| Background and objectivesThe formation mechanism of aortic dissection is mainly due to aortic medial degeneration or necrosis. Caused by certain predisposing factors, the arterial intima tear, the blood enters into gap between intima and midedle layer,lead to hematoma formation. This is one of the most common and also the most complex, the most dangerous cardiovascular disease; its incidence is50-100/100000groups each year. Early diagnosis is the key to achieve good therapeutic effect. In the past, people do not have a clear understanding of the disease, caused a lot of misdiagnosis and missed diagnosis, and even cause medical disputes, it’s very important to looking for a timely, accurate, rapid, noninvasive diagnostic methods, in order to make a rational treatment plan, and save the patient’s life. The invention and the medical applications of the multi-slice spiral CT (multi-slice computed tomography, MSCT) is an important milepost in imaging. Scanning speed is greatly enhanced and the Z axis resolution rises significantly, realized completed within a short time large scale regional volumetric scanning, and can use these data to various post-processing reconstruction. Vascular anatomy and localization of lesions, qualitative diagnosis obtained the considerable development. In recent years, as people living habits change, the incidence of aortic dissection is in an upward trend. But with the in-depth understanding of the lesions of aortic dissection and the improvement in aortic screening technology, the detection rate of the patients suffering from aortic dissection is also greatly improved. As a noninvasive screening, rely on its powerful data processing function, MSCT can intuitively reflect the lesion, enhanced scan can clarify the location, range, degree of the lesion and the relation with surrounding tissue. It plays an important guiding role in the clinical diagnosis and treatment. With the maturity of CTA and widely applied in clinical diagnosis of arterial lesions, DSA (digital subtraction angiography, DSA) has been a great challenge as a traditional diagnostic methods.[1-3]Purpose:To evaluate the value of16-SCT in the diagnosis of aortic dissection and preoperative evaluation of aortic dissection, to explore of rapid diagnosis and to guide the clinical treatment.Subjects and methodsThe clinical data:Choose68patients with aortic dissection in our hospital to do the16slice spiral CT coronary artery imaging (16-SCTA) examination from June2005to December2011, and in order to confirm the result, part of the patients do the selective aortic angiography, operation and autopsy after CTA.Method:TOSHIAB Aqulion16-SCT (16row), continuous scanning. The scan range was aortic arch above10mm to iliac artery branches and further, used of ECT-720high pressure syringe,20G indwelling needle (BD) and double handle30cm length of hose transfusion needle (Berenger company), all used of nonionic contrast agent (Ultravist, Omnipaque and Optiray). Injected in the forearm venous bolus, with the application of surestart tracking technology, choice the region of interest in the aortic arch, after injecting contrast agent, when the CT value increased130-150Hu, we began to scan. Reconstructing at1.0, spacing at0.5. Then, we putted the reconstruction image into volume rendering (VR), multiple planar reconstructions (MPR), surface reconstruction (CPR), maximum intensity projection (MIP) and other post-processing. According to the position of the intimal teared and extended range of dissecting aneurysm of aorta, comprehensive axial original image and post processing image,we analyzed it had aortic dissection or not and the dissecting range. Conventional CAG methods:Siemens Angostura plus C arm, gold markers catheterization through left subclavian artery to do the aortic angiography.In terms of treatment, first, taked a protective treatment, given a sedative, analgesic and antihypertensive treatment. Maked the blood pressure decreased to100-110/60-70mmHg in6hours, controlled of heart rate during60-80times/min; to control the heart rate and blood pressure at a better level by the drug that could effectively stabilize or suspense aortic dissection in the separation, could relieve the symptoms, some patients were old, the cost of operation was high, the operation risk was big, so part of the patients chose conservative treatment. In principle we advocated general interventional or surgical operation treatment, Debakey type Ⅰ used the ascending aorta and aortic arch artificial vascular replacement+improved stented elephant trunk operation; Debakey type Ⅱ used the ascending aorta vascular prosthesis replacement, type B aortic dissection patients (equal to that of type DebakeyⅢ) preferred to percutaneous stent implantation.ResultsThrough the MSCTA image analysis,51cases were diagnosed as atypical aortic dissection,17cases were diagnosed as atypical aortic dissection. Including:(1) within51cases of aortic dissection, true and false lumen showed a rate of100%(51/51), the film shows the rate was100%(51/51), intimal breach displayed rate was100%(51/51). The false lumen of blood formation was41cases. Left renal artery involvement in24cases, right common iliac artery involvement for25patients, as the most easily affected vascular branches. MSCTA showed the size and location of the initial gap, to compare with the results of DSA, operation and autopsy, the coincidence rate was100%(51/51).(2) In the face of true and false lumen cross-sectional display was superior to MIP and VR (P<0.05); MPR on the interlayer of the true lumen showed also was superior to MIP and VR (P<0.05).(3)14patients with intramural hematoma, without intimal tear,13cases aortic wall showed crescent and ring slightly high density.11patients with intramural hematoma and penetrating ulcer (11/14,78.6%).Accorded to the Debakey classification, in the51typical aortic dissection:17cases of type Ⅰ,2cases of type2,32cases of type3; MSCTA could show its true, false lumen and intimal flap, included flat, curved and spiral shape. The true lumen was smaller, located within the false lumen after medial, the true lumen density was higher than that of the false lumen in31cases, and they had similar densities in20cases. Accorded to Stanford classification, type A in19cases, type B in32cases. In the17cases of atypical aortic dissection, according to the DeBakey classification, type Ⅰ was3cases, type Ⅱ was14cases; According to Stanford classification, type A was3cases, type B was14cases.ConclusionsThrough some sound image processing techniques,16-SCTA can fast, accurate, noninvasive and overall show the location and extent of aortic dissection, and pathology anatomy. The specificity is high.16-SCTA plays a important role in diagnosis of aortic dissection and preoperative assessment. |
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