Aortic branch artery pseudoaneurysms accompanying aortic dissection. Part I. Pseudoaneurysm anatomy

PURPOSE: Small areas of blood flow are sometimes seen within an otherwise thrombosed false lumen on computed tomography (CT) scans of intramural hematomas of the aorta. These are blood-filled spaces that, although they have no apparent communication with the true lumen, appear isodense with the aorta on contrast-enhanced CT scans. The purpose of this report is to describe angiographic and autopsy studies that establish the nature of this entity and describe the principal CT features distinguishing it from a penetrating ulcer. MATERIALS AND METHODS: Conventional angiographic and CT aorta findings in two cases with small collections of contrast material within an otherwise thrombosed false lumen of an aortic dissection are discussed. Also examined is another case with pathologic and histologic findings in addition to those of small collections of contrast material within an otherwise thrombosed false lumen of an aortic dissection, which illustrate the pathoanatomy of these lesions. RESULTS: Angiographic and necropsy evidence shows that some of these lesions represent branch artery pseudoaneurysms and, as such, are secondary to an intramural hematoma, not the primary cause of it. CONCLUSIONS: Difficulty in demonstrating communication between these collections of contrast material and the adjacent true lumen of the aorta on helical CT examinations and the characteristic location of these lesions along the nonpleural portion of the aortic circumference distinguish them from penetrating ulcers and should suggest the diagnosis of branch artery pseudoaneurysm. Demonstration of a branch artery originating from the contrast collection confirms the diagnosis. These branch artery pseudoaneurysms should be distinguished from penetrating atherosclerotic ulcers.     

Penetrating atherosclerotic ulcers of the descending thoracic aorta: evaluation with CT and distinction from aortic dissection.

Penetrating atherosclerotic ulceration of the aorta is a poorly understood entity that clinically mimics classic aortic dissection but has imaging features that are distinctly different. In a review of 16 patients with penetrating atherosclerotic ulceration, patients were typically hypertensive (n = 14), and they experienced chest or back pain (n = 13). All patients had an abnormal chest radiograph, with diffuse (n = 14) or focal (n = 2) enlargement of the descending thoracic aorta. Features at contrast material-enhanced computed tomography (CT) included intramural hematoma (n = 16), focal ulcer (n = 15), displaced intimal calcification (n = 13), pleural and/or extrapleural fluid (n = 7), mediastinal fluid (n = 4), and a thick or enhancing aortic wall (n = 6). The chest radiograph and CT findings were compared in patients treated conservatively (n = 9) and surgically (n = 7). These findings did not correlate with the need for surgery. Eight of nine conservatively treated patients were asymptomatic after treatment with antihypertensive medication. Contiguous dynamic contrast-enhanced CT of the aorta enables distinction of ulceration from dissection, which is particularly important in the hemodynamically unstable patient because the surgical management of ulceration is more extensive than that for aortic dissection.     

Atherosclerotic penetrating ulcer of the aorta: typical morphology on CT. A review of five cases

Multiple penetrating atherosclerotic ulcers of the abdominal and thoracic aorta were detected in five elderly patients with well-known cardiovascular risk factors who were referred to our department for the investigation of an unrelated disease or acute chest pain. Penetrating ulcers of the aorta are defined as atherosclerotic intimal aortic plaques that ulcerate and penetrate into the media, allowing haematoma formation within the media. The progression of the disease is often limited by the presence of an associated fibrosis within the aortic media (medial fibrosis), but secondary formation of a pseudoaneurysm or very rarely a spontaneous perforation into the pleural space, mediastinum or peritoneal cavity have been observed. In our restrospective study we describe the morphology of the penetrating aortic ulcer on CT and in one case on sonography and angiography. A review of the literature is included.     

Thoracic aortic disease: Spectrum of multidetector computed tomography imaging findings

The clinical presentation of diseases involving the thoracic aorta ranges from a large number of asymptomatic patients with clinically undetectable thoracic aortic aneurysm to patients with symptoms of severe chest pain as a result of acute aortic dissection. Thoracic aortic disease often remains undiagnosed until a life-threatening complication occurs or the disease is discovered serendipitously on imaging studies performed for other purposes. Multidetector row computed tomography (MDCT) imaging of the aorta is used to diagnose various acute and chronic conditions, including aortic aneurysms, aortic dissection, intramural hematoma, penetrating atherosclerotic ulcer, traumatic injury, rupture, inflammatory disorders, and congenital malformations. This review illustrates the wide range of MDCT imaging findings of thoracic aortic disease.     

Pitfalls in the diagnosis of thoracic aortic dissection at CT angiography.

Two hundred seventy-five computed tomographic (CT) angiograms of the thoracic aorta were obtained over a period of approximately 4 years in patients with suspected or known aortic dissection. In all cases, unenhanced images were initially obtained, followed by contrast material-enhanced images. A variety of pitfalls were encountered that mimicked aortic dissection. These pitfalls were attributable to technical factors (eg, improper timing of contrast material administration relative to image acquisition); streak artifacts generated by high-attenuation material, high-contrast interfaces, or cardiac motion; periaortic structures (eg, aortic arch branches, mediastinal veins, pericardial recess, thymus, atelectasis, pleural thickening or effusion adjacent to the aorta); aortic wall motion and normal aortic sinuses; aortic variations such as congenital ductus diverticulum and acquired aortic aneurysm with thrombus; and penetrating atherosclerotic ulcer. Although several of these pitfalls are easy to recognize and therefore unlikely to present a diagnostic problem, others are potentially confusing. Familiarity with these common pitfalls, coupled with a knowledge of normal intrathoracic anatomy, will facilitate recognition of true aortic dissection and help avoid misdiagnosis at thoracic aortic CT angiography.     

Spontaneous progression of ascending aortic intramural hematoma to Stanford type A dissection fortuitously witnessed during an MR examination

Aortic intramural hematoma may occur as a primary event (spontaneous dissection without intimal flap) or secondary to a penetrating atherosclerotic ulcer. The management of intramural hematoma of the ascending aorta is somewhat controversial because of limited published data, but some centers advocate early surgical intervention. We describe a patient with an intramural hematoma of the ascending aorta that progressed to a classic communicating dissection during an MR examination. This case graphically demonstrates the potential instability of patients with intramural hematoma of the ascending aorta.     

多层螺旋CT造影在主动脉病变腔内修复术后随访的价值

目的:探讨多层螺旋CT血管造影(multi-detector rowspiral computed tomography angiography,MDCTA)及后处理技术在主动脉覆膜支架腔内修复术(transluminal stent-graft placement,TSGP)术后随访的临床应用价值。方法:21例接受TSGP主动脉疾病患者,包括:Stanford B型夹层13例,真性动脉瘤3例,假性动脉瘤2例,弓降部穿透性溃疡1例,胸主动脉瘤合并局限性夹层1例,胸主动脉瘤合并Stanford B型夹层1例,术后采用MDCTA进行随访,平均随访13个月(1~24个月)。采用轴位图像与多种重建图像相结合来显示支架形态、术前术后主动脉管腔情况的变化和有无并发症。结果:13例主动脉夹层覆膜支架置入后:所有患者均真腔扩大,假腔减小或消失并伴血栓形成,支架未发现移位或断裂;共3例(14%)随访中发现内漏,1例Ⅱ型内漏,建议随访观察;1例术后8个月复查新发现支架近端Ⅰ型内漏,密切随访2个月后患者出现胸痛,复查CT内漏增多,转外科治疗。1例腹主动脉瘤术后1月复查发现Ⅲ型内漏。所有患者介入术后CT随访图像均满足临床诊断需要。结论:MDCTA对主动脉覆膜支架置入术后随访较其他检查手段具有多方面的优越性,能及时观察术后疗效、发现并发症,对主动脉疾病覆膜支架腔内修复术后随访具有重要价值。     

Placement of endovascular stent-grafts for emergency treatment of acute disease of the descending thoracic aorta

OBJECTIVE: The aim of this study was to evaluate the feasibility, safety, and effectiveness of endovascular stent-graft placement for the emergency treatment of acute descending thoracic aortic disease. MATERIALS AND METHODS: From January 1996 through November 2001, 18 patients underwent emergency endovascular stent-graft placement for various types of acute descending thoracic aortic disease. Five patients had Stanford type B aortic dissection, six had traumatic ruptures of the thoracic aorta, five had ruptured aortic aneurysms, and two had penetrating atherosclerotic aortic ulcers. All patients presented with life-threatening symptoms requiring treatment with stent-grafts from the emergency kit. All were at high surgical risk due to serious comorbidities. The efficacy of the procedure was assessed at follow-up studies before discharge and at 3, 6, and 12 months after intervention and yearly thereafter. RESULTS: The primary technical success rate was 78%. Four patients had primary perigraft leaks. The secondary technical success rate was 83%. One patient died 20 hr after intervention from stent-graft-related causes. Follow-up studies revealed stent-graft migration in one patient. Progression of disease was observed in one patient treated for dissection and in both patients treated for penetrating ulcers. One patient died 7 months after intervention of unknown reasons; all other patients are alive. The mean follow-up time was 17.4 months (range, 0-38 months). CONCLUSION: Emergency repair of acute descending thoracic aortic disease with stent-graft placement can be successfully accomplished and may be a promising alternative to open-chest surgery, especially in patients at high risk.     

特殊类型主动脉夹层的电子束CT表现及诊断

目的探讨表现特殊的主动脉夹层的电子束CT(EBCT)影像特征及诊断.材料和方法20例表现特殊的主动脉夹层,其中不典型夹层13例,三腔以上夹层动脉瘤3例,合并升主动脉壁内血肿的Stanford B型夹层2例,动脉瘤样夹层1例,外伤性主动脉夹层1例.结果主动脉不典型夹层为主动脉壁新月形或环形的低密度血肿包绕,常可见穿透性溃疡或钙化内移等征象;三腔以上夹层动脉瘤有2～3个内膜片,3～4个腔,瘤体管径较大;合并升主动脉壁内血肿的B型夹层见升主动脉管壁低密度新月形或环形增厚,降主动脉则见内膜片及真假两腔形成;动脉瘤样主动脉夹层见降主动脉局限性瘤样扩张,破口大,内膜片不易发现.1例外伤性夹层于主动脉弓峡部及降部起始见破裂内膜片.结论特殊类型的主动脉夹层表现各具特征,EBCT可清晰显示,是极适用于胸部急症的快速、无创的检查方法.     

Intramural hematomas of the aorta

Intramural hematomas (IMH) are regarded as a hemorrhage into the aortic wall. In general a traumatic form can de differentiated from a spontaneous non-traumatic. There is a predisposition of IMH with arterial hypertension and mesoectodermal dysplastic syndromes. The diagnosis is established with the clinical presentation in combination with the findings of different imaging modalities. Acute and subacute discomfort associated with a tendency of collaps are considered as typical presenting complaints. A semicircular or concentric thickening of the aortic wall with the absence of blood flow or a dissection membran are typical findings in transesophageal echocardiography, computed tomography and magnetic resonance tomography. From a differential diagnostic point of view a distinction from atherosclerotic wall changes, intraluminal thrombi and inflammatory aortic diseases is essential. The IMH is considered as an early presentation of aortic dissection, put into and treated according to the Stanford classification. In the course of natural history an IMH can disappear, rupture or progress into a classic aortic dissection.     

Aortic branch artery pseudoaneurysms accompanying aortic dissection. Part II. Distinction from penetrating atherosclerotic ulcers

PURPOSE: Small collections of contrast material are frequently seen within the otherwise thrombosed false lumen of an aortic dissection (AD). These collections can be divided into those without apparent communication with the aortic lumen (ie, pseudoaneurysms) and those with obvious communications (ie, ulcers). The present study was performed to test the hypotheses that pseudoaneurysms and ulcers differ in their distribution around the aorta and that the distribution of pseudoaneurysms is similar to that of small aortic branch arteries. MATERIALS AND METHODS: Computed tomography (CT) scans in 187 patients with AD and thrombosed false lumens showed 335 intramural contrast medium collections, including 128 pseudoaneurysms and 207 ulcers. CT scans in 40 control individuals without AD were reviewed to localize small aortic branch arteries. The angular distributions around the circumference of the aorta of pseudoaneurysms and ulcers and the branch artery origins were tabulated and compared. The frequency of detection of small branch arteries arising from the contrast material collections was noted. RESULTS: The angular distribution of pseudoaneurysms did not differ significantly from that of branch artery origins but did differ from that of ulcers. Pseudoaneurysms were found along the posterior, medial, and anterior walls of the aorta in the chest, sparing the lateral wall abutting the pleura. Ulcers tended to spare the arc containing branch artery origins. The composite distribution of ulcers and pseudoaneurysms appears uniform around the circumference of the aorta except at the T10-T12 levels. CONCLUSIONS: Branch artery pseudoaneurysms spare the pleural surface of the aorta and have nearly the same distribution around the circumference of the aorta as the origins of small aortic branch arteries. In contrast, ulcers tend to spare branch artery origins. The characteristic appearance and distribution of pseudoaneurysms on CT can help differentiate them from ulcers.     

主动脉壁内血肿的多层面螺旋CT诊断

目的:评价多层面螺旋CT诊断主动脉壁内血肿的价值.材料和方法:对23例怀疑主动脉病变的患者进行多层面螺旋CT扫描并诊断为主动脉壁内血肿.两名有经验的心血管放射医师按照CT标准做出诊断.使用16排多层面螺旋CT获得1.25mm层厚(1mm重建间隔)图像,应用多平面重建、曲面重建、最大密度投影和容积重建等方法显示壁内血肿及穿透溃疡.结果:23例主动脉壁内血肿中,1例A型,22例B型;B型壁内血肿中,仅累及降主动脉的8例,胸腹主动脉受累11例,局限于腹主动脉3例;11壁内血肿伴主动脉穿透溃疡,其中2例行带膜内支架治疗.结论:多层面螺旋CT能为主动脉壁内血肿的诊断、鉴别诊断和治疗提供重要信息.     

Multi-detector row computed tomography: imaging in acute aortic syndrome

Acute aortic syndromes (AAS) encompass a spectrum of emergencies. These include those non-traumatic disease entities of the aorta namely, penetrating atherosclerotic ulcer, intramural haematoma, dissection and aneurysm rupture. The various types of AAS cannot be reliably differentiated on clinical grounds alone. Acute thoracic aortic injury is usually included in this group even though clinical presentation is different, i.e., in the context of trauma, the imaging features are very similar. Differentiation of AAS from acute coronary syndrome (ACS) is important, however, it must be remembered that ACS may occur as a result of AAS. Now electrocardiogram (ECG)-gating technology is widely available, ECG-gated multi-detector row computed tomography (MDCT) is a powerful clinical tool in the acute emergency setting, which enables rapid and specific diagnosis of aortic pathology. ECG-gated MDCT significantly reduces motion artefact, avoids potential pitfalls in diagnosis and often provides diagnostic information about the coronary arteries. It should be used as a first-line imaging technique. This article examines the role of MDCT imaging and cardiac gating in the assessment of AAS and discusses the differentiation of this spectrum of aortic diseases with reference to the key imaging findings as obtained by experience in our institution.     

Penetrating aortic ulcers: diagnosis with MR imaging

The authors studied seven patients with penetrating aortic ulcers with use of magnetic resonance (MR) imaging. All patients were evaluated for acute chest symptoms, and the presence of aortic ulcers was confirmed by means of angiography in all seven patients. Five patients also underwent computed tomography (CT). Three patients underwent surgical repair of the thoracic aorta. MR findings included intramural hematoma and focal aortic wall ulceration in four patients, focal ulceration in one, focal intramural hematoma in one, and focal intramural hematoma with rupture in one. The diagnosis of intramural hematoma was made by the detection of increased signal intensity on T1- and T2-weighted MR images. MR imaging was superior to angiography in depicting the extent of intramural thrombus, although one ulceration diagnosed at angiography was missed at MR imaging. MR imaging was superior to CT in differentiating acute intramural hematoma from atherosclerotic plaque and chronic intraluminal thrombus, although it did not depict displaced intimal calcification in one patient with extensive intramural hematoma.     

Penetrating atherosclerotic ulcer of the descending thoracic aorta: Treatment by endovascular stent-Graft

Purpose: To present four cases of penetrating ulcer of the descending thoracic aorta treated by transfemoral insertion of an endoluminal stent-graft. Methods: Four patients with penetrating aortic ulcers were reviewed. Three cases were complicated by rupture, false aneurysm, or retrograde dissection. All patients were treated by endovascular stent-graft and were followed by helical computed tomography (CT). Results: Endovascular stent-graft deployment was successful in all patients. However, in one case we observed a perigraft leak that spontaneously disappeared within the first month, and two interventions were needed for another patient. Following treatment, one episode of transient spinal ischemia was observed. The 30-day survival rate was 100%, but one patient died from pneumonia with cardiac failure 34 days after the procedure. In one patient, helical CT performed at 3 months showed a false aneurysm independent of the first ulcer. This patient refused any further treatment and suddenly died at home (unknown cause) after a 6-month follow-up period. Conclusion: Transluminal placement of endovascular stent-grafts for treatment of penetrating ulcers of the descending thoracic aorta appears to be a possible alternative to classical surgery. After treatment, follow-up by CT is essential to detect possible complications of the disease.     

Multidetector-row CT evaluation of nontraumatic acute thoracic aortic syndromes

Acute thoracic aortic syndromes encompass a spectrum of emergencies presenting with acute chest pain and marked by a high risk of aortic rupture and sudden death. These include nontraumatic disease entities of the thoracic aorta, namely, dissection, intramural haematoma, penetrating atherosclerotic ulcer and aneurysm rupture. In clinical practice, the most frequent imaging procedure used in the diagnostic assessment of these diseases is computed tomography (CT), which, thanks to recent technological developments [multidetector-row computed tomography (MDCT)], affords important diagnostic possibilities and very interesting future perspectives. This paper on the use of MDCT in the evaluation of acute thoracic nontraumatic aortic syndromes illustrates the examination technique and the key imaging findings related to each disease. Moreover, the role of MDCT for planning specific treatment is also highlighted.     

The role of multidetector-row CT in the diagnosis,classification and management of acute aortic syndrome

The term “acute aortic syndrome” (AAS) encompasses several non-traumatic life-threatening pathologies of the thoracic aorta presenting in patients with a similar clinical profile. These include aortic dissection, intramural haematoma and penetrating atherosclerotic ulcers. These different pathological entities can be indistinguishable on clinical grounds alone and may be confused with other causes of chest pain, including myocardial infarction. Multidetector-row CT (MDCT) is the current modality of choice for imaging AAS with a sensitivity and specificity approaching 100%. Early diagnosis and accurate radiological classification is associated with improved clinical outcomes in AAS. We review the characteristic radiological features of the different pathologies that encompass AAS and highlight the vital role of MDCT in determining the management of these life-threatening conditions.The term “acute aortic syndrome” (AAS) encompasses a heterogeneous group of patients with a similar clinical profile presenting with one of several non-traumatic life-threatening pathologies of the thoracic aorta.¹ These include aortic dissection, intramural haematoma (IMH) and penetrating atherosclerotic ulcers (PAUs).^2,3 These different pathological entities can be difficult to distinguish clinically and may be confused with other causes of chest pain, including myocardial infarction, oesophageal perforation or pulmonary embolism.^2–4 Aortitis and traumatic aortic injury are not considered as part of the clinical spectrum of AAS, as they both demonstrate distinct pathophysiological and clinical features.^2,3We provide a literature review of the role of multidetector-row CT (MDCT) in the acute assessment of patients with suspected AAS and highlight the importance of early diagnosis and accurate classification in the management of AAS.     

Chest radiography in acute aortic syndrome: pearls and pitfalls

Acute aortic syndrome is a group of life-threatening diseases of the thoracic aorta that usually present to the emergency department. It includes aortic dissection, aortic intramural hematoma, and penetrating aortic ulcer. Rare aortic pathologies of aorto-esophageal fistula and mycotic aneurysm may also be included in this list. All these conditions require urgent treatment with complex clinical care and management. Most patients who present with chest pain are evaluated with a chest radiograph in the emergency department. It is important that maximum diagnostic information is extracted from the chest radiograph as certain signs on the chest radiograph are extremely useful in pointing towards the diagnosis of acute aortic syndrome.     

Atypical presentation of dissection of the ascending aorta in young men with cystic medial necrosis: MR findings

Dissection of the ascending aorta is usually associated with severe chest and/or back pain. We describe three young men, with pathologically proven cystic medial necrosis, who presented with atypical clinical symptoms and ascending aortic dissection diagnosed by MR imaging and surgery. Patients with cystic medial necrosis and aortic dissection may not present with a classic acute chest pain syndrome.     

不典型主动脉夹层的多层螺旋CT诊断价值

目的:回顾性分析不典型主动脉夹层(atypical aortic dissection,AAD)的CT表现,探讨螺旋CT诊断AAD的价值。方法:25例AAD患者,全部行平扫及增强扫描,并结合多平面重组、曲面重组等方法显示AAD及穿透溃疡,根据Stan-ford分类法分型。结果:25例AAD,A型7例,B型18例。主要CT表现:主动脉壁呈新月型或环形增厚,无内膜破裂形成的双腔主动脉征象,增强扫描假腔无强化。内膜钙化向内移位7例,穿透性溃疡征3例。并发心包、纵隔及胸腔积液和积血共10例。经内科保守治疗后,6例完全吸收,3例部分不典型吸收,2例无明显变化。结论:螺旋CT清楚显示夹层的部位、范围及并发症,可作为主动脉夹层的首选检查及随访方法。