT angiography on a 256-slice multidetector CT scanner

Computed tomography angiography (CTA) of the thorax other than cardiac CTA, is utilized for a multitude of conditions and ranges in application from a diagnostic test, to presurgical planning and postsurgical follow-up. Helical CTA without electrocardiogram (ECG) gating has been routinely utilized for the evaluation of thoracic vasculature. However, its applicability can be limited in the evaluation of the thoracic aorta and pulmonary vasculature because of the artifacts resulting from cardiac motion. Traditional retrospective ECG-gated helical scans address this issue but at the price of a high radiation dose to the patient. In this paper we review CTA dose reduction strategies for non-coronary indications, examine field of view requirements, and discuss breath hold challenges for ECG-gated acquisitions. In addition, we present clinical examples performed using low-dose prospective gating technique for evaluation of the aorta acquired on a 256-slice multidetector computed tomography system.