Since its inception in the early 1990s, shortly after the introduction of spiral-computed tomography (CT), computed tomographic angiography (CTA) has experienced a dramatic rise in clinical indications, universal acceptance, and number of studies performed worldwide. Although initially met with skepticism regarding its ability to adequately image the arterial system when compared to conventional angiography (CA), CTA has rapidly become the imaging modality of choice in many clinical situations, including the evaluation of aortic aneurysm, dissection, trauma, and penetrating atherosclerotic ulcer. CTA is clearly well-suited for the pre- and post-procedural evaluation of stent grafts. Other aortic abnormalities, including congenital anomalies, arteritides (such as Takayasus), and intramural hematoma, are evaluated well by CTA [1]. It also shows great promise in the imaging of renal and visceral arteries and the peripheral arterial system. Clear indications for CTA in the evaluation of the cerebral, coronary, and pulmonary arterial systems are also evolving and are discussed elsewhere in this isssue.
The explanation for the rapid development of CTA is, of course, multifactorial. The technologic developments with slip-ring gantry design, faster gantry rotation times, and, ultimately, multiple-row-detector arrays have paved the way for CTA, rapidly overcoming its major initial limitation�longitudinal anatomic coverage. Additionally, when compared with other imaging modalities, such as CA and magnetic resonance angiography (MRA), CTA is faster and generally more available with 24-hour-a-day staffing of CT scanners in many institutions. Few centers are able to offer either MRA or CA as quickly as CT imaging.
This feature of CTA is particularly salient in the setting of trauma, where rapid diagnosis is critical and where evaluation of other structures for traumatic injury often requires the use of CT. Furthermore, CTA combines the luminal information provided by CA with the cross-sectional advantages conferred by traditional axial CT. Visualization of the wall of vessels, extraluminal processes, and anatomic relationships with adjacent structures is clearly a strength of CT that cannot be matched by CA. Finally, CTA represents a noninvasive study with high diagnostic yield, convenience, and speed at a substantial cost savings when compared with CA [2]. It is easy to see why CTA has seen such tremendous growth as a distinct diagnostic modality in recent years.