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Emergency Radiology |
1 From the Departments of Radiology (F.M., J.A.S., D.M.P., J.C., J.E.G.) and Surgery, Divisions of Trauma Surgery (C.M., A.S.) and Vascular Surgery (G.G.), Universidad de Antioquia, Medellín, Colombia. Received May 29, 2001; revision requested June 26; revision received November 9; accepted January 7, 2002. Address correspondence to F.M., Department of Radiology (R019), University of Miami School of Medicine/Jackson Memorial Hospital, Ryder Trauma Center, 1611 NW 12th Ave, West Wing 279, Miami, FL 33136 (e-mail: fmunera@med.miami.edu).
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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MATERIALS AND METHODS: During 27 months, 175 patients were referred for helical CT angiography of the neck because of clinical suspicion of arterial injuries. The protocol included a 100-mL bolus of nonionic contrast material injected at 4.5 mL/sec, with 11-second scanning delay, 3-mm collimation, and pitch of 1.3–2.0. CT images were interpreted prospectively by the emergency radiologist, and two radiologists retrospectively interpreted studies with consensus. Outcome was determined with examination of patients and their charts. The sensitivity, specificity, and positive and negative predictive values were calculated.
RESULTS: Studies in two patients were considered inadequate for diagnosis; these patients were referred for conventional arteriography and had normal findings. In 27 patients (15.6%), arterial lesions were detected. One patient had two arterial injuries. Lesions demonstrated with helical CT angiography were arterial occlusion (n = 14), pseudoaneurysm (n = 8), pseudoaneurysm and arteriovenous fistulae (n = 4), and partial thrombosis (n = 2). The remaining 146 patients had normal arteries. On the basis of these findings, patients were treated with surgery (n = 21), endovascular intervention (n = 7), and observation alone (n = 146).
CONCLUSION: Results indicate that helical CT angiography can be used as the initial method for evaluation in patients with possible arterial injuries of the neck.
© RSNA, 2002
Index terms: Arteries, injuries, 90.411, 90.4124, 90.494, 90.732 • Carotid arteries, angiography, 904.1222 • Computed tomography (CT), angiography, 90.12912, 90.12915, 90.12916, 90.12917 • Gunshot injuries, 90.411, 90.494, 90.732
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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Conventional arteriography has traditionally been considered the method of choice for detection of arterial injuries (3,7). Use of routine arteriography has been discouraged because of the high number of normal examination results (10–12) and the availability of alternative noninvasive diagnostic methods, such as color Doppler ultrasonography (US) (13–18), magnetic resonance (MR) angiography (19–21), and helical computed tomographic (CT) angiography (22–30). Authors of several articles (22–25) on prospective series have compared helical CT angiography and conventional arteriography for detection of arterial injuries of the neck; they reported sensitivity and specificity as high as 90%–100%.
At our institution (Hospital San Vicente, Universidad de Antioquia, Medellín, Colombia), we used helical CT arteriography for 27 months as the initial diagnostic modality in patients with penetrating neck injuries. The purpose of this study was to report our experience with helical CT angiography as the initial procedure to rule out arterial lesions caused by penetrating neck injuries.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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All patients 16 years or older referred for cervical helical CT angiography after sustaining a penetrating neck injury were candidates for enrollment in this study. During the 27 months, 865 patients with penetrating neck injuries were admitted to the emergency department. Three hundred forty-four of these patients were considered to be at risk for cervical arterial injuries. Twenty-six patients had injuries close to major vasculature in zone II but no physical finding to suggest arterial involvement, and the trauma surgeons on duty at that time decided not to order any diagnostic imaging. On the basis of physical examination findings, 141 patients were taken to surgery after admission. The remaining 177 patients had an indication for helical CT angiography. Two patients who were at higher risk of nephrotoxicity induced by iodinated contrast agents because of diabetes, renal dysfunction, or both underwent conventional arteriography instead of helical CT angiography, since the volume of contrast material used for helical CT angiography is higher than that usually required for conventional angiography.
The remaining 175 patients (153 male patients, 22 female patients; mean age, 23 years; age range, 16–65 years) represent the patient population included in our study. Mechanism of injury was gunshot wounds (n = 134) or stab wounds (n = 41). Anatomic location of injury was zone I in 34 patients (19.4%), zone II in 128 patients (73.1%), and zone III in 13 patients (7.4%). The investigation’s review board at our institution approved the study, and informed consent was obtained from either the patients themselves or from a close relative when the patient was unable to give consent.
Helical CT Arteriographic Technique and Interpretation
All CT arteriograms were acquired with a helical CT scanner (Prospeed; GE Medical Systems, Milwaukee, Wis). We injected 100 mL of iopamidol (Iopamiron, 300 mg/mL; Schering, Erlangen, Germany) through an 18-gauge catheter placed in an antecubital vein. We used an injection rate of 4.5 mL/sec and a scanning delay of 11 seconds. This scanning delay was reported to be adequate in a previous article (21). The caudocranial helical acquisition was planned on the basis of a lateral digital scout view of the neck, starting at the top of the aortic arch and ending at the base of the skull. Scanning parameters were 3-mm collimation with a 4–6-mm table increment (pitch, 1.3–2.0), 20-cm field of view, 20–36-second exposure at one revolution of the x-ray tube per second, tube current of 250 mAs, and tube potential of 120 kVp. Once acquired, the volumetric data set was reconstructed at 1-mm intervals, and the resulting data set was transferred to a workstation (Advantage Windows; GE Medical Systems) for postprocessing and interpretation.
The radiologist in charge of the emergency procedures, who was informed of the mechanism of injury, physical examination findings, and clinical status of the patients, performed an initial prospective interpretation of helical CT angiographic results immediately following acquisition of data. For interpretation, the radiologists used the set of transverse source images and, when necessary, they generated two-dimensional or three-dimensional reformations by using the software available at the workstation—multiplanar maximum intensity pixel projection and volume rendering algorithms. The time spent in interpretation and postprocessing was 10–15 minutes per patient. This initial interpretation was the one used by the surgeon to determine patient care.
For purposes of this study, two radiologists (F.M., J.A.S.) fellowship trained in body imaging performed a second (retrospective) interpretation with consensus within 72 hours after acquisition. They were blinded to the clinical status of patients and to the result of the initial interpretation. Since these radiologists were blinded to all clinical information about the patients, their interpretation of the CT angiograms was the one we used in the study for determination of diagnostic accuracy of helical CT angiography and comparison with surgical and conventional angiographic findings, as well as with clinical outcome.
Both interpretations were performed at the workstation in an interactive manner. In both cases, the radiologists were initially asked to assess helical CT arteriograms for overall quality, especially for presence of artifacts resulting from patient motion or metallic bullet fragments. Image quality was classified as being adequate for interpretation or not. If it was considered not adequate, the study was not evaluated further, and those patients were referred for diagnostic conventional arteriography.
For studies considered adequate for diagnosis, the common, internal, and proximal external carotid arteries, as well as the vertebral arteries, of both sides were evaluated for abnormalities. Therefore, eight arterial segments were examined in each patient. Peripheral branches of the external carotid artery were not assessed. Abnormalities were determined as being absent (normal examination results) or present (abnormal examination results). Arterial abnormalities were classified as follows: partial thrombosis or complete obstruction (occlusion), pseudoaneurysm (extravascular collection of contrast medium), arteriovenous fistula (early filling of venous structures), and intimal flap (intraluminal linear filling defect). Finally, the radiologists were asked to look for associated, or nonarterial, abnormalities such as fractures, soft-tissue hematoma, airway injuries, and spinal cord lesions.
Follow-up
Patient outcome after admission to the hospital was used as the standard of reference for comparison with results of helical CT angiography. Patients with normal helical CT angiographic results were admitted for observation and discharged 12–24 hours later, if their clinical status remained stable. After discharge, these patients were followed-up clinically with weekly physical examinations and interviews for 4 weeks and then with monthly telephone interviews for 6 months. These examinations and telephone contacts were conducted by one of the investigators (A.S.). For patients who remained asymptomatic after clinical follow-up, we assumed that no arterial damage had been caused by the injury and that negative helical CT angiographic interpretations were true-negative results.
Patients with arterial abnormalities demonstrated at helical CT angiography were referred for conventional arteriography for endovascular therapy or were sent directly to surgery. Conventional arteriography was performed for diagnosis in subjects who were initially admitted for observation after negative helical CT arteriographic results but who later developed signs or symptoms of a potential arterial injury. Conventional arteriography was also performed for diagnosis in patients whose helical CT angiographic studies were considered not adequate for interpretation by the radiologists responsible for the initial interpretation. Findings at conventional arteriography or surgical exploration were used as the standard of reference for comparison with helical CT angiographic results in these patients. If only one side of the neck, or one artery in the affected side, was explored surgically or examined with conventional arteriography, clinical follow-up similar to that described for patients who were observed and discharged was used as the standard of reference for the remaining arteries.
Statistical Analysis
We calculated the sensitivity, specificity, and positive and negative predictive values, as well as the 95% CIs, for helical CT arteriography. Since an inadequate study was considered an indication to perform conventional angiography, these studies were considered false-positive interpretations for the purpose of statistical analysis.
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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The remaining 173 (98.9%) examinations were deemed adequate for diagnosis. Therefore, 1,384 arteries (1,038 carotid arteries, including the common, internal, and proximal external carotid arteries and 346 vertebral arteries) were evaluated with helical CT angiography.
The radiologists reported vascular injuries, either carotid or vertebral, at both prospective and retrospective interpretations in 27 (15.6%) of 173 patients with adequate helical CT angiographic results. In one patient, helical CT angiographic results demonstrated injuries in two arteries (internal carotid and vertebral arterial occlusion); all other patients had injuries in a single arterial segment. Therefore, there were injuries in 28 arterial segments in these 27 patients. Seven injuries occurred in the internal carotid artery (Fig 1), 13 in the common carotid artery (Figs 2, 3), seven in the vertebral artery, and one in the proximal external carotid artery. The Table lists the injuries and their distribution according to location and type. All of these injuries were confirmed at surgical exploration (n = 21) or conventional angiography (n = 7) performed prior to endovascular therapy.
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The remaining 146 subjects underwent conservative management and clinical follow-up for the next 6 months (mean follow-up, 46 days; range, 7 days to 6 months). Nine patients were lost to follow-up after 7 days. During clinical follow-up, none of the patients developed signs or symptoms to suggest arterial trauma.
We found lesions other than vascular injuries in 61 (34.9%) patients. These injuries were vertebral fractures (n = 21), mandibular fractures (n = 17), major airway injuries (n = 4) (Fig 4), soft-tissue hematoma compressing the airway (n = 16), and hematoma causing cord compression (n = 3) (Fig 5).
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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Conventional angiography is a relatively safe invasive procedure with a low reported incidence of complications of 0.16%–2.0% (34), including hematomas at the puncture site, vascular spasms, thrombosis, distal embolization of atheromatous plaques and thrombus, and vascular dissection. Unfortunately, complications involving the central nervous system can be catastrophic and potentially result in permanent damage. The use of angiography in patients in stable condition with penetrating neck trauma has also been questioned because of the reported high (range, 70%–90%) number of negative examination results (10–12,15,23,35).
Color Doppler US (13–18,36) has been proposed as a noninvasive test for the diagnosis of traumatic vascular injuries. Carotid arterial dissection, for example, is a common cause of stroke in young patients with closed trauma to the neck. It can lead to distal embolization, complete occlusion, stenosis, pseudoaneurysm development, or even vascular recanalization. Color Doppler US gives adequate information about flow, lumen, vascular wall, and thrombus features (36). In patients with penetrating trauma to the neck, some articles (13,14) had also shown promising study results.
Color Doppler US is inexpensive and completely noninvasive, and it does not require administration of contrast medium. However, it is operator dependent and may take a long time, even in skilled hands, which is not desirable in patients in potentially unstable condition. Additionally, technical difficulties diminish its usefulness in subjects with large hematomas or subcutaneous emphysema. Some areas may not be well evaluated, and complete occlusion may be missed in zones I and III (13,29,36).
MR imaging has been also described for evaluation of potential vascular injuries (19,37,38), as these lesions may arise clinically, with late manifestation and neurologic deterioration due to bleeding and embolism or ischemia. Posttraumatic dissections of the carotid artery are well depicted with this method and give exact information about extension and direct visualization of wall hematomas. Nevertheless, it has limitations for the immediate assessment of potential associated injuries mainly arising from bone structures. Furthermore, MR angiography is time consuming, and the support equipment may not be compatible with the magnet.
Helical CT has gained wide acceptance in the evaluation of a variety of traumatic and nontraumatic emergency conditions (39–43). High-quality diagnostic images are obtained in a short time; this is an essential factor to consider in critically ill patients. It also offers less discomfort for the patient and decreases costs. In the emergency setting, helical CT has gradually replaced traditional imaging techniques such as conventional radiography, conventional contrast material–enhanced studies, and conventional angiography.
Transverse images are usually sufficient to make a proper diagnosis in most patients. Reformatted and three-dimensional images are complementary in complex cases. These images are also useful in planning the surgical procedure, since the surgeons usually preferred the reconstructions that more closely resembled the conventional angiograms. In our study, the postprocessing time was no more than 15 minutes. The capability to give information about potential associated lesions from such vital structures as the cervical spine and airway (23,24,30,44) is an additional advantage that allows rapid triage of the patient. Our study findings showed associated lesions in 61 patients.
Helical CT angiography is a nonoperator-dependent diagnostic study, and results can be easily reproducible in any trauma center by using established technical parameters. Helical CT angiography has also been used to plan large facial and neck reconstructions in trauma and oncology because it allows correct assessment of the vascular anatomy and the evaluation of blunt traumatic dissection (27,28,44).
We evaluated helical CT angiography as an initial diagnostic test in patients who were hemodynamically stable and had penetrating trauma to the neck. Our results showed a high positive predictive value when correlated with surgical and angiographic findings. In cases interpreted as negative, there was no further complication during follow-up, and these patients did not require further treatment or diagnostic studies.
Helical CT angiographic limitations include artifacts caused by metal, such as dental fillings or bullet fragments that may obscure arterial segments. In these cases, helical CT angiographic results should be reported as nondiagnostic, and these patients must undergo conventional angiography. In our study, results in only two (1.1%) helical CT angiographic examinations were considered inadequate for diagnosis.
Another limitation of helical CT angiography, as compared with conventional angiography, is the inability to perform therapeutic interventions with this method. However, helical CT angiography may be used to select patients as candidates for endovascular therapy such as embolization, prosthesis placement, or temporary vascular occlusion (45–50); this occurred in seven patients in our study. Perhaps patients presenting with thrill or bruit at admission to the emergency department should not undergo helical CT angiography prior to conventional angiography because of the greater likelihood of the need for endovascular therapy, as suggested by Leblang and Nuñez (29). However, not all of these patients may be suitable for this type of care, and helical CT angiography may be useful in identifying those who would benefit from surgical rather than endovascular treatment. Further studies will be needed to clarify this issue.
Subtle lesions such as intimal flaps may not be well demonstrated at helical CT angiography, as compared with conventional angiography, because of less spatial resolution. Since most patients did not have angiographic correlation, we may have underestimated the number of intimal injuries. Although some reported (51–53) results suggest that there is a benign outcome of this type of lesion with spontaneous resolution, there is also controversy around this point to be elucidated in future studies.
The percentage of positive results in our study (15.6% [27 of 173]) was slightly lower than that reported in an article (10) in which conventional angiography was used (18%–30%). This result may be because of the higher number of patients who underwent helical CT angiography, perhaps because of its noninvasive properties, time-saving benefits, the possibility of obtaining additional information, and lower cost, which made it easier to perform than any other diagnostic method, including conventional angiography. Conceivably, other types of subclinical lesions might have gone undetected during follow-up, which could also explain the slightly lower positive rate in our study. This follow-up may be insufficient for identifying significant stenosis, false aneurysm, or arteriovenous fistula that may take months or years to become clinically apparent. Additional studies with longer follow-up would be required to solve this issue.
Another limitation of our study is that we did not evaluate peripheral branches of the proximal external carotid arteries because of the limitations in spatial resolution of helical CT angiography, as compared with the limitations at conventional angiography. When there is substantial persistent bleeding, conventional angiography should be performed, despite normal helical CT angiographic results.
In summary, with this study we report our experience with helical CT angiography in the initial evaluation in patients suspected of having injuries to cervical arteries. Our results indicate that helical CT angiography is a good alternative to conventional angiography for patients who are hemodynamically stable. It is a rapid, accurate, noninvasive technique and is less expensive than conventional angiography; we believe helical CT angiography can replace conventional angiography in this setting. The high sensitivity is an additional reason to prefer a low-risk, noninvasive, and reproducible method as an initial diagnostic examination in a majority of these patients. Widespread use of multi–detector row CT scanners and faster postprocessing software may expand even further the use of helical CT angiography for evaluation in this patient population.
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FOOTNOTES |
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REFERENCES |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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This article has been cited by other articles:
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  J J Brywczynski, T W Barrett, J A Lyon, and B A Cotton Management of penetrating neck injury in the emergency department: a structured literature review Emerg. Med. J., November 1, 2008; 25(11): 711 - 715. [Abstract] [Full Text] [PDF]
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J. W. Stuhlfaut, G. Barest, O. Sakai, B. Lucey, and J. A. Soto Impact of MDCT Angiography on the Use of Catheter Angiography for the Assessment of Cervical Arterial Injury After Blunt or Penetrating Trauma Am. J. Roentgenol., October 1, 2005; 185(4): 1063 - 1068. [Abstract] [Full Text] [PDF]
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D. B. Nunez Jr, M. Torres-Leon, and F. Munera Vascular Injuries of the Neck and Thoracic Inlet: Helical CT-Angiographic Correlation RadioGraphics, July 1, 2004; 24(4): 1087 - 1098. [Abstract] [Full Text] [PDF]
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R. L. Wolf Invited Commentary RadioGraphics, July 1, 2004; 24(4): 1099 - 1100. [Full Text] [PDF]
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