The utility of intravascular ultrasound compared to angiography in the diagnosis of blunt traumatic aortic injury

Background Blunt traumatic aortic injury (TAI) refers to a spectrum of pathology that ranges from intimal tears to aortic rupture. Computed tomography angiography (CTA) has been widely used as a diagnostic tool in this setting. Additional imaging is required when CTA studies are equivocal. The purpose of this study is to evaluate the utility of intravascular ultrasound (IVUS) versus angiography in the diagnosis of TAI. Methods We performed an analysis of prospectively collected trauma registry data. CTA was used as the initial screening test. Patients with a positive or equivocal CTA underwent angiography and IVUS. Injuries were classified into Grades 1 to 4 (intimal tear, intramural hematoma, pseudoaneurysm, and rupture). Patients with Grade 1 injuries were managed medically. Patients with Grade 2 to 4 injuries underwent repair. A blinded randomized retrospective review of positive and equivocal imaging studies was performed. Standard screening test assessments (sensitivity, specificity), inter-rater agreement (Kappa), and frequency (Chi-square for the difference) were computed to evaluate the measurement characteristics of the multiple imaging techniques. Results Between May 2008 and August 2009, 7961 patients were admitted to our trauma center, and 2153 (27%) underwent a chest CTA. Twenty-five (0.3%) patients (21 males, mean age 21.9 years) had a positive or equivocal study for TAI. The mean Injury Severity Score was 33.9. Ten patients underwent repair (nine endovascular, one open), and 15 patients were managed medically. The 30-day mortality, paraplegia, and stroke rates were zero. Equivocal results were more common with CTA images than with either IVUS or angiography (27% vs 2.5 and 5%, respectively; overall P = .0002). Compared with angiography, IVUS changed the diagnosis in 13% of cases; identifying injuries in 11% and ruling them out in 2%. Sensitivity and specificity of angiography with respect to IVUS was 38% and 89%, respectively. Conclusions CTA is useful as a screening test in suspected TAI. When additional imaging is required after an equivocal CTA, IVUS is better than angiography. Therefore, we advocate the use of IVUS in potential TAI patients in whom angiography is being considered.