Distal Aortic Intramural Hematoma: Clinical Importance of Focal Contrast Enhancement on CT Images

Purpose: To investigate the prevalence, fate, and effect of focal contrast enhancement lesion within the hematoma on contrast material-enhanced computed tomographic (CT) images in patients with distal aortic intramural hematoma (IMH). Materials and Methods: This retrospective study was approved by the institutional review board; informed consent was waived. Clinical and CT data in 107 patients with distal IMH who received medical treatment were analyzed, including remodeling processes of IMH at follow-up CT. IMH progression was defined as development of aortic dissection (AD) and aneurysm or hematoma increase. Results: The frequency of focal contrast enhancement was 39.3%, and hematoma was thicker in patients with focal contrast enhancement than in those without (12.3 mm +/- 3.6 [standard deviation] vs 10.1 mm +/- 4.1, P = .006). Although development of AD occurred more frequently in patients with focal contrast enhancement (21% vs 3%, P = .006), hematoma resorption (57% vs 71%) was the most common pattern of remodeling in both groups without any significant difference (P = .148). The frequency of development of aortic aneurysm (17% vs 14%, P = .690) and increase of hematoma (0% vs 5%, P = .278) was not significantly different between groups. The 1-, 3-, 5-, and 7-year survival rates were 96.3% +/- 1.8, 95.2% +/- 2.1, 87.9% +/- 3.4, and 80.7% +/- 4.4, respectively. Patients with IMH progression showed lower survival rates than those without (P = .028). While no significant difference in the overall survival rates could be demonstrated in patients with and those without focal contrast enhancement (P = .442), our study had only 17% power to detect a difference of 10%. Initial maximal aortic diameter was the only factor associated with survival rates (hazard ratio = 1.129; 95% confidence interval: 1.063, 1.199). The optimal cutoff for prediction of mortality within 7 years was 41 mm. Conclusion: Urgent intervention for patients with focal contrast enhancement is not necessary during the acute stage, and long-term close monitoring with imaging is a better option considering diverse remodeling processes of distal IMH. (C) RSNA, 2011