If there are acute symptoms an urgent CT of the abdomen or thorax (or both) with IV contrast with aorta angiogram protocol without oral contrast is the first examination. This is a potential surgical emergency. In cases of suspected traumatic injury to the aorta angiography may be elected, since definitive evaluation of anatomy is required for potentially emergent surgery. If elective evaluation of a potential abdominal aortic aneurysm without acute symptoms is desired, the most cost-effective screening test is an ultrasound of the aorta. Ultrasound is safer than CT. MRI evaluation of the aorta is not a first-line examination.