is an Assistant Professor of Radiology, Department of Radiology,
University of Miami, Jackson Memorial Hospital, Ryder Trauma
Center, Miami, FL.
In the evaluation of vascular injuries, catheter angiography has
been the gold standard imaging modality. As computed tomography
(CT) technology has evolved, helical multislice CT (MSCT)
angiography has become an integral part of the initial assessment
of many injured patients. The ability to obtain high-resolution
images with MSCT during optimal contrast enhancement helps detect
the presence and define the extent of vascular injuries. CT
angiography (CTA) has increasingly been used to diagnose arterial
injuries resulting from blunt and penetrating trauma of the neck
At our institution, CTA has replaced angiography for diagnosis of
most vascular injuries resulting from penetrating and blunt trauma
to these regions. This article describes the author's current
imaging protocol with MSCT, the spectrum of diagnostic findings
seen in vascular trauma, and the role of CTA in the planning of
vascular injury management.
Scan parameters of our MSCT examinations are as follows: 120 to
140 Kvp; 250 mAs. Other technical parameters vary according to the
specific anatomic area and depend upon the specific CT scanner
used; at our institution, we currently use 4-channel detector
scanners (Table 1). The injection protocol utilizes 100 to 120 mL
of intravenous nonionic contrast material at a rate of 4.5-mL/sec
by means of a power injector via an 18gauge catheter placed in an
antecubital vein and an automated triggering device (bolus
tracking). A fixed scan delay may be used at institutions where the
automatic delay is not used or where it is not available (Table 1).
An alternative method of establishing the scan delay is to use a
test bolus. With the test bolus technique, a small contrast bolus
is administered while scanning at a fixed level in the region of
interest-for example, the aortic arch. From this test, a
time-density curve is obtained.
Axial images are reviewed at a workstation or picture archiving
and communication system (PACS) station, and multi-planar
reformations (MPR) or 3-dimensional (3D) renderings are obtained
using volume rendering (VR) algorithms. Scrolling through the
images on the PACS workstation using the cine mode allows for easy
detection of subtle changes in vessel caliber and small
extraluminal collections of contrast. Multiplanar reformations and
3D reconstructions are often useful in the interpretation of
challenging cases as well as in planning subsequent interventions
because most surgeons prefer these reconstructions that closely
resemble the more familiar digital subtraction angiogram images.
The 3D im-ages are also useful in the evaluation of arterial
segments that course in the plane of the axial CT, such as the
subclavian and axillary arteries (Figure 1).
CT findings of arterial trauma
Direct signs of injury on CT angiography include irregular
arterial margins and filling defects, contrast extravasation, lack
of vascular enhancement, and vascular caliber changes. Indirect
signs of vascular injury include indistinctness of the perivascular
fat planes, perivascular hematoma, and bone and bullet fragments
<5 mm from a major vessel. The presence of an indirect sign
should be considered a potential indication for a conventional
angiogram. The decision to perform a catheter angiogram on patients
with indirect findings depends on the experience of the
interpreter, the quality of the scan, and the clinical condition of
the patient. In patients with an indirect finding around the
carotid circulation, angiography is usually warranted because of
the potential catastrophic consequence of missing an arterial
injury on this location. The arterial lesions include intimal
tears, dissections (which are visualized as intraluminal linear or
round filling defects surrounded by contrast material on both
sides) (Figure 2), and pseudoaneurysms (which are seen as
extravascular collections of contrast medium) (Figure 3). The CT
signs of a pseudoaneurysm also include irregularity of the vessel
wall and an abrupt change in caliber (Figure 4). Partial or total
occlusions are visualized as a lack of opacification following the
administration of contrast material. Arteriovenous fistulas (AVFs)
are visualized by early filling of venous structure (Figure 5).
These AVFs represent simultaneous injury of an adjacent artery and
a vein. The main CTA finding of vessel transection is the presence
of prompt contrast extravasation into surrounding structures
(Figure 6). The presence of active extravasation of contrast must
be recognized because it indicates a need for urgent surgery to
prevent exsanguination. Most patients with vessel transection are
hemodynamically unstable and require immediate surgical
intervention; therefore, these lesions are rarely encountered on
Injuries to the neck are more frequently the consequence of
penetrating trauma. The management of hemodynamically unstable
patients who have suffered a penetrating neck injury is emergency
On the contrary, the diagnostic evaluation of hemodynamically
stable patients who present with wounds that penetrate the platysma
muscle is still controversial. Most surgeons currently practice
selective conservative management based on the use of multiple
diagnostic studies including angiography. Recently, the use of
invasive routine angiography in stable patients has been
discouraged because of the high number of negative examinations
and the availability of alternative noninvasive diagnostic methods,
such as helical or multislice CTA.
In some recent series, the sensitivity and specificity of CT
angiography for diagnosis of cervical vascular injuries have been
reported to be in the range of 90% to 100%.
CT angiography can also provide additional information about
nonarterial injuries, such as those of the cervical spine and the
In gunshot wounds to the neck, CT can delineate the bullet
trajectory and help identify potential injuries, thus reducing the
need for additional studies such as endoscopy and/or contrast
esophageal studies in patients whose trajectories are clearly away
from the aerodigestive tract. Further studies are needed to more
precisely define the possible role of CT for the evaluation of the
aerodigestive tract injuries.
Blunt traumatic injuries of the extracranial carotid and
vertebral arteries have been regarded as uncommon injuries with
potentially devastating consequences. Recent literature suggests
that the true incidence of blunt cerebrovascular injury is higher
than was initially described.
Centers performing an aggressive screening of selected patients
using angiography have reported a higher incidence of 0.33 to 2.7%.
Although noninvasive techniques, such as multislice CTA and
magnetic resonance angiography (MRA), have potential as screening
tools in patients with blunt cerebrovascular injury, angiography is
still considered the study of choice.
Recently, CT of the carotid and vertebral arteries in all trauma
patients who are scheduled to undergo CT of the cervical spine has
been recommended by Mutze et al.
The use of CTA as a screening method for these blunt
cerebrovascular injuries will require further investigation.
Vascular injury that involves the lower extremities is a serious
complication following both penetrating and blunt trauma. In order
to reduce morbidity and mortality, prompt diagnosis and subsequent
treatment of these injuries are critical. Clinical signs of
arterial injury include "hard signs" (such as pulsatile bleeding,
expanding hematoma, pulse deficits, distal ischemia, and
thrill/bruit due to AVFs) and "soft signs" (such as proximity of
the injury to a major artery, stable hematoma, hypotension, and
A penetrating wound in proximity to vascular structures is
considered an indication for angiography only in cases in which a
bullet follows the course of a major artery over a long segment.
Traditionally, patients who remain hemodynamically stable following
lower extremity injury undergo evaluation with direct contrast
angiography. However, this technique has limitations, including its
invasive nature as well as transporting and monitoring issues.
Additionally, this invasive procedure may result in unnecessary
risks to these patients, as nonsurgical diagnoses (such as
nonocclusive intimal flaps, partial narrowing, and branch vessel
occlusions) may be revealed. Multislice CTA provides a rapid,
minimally invasive study to evaluate lower extremity arterial
injury. In addition, CTA aids in diagnosing the location, extent,
and type of vascular injury to the lower extremity.
In many major trauma centers throughout the world, helical and
multislice CTA is now being used for the evaluation of arterial
injuries. The advantages of CTA include, among many others, the
speed at which the examination can be completed and its minimally
invasive nature. We believe that CTA might be warranted as an
initial method of diagnosis in patients who are hemodynamically
stable and who do not have an indication for immediate surgical
exploration. CT angiography demonstrates the potential to
discriminate between patients who require further invasive
imaging/exploration and those who can be safely discharged home.
Patients with direct signs of vascular injury on CT do not need
further evaluation, and, at many centers, including our own,
patients are taken to surgery without angiography. A minority of
patients may still require digital subtraction angiography when CTA
examinations are nondiagnostic or have equivocal or indirect