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Direct versus indirect signs of traumatic aortic injury revealed by helical CT: performance characteristics and
1Department of Radiology, University of Miami School of Medicine, Jackson Memorial Hospital, FL 33136, USA.
Insights
Direct signs of traumatic aortic injury on helical CT scans are more accurate and reliable than indirect signs like hematoma. This finding improves confidence in using helical CT for diagnosing aortic injuries.
Area of Science:
- Radiology
- Trauma Imaging
- Cardiovascular Imaging
Background:
- Traumatic aortic injury diagnosis can be challenging.
- Helical CT is a key imaging modality in trauma assessment.
- Distinguishing direct from indirect signs of injury is crucial for accurate diagnosis.
Purpose of the Study:
- To compare the diagnostic value of direct versus indirect (hematoma) signs of traumatic aortic injury on helical CT.
- To assess interobserver agreement for interpreting these signs.
Main Methods:
- Retrospective review of contrast-enhanced helical CT scans from 40 patients with suspected traumatic aortic injury.
- Inclusion of 13 additional negative scans with no evidence of injury on follow-up.
- Independent review by three radiologists (two emergency, one non-emergency) to identify direct signs, mediastinal hematoma, and periaortic hematoma.
Main Results:
- Direct signs of aortic injury were identified in all 17 confirmed cases with no false positives.
- Indirect signs (mediastinal/periaortic hematoma) had higher false-negative rates.
- Interobserver agreement was significantly higher for direct signs (kappa = .93) compared to hematomas (kappa = .65 and .71).
Conclusions:
- Helical CT demonstrates direct signs of traumatic aortic injury with high accuracy and reliability.
- Focusing on direct signs enhances diagnostic confidence in evaluating traumatic aortic injury.
- Direct signs are superior to indirect signs for diagnosis using helical CT.
Objective:
The purpose of this study was to evaluate the relative value of and interobserver agreement on direct versus indirect (hematoma) signs of traumatic aortic injury using helical CT.
Materials And Methods:
From April 1994 through January 1997, 40 patients who were suspected to have traumatic aortic injury and who underwent contrast-enhanced helical CT had subsequent proof or exclusion of aortic injury. All available CT scans of these patients were combined with CT scans of 13 randomly chosen patients that had been initially interpreted as negative, and clinical follow-up showed no evidence of aortic injury. Two emergency radiologists and a nonemergency radiologist who were unaware of clinical outcome performed independent review of these cases to evaluate for mediastinal hematoma, periaortic hematoma, and direct signs of aortic injury.
Results:
Direct signs of injury were seen on helical CT by both emergency radiologists in all 17 cases of aortic injury with no false-positive interpretations. The nonemergency radiologist failed to observe subtle direct signs in two cases of aortic injury, but patient management would not have been adversely affected. All observers had more false-negative interpretations for both mediastinal hematoma and periaortic hematoma than for direct signs. Interobserver agreement was higher for direct signs (kappa = .93) than for either mediastinal hematoma (kappa = .65) or periaortic hematoma (kappa = .71).
Conclusion:
In this study, helical CT revealed direct signs of traumatic aortic injury that were more accurate and more often observed than were indirect signs. Emphasis on direct signs should improve confidence in using helical CT to evaluate traumatic aortic injury.