Usefulness Of Multislice Spiral CT For Diagnosis Of Aortic Intramural Hematoma

Objective: To investigate the diagnostic role of multislice spiral CT (MSCT) in aortic intramural hematoma (AIH).Materials and Methods: we retrospectively evaluated MSCT images obtained between Oct 2001 and Jan 2005, in 272 patients who underwent aortic MSCT angiography, only 20 patients had typical findings of AIH (male 16, female 4, 41-79y, 66.1±9.2y), the correct diagnosis is made on the basis of the typical clinical presentation of aortic dissection and the typical CT imaging of AIH. We chosen 20 patients of single atherosclerosis randomly as contrast group(male 14, female 6, 50-80y, 68.2±10.2y). All patients were examined with MSCT (GE Lightspeed Plus or Lightspeed 16) using these parameters: Scan speed: 0.8s/r, 0.6s/r or 0.5s/r; slice thickness: 2.5mm; table speed:27.0mm. standard algorithm with minimum values of 120kW and 300~420mA.CT scans were performed before and after a power injection of 80~ 120ml nonionic contrast material into the cubital vein at a rate of 3.5ml/s Reconstruction techniques , including MPR, MIP and so on were adopted, and the images thus obtained were compared with each other. CT images were evaluated by searching these parameters: the location and range of the thickness of the aortic wall, the maximum thickness and density of the aortic wall, PAU, leakage, involvement of the large branches and so on. A probability value P<0.05 was considered statistically significant, P < 0.01 was considered quite statistically significant.Result: (一) MSCT signs of AIH 1 , thickness and density of the aortic wall: continuous crescentic or circle areas along the wall of aorta (20 cases) with CT value of 45.60Hu~75.40Hu(63.0±6.7Hu), the CT value of blood is 34.9Hu ~ 48.0Hu(42.4±3.6Hu). thickness: 5.0mm ~ 12.30mm(9.2±2.0mm); the aortic length of involvement: 74.80mm— 302.10mm(189.6±67.1mm). the rate of compression: 1.00—1.08mm (average :1.03±3. lmm) . 2, Displacement of intimal calcification (14 cases), distance: 3.0mm—10.3mm(6.9±2.lmm); 3, aortic atherosclerosis and PAU: all located in descending aorta, atherosclerotic plaque and calcification on the aortic wall (18 cases). PAU(15 places), there were significant differences in compression of PAU and non-PAU place in AIH combinated with PAU. 4, leakages (7 places), all located in descending aorta. 5, other imaging: hemopericardium (7cases), unilateral or bilateral hemothorax (14 cases), hemoperiaorta (6 cases), aortic aneurysms (4 case), involvement of the large branches (3 cases). (二)The differentiation of AIH and atherosclerosis: There were significant differences in the maximum thickness of aortic wall, density of pre-contrast and post-contrast, maximum diameter of aorta, displacement of intimal calcification.Conclusion: (一) The basal CT imaging of AIH is the thickness , increased-attenuation of the aortic wall and displacement of intimal calcification. PAU, leakage, hemopericardium, hemothorax, hemoperiaorta is the combined signs of AIH, MSCT can show all these signs clearly. (二) the thickness , increased-attenuation of the aortic wall and displacement of intimal calcification>4.0mm is the important signs of diagnosis for AIH, and they are also useful in differentiating AIH and atherosclerosis. In a word, MSCT is useful for revealing AIH, it can be used as the first means in the diagnosis of AIH. (三)Diagnosis of AIH depend on the axis image of CT, the reconstruction technique can provide necessary information.