Abstract T P52: Technique for Measurement of Traumatic Aneurysms of the Cervical Internal Carotid Artery and Assessment of Reproducibility

Abstract

Background: Traumatic aneurysms occur in 10-20% of blunt traumatic extracranial carotid artery injuries. There is currently no standardized method for characterization of traumatic aneurysms. This study presents a systematic method for aneurysm characterization on both digital subtraction angiography (DSA) and CT angiography (CTA). Methods: Four raters, including one vascular neurosurgeon, one neuroradiologist, and two senior neurosurgical residents independently reviewed 15 CTAs and 13 DSAs obtained at the time of diagnosis of the traumatic aneurysm. Raters were asked to categorize the aneurysms as either ‘saccular’ or ‘fusiform’ and obtain measurements. Saccular aneurysm size was defined as the greatest linear distance between the expected location of the normal artery wall and the outer edge of the aneurysm lumen (‘depth’). Fusiform aneurysm size was defined as the depth and longitudinal extent (‘length’) parallel to the normal artery. The size of the aneurysm (‘aneurysm plus parent artery’) in relationship to the normal artery (‘parent artery’) was assessed as well. Assessments of five scans of each imaging modality were repeated for measurement of intra-rater reliability. Fleiss's free-marginal multi-rater kappa (κ), Cohen’s kappa (κ), and interclass correlation coefficient (ICC) were applied to determine inter- and intra-rater reliability. Results: Inter-rater agreement on aneurysm shape, ‘saccular’ versus ‘fusiform’, was almost perfect for CTA (κ = 0.82) and DSA (κ = 0.897). Agreement on aneurysm ‘depth’, ‘length’, ‘aneurysm plus parent artery’, and ‘parent artery’ for CTA and DSA were excellent (ICC > 0.75). Intra-rater agreement on aneurysm shape was substantial to almost perfect (κ > 0.6) in all four raters. Conclusions: This study demonstrates a clinically oriented, standardized method to characterize traumatic aneurysms with remarkable inter- and intra-rater reliability. This approach may help to define this disease entity more clearly and better understand the natural history. While certain characteristics of traumatic aneurysms may be associated with low risk and treatment with antithrombotic therapy may be sufficient, other characteristics may carry increased risk warranting endovascular repair.