主动脉病变CT诊断

主动脉病变的CT诊断,朱晓梅,主动脉病变诊断常用方法CT，经食管超声，MR，主动脉造影多排螺旋CT的发展，CTA已经成为首选的诊断手段CTA在诊断方面，优于DSA无创三维显示管壁，周围结构,CT扫描技术,扫描范围：主动脉弓上3cm到两侧股骨头水平（股动脉）120KV，120mAs；低KV，低mAs噪音增加，但不影响诊断升主动脉建议ECG-gateing升主动脉假夹层：右前缘和左后缘ECG-gating增加放射剂量,主动脉搏动伪影,of 100cm,Scan protocols for CTA of the entire aorta with a range of 100cm for different Siemens scanners (Somatom Volume Zoom, Somatom Sensation 16 and sensation 64),对比剂注射方案,主动脉内密度：200HU高浓度，高流速350mg I/ml-400mg I/ml3-4ml/s剂量：根据患者体重及扫描持续时间确定进床速度与对比剂流动的一致性进床太快：远端动脉充盈欠佳进床过慢：错失动脉内对比剂高峰时间,对比剂注射方案,双筒注射器生理盐水冲洗减少上腔静脉内的条状伪影改善对比剂拖尾效应，减少对比剂用量增强对比剂的团注效应延迟时间： test bolus bolus tracking固定延迟时间（基本废除）,图像后处理,原始断层最重要分节分段显示后处理图像提示诊断MIP，MPR，VR，CPR等显示畸形，走形：VR血管内腔及管壁：MIP，MPR去骨和不去骨都重要,主动脉解剖,升主动脉：主动脉根部（主动脉窦），升主动脉主动脉弓（无名动脉开口-动脉导管或动脉韧带）左侧右位主动脉弓，多伴有心脏畸形无名动脉，左颈总动脉，左锁骨下动脉（迷走）降主动脉主动脉弓与降主动脉连接处：主动脉峡部,主动脉解剖,胸部降主动脉腹主动脉腹腔干根部受韧带压迫常会比较细变异较多肠系膜上动脉诊断分支闭塞时，厚MIP或VR重要肠系膜下动脉肾动脉检查肾动脉变异时，扫描范围要广,主动脉先天变异,主动脉离断定义：升主动脉和降主动脉分离分型（离断点定分型）Type A：左锁骨下动脉远端Type B：左颈总动脉远端Type C：左颈总动脉近端右侧颈总动脉起始可正常也可异常常见异常：起源于左侧锁骨下动脉远端（迷走右侧锁骨下动脉）,主动脉先天变异,主动脉缩窄常见位置：左锁骨下动脉远端（主动脉峡部）分型管型局限型缩窄远端，主动脉管腔常扩张右侧迷走锁骨下动脉长起源于狭窄远端,主动脉先天变异,主动脉缩窄管型缩窄可以无症状，偶然发现症状：高血压引起头痛；远端血运差导致陂行严重缩窄：3-5岁需手术术前CTA：显示缩窄的部位和程度，近端升主动脉扩张，有无伴发的动脉瘤，有无心脏畸形术后CTA：测量主动脉内径观察恢复情况测量时，一定要MIP重建，垂直于血管长径测量内径比较内径大小时，考虑年龄增长因素，一般1mm/y,Sagittal reformatted CT image demonstrating a membranous septation (arrow) distal to the left subclavian artery in a patient with a classic aortic coarctation,主动脉先天变异,主动脉憩室定义：右侧迷走锁骨下动脉起始的主动脉弹性扩张部位：左侧锁骨下动脉起始远端症状：右侧迷走锁骨下动脉压迫食管引起吞咽困难,主动脉先天变异,右位主动脉弓通常无症状常伴左侧迷走锁骨下动脉分支与正常呈镜像时：常伴有心脏畸形左侧锁骨下动脉离断时：先天性锁骨下动脉盗血症（左上肢动脉搏动减弱）,(A) Axial CT image demonstrating a right aortic arch (asterisk). (B) The right common carotid (black arrow) and the right subclavian (white arrow) arteries have separate origins at the aortic arch. There is a common trunk (arrowhead) of the left common carotid (CCA) and left subclavian (LSA) arteries. (C) Coronal reformat image demonstrates a saccular aneurysm of the ascending aorta (asterisk). The origin of the common trunk of the left CCA and LSA is also seen (arrow).,主动脉瘤,定义 局限性，持久性，主动脉全层扩张，超过正常内径的50%扩张不到50%：主动脉扩张原因动脉粥样硬化：最常见感染主动脉中膜坏死囊变,主动脉瘤,常见的伴发致死因素高血压，冠心病，阻塞性肺疾病，心衰动脉粥样硬化动脉瘤梭形腹部降主动脉多发马凡综合症升主动脉，累及主动脉环梨形升主动脉,主动脉瘤,CTA部位最大径长度累及的重要血管分支内径大约6cm易形成夹层，破裂腹主动脉瘤人口老龄化，发病率增加无症状，破裂致死率增加高危险人群，建议筛查：吸烟，高血压，男性，大于65岁，家族史,主动脉瘤,腹主动脉假性动脉瘤：医源性最多见支架植入术下腔静脉滤器植入术心脏移植术外伤感染破裂,(A) Axial CT image in a patient with a chronic aortic pseudoaneurysm. The thick pseudocapsule formed by blood and fibrotic tissue is invading the thoracic vertebrae resulting in bone resorption. (B) Sagittal reformat CT image demonstrates a narrow neck connecting the aorta and the sac of the pseudoaneurysm (arrow).,主动脉瘤,主动脉瘤破裂定义：主动脉壁全层不连续致死率：院外，90%原因：复杂，多因素主动脉内径，扩张率，舒张压，主动脉壁所受的剪切力和强度，内壁血栓和血管壁弹性改变等破裂位置：主动脉后壁最常见,主动脉瘤,主动脉瘤破裂CT特点特征性改变：造影剂外漏其他：主动脉壁不连续与主动脉分界不清的软组织状况肿块腰大肌边缘模糊内脏移位,主动脉瘤,主动脉瘤破裂局限性主动脉破裂特点：主动脉旁软组织肿块边缘较清晰积极筛查和随访高危人群，在主动脉破裂前采取措施，减低死亡率,Axial CT image demonstrating an abdominal aortic aneurysm (AAA), which has ruptured retroperitoneally with resultant hematoma (asterisk).,主动脉瘤,感染性主动脉瘤发病率：0.7%-2.6%感染路径：原发灶播散，外伤，医源性因素与动脉粥样硬化性动脉瘤相比：进展快CT特点：主动脉旁软组织肿块，索条影，积液,主动脉瘤,腹主动脉瘤处理手术：内径5cm内径4.5cm, 半年内径增加大约0,5cm,Axial CT image in a patient with tuberculosis in the posterior segment of the lower lobe of the left lung. A pseudoaneurysm (asterisk) of the descending thoracic aorta has developed due to necrosis of the aortic wall.,Axial CT image demonstrating a mycotic aneurysm of the descending thoracic aorta with periaortic soft-tissue mass (arrowhead) and fluid (arrow).,主动脉夹层动脉瘤,致死率高累及升主动脉成活率低于仅累及降主动脉患者影响因素高血压马综合征，Turner 综合征，结缔组织病，先天性主动脉瓣膜缺陷，主动脉缩窄，主动脉瘤，主动脉炎，妊娠，可卡因等分型Standford分型：A型和B型Debakey分型：I型，型和型,Diagram illustrating the DeBakey and Stanford Systems of classification of aortic dissection.,主动脉夹层动脉瘤,急性：周；慢性：周患者死亡多在急性期累及颈总动脉时可引起大面积脑梗死二聚体和凝血酶-抗凝血酶复合物与夹层动脉瘤形状改变呈线性关系可以用来慢性患者的随访,主动脉夹层动脉瘤,Type A：并发症：心包积液（心包填塞），胸腔积液，累及冠状动脉和主动脉环致死率高，需要立即手术治疗Type B致死率低致死三联征：低血压/休克，无胸痛，分支受累,主动脉夹层动脉瘤,Type B一般，积极控制血压，择期介入治疗随访受累主动脉直径易增大胸主动脉增长较腹主动脉快大于60岁假腔内有血流破裂，分支闭塞或变大，需紧急手术或介入治疗TypeA和Type B手术治疗并发症： 分支开口受阻致供血不足 处理：主动脉内膜开窗术,主动脉夹层动脉瘤,CT表现平扫，增强都很重要平扫钙化的内膜内移管腔内密度正常急性期，假腔高密度影需与动脉瘤内膜钙化伴血栓形成鉴别管腔内密度增高,主动脉夹层动脉瘤,CT增强表现内移内膜片真腔，假腔真腔假腔鉴别必要性：支架必须在真腔假腔：蜘蛛网征(cobweb sign), 鸟嘴征，两端是盲端，易发附壁血栓真腔：与近端和远端管腔连续，外壁钙化（慢性期，假腔外壁偶可钙化），离心性内膜片钙化,主动脉夹层动脉瘤,CT增强表现真腔假腔鉴别上四分之一处假腔较大（85%）内膜片：急性期：凸向假腔（56%），平直（38%），凸向真腔（6%）慢性期：平直（75%），凸向假腔（25%）中段水平假腔大（94%）内膜片急性期：平直（37%），凸向假腔（33%），凸向真腔（30%）慢性期：平直（67%），凸向假腔（29%），凸向真腔（4%）下四分之一处假腔大（91%）内膜片急性期：平直（33%），凸向假腔（39%），凸向真腔（28%）慢性期：平直（100%）,主动脉夹层动脉瘤,CT增强表现真腔假腔鉴别真腔：对比剂早到早走，峰值较高假腔：对比剂迟到迟走，峰值较低急性期和慢性期鉴别急性期：上四分之一处和下四分之一处，内膜片凸向假腔慢性期：内膜片钙化，假腔外壁钙化，假腔内附壁血栓,(A) Axial CT image in a patient with a Type A aortic dissection. The true lumen (arrowhead) is smaller and of higher density than the false lumen (arrow). (B) Coronal reformat image demonstrates extension of the dissection flap into the innominate and right common carotid arteries (arrow).,(A) Sagittal reformat CT image in a patient with Marfan syndrome demonstrating a type A aortic dissection involving the entire length of the aorta. (B) Axial CT image at the level of the main pulmonary artery showing involvement of the ascending and descending thoracic aorta. The larger cavity is the false lumen with a lower density (arrows) while the true lumen is smaller with a higher density (arrowheads).,41-year-old man with acute aortic dissection. CT scan obtained at one-quarter distance along length of dissected portion of aorta shows descending aortic dissection flap (arrows) that is curved toward false lumen (F). Beak sign (arrowheads) is present in false lumen. Note that false lumen area is larger than true lumen area.,51-year-old woman with chronic aortic dissection. CT scan obtained at one-half distance along length of dissected portion of aorta shows flat dissection flap. False lumen beaks are filled with lowattenuation thrombus (arrowheads). Faintly visualized cobweb (arrows) is present in false lumen (F).,65-year-old woman with chronic aortic dissection. CT scan obtained at one-quarter distance along length of dissected portion of aorta shows flat dissection flap. Outer wall calcification (straight arrow) is present in true lumen (T). Thrombus (arrowheads) is present in false lumen. Curved arrow indicates thrombus within false lumen beak.,76-year-old man with chronic aortic dissection. CT scan obtained at three-quarters distance along length of dissected portion of aorta shows flat dissection flap. Outer wall calcification (arrows) and thrombus (asterisk) are present in false lumen (F). T = true lumen.,59-year-old man with chronic aortic dissection. CT scan obtained at one-quarter distance along length of dissected portion of aorta shows flat dissection flap. Eccentric flap calcification (arrow) is present along true lumen side of flap. Notice that false lumen (F) contains thrombus (arrowheads) and is larger than true lumen at this level.,Unenhanced axial CT image (A) demonstrates displacement of the calcified intima (arrow) which corresponds to the intimal flap (arrowhead) on the contrast-enhanced CT (B). The true lumen (TL) is brightly enhancing, while the false lumen (FL) is partially enhancing and to a lesser degree due to slower flow and thrombosis.,65-year-old man with acute aortic dissection. CT scan obtained at one-quarter distance along length of dissected portion of aorta shows dissection flap that is curved toward true lumen. Anterior false lumen beak (arrowheads) is partially opacified and partially filled with thrombus. F = false lumen.,7.69-year-old woman with acute aortic dissection. CT scan obtained at level of transverse aortic arch shows that outer false lumen (F) wraps around inner true lumen (T). Dissection flap extends into innominate artery. Note cobweb in false lumen (arrow) and bilateral pleural effusions (P).,(A) Axial CT image in a patient with an acute Type B aortic dissection. The right kidney is less enhanced than the left kidney due to slower blood flow through the right renal artery which originates from the false lumen of the aorta (arrow). (B) Axial CT image in a different patient demonstrating a chronic Type B aortic dissection. Long-standing decreased perfusion to the left kidney due to obstruction of the left renal artery origin (arrowhead) by the dissection flap has caused atrophy of the left kidney. The right kidney shows compensatory hypertrophy.,主动脉膜内血肿,夹层动脉瘤早期或不典型夹层动脉瘤中膜内滋养血管破裂出血，内膜片完整，无破口急性夹层动脉瘤，13%为膜内血肿分型：Stanford分型CT表现平扫：新月形稍高密度影增强：膜内血肿密度多变，可高可低,(A) Axial CT image in a patient with a Type A IMH involving the ascending and descending thoracic aorta. Curvilinear hypodensities correspond to the intramural hematoma (arrows). (B). Axial CT image in a patient with a Type B IMH (arrow) with calcified aortic adventitia (arrowhead). (C) Axial CT image in a patient with a Type B IMH with extensive hematoma (arrow) circumferentially within the wall of aorta.,主动脉粥样硬化,老年代谢性疾病，女性绝经后进展迅速主动脉穿透性溃疡（penetrating aortic ulcer，PAU）粥样斑块侵蚀主动脉壁内层和弹性膜，中膜内血肿形成可致主动脉瘤形成或主动脉破裂囊状动脉瘤多PAU引起多发生在老龄患者，动脉粥样硬化较重主动脉弓和降主动脉多见，升主动脉少见,Diagrams illustrate the four stages in the formation of a penetrating atherosclerotic ulcer: (A) aortic atheroma, (B) benign intimal plaque ulceration contained in the intima, (C) medial hematoma with potential adventitial false aneurysm, and (D) transmural rupture.,主动脉粥样硬化,PAU治疗随访手术：适应症：血流动力学不稳定，持续疼痛，主动脉破裂，远端栓塞，主动脉直径快速增大难度大，并发症多PAU CT表现粥样斑块局部溃疡形成，主动脉管腔局部尖角样突起可单发或多发,Aortic changes due to atherosclerosis in different stages. (A) Aortic atheroma, (B) benign intimal plaque ulceration (white arrow) contained in the intima and (C) medial hematoma (white arrow) with potential adventitial false aneurysm.,外伤性主动脉损伤,主动脉不完全破裂主动脉完全破裂外伤性主动脉夹层动脉瘤外伤性主动脉膜内血肿,外伤性主动脉损伤,CT表现纵隔内积血主动脉变形内移的内膜片主动脉内血栓假性动脉瘤降主动脉逐渐变细,(a) CT scan shows a crescent of periaortic blood surrounding the descending aorta(arrow).(b) CT scan shows a contour deformity, compatible with a pseudoaneurysm, near the ligamentum arteriosus (arrow).,Aortic transection in a 39-year-old woman following blunt trauma to the chest. (a) CT scan demonstrates blood in the mediastinum and around the aorta. An intimal flap is present in the descending aorta (arrow).(b) On another scan obtained at a lower level, luminal debris and aortic contour irregularity are noted.,Acute blunt chest trauma. Axial CT scans (a, b) show a small amount of blood in the anterior mediastinum but a normal aortic contour. The sternal fracture (arrowhead in b) is the source of blood.,(A) Axial CT image demonstrating a contained traumatic aortic transection. A pseudoaneurysm (arrow) has formed at the site of the aortic wall disruption and the arch