Background: Previous pathological and clinical studies demonstrated an intimal defect in patients with acute aortic intramural hematoma (IMH). The purpose of this study was to investigate the prevalence and clinical outcome of intimal defect detected by multidetector computed tomography (MDCT) in patients with IMH.
Methods and results: We retrospectively analyzed 38 consecutive patients with IMH in whom 64-row MDCT was performed during the acute phase (median, 5 days from the onset). Intimal defect was defined as continuity disruption of the inner layer of thrombosed false lumen, which could be detected by 1-mm axial and longitudinal interactive multiplanar reformation images. Clinical outcome of intimal defect was assessed in patients with type B IMH (n=32). A total of 48 lesions in 27 (71%) patients were recognized as intimal defects. The incidence of intimal defect was not affected by the timing of MDCT examination (1 to 3 days, 79%; 4 to 7 days, 58%; 8 to 14 days, 75%; P=0.56). In type B IMH, 16 (76%) of 21 patients with intimal defect showed progression (enlargement or progression to aortic aneurysm) in the chronic phase. In contrast, all 11 patients without intimal defect had complete resorption of hematoma. In lesion-based analysis, a depth of intimal defect of ≥ 5 mm predicted progression with sensitivity, specificity, and positive and negative predictive values of 84%, 95%, 94%, and 86%, respectively.
Conclusions: A considerable portion of patients with IMH showed intimal defect detected by MDCT even in the very early stage, and defects frequently enlarged. Patients with intimal defect should be carefully followed up with serial imaging.