What modalities are used to study aneurysms, and when is each best used?

Angiography: excellent for delineating branch vessel involvement and for preoperative assessment
Ultrasound: ideal for following the progress of aneurysm size over time
CT: very accurate means of measuring aneurysms; identifies mural thrombus and extraluminal hematoma; reproducible
MRI: very accurate; can image aneurysms in any plane; reproducible; especially useful in patients allergic to iodinated contrast