Uttam K. Bodanapally

Imaging of Traumatic Brain Injury

Imaging plays an important role in the management of patients with traumatic brain injury (TBI). Computed tomography (CT) is the first-line imaging technique allowing rapid detection of primary structural brain lesions that require surgical intervention. CT also detects various deleterious secondary insults allowing early medical and surgical management. Serial imaging is critical to identifying secondary injuries. MR imaging is indicated in patients with acute TBI when CT fails to explain neurologic findings. However, MR imaging is superior in patients with subacute and chronic TBI and also predicts neurocognitive outcome.

Vascular complications of penetrating brain injury: comparison of helical CT angiography and conventional angiography

OBJECT The authors conducted a study to compare the sensitivity and specificity of helical CT angiography (CTA) and digital subtraction angiography (DSA) in detecting intracranial arterial injuries after penetrating traumatic brain injury (PTBI). METHODS In a retrospective evaluation of 48 sets of angiograms from 45 consecutive patients with PTBI, 3 readers unaware of the DSA findings reviewed the CTA images to determine the presence or absence of arterial injuries. A fourth reader reviewed all the disagreements and decided among the 3 interpretations. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of CTA were calculated on a per-injury basis and in a subpopulation of patients with traumatic intracranial aneurysms (TICAs). RESULTS Sensitivity of CTA for detecting arterial injuries was 72.7% (95% CI 49.8%-89.3%); specificity, 93.5% (95% CI 78.6%-99.2%); PPV, 88.9% (95% CI 65.3%-98.6%); and NPV, 82.9% (95% CI 66.4%-93.4%). All 7 TICAs were correctly identified by CTA. Sensitivity, specificity, PPV, and NPV of CTA in detecting TICAs were 100%. To compare agreement with DSA, the standard of reference, confidence scores categorized as low, intermediate, and high probability yielded an overall effectiveness of 77.8% (95% CI 71.8%-82.9%). CONCLUSIONS Computed tomography angiography had limited overall sensitivity in detecting arterial injuries in patients with PTBI. However, it was accurate in identifying TICAs, a subgroup of injuries usually managed by either surgical or endovascular approaches, and non-TICA injuries involving the first-order branches of intracranial arteries.

Diagnosis of Traumatic Optic Neuropathy: Application of Diffusion Tensor Magnetic Resonance Imaging

Background: Using diffusion tensor imaging, we evaluated the directional diffusivities of the optic nerve in patients with traumatic optic neuropathy (TON). Methods: Our study consisted of 12 patients with unilateral TON, 6 patients with severe traumatic brain injury (comparison group A), and 6 patients with normal conventional brain magnetic resonance imaging (comparison group B). The contralateral optic nerve in patients with TON also was evaluated (comparison group C). Two trauma radiologists, blinded to the clinical diagnosis, independently obtained the directional diffusivities. The intraorbital optic nerve was divided into anterior and posterior segments to evaluate intersegmental differences in directional diffusivities. Results: The mean axial diffusivity (AD) in both optic nerve segments and the mean diffusivity (ADC) in the posterior segment on the affected side were significantly lower and differentiated subjects with TON from those in comparison groups A and B. Area under the receiver operating characteristic curve was 0.762, 0.746, and 0.737 for posterior AD, anterior AD, and posterior ADC, respectively. The mean AD, mean diffusivity, and radial diffusivity were lower in the affected nerves in comparison to the contralateral nerve (comparison group C), but the values did not reach statistical significance. Conclusion: Decreased AD and mean diffusivity in the posterior segment of the optic nerve may serve as a biomarker of axonal damage in patients with TON and merits further investigation as a predictor of initial visual acuity and potential visual recovery.

Traumatic Optic Neuropathy Prediction after Blunt Facial Trauma: Derivation of a Risk Score Based on Facial CT Findings at Admission

PURPOSE To determine the specific facial computed tomographic (CT) findings that can be used to predict traumatic optic neuropathy (TON) in patients with blunt craniofacial trauma and propose a scoring system to identify patients at highest risk of TON. MATERIALS AND METHODS This study was compliant with HIPAA, and permission was obtained from the institutional review board. Facial CT examination findings in 637 consecutive patients with a history of blunt facial trauma were evaluated retrospectively. The following CT variables were evaluated: midfacial fractures, extraconal hematoma, intraconal hematoma, hematoma along the optic nerve, hematoma along the posterior globe, optic canal fracture, nerve impingement by optic canal fracture fragment, extraconal emphysema, and intraconal emphysema. A prediction model was derived by using regression analysis, followed by receiver operating characteristic analysis to assess the diagnostic performance. To examine the degree of overfitting of the prediction model, a k-fold cross-validation procedure (k = 5) was performed. The ability of the cross-validated model to allow prediction of TON was examined by comparing the mean area under the receiver operating characteristic curve (AUC) from cross-validations with that obtained from the observations used to create the model. RESULTS The five CT variables with significance as predictors were intraconal hematoma (odds ratio, 12.73; 95% confidence interval [CI]: 5.16, 31.42; P < .001), intraconal emphysema (odds ratio, 5.21; 95% CI: 2.03, 13.36; P = .001), optic canal fracture (odds ratio, 4.45; 95% CI: 1.91, 10.35; P = .001), hematoma along the posterior globe (odds ratio, 0.326; 95% CI: 0.111, 0.958; P = .041), and extraconal hematoma (odds ratio, 2.36; 95% CI: 1.03, 5.41; P = .042). The AUC was 0.818 (95% CI: 0.734, 0.902) for the proposed model based on the observations used to create the model and 0.812 (95% CI: 0.723, 0.9) after cross-validation, excluding substantial overfitting of the model. CONCLUSION The risk model developed may help radiologists suggest the possibility of TON and prioritize ophthalmology consults. However, future external validation of this prediction model is necessary.

Hyperintense Optic Nerve due to Diffusion Restriction: Diffusion-Weighted Imaging in Traumatic Optic Neuropathy

BACKGROUND AND PURPOSE: Abnormal signal intensity of the optic nerve due to diffusion restriction may be seen in traumatic optic neuropathy. In addition to evaluating optic nerve hyperintensity on diffusion-weighted imaging, we compared the group differences of ADC values between the injured and uninjured contralateral nerve and identified the relation between measured ADC values and admission visual acuity. MATERIALS AND METHODS: We retrospectively evaluated 29 patients with traumatic optic neuropathy who underwent MR imaging with DWI. Uninjured contralateral optic nerves were used as controls. Two attending radiologists, blinded to the side of injury, independently reviewed the DWI for the presence of signal-intensity abnormality and obtained ADC values after manually selecting the ROI. RESULTS: Hyperintensity of the optic nerve was demonstrated in 8 of the 29 patients, with a sensitivity of 27.6% (95% CI, 12.8–47.2) and a specificity of 100% (95% CI, 87.9–100). ADC values were obtained in 25 patients. The mean ADC in the posterior segment of the injured nerve was significantly lower than that in the contralateral uninjured nerve (Welch ANOVA, F = 9.7, P = .003). There was a moderate-to-strong correlation between low ADC values and poor visual acuity in 10 patients in whom visual acuity could be obtained at admission (R = 0.7, P = .02). Patients with optic nerve hyperintensity presented with worse visual acuity. CONCLUSIONS: Hyperintensity of the optic nerve due to diffusion restriction can serve as a specific imaging marker of traumatic optic neuropathy. When paired with reduced ADC values, this finding may be an important surrogate for visual acuity.

Arterial injuries after penetrating brain injury in civilians: risk factors on admission head computed tomography.

OBJECT The object of this study was to determine the specific CT findings of the injury profile in penetrating brain injury (PBI) that are risk factors related to intracranial arterial injuries. METHODS The authors retrospectively evaluated admission head CTs and accompanying digital subtraction angiography (DSA) studies from patients with penetrating trauma to the head in the period between January 2005 and December 2012. Two authors reviewed the CT images to determine the presence or absence of 30 injury profile variables and quantified selected variables. The CT characteristics in patients with and without arterial injuries were compared using univariate analysis, multivariate analysis, and receiver operating characteristic (ROC) curve analysis to determine the respective risk factors, independent predictors, and optimal threshold values for the continuous variables. RESULTS Fifty-five patients were eligible for study inclusion. The risk factors for an intracranial arterial injury on univariate analysis were an entry wound over the frontobasal-temporal regions, a bihemispheric wound trajectory, a wound trajectory in proximity to the circle of Willis (COW), a subarachnoid hemorrhage (SAH), a higher SAH score, an intraventricular hemorrhage (IVH), and a higher IVH score. A trajectory in proximity to the COW was the best predictor of injury (OR 6.8 and p = 0.005 for all penetrating brain injuries [PBIs]; OR 13.3 and p = 0.001 for gunshot wounds [GSWs]). Significant quantitative variables were higher SAH and IVH scores. An SAH score of 3 (area under the ROC curve [AUC] for all PBIs 0.72; AUC for GSWs 0.71) and an IVH score of 3 (AUC for all PBIs 0.65; AUC for GSWs 0.65) could be used as threshold values to suggest an arterial injury. CONCLUSIONS The risk factors identified may help radiologists suggest the possibility of arterial injury and prioritize neurointerventional consultation and potential DSA studies.

Traumatic optic neuropathy: facial CT findings affecting visual acuity.

The purpose of this study was to determine the relationship between admission visual acuity (VA) and facial computed tomographic (CT) findings of traumatic optic neuropathy (TON). We retrospectively evaluated CT findings in 44 patients with TON. Mid-facial fractures, extraconal and intraconal hematomas, hematomas along the optic nerve and the posterior globe, optic canal fracture, nerve impingement by optic canal fracture fragment, and extraconal and intraconal emphysema were evaluated. CT variables of patients with and without available VA were compared. VA was converted into logarithm of the minimum angle of resolution (logMAR) to provide a numeric scale for the purpose of statistical analysis. The risk factors related to poor VA on univariate analysis were as follows: intraconal hematoma [median logMAR −4.7 versus −1.15, p = 0.016] and hematoma along the optic nerve [median −4.7 versus −1.3, p = 0.029]. Intraconal hematoma was the best predictor of poor VA (coefficient, 1.01; SE, 0.34; and p = 0.008). Receiver operating characteristic (ROC) curve analysis showed that the presence of intraconal hematoma and hematoma along the optic nerve predicted poor VA (logMAR of −3.7 or lower) with an area under the curve of 0.8 and 0.85, respectively. TON patients at higher risk of severe visual impairment may be identified based on admission facial CT.

Vascular Injuries to the Neck After Penetrating Trauma: Diagnostic Performance of 40- and 64-MDCT Angiography

OBJECTIVE The purposes of this study were to assess the diagnostic performance of 40- and 64-MDCT angiography with digital subtraction angiography as the reference standard in the detection of arterial injuries in patients at high risk after penetrating neck trauma and to perform a separate analysis of injuries to the external carotid artery. MATERIALS AND METHODS In a retrospective evaluation of 53 sets of angiograms from 51 patients with penetrating neck injury, three reviewers unaware of the digital subtraction angiographic findings reviewed the CT angiographic (CTA) images to discern the presence or absence of arterial injuries. Sensitivity and specificity of CTA were calculated per injury, and a separate analysis of external carotid artery injuries was performed. RESULTS Sensitivity of CTA for detecting arterial injuries ranged from 75.7% (95% CI, 62.3-86.9%) to 82.2% (95% CI, 69.5-92.1%). Specificity ranged from 96.4% (95% CI, 94.0-98.4%) to 98.4% (95% CI, 96.0-100%). CTA was highly sensitive for detection of the subgroup of injuries involving the large-caliber vessels that contribute to cerebral circulation. These sensitivities ranged from 92.8% (95% CI, 66-98.8%) to 100% (95% CI, 76.6-100%) for internal carotid artery injuries and from 88.9% (95% CI, 65.2-98.3%) to 94.4% (95% CI, 72.6-99.0%) for vertebral artery injuries. In contrast, sensitivity of CTA was limited for external carotid artery injuries, ranging from 63.4% (95% CI, 45.5-79.5%) to 70.0% (95% CI, 52.0-85.0%). CONCLUSION CTA can be used for initial evaluation and may help guide management decisions if an external carotid artery injury is detected. Negative findings should not preclude close clinical follow-up, repeat CTA evaluation, or, in the presence of high suspicion of arterial injury due to clinical findings or wound trajectory, evaluation with digital subtraction angiography.

Evolving concepts in MDCT diagnosis of penetrating diaphragmatic injury

This article reviews current and evolving concepts in the diagnosis of penetrating diaphragmatic injury with multidetector CT (MDCT). As criteria for nonoperative management in the setting of penetrating trauma become more inclusive, confident exclusion of penetrating diaphragmatic injury (PDI) has become imperative. Diagnostic performance of MDCT for PDI has improved substantially with the use of thin sections and multiplanar reformats. Evaluation of injury trajectory in nonstandard planes using 3D post-processing software can aid in the diagnosis. Contiguous injury and transdiaphragmatic trajectory are the best predictors of PDI. Careful appraisal of the diaphragm for defects should be undertaken in all patients with thoracoabdominal penetrating trauma.

Predicting Arterial Injuries after Penetrating Brain Trauma Based on Scoring Signs from Emergency CT Studies

The objective of this study was to determine the accuracy of individual radiologists in detection of vascular injury in patients after penetrating brain injury (PBI) based on head CT findings at admission. We retrospectively evaluated 54 PBI patients who underwent admission head CT and digital subtraction angiography (DSA), used here as a reference standard. Two readers reviewed the CT images to determine the presence or absence of the 29 CT variables of injury profile and quantified selected variables. Four experienced trauma radiologists and one neuroradiologist assigned their own specific scores for each CT variable, a high score indicative of a high probability of artery injury. A sixth set consisted of the average score obtained from the five sets, generated by five experts. Receiver operating characteristic (ROC) curves were constructed for each set to assess the diagnostic performance of an individual radiologist in predicting an underlying vascular injury. The area under ROC curve (AUC) was higher for CT scores obtained from the sixth set (average of five sets of scores) of variable rank score 0.75 (95% CI 0.62–0.88) and for the rest of the data sets, the value ranged from 0.70 (95% CI 0.56–0.84) to 0.74 (95% CI 0.6–0.88). In conclusion, radiologists may be able to recommend DSA with a fair accuracy rate in selected patients, deemed ‘high-risk’ for developing intracranial vascular injuries after PBI based on admission CT studies. A better approach needs to be developed to reduce the false positive rate to avoid unnecessary emergency DSA.