| Aortic dissection (AD) is one of the most common artery emergency diseases. It has notable clinical significance to confirm the coverage of AD and to determine whether the aortic branch is involved. It is a key point in selecting therapeutic method and improving diagnosis and treatment level that confirm the type of AD and its complete morphologic change as soon as possible. Usually, image analysis includes CT, MRI, DSA and US, et al. Since SCTA was applied to clinical in 1992, it has played a more and more important role with an increasing number of image post-processing. Objective:1. To study the appropriate scan condition of SCTA in AD, especially in selecting scan parameter and using contrast medium.2. To explore the method and skill of post-processing in SCTA image for AD.3. To evaluate the clinical application of SCTA in the diagnosis of AD, and to compare the diagnosis value of different post-processing in SCTA imagingtechniques. To explore the value of SCTA in postoperatively follow-up and selection of therapeutic method.4. To explore the value of SCTA image for diagnosis of AD compared with magnetic resonance image (MRl),dighal subtraction angiography(DSA), transthoracic echocardiography(TTE) and transesophageal echocardiography(TEE).5. To compare the value of SCTA and electron beam CT angiography (EBCTA) image for diagnosis of AD.Methods:1 .The SCTA examinations of 51 cases with AD were retrospectively studied.The CT scan parameters, methods of post-processing were reviewed andanalysed one by one.2. 25 cases of AD underwent SCTA the methods of injection contrast mediumincluding ankle vein method and perivenous vein method were chosen atrandom. The perivenous vein method has two pathway: right and left. Thequantity of image in different methods were compared and analysed.3.51 cases with AD were selected for SCTA. Slice thickness 4~8mm, index2~3mm, pitch 1.25-1.75. All data were transfered to work-station andpost-processed with MPR, MIP, SSD and VR to explore the proper methodand skill of poet-processing.4. The value of different post-processing methods in clinical treatment, selection of operation methods and postoperative follow-up was compared and analysed.5. 28 cases with AD verified in operation were studied. The accuracy of SCTA for diagnosis of AD and classification of AD relative to the results of operation, MRI, DSA, TTE and TEE was evaluated.6. 28 cases with AD undergoing SCTA and EBCTA were studied. Theaccuracy of SCTA for diagnosis of AD and classification of AD relative to theresults of operation, MRJ, DSA, TTE and TEE was evaluated.7. Statistical analysis: The primary data were processed with X2 check andanalysis by SPSS 10.0 software.Results:1. 51 cases were diagnosed as AD and classified correctly, in accordance with the result of operation and DSA. The quality of image was satisfied and the rate of success at least above 81.8%. The main scan parameters were used as follow: (1) the ascend AD: slice thickness 4 mm reconstruction interval 2 mm, pitch 1.25; tube current 175mA; (2) ascend, arch, descend and thoracic AD: slice thickness 5mm, reconstruction interval 2-3mm, pitch 1.5; tube current 150mA; (3) abdominal AD: slice thickness 6-8mm, reconstruction interval 2~3 mm, pitch 1.5 or 1.75; tube current 125mA. All tube voltages were 120kV. The dosage of contrast media was 90~100ml;the delayed scan time was 20 second in throacic aortic and 25 second in abdominal aortic.2. The best method of contrast medium injection is from right perivenous, and second is ankle vein. The injection of contrast medium from left has got most perivenous streak artifacts3. The post-processing image methods included MPR, SSD, MIP and VR. The method and skill of SCTA imaging post-processing can be mastered only through exercising and exploring many times on the workstation. Different image got by way of imaging post-processing has differen...
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