N e u r o r a d i o l o g y / H e a d a n d N e c k I m a g i n g • R ev i ew Liang et al. Screening and Imaging of BCVI

Downloaded from www.ajronline.org by 37.44.207.85 on 01/21/17 from IP address 37.44.207.85. Copyright ARRS. For personal use only; all rights reserved

Neuroradiology/Head and Neck Imaging Review

Imaging of Blunt Vascular Neck Injuries: A Review of Screening and Imaging Modalities Teresa Liang1 David K. Tso1 Rita Y. W. Chiu1 Savvakis Nicolaou2 Liang T, Tso DK, Chiu RYW, Nicolaou S

OBJECTIVE. We will review the epidemiology of blunt cerebrovascular injuries (BCVIs) and the rationale for screening. Current imaging modalities used to screen for BCVIs will be discussed with an emphasis on CT angiography. CONCLUSION. Screening for BCVIs can decrease rates of postinjury complications, such as stroke. The use of standardized screening criteria and the appropriate imaging modalities can allow early detection of BCVIs and effective intervention.

T

he term “blunt cerebrovascular injury” (BCVI) encompasses injuries to the carotid and vertebral arteries. These injuries can occur in the setting of polytrauma or injury to the craniocervical region. Although BCVIs have previously been believed to be rare, recent studies in the literature report a significantly higher incidence of these injuries. This article will discuss the incidence of BCVIs and initial benign clinical presentation to emphasize the importance of appropriate screening protocols. Studies in the literature pertaining to imaging modalities used in the setting of BCVIs, with an emphasis on CT, will also be reviewed. Keywords: blunt cerebrovascular injury, blunt vascular neck injury, CT angiography DOI:10.2214/AJR.12.9664 Received July 21, 2012; accepted after revision November 18, 2012. 1 Department of Radiology, University of British Columbia, Vancouver, BC, Canada. 2 Department of Radiology, ER Radiology Division, Vancouver General Hospital, 899 W 12th Ave, Vancouver, BC, V5Z 1M9, Canada. Address correspondence to S. Nicolaou ([email protected]).

CME/SAM This article is available for CME/SAM credit. AJR 2013; 201:884–892 0361–803X/13/2014–884 © American Roentgen Ray Society

884

Incidence In their 1990 study, Davis and colleagues [1] estimated the incidence rate of BCVIs to be as low as 0.08% in all blunt trauma cases. However, in the past few years, significantly higher incidence rates have been reported. A retrospective study of 87 blunt trauma injuries reported a fourfold increase of 0.67% carotid artery injuries in blunt trauma patients [2]. More recently, higher incidence rates of BCVIs have been reported, ranging from 0.3% to 1.60% among all blunt trauma patients [3–14]. The incidence rates of BCVIs reported in the literature are summarized in Figure 1. An increase in the detection of BCVIs may be partially attributed to aggressive screening protocols and enhancements in imaging technology. Penetrating neck injuries are the major cause of jugular venous injuries and are

often diagnosed during exploration after an arterial injury [15]. Venous injuries usually tamponade or occlude without a major hematoma or hemorrhage because of the low-pressure system. However, in this article, we will focus on blunt neurovascular arterial injuries. An important cause of morbidity and mortality in the setting of BCVIs is stroke or cerebrovascular ischemia. Complications can appear 10–72 hours after trauma, after a latent phase with minimal signs and symptoms [16–18]. This latent phase may delay diagnosis and management. Mortality and morbidity rates have been reported to be 24% and 58%, respectively [17, 19], although a more recent study has shown mortality rates of up to 33% [20]. Rationale for Screening Standardized protocols aimed at early diagnosis and intervention in the setting of BCVIs could potentially reduce the associated morbidity and mortality. The reference standard modality has been digital subtraction angiography (DSA); however, DSA is an invasive procedure that has a stroke complication rate of 0.1–1% [21, 22]. BCVIs can often be clinically occult on admission and have a delayed onset of symptoms. Screening protocols to detect early complications of BCVIs may have a role in decreasing mortality and morbidity rates. A recent study showed the utility of a CT angiography (CTA) screening program for highrisk trauma patients; the detection of BCVIs increased 10-fold from an incidence rate of 0.17–1.4% in a study of 1313 blunt trauma

AJR:201, October 2013

Indications for Imaging Presenting signs and symptoms and the mechanism of the injury contribute to the indications for screening for BCVIs. Signs and symptoms include arterial hemorrhage, cervical bruits, expanding cervical hematomas, focal neurologic deficits, discrepancy between the neurologic examination and radiologic findings, and ischemic stroke on followup CT [23, 25]. When one of these signs or symptoms is present, emergent CTA of the carotid and vertebral arteries should be conducted. Other independent risk factors include high-energy mechanism of injury and associated cervical spine fracture, diffuse axonal brain injury with Glasgow coma scale (GCS) score of less than 6, LeFort II or III fracture, basilar skull fracture with carotid ca-

BCVI Incidence Rate (%)

1.60 1.40

1.25

1.20

1.05

1.03

1.10

1.10 0.66

0.53

0.58

20 al 06 ho tr a 20 07 Sl ik er 20 08 B er ne G 20 oo 09 dw in 20 Em 09 m et t2 01 1

M

B

iff l

20

00 Ea

st

m an

r2

06

6

6 00 tte

U

Sc

hn ei de r

ei t2

20

05

04 e ut z M

B

er

ne

20

20

02

0.30

ill er

patients [6]. In that study, 170 patients were identified to be at risk for BCVIs and were screened with CTA, which decreased the incidence of delayed stroke from 67% in patients who did not undergo screening to 0% in patients who underwent screening with CTA [6]. The overall mortality rate was reduced from 38% to 10% with the implementation of CTA screening [6]. Another study using a CTA screening protocol reported an overall incidence rate for BCVIs of 1.25%, which was increased to 28.4% in a screened population [8]. An appropriate screening algorithm for BCVIs allows early detection and the ability to promptly initiate pharmacologic or interventional treatment. Eastman and colleagues [22] reported a 12-fold decrease in the time from admission to diagnosis using CTA versus DSA. The stroke rate was also significantly decreased in the patients receiving CTA screening (CTA vs DSA, 3.8% vs 15.2%, respectively) [22]. In a study of 15,767 blunt trauma patients screened with DSA, 34% were identified to have BCVIs; of these patients, patients who received antithrombotic treatment, only 0.5% suffered a stroke versus 21% of patients who did not receive treatment [23]. A recent meta-analysis of diagnostic screening for BCVIs found the incidence to be 0.18–2.70% in approximately 122,176 blunt trauma admissions [24]. In the analysis of screening criteria, the investigators found that cervical spine and thoracic injuries showed the greatest association with BCVIs and concluded that patients with these injuries should be screened. Overall, appropriate screening algorithms for BCVIs improve detection of occult BCVIs, allow early diagnosis and treatment, and ultimately decrease mortality and morbidity rates.

M

Downloaded from www.ajronline.org by 37.44.207.85 on 01/21/17 from IP address 37.44.207.85. Copyright ARRS. For personal use only; all rights reserved

Screening and Imaging of BCVI

Fig. 1—Bar graph shows results of literature review of incidence rates of blunt cerebrovascular injuries (BCVIs) in blunt trauma admissions [3–14].

nal involvement, and near hanging with axonal brain injury [23, 25, 26]. This collective set of signs, symptoms, and risk factors is commonly referred to as the “Modified Denver Risk Criteria” (Appendix 1) and is used to aid in CTA screening for the early diagnosis and management of BCVIs [26, 27]. However, approximately 20% of patients diagnosed with BCVIs may not fulfill the reported screening criteria [26]; thus, more liberal screening criteria may be indicated to enhance detection rates. For example, at our institution, it was shown that 39% of patients who presented with BCVIs had a GCS score of less than 13, which is consistent with the previously reported rate of GCS of less than 13 in 31% of carotid artery injuries [6, 28]. The study results also reinforced the utility of a cervical spine fracture as a significant risk factor for BCVIs [6]. The Modified Denver Screening Criteria for BCVIs are currently in clinical use and are summarized in Appendix 1. Digital Subtraction Angiography DSA has been the traditional reference standard for the detection of BCVIs because of its high sensitivity and specificity compared with other noninvasive modalities such as CTA and MR angiography (MRA) and its ability to provide flow analysis [3, 5, 10, 13, 25, 29, 30]. However, DSA is relatively costly and requires appropriate equipment and personnel skills to perform. DSA has a 1.3% complication rate including arterial dissection, thrombosis with or without embolization, and renal failure due to contrast material [29, 31]. If liberal screening criteria are applied, DSA may not be a suitable modality because of the associated risks of the procedure. In addition, DSA can result in prolonged time to diagnosis compared with less invasive modalities because of barriers to availability and acces-

sibility [8]. Finally, DSA cannot provide information about the vessel wall itself or other vital structures, which is essential information for a trauma surgeon in assessing the polytrauma patient. The advantages and disadvantages of DSA for BCVIs are summarized in Appendix 2. An example of narrowing of the left vertebral artery on DSA is shown in Figure 2. MRI and MR Angiography MRI and MRA are noninvasive imaging techniques that have been used in the evaluation of carotid and vertebral artery dissections. Cross-sectional MR images can provide direct visualization of the intramural hematoma, and fat saturation allows better visualization of the hyperintense areas from subacute hematomas [32]. Time-of-flight MRA can also show intramural hematomas because it does not suppress completely stationary tissues with short T1 values, whereas phase-contrast MRA and contrast-enhanced MRA show only the vessel lumen [32]. The hematoma on MRI typically shows an evolution of signal intensity related to the paramagnetic effects of the products of hemoglobin breakdown. In the hyperacute and acute phases, the hematoma is isointense to surrounding structures because of the presence of oxyhemoglobin and deoxyhemoglobin, respectively, whereas it is bright on T1-weighted images during the subacute phase (> 3 days) because of the presence of methemoglobin [32, 33]. Thus, acute dissection can be difficult to detect on T1-weighted images with fat saturation because the isointense hematoma may be obscured by the surrounding isointense tissues. Subacute hematomas are much more clearly visualized on T1-weighted images with fat saturation and appear as the characteristic crescent-shaped hyperintense area around an eccentric flow void cor-

AJR:201, October 2013 885

Downloaded from www.ajronline.org by 37.44.207.85 on 01/21/17 from IP address 37.44.207.85. Copyright ARRS. For personal use only; all rights reserved

Liang et al. responding to the vessel lumen. MRI examples of BCVIs are shown in Figures 3 and 4. Recent advances have allowed MR scanners to produce excellent image quality at faster acquisition times. The ability to avoid overlapping of vessels and bony interference makes MR techniques attractive imaging modalities for BCVIs. In addition, MRI is the most sensitive imaging technique for detecting diffuse axonal injury, and diffusion-weight-

Fig. 2—42-year-old man who presented after motor vehicle collision. Digital subtraction angiography image of left vertebral artery reveals selective catheterization and examination of left vertebral artery displays diffuse narrowing of lumen and irregularity and minute outpouchings of contrast material of wall of left vertebral artery. These findings are compatible with dissection of left vertebral artery in setting of blunt trauma.

886

ed sequences allow the rapid identification of ischemic infarction. MRI is able to image the entire head and neck anatomy to evaluate for associated injuries and to detect brain and spinal injuries, ligamentous disruption, disk herniation, and cord edema associated with BCVIs [34]. MRA allows the evaluation of arterial stenosis, occlusions, or aneurysms. Thus, MR techniques have been proposed as an imaging modality for detecting BCVIs [35– 37]. Prospective [3, 38–40] and retrospective [30, 33, 41–45] studies have compared MRA with DSA, with the sensitivity for MRA ranging from 50% to 100% and specificity between 29% and 100% as summarized in Figure 5. A review of the literature showed MRA to have similar sensitivity and specificity for diagnosing carotid and vertebral artery dissections as compared with DSA, and CTA techniques [46]. However, study design and test performance characteristics in published studies vary substantially [46]. Some of the shortcomings of MRI include the inability to adequately visualize traumatic injuries to the thorax and abdomen, limited accessibility, its contraindications (i.e., pacemakers or metallic foreign bodies), and logistical limitations in the acute trauma setting. Additionally, mural hematomas can be difficult to visualize if they present with T1 hyperintensity because they may be difficult to differentiate from surrounding hematoma or intraluminal thrombus [46]. Dissection of vertebral

arteries at vertebral artery segment 2 (V2) may be difficult to identify because inflow enhancement in the venous plexus of the foramen transversarium may mimic a subacute hematoma [32]. Another concern with MRI is that an acute hematoma can be isointense to surrounding tissues on T1-weighted images, because of the presence of oxyhemoglobin, and may be missed. Gradient-echo sequences may show a blooming artifact from hemosiderin deposition that can be mistaken for a hematoma. Contrast-enhanced MRA, although able to show luminal irregularities and stenosis, can occasionally result in “feathering” artifact; this artifact results from rapidly changing signal intensity in small vascular structures and may mimic artery dissections [32, 47]. The advantages and disadvantages of MRI techniques for BCVIs are summarized in Appendix 2. Because of the shortcomings discussed, variable sensitivity and specificity, and the inability to screen for other injuries, MRI is not recommended for BCVIs in the polytrauma setting. However, at some institutions, if the injury is limited to only the cervical spine, MRI could be helpful to diagnose and rule out infarction of brain parenchyma or injury to the integrity of the spinal cord.

A

B

Duplex Sonography Duplex sonography is commonly used in the setting of trauma, and advantages include its noninvasive nature, easy mobility, low cost,

Fig. 3—47-year-old man who experienced trauma. A and B, Axial fat-suppressed T1-weighted images obtained at two different anatomic levels at base of neck reveal severe narrowing of right internal carotid artery (ICA) lumen with circumferential high-signal material along wall of right ICA consistent with intracellular methemoglobin in acute right ICA dissection (thick arrow). Left ICA (thin arrow) is normal and shows normal low-signal void consistent with patent lumen and no thickening or irregularity of ICA wall.

AJR:201, October 2013

A

B

Fig. 4—44-year-old woman who experienced trauma. Axial MR images show left vertebral artery occlusion. A, Axial T2-weighted MR image shows loss of normal flow void in left vertebral artery as shown by hyperintensity (thin arrow). Normal right vertebral artery (thick arrow) is seen with normal flow void. B, Flow-encoding gradient-recalled echo MR image shows normal flow in right vertebral artery (thick arrow) as shown by high signal. Left artery (thin arrow) does not show high signal indicating lack of flow and complete thrombotic occlusion.

and lack of ionizing radiation, making it a reasonable screening modality for detecting BCVIs [48]. The sensitivity of duplex sonography for BCVIs ranges from 38.5% to 86% [5, 49]. Findings consistent with vessel injury on ultrasound include the presence of lumi-

MRA Performance Value (%)

100

99

100

nal narrowing, hypoechoic intramural hematomas, dissected arterial walls, hemodynamically relevant stenoses, and occlusions [5]. A mural hematoma and intraluminal thrombus may be detected as a thickened hypoechoic wall and can be difficult to differentiate from

98

95

79

75

67 50

29

Lévy 1994

Stringaris 1996

Auer 1998 Sensitivity

Biffl 2002

Miller 2002

Specificity

Fig. 5—Bar graph shows results of literature review of sensitivities and specificities of MR angiography (MRA) compared with digital subtraction angiography in detection of blunt cerebrovascular injuries [3, 30, 39, 40, 45].

CTA Performance Value (%)

Downloaded from www.ajronline.org by 37.44.207.85 on 01/21/17 from IP address 37.44.207.85. Copyright ARRS. For personal use only; all rights reserved

Screening and Imaging of BCVI

one another with “B-mode” imaging [32]. An intimal flap is rarely depicted floating in the lumen or separating the lumina with two different Doppler signals [32]. However, the use of “B-flow” ultrasound may improve visualization of the intimal flaps, intramural hematomas, and residual flow [32, 50]. Difficulties may arise when attempting to visualize vessels as they pass through bony foramina and when attempting to assess the skull base. In distal parts of the internal carotid artery (ICA), a low-frequency transducer (1.5–3.6 MHz) should be used; imaging using a low-frequency transducer is able to show only hemodynamic abnormalities (stenosis or occlusion), whereas wall abnormalities are hardly depicted [32]. Thus, specific signs of dissection are rarely detected in the depth of the neck and are often missed [32]. There may also be significant variability among different operators [5]. The pitfalls in ultrasound imaging for ICA dissec-

120 100 80 60 40 20 0

Miller 2002 4-MDCTA

Biffl 2002 Helical MDCTA

Berne 2004 4-,16MDCTA

Eastman 2006 16-MDCT

Malhotra Sliker Sliker 2007 2008 2008 16-MDCTA 16-MDCTA 16-MDCTA of CA of VA

Sensitivity

47

68

100

98

74

64

Specificity

99

67

94

100

86

94

Sliker 2008 16-MDCT of CA

Sliker 2008 16-MDCT of VA

Langner 2008 16-CTA

Goodwin 2009 16-CTA

Goodwin 2009 64-CTA

DiCocco 2011 32-CTA

68

69

74

100

29

54

51

100

82

91

100

97

97

97

Fig. 6—Bar graph shows results of literature review of sensitivities and specificities of CT angiography (CTA) compared with digital subtraction angiography for detection of blunt cerebrovascular injuries [3, 4, 8, 10, 11, 13, 20, 29, 40]. MDCTA = MDCT angiography, VA = vertebral arteries, CA = carotid arteries.

AJR:201, October 2013 887

Liang et al. TABLE 1: CT Angiography (CTA) Protocol at Our Institution for the Detection of Blunt Cerebrovascular Injuries (BCVIs)

Downloaded from www.ajronline.org by 37.44.207.85 on 01/21/17 from IP address 37.44.207.85. Copyright ARRS. For personal use only; all rights reserved

Parameter

Description or Value

Arterial phase scanning

From arch to circle of Willis

Tube current modulation

Yes

Tube A kV

120

mAseff

250

Kernel B46, mediastinum

1-mm axial

B46, MIP reconstructions through circle of Willis and carotids

4-mm axial, coronal, oblique sagittal

B75, bone

1-mm axial and 2-mm coronal and sagittal for cervical spine

Collimation

128 slice × 0.6 mm

Pitch

1.2

Rotation time (s)

0.33

CTDIvol (mGy)

25

Note—Bolus tracking is performed using 100 mL of ioversol 350 (Optiray 350, Mallinckrodt Imaging) at a flow rate of 5.0 mL/s for arterial phase trigger at 120 HU at the arch followed by saline chaser. Multiplanar reformation is applied for precise quantitative analysis of lumen and vessel wall. Routine reformatted series include: Axial source images 1 mm, MIPs 4 mm: cervical coronal, oblique sagittal of carotid bifurcations, MIPs 4 mm: head and neck axial, cervical carotid bifurcations, coronal and sagittal head, and sagittal head to circle of Willis. MIP = maximum intensity projection, CTDIvol = volume CT dose index.

A

B

Fig. 7—38-year-old man who presented after motor vehicle crash. A and B, Axial CT angiography source image (A) and coronal multiplanar reformatted MDCT image (B) show saccular outpouching of contrast material (thick arrow) in right internal carotid artery indicating presence of pseudoaneurysm. Normal left carotid artery (thin arrow) that does not show any evidence of arterial injury is seen.

tion include other conditions associated with increased or decreased flow velocities, such as ICA redundancies, fibromuscular dysplasia, vasospasm, anemia, and hyperthyroidism [32, 51]. The advantages and disadvantages of ultrasound for BCVIs are summarized in Appendix 2. Because of a low sensitivity, operator and injury location dependency, and the inability to provide efficient whole-body screening for traumatic injuries, ultrasound is

888

not considered adequate as a screening modality for BCVIs [5, 25]. MDCT Angiography MDCT angiography (MDCTA) is a readily accessible, noninvasive, rapid, cost-efficient imaging modality that is capable of detecting other associated injuries. These advantages make CTA a potential reference standard for screening for BCVIs. On CT, a narrow eccen-

tric lumen surrounded by a crescent-shaped hyperattenuating mural area of thickening is specific for a dissection. However, the characteristic findings on CTA associated with BCVI will be discussed further in Part 2 [52]. Earlier work with 1-, 2-, and 4-MDCTA showed unacceptably poor sensitivities and specificities. A prospective study comparing 46 patients who underwent 4-MDCTA and DSA showed a sensitivity and specificity of 68% and 67%, respectively [40]. Advancements in CT technology have allowed the development of MDCT. Initial prospective studies in 2006 reported the sensitivity and specificity of 16-MDCTA to be 97.7–100% and 94–100%, respectively [4, 8]. However, in 2007 and 2009, studies reported markedly lower sensitivities (74% and 29%) [10, 13], casting doubt on CTA’s capability as a screening modality. However, some investigators have recommended that these results be interpreted with caution because a potential learning curve for the radiologists was suggested in the study [10, 53]. All the false-negatives were interpreted during the first half of the study, and the authors noted marked improvements in sensitivity and specificity in the second half study; the first half of the study had a sensitivity and specificity of 67% and 78%, whereas the second half had 100% and 86%, respectively [10]. A review of the studies determining the sensitivity and specificity of CTA is shown in Figure 6. The technique and protocol for CTA for BCVIs at our institution are shown in Table 1.

AJR:201, October 2013

Downloaded from www.ajronline.org by 37.44.207.85 on 01/21/17 from IP address 37.44.207.85. Copyright ARRS. For personal use only; all rights reserved

Screening and Imaging of BCVI MDCTA enables higher-resolution images and decreased motion artifact because of its rapid image acquisition. Additionally, postprocessing tools allow multiplanar reformatting, which allow easier visualization and quantitative analysis of both lumen and vessel wall of carotid and vertebral arteries [32]. These benefits allow CTA to serve as a valuable tool for the initial screening for a suspected BCVI. An example of a BCVI is shown on MDCTA in Figure 7. However, limitations inherent to CT include the presence of streak artifacts from dental amalgams, difficulty visualizing vessels through bone (excluding MDCTA with bone removal technology), radiation exposure, and contrast-mediated renal toxicity. The advantages and disadvantages of MDCTA for BCVIs are summarized in Appendix 2. However, newer techniques, such as iterative reconstruction, have shown the ability to reduce radiation dose while maintaining image quality [54]. 16-slice MDCTA has been recommended by the Western Trauma Association, with DSA used for cases with equivocal findings on CTA [55]. As CT technology continues to improve and radiologists gain experience with diagnosing BCVIs and their artifacts mimics (which are discussed in [52]), MDCTA will likely become the new reference standard for imaging BCVIs. Dual-Energy CT The introduction of advanced CT techniques such as dual-energy CT has allowed pure automated better bone removal without bony interference, which allows better visualization of the neck vessels, especially petrous portions of the carotids and vertebral arteries coursing through the foramen transversarium [56]. Although this technique has been effective for detecting carotid artery injuries, the bone removal near vertebral arteries has not been as effective [56]. However, newer dual-energy bone subtraction algorithms may be used to effectively improve the imaging of the cervical vessels. Conclusion BCVIs, once thought rare, are now recognized to be more common and are associated with significant mortality and morbidity. Early diagnosis and management are crucial for decreasing the neurovascular complications; thus, a screening algorithm to detect occult BCVIs early is essential. DSA has been considered the reference standard investigation previously but has been criticized

for being invasive and time-consuming. Both MRA and duplex sonography have variable sensitivity and specificity rates. In addition, these modalities are not able to rapidly assess associated injuries outside the craniocervical region. CTA, especially MDCTA with 16-slice or more, has become a modality of choice for the detection of BCVIs because of its efficiency, availability, and ability to scan the whole body for associated injuries. Although the use of CTA for the detection of BCVIs has been criticized from initial reports of inconsistent sensitivity and specificity rates, newer techniques compatible with CTA have allowed increased accuracy and ease of visualization of injuries at decreased radiation exposure. Based on these improvements, MDCTA will likely become the new reference standard for screening for BCVIs. References 1. Davis JW, Holbrook TL, Hoyt DB, Mackersie RC, Field TO Jr, Shackford SR. Blunt carotid artery dissection: incidence, associated injuries, screening, and treatment. J Trauma 1990; 30:1514–1517 2. Fabian TC, Patton JH Jr, Croce MA, Minard G, Kudsk KA, Pritchard FE. Blunt carotid injury: importance of early diagnosis and anticoagulant therapy. Ann Surg 1996; 223:513–522; discussion, 522–525 3. Miller PR, Fabian TC, Croce MA, et al. Prospective screening for blunt cerebrovascular injuries: analysis of diagnostic modalities and outcomes. Ann Surg 2002; 236:386–393; discussion, 393–395 4. Berne JD, Norwood SH, McAuley CE, Villareal DH. Helical computed tomographic angiography: an excellent screening test for blunt cerebrovascular injury. J Trauma 2004; 57:11–19 5. Mutze S, Rademacher G, Matthes G, Hosten N, Stengel D. Blunt cerebrovascular injury in patients with blunt multiple trauma: diagnostic accuracy of duplex Doppler US and early CT angiography. Radiology 2005; 237:884–892 6. Schneidereit NP, Simons R, Nicolaou S, et al. Utility screening for blunt vascular neck injuries with computed tomographic angiography. J Trauma 2006; 60:209–215; discussion, 215–216 7. Utter GH, Hollingworth W, Hallam DK, Jarvik JG, Jurkovich GJ. Sixteen-slice CT angiography in patients with suspected blunt carotid and vertebral artery injuries. J Am Coll Surg 2006; 203:838–848 8. Eastman AL, Chason DP, Perez CL, McAnulty AL, Minei JP. Computed tomographic angiography for the diagnosis of blunt cervical vascular injury: is it ready for primetime? J Trauma 2006; 60:925–929 9. Biffl WL, Egglin T, Benedetto B, Gibbs F, Cioffi WG. Sixteen-slice computed tomographic angi-

ography is a reliable noninvasive screening test for clinically significant blunt cerebrovascular injuries. J Trauma 2006; 60:745–751 10. Malhotra AK, Camacho M, Ivatury RR, et al. Computed tomographic angiography for the diagnosis of blunt carotid/vertebral artery injury: a note of caution. Ann Surg 2007; 246:632–642 11. Sliker CW, Shanmuganathan K, Mirvis SE. Diagnosis of blunt cerebrovascular injuries with 16MDCT: accuracy of whole-body MDCT compared with neck MDCT angiography. AJR 2008; 190:790–799 12. Berne JD, Norwood SH. Blunt vertebral artery injuries in the era of computed tomography angiographic screening: incidence and outcomes from 8292 patients. J Trauma 2009; 67:1333–1338 13. Goodwin RB, Beery PR 2nd, Dorbish RJ, et al. Computed tomographic angiography versus conventional angiography for the diagnosis of blunt cerebrovascular injury in trauma patients. J Trauma 2009; 67:1046–1050 14. Emmett KP, Fabian TC, DiCocco JM, Zarzaur BL, Croce MA. Improving the screening criteria for blunt cerebrovascular injury: the appropriate role for computed tomography angiography. J Trauma 2011; 70:1058–1063 15. Kumar SR, Weaver FA, Yellin A. Cervical vascular injuries: carotid and jugular venous injuries. Surg Clin North Am 2001; 81:1331–1344 16. Mokri B, Piepgras DG, Houser OW. Traumatic dissections of the extracranial internal carotid artery. J Neurosurg 1988; 68:189–197 17. Krajewski LP, Hertzer NR. Blunt carotid artery trauma: report of two cases and review of the literature. Ann Surg 1980; 191:341–346 18. Fabian TC, George SM Jr, Croce MA, Mangiante EC, Voeller GR, Kudsk KA. Carotid artery trauma: management based on mechanism of injury. J Trauma 1990; 30:953–961 19. Perry MO, Snyder WH, Thal ER. Carotid artery injuries caused by blunt trauma. Ann Surg 1980; 192:74–77 20. Langner S, Fleck S, Kirsch M, Petrik M, Hosten N. Whole-body CT trauma imaging with adapted and optimized CT angiography of the craniocervical vessels: do we need an extra screening examination? AJNR 2008; 29:1902–1907 21. Biffl WL, Ray CE, Moore EE, et al. Treatment related outcomes from blunt cerebrovascular injuries: importance of routine follow-up arteriography. Ann Surg 2002; 235:699–706 22. Eastman AL, Muraliraj V, Sperry JL, Minei JP. CTA-based screening reduces time to diagnosis and stroke rate in blunt cervical vascular injury. J Trauma 2009; 67:551–556 23. Cothren CC, Moore EE, Ray CE Jr, et al. Screening for blunt cerebrovascular injuries is cost-effective. Am J Surg 2005; 190:845–849

AJR:201, October 2013 889

Downloaded from www.ajronline.org by 37.44.207.85 on 01/21/17 from IP address 37.44.207.85. Copyright ARRS. For personal use only; all rights reserved

Liang et al. 24. Franz RW, Willette PA, Wood MJ, Wright Ml, Hartman JF. A systematic review and meta-analysis of diagnostic screening criteria for blunt cerebrovascular injuries. J Am Coll Surg 2012; 214:313–327 25. Bromberg WJ, Collier BC, Diebel LN, et al. Blunt cerebrovascular injury practice management guidelines: the Eastern Association for the Surgery of Trauma. J Trauma 2010; 68:471–477 26. Biffl WL, Moore EE, Offner PJ, Brega KE, Franciose RJ, Burch JM. Blunt carotid arterial injuries: implications of a new grading scale. J Trauma 1999; 47:845–853 27. Cothren CC, Moore EE, Ray CE Jr, Johnson JL, Moore JB, Burch JM. Cervical spine fracture patterns mandating screening to rule out blunt cerebrovascular injury. Surgery 2007; 141:76–82 28. Kraus RR, Bergstein JM, DeBord JR. Diagnosis, treatment, and outcomes of blunt carotid arterial injuries. Am J Surg 1999; 178:190–193 29. DiCocco JM, Emmett KP, Fabian TC, Zarzaur BL, Williams JS, Croce MA. Blunt cerebrovascular injury screening with 32-channel multidetector computed tomography: more slices still don’t cut it. Ann Surg 2011; 253:444–450 30. Stringaris K, Liberopoulos K, Giaka E, et al. Three-dimensional time-of-flight MR angiography and MR imaging versus conventional angiography in carotid artery dissections. Int Angiol 1996; 15:20–25 31. Willinsky RA, Taylor SM, TerBrugge K, Farb RI, Tomlinson G, Montanera W. Neurologic complications of cerebral angiography: prospective analysis of 2,899 procedures and review of the literature. Radiology 2003; 227:522–528 32. Rodallec MH, Marteau V, Gerber S, Desmottes L, Zins M. Craniocervical arterial dissection: spectrum of imaging findings and differential diagnosis. RadioGraphics 2008; 28:1711–1728 33. Kitanaka C, Tanaka J, Kuwahara M, Teraoka A. Magnetic resonance imaging study of intracranial vertebrobasilar artery dissections. Stroke 1994; 25:571–575 34. Stallmeyer MJ, Morales RE, Flanders AE. Imag-

ing of traumatic neurovascular injury. Radiol Clin North Am 2006; 44:13–39 35. Bok AP, Peter JC. Carotid and vertebral artery occlusion after blunt cervical injury: the role of MR angiography in early diagnosis. J Trauma 1996; 40:968–972 36. Giacobetti FB, Vaccaro AR, Bos-Giacobetti MA, et al. Vertebral artery occlusion associated with cervical spine trauma: a prospective analysis. Spine 1997; 22:188–192 37. Weller SJ, Rossitch E Jr, Malek AM. Detection of vertebral artery injury after cervical spine trauma using magnetic resonance angiography. J Trauma 1999; 46:660–666 38. Müllges W, Ringelstein EB, Leibold M. Non-invasive diagnosis of internal carotid artery dissections. J Neurol Neurosurg Psychiatry 1992; 55:98–104 39. Lévy C, Laissy JP, Raveau V, et al. Carotid and vertebral artery dissections: three-dimensional time-of-flight MR angiography and MR imaging versus conventional angiography. Radiology 1994; 190:97–103 40. Biffl WL, Ray CE Jr, Moore EE, Mestek M, Johnson JL, Burch JM. Noninvasive diagnosis of blunt cerebrovascular injuries: a preliminary report. J Trauma 2002; 53:850–856 41. Zuber M, Meary E, Meder JF, Mas JL. Magnetic resonance imaging and dynamic CT scan in cervical artery dissections. Stroke 1994; 25:576–581 42. Ozdoba C, Sturzenegger M, Schroth G. Internal carotid artery dissection: MR imaging features and clinical-radiologic correlation. Radiology 1996; 199:191–198 43. Yoshimoto T, Mizoi K. Importance of management of unruptured cerebral aneurysms. Surg Neurol 1997; 47:522–525 44. Mascalchi M, Bianchi MC, Mangiafico S, et al. MRI and MR angiography of vertebral artery dissection. Neuroradiology 1997; 39:329–340 45. Auer A, Felber S, Schmidauer C, Waldenberger P, Aichner F. Magnetic resonance angiographic and clinical features of extracranial vertebral artery dissection. J Neurol Neurosurg Psychiatry 1998;

64:474–481 46. Provenzale JM, Sarikaya B. Comparison of test performance characteristics of MRI, MR angiography, and CT angiography in the diagnosis of carotid and vertebral artery dissection: a review of the medical literature. AJR 2009; 193:1167–1174 47. Huston J 3rd, Bernstein MA, Riederer SJ. Feathering: vertebral artery pseudostenosis with elliptical centric contrast-enhanced MR angiography. AJNR 2006; 27:850–852 48. Fry WR, Dort JA, Smith RS, Sayers DV, Morabito DJ. Duplex scanning replaces arteriography and operative exploration in the diagnosis of potential cervical vascular injury. Am J Surg 1994; 168:693–695 49. Cogbill TH, Moore EE, Meissner M, et al. The spectrum of blunt injury to the carotid artery: a multicenter perspective. J Trauma 1994; 37:473–479 50. Clevert DA, Jung EM, Johnston T, et al. Cervical artery dissection: improved diagnosis by B-flow ultrasound. Clin Hemorheol Microcirc 2007; 36:141–153 51. Benninger DH, Caso V, Baumgartner RW. Ultrasound assessment of cervical artery dissection. Front Neurol Neurosci 2005; 20:87–101 52. Liang TIH, Tso DK, Chiu RYW, Nicolaou S. Imaging of blunt vascular neck injuries. A clinical perspective. AJR 2013; 201:893–901 53. Biffl WL. Computed tomographic angiography for blunt cerebrovascular injuries: is it good enough? J Trauma 2010; 68:508–509 54. Winklehner A, Karlo C, Puippe G, et al. Raw data-based iterative reconstruction in body CTA: evaluation of radiation dose saving potential. Eur Radiol 2011; 21:2521–2526 55. Biffl WL, Cothren CC, Moore EE. Western Trauma Association critical decisions in trauma: screening for and treatment of blunt cerebrovascular injuries. J Trauma 2009; 67:1150–1153 56. Deng K, Liu C, Ma R, et al. Clinical evaluation of dual-energy bone removal in CT angiography of the head and neck: comparison with conventional bone-subtraction CT angiography. Clin Radiol 2009; 64:534–541 (Appendixes follow on next page)

890

AJR:201, October 2013

Screening and Imaging of BCVI APPENDIX 1: Modified Denver Screening Criteria for Blunt Cerebrovascular Injuries (BCVIs): Signs, Symptoms, and Risk Factors for BCVIs [24, 27]

Downloaded from www.ajronline.org by 37.44.207.85 on 01/21/17 from IP address 37.44.207.85. Copyright ARRS. For personal use only; all rights reserved

If any of these signs, symptoms, or risk factors is present, an urgent CT angiography examination should be performed to look for a potential BCVI. Signs and Symptoms of BCVIs • Arterial hemorrhage • Cervical bruit • Expanding cervical hematoma • Focal neurologic deficit • Neurologic examination findings unexplained by neurologic imaging • Ischemic stroke on secondary head CT Risk Factors for BCVIs • Cervical spine fracture • Diffuse axonal injury with Glasgow coma scale < 6 • LeFort II or III fracture • Basilar skull fracture with carotid canal involvement • Near hanging with anoxic brain injury APPENDIX 2: Advantages and Disadvantages of CT Angiography (CTA) and MR Angiography (MRA) in the Setting of Suspected Blunt Cerebrovascular Injuries (BCVIs) CTA for Initial Screening Advantages • Widely available and reliable • Less invasive than DSA • Faster than DSA • Cost-effective screening strategy • Feasible because most patients with blunt neck trauma have other injuries requiring CT • Can assess soft tissues and rule out other injuries Disadvantages • Streak artifacts from dental amalgams can compromise image quality • Vessels running through bone can be difficult to visualize in entirety • Dynamic flow analysis and detection of arteriovenous fistula (early venous filling) are difficult • Radiation • Contrast toxicity MRI and MRA for Evaluation of Neurologic Impairment Advantages • Noninvasive • Avoidance of overlap of vessels and bony interference • Remainder of head and neck can be imaged concurrently • Prognostic information for spinal cord injuries provided • With use of diffusion-weighted sequences, ischemic infarction can be identified within minutes • Most sensitive for diagnosing diffuse axonal injuries Disadvantages • Limited availability • Not an option for patients with contraindications to MRI • Not practical in initial acute trauma setting for imaging lung, abdomen, pelvis • Slow flow can create false-positives simulating thrombus • Hematoma in acute stage may appear isointense to surrounding structures (Appendix 2 continues on next page)

AJR:201, October 2013 891

Liang et al.

Downloaded from www.ajronline.org by 37.44.207.85 on 01/21/17 from IP address 37.44.207.85. Copyright ARRS. For personal use only; all rights reserved

APPENDIX 2: Advantages and Disadvantages of CT Angiography (CTA) and MR Angiography (MRA) in the Setting of Suspected Blunt Cerebrovascular Injuries (BCVIs) (continued) DSA Reference Standard: Consider If CTA or MRA Findings Are Equivocal Advantages • Traditional reference standard • Allows flow analysis Disadvantages • Is invasive, with 1.3% complication rate • Is associated with significant complications including arterial dissection, thrombosis or embolization, vascular spasm, and renal failure • Is resource-intensive and availability is limited • Does not provide information about vessel wall or other vital structures Doppler Ultrasound (Not Used for Screening) Advantages • Is quick and affordable • No radiation • Is noninvasive • Has high specificity Disadvantages • Is operator dependent • Vertebral arteries are difficult to visualize because of overlying bony foramina; skull base cannot be assessed • Has low sensitivity • Is not adequate for screening for BCVIs

F O R YO U R I N F O R M AT I O N

This article is available for CME/SAM credit. To access the exam for this article, follow the prompts associated with the online version of the article. The reader’s attention is directed to an accompanying article, titled “Imaging of Blunt Vascular Neck Injuries: A Clinical Perspective,” which begins on page 893.

892

AJR:201, October 2013