[en] Objective: To evaluate the dynamic changing and prognosis of aortic intramural hematoma (IMH) by electron beam CT(EBCT). Methods: A retrospective study was performed during a period of time from January. 2002 to September 2004. Twenty-three patients with aortic IMH were scanned by EBCT more than 2 times. The patients were followed-up for 4-405 days (mean 105.8 days). Mean follow-up was 105.84 days. In this group 23 patients (19 men and 4 women, aged from 30 to 81 years, mean 57.78 years) who had been undergone EBCT were diagnosed with IMH. EBCT scanner was used with a model of Imatron C-150XP. Contrast-enhanced continuous volume scanning (CVS) was performed. The slice thickness was 6 mm or 3 mm with an acquisition time of 100 milliseconds. A total amount of contrast media (Ultravist 300 or 320, or Ominpaque 300 or 320 mg/ml) of 80-100 ml was used with the rate of 3.5- 4.5 ml/s. The scan delayed time was 18-30 s. Results: Four patients with Standford A IMH were diagnosed. Among them, 3 patients were observed in complete regression, 1 patient was observed without changing. Nineteen patients with Standford B IMH were diagnosed. Among them, 9 patients were observed in complete regression, 4 patients were observed in incomplete regression, 4 patients were observed without changing, 2 patients were observed in progression on EBCT. From 4 days to 15 days, IMH was observed without change or worse. From 16 days to 30 days IMH was observed in regression. Conclusion: EBCT was a very useful tool for detecting and following up of IMH. The different features of the involved aortic walls shown on EBCT were used for planning surgery. (authors)