The Study Of The Application Of Multi-slice Computed Tomography Angiography And Postprocessing Technique In The Aortic Dissection

Part I The Study of The Application of Multi-slice Computed TomographyAngiography and Postprocessing Techniques in The Aortic DissectionObjective:The objectives of this study were to discuss the diagnosisvalue of multi-slice computed tomography angiography in aortic dissection.To compare which is the best postprocessing technique in displaying tearentry, the extent of intimal flap, and the true and false channel of dissection.Method and Material:41 consecutive patients with MSCTangiography confirmed AD in the Affiliated Hospital of North MedicalCollege during Jan.2010 to Mar.2012 were enrolled into our study andunderwent contrast enhanced scanning by 16-slice mutidetector CT, 18 of allthe 42 patients were confirmed by surgery. To illustrate the diagnosticsignificance of MSCTA for AD and make comparison among theobservational results from several reconstruction techniques such as MPR,CPR, MIP and VR in the displaying tear entry, the extent of intimal flap, andthe true and false channel of dissection, other imaging features andcomplications; analysis and summary suffered the characteristics of abdominal aortic branch vessels.Results:41 patients all obtained satisfying images after the examinationof computed tomography angiography (CTA), which satisfies the diagnosticrequest based on cross-sectional images and the combination of severalreconstruction techniques.1. Apart from 6 patients, tear entry was seen in the rest of 35 patients, 6of them had multiple tear entry. The rate of all kind of postprocessingtechniques in showing the intimal tear from high to low were axial sequencecombined with MPR and CPR (38/41,92.48%), MPR (36/41,87.80%), CPR(34/41,82.93%), axial sequence combined（33/41,80.49%）, VR and MIP(0/41,0.00%); there were significantly difference between them (P＜0.05).The demonstration rate of MPR, CPR, and VR on the true and false channelwas 100% respectively, and MIP was 58.9%. And for intimal flap, MPR,CPR, and VR was 100% respectively, MIP didn’t demonstrate the tear entryand intimal flap.2. Other imaging signs contains cobwebs, beak sign, whether hadformation of thrombus in false lumen and intrinsic wall calcification or not.Among 41 cases, apart from 5 patients, beak sign was seen in the rest of 36patients, only 1 patient showed cobwebs; 25 patients had formation ofthrombus in false lumen and 13 had intrinsic wall calcification. 3. All of the three main branches of aortic arch were involved in 4patients; involvement of the celiac trunk was showed in 5 patients, superiormesenteric artery in 4 patients, and renal artery in 19 patients (unilateralrenal artery in 17 patients, both left and right renal artery in 2 patients). Theorigination from the true lumen in the celiac trunk is more common; theorigination from the true lumen in the right renal artery is more commonthan which in the left renal artery.4. Complications contained pleural effusion, pericardial effusion,increased heart volume (mainly enlarged of left atrium and left ventricular),each observed in 25, 17 and 13 cases.Conclusion:1. Multi-slice spiral computed tomography angiography was a veryuseful tool for detecting aortic dissection, which can provide abundantimaging information.2. MPR and CPR visual display location of rupture, combined with axialimages can improve the display rate of the intimal tear; MPR and CPR asshown on the break significantly increased compared with VR and MIP.