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.     

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.     

Comprehensive cardiovascular ECG-gated MDCT as a standard diagnostic tool in patients with acute chest pain

Acute myocardial infarction, pulmonary embolism, and aortic dissection are diseases associated with acute chest pain and may lead to severe morbidity and mortality. These diseases may not be trivial to diagnose in the settings of emergency room. ECG-gated multi-detector computed tomography (MDCT), already established for the assessment of pulmonary embolism and aortic dissection, provides reliable information regarding the triage of patients with acute coronary syndrome in the emergency room. MDCT recently appeared to be logistically feasible and a promising comprehensive method for the evaluation of cardiac and non-cardiac chest pain in emergency department patients. The possibility to scan the entire thorax visualizing the thoracic aorta, the pulmonary arteries, and the coronary arteries could provide a new approach to the triage of acute chest pain. The inherent advantage of MDCT with cardiac state-of-the-art capabilities is the rapid investigation of the main sources of acute chest pain with a high negative predictive value. Recent studies also reports an advantage in terms of costs. With current evidence, the selection of patients with acute chest pain candidates to MDCT should remain restricted to avoid unjustified risk of ionizing radiation.     

急性主动脉综合征高风险MDCT特征评估及研究进展

急性主动脉综合征(AAS)包括主动脉夹层、壁内血肿、穿透性主动脉溃疡、创伤性主动脉撕裂及不稳定的胸主动脉瘤,是一组病情进展迅速,具有较高病死率的病变。采用多层螺旋CT可对AAS高风险影像特征进行动态定量评估。综述各类病变的病理机制及典型CT表现,从病灶位置、大小、累及范围、有无并发症及随访中的变化等角度介绍AAS高风险影像特征,分析其中哪些征象可为临床选择治疗方案提供依据。     

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。     

CT of acute abdominal aortic disorders

Aortic aneurysm rupture, aortic dissection, PAU, acute aortic occlusion, traumatic aortic injury, and aortic fistula represent acute abdominal aortic conditions. Because of its speed and proximity to the emergency department, helical CT is the imaging test of choice for these conditions. MR imaging also plays an important role in the imaging of aortic dissection and PAU, particularly when the patient is unable to receive intravenous contrast material. In this era of MDCT, conventional angiography is used as a secondary diagnostic tool to clarify equivocal findings on cross-sectional imaging. Ultrasound is helpful when CT is not readily available and the patient is unable or too unstable to undergo MR imaging.     

Clinical application of single shot GRE-EPI as non-enhanced MRA (EPI-MRA) for aortic aneurysm and dissection

We investigated the usefulness of single shot gradient echo type echo planar imaging (GRE-EPI) as magnetic resonance angiography (MRA) for the diagnosis of aortic aneurysm and dissection. This technique can detect blood flow signals in several tenths of a milliseconds without the need for contrast medium, breath-holding, or electrocardiographic (ECG) gating. By scanning approximately 20 frames in the coronal plane, three-dimensional (3D) imaging can be achieved by maximum intensity projection (MIP) at different angles. Three radiologists evaluated the ability of this single shot GRE-EPI as non-enhanced MRA (EPI-MRA) to diagnose aortic aneurysm and dissection. The examined lesions consisted of three cases of thoracic aortic aneurysm, seven of abdominal aortic aneurysm and eight of aortic dissection with a total of 15 involved aorta. In all patients with aortic aneurysm, EPI enabled detection and diagnosis of the aneurysm. However, the size of the lesion and relationship with major branches were determined only in the abdominal aorta, and could not be determined precisely in thoracic lesions. Similar results were obtained for patients with aortic dissection. The technique visualized the intimal flap and enabled determination of the extent of dissection in the abdominal aorta. In the thoracic aorta, serious magnetic susceptibility artifacts caused image distortion, and as a result only the dissection could be detected and diagnosed. No entry site was detected at either the abdominal or thoracic aorta. These results suggest that EPI-MRA may have a clinical potential for screening patients with acute aortic disease who cannot undergo physical restraint for scanning.     

Intimal tears in thoracic aortic dissection: appearance on MDCT with virtual angioscopy

OBJECTIVE: The location, number, size, and configuration of intimal tears in aortic dissection have important therapeutic and prognostic implications. Planning of procedures to treat complications of aortic dissection may require precise delineation of the intimal tears. The purpose of this article is to illustrate the ability of MDCT using multiplanar image reformatting and virtual angioscopy to depict the location and appearance of intimal tears and fenestrations within dissection flaps in cases of thoracic aortic dissection. CONCLUSION: MDCT with virtual angioscopy can depict the configuration of intimal tears in cases of thoracic aortic dissection, which may facilitate therapeutic planning.     

The thoracic aorta studied by MR imaging

Thirty-three patients with a variety of disorders of the thoracic aorta (aneurysm, dissection, Marfan syndrome, coarctation/pseudocoarctation, L-transposition, and Takayasu disease) were evaluated with magnetic resonance (MR) imaging. MR imaging delineated the presence and extent of thoracic aortic aneurysms and showed the relationship of the aneurysm to arch vessels; it also demonstrated intimal flaps and individual lumina in types A and B aortic dissection. Dilation of the ascending aorta in Marfan syndrome and focal narrowing of the aorta in coarctation were well visualized. The anteroposterior and side-to-side relationships of the aorta and pulmonary artery in L-transposition were demonstrated, as were aortic wall thickening and branch vessel narrowing in Takayasu arteritis. Initial experience suggests that MR imaging may provide a noninvasive method for evaluating thoracic aortic disease. Limitations include inferior spatial resolution, occasional difficulty in imaging the entire region of interest in one section, lack of signal from calcifications, and inability to monitor critically ill patients.     

Acute aortic syndromes: Role of multi-detector row CT

Acute thoracic aortic syndromes encompass a spectrum of emergencies including aortic dissection, intramural haematoma, penetrating atherosclerotic ulcer and aneurysm rupture. All these life-threatening conditions require prompt diagnosis and appropriate management. To date multi-detector row Computed Tomography represents a valuable diagnostic tool especially in the emergency setting. This paper focus on the use of multi-detector row Computed Tomography in the evaluation of acute thoracic aortic syndromes and illustrates the key imaging findings related to each disease.     

Catheter-induced aortic dissection after invasive coronary angiography: evaluation with MDCT

OBJECTIVE: The purpose of this study was to describe the MDCT findings of retrograde aortic extension of catheter-induced coronary artery dissection and the use of MDCT in follow-up of this complication. CONCLUSION: Coronary artery dissection with aortic extension can be a fatal although infrequent complication. The coronary artery entry point is usually stented in the catheterization laboratory. Thereafter, CT is the imaging modality of choice for immediate confirmation of the presence of residual iatrogenic aortic dissection and evaluation of its extent and later noninvasive follow-up.     

Diagnosis of blunt traumatic aortic injury 2007: still a nemesis

In recent years, the use of multidetector computed tomography (MDCT) for the diagnosis of acute thoracic injury in blunt trauma has expanded. MDCT has shown high accuracy for the diagnosis or exclusion of injury to the aorta and its primary branches, decreasing the need for thoracic angiography and allowing earlier treatment of this often rapidly fatal lesion. With increasing use of MDCT, more subtle injuries and variants of vascular anatomy are being recognized that create pitfalls in the diagnosis. Of perhaps more concern is the recognition that aortic injury can occur with little or no associated mediastinal hematoma, the principle chest radiographic finding indicating a need for further imaging. The importance of recognizing unusual sites of aortic injury, congenital variants of mediastinal anatomy, the precise extent of injury, and the anatomic pathology present as key factors in deciding among treatment options is emphasized.     

Endovascular treatment of late in-stent-graft dissection after thoracic endovascular aneurysm repair

Complications after endovascular repair of thoracic aortic pathologies may be devastating. We report the case of endovascular treatment of late in–stent-graft dissection after thoracic endovascular aneurysm repair (TEVAR). A 25-year-old man was admitted to our hospital 2 years after endovascular treatment of posttraumatic aortic pseudoaneurysm using stent-graft implantation with an acute sudden onset of ischemia in both legs with absent femoral pulses, numbness, and renal functions deterioration. Multidetector computed tomography (MDCT) angiography showed an intimal flap in the distal part of the stent-graft with critical stenosis of the residual lumen. The patient was successfully treated with stent-graft implantation by way of percutaneous approach while under local anesthesia. The risk of this late complication after TEVAR should be considered during follow-up, especially in young patients with increased physical activity. Endovascular treatment can be the method of choice for these patients.     

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.     

Intimomedial rupture: a new CT finding to distinguish true from false lumen in aortic dissection

OBJECTIVE: The purpose of our study is to describe a new imaging finding observed on contrast-enhanced MDCT of discontinuity in the intimomedial flap seen with aortic dissection that may identify the level of intimomedial entrance tear and distinguish true from false lumen. CONCLUSION: Direct visualization of an intimomedial rupture on MDCT is a valuable cross-sectional imaging sign indicating direction of the intimomedial entrance tear from true to false lumen in cases of aortic dissection. The presence of this finding enables reliable distinction of the true lumen, where the tear is broad-based and erupts into the false lumen, which receives the evaginating tear. Improved scanning techniques through MDCT may have enabled recognition of this relatively infrequent, yet highly specific, finding.     

Congenital thoracic vascular anomalies: evaluation with state-of-the-art MR imaging and MDCT

Congenital thoracic vascular anomalies include embryologic developmental disorders of the thoracic aorta, aortic arch branch arteries, pulmonary arteries, thoracic systemic veins, and pulmonary veins. Diagnostic evaluation of these anomalies in pediatric patients has evolved with innovations in diagnostic imaging technology. State-of-the-art magnetic resonance (MR) imaging, MR angiography multidetector-row computed tomographic (MDCT) angiography, and advanced postprocessing visualization techniques offer accurate and reliable high-resolution two-dimensional and three-dimensional noninvasive anatomic displays for interpretation and clinical management of congenital thoracic vascular anomalies. This article reviews vascular MR imaging, MR angiography, MDCT angiography, and advanced visualization techniques and applications for the assessment of congenital thoracic vascular anomalies, emphasizing clinical embryology and the characteristic imaging findings.     

Dissection of retroesophageal aortic diverticulum and descending aorta in a patient with right aortic arch: Magnetic resonance demonstration

An acute aortic dissection involved the retroesophageal aortic diverticulum (RAD) and descending thoracic aorta in a patient with right aortic arch. The RAD, which was separated into false and true lumens by an intimal flap—the classic diagnositc sign of aortic dissection—was overlooked on transesophageal echocardiography and computed tomography but was clearly depicted on magnetic resonance imaging (MRI). It was found that MRI can delineate the anatomy of a congenital arch anomaly complicated by great vessels disease.     

MDCT in diagnosing acute aortic syndromes: reviewing common and less common CT findings

Nontraumatic acute thoracic aortic syndromes (AAS) describe a spectrum of life-threatening aortic pathologies with significant implications on diagnosis, therapy and management. In this context, multidetector computed tomography (MDCT) is the gold standard due to its intrinsic diagnostic value; its performance approaches 100% sensitivity and specificity, and it is accepted as a first-line modality for suspected acute aortic disease. MDCT allows early recognition and characterisation of acute aortic syndromes as well as the presence of any associated complications - findings that are essential for optimising treatment and improving clinical outcomes. Although classic CT findings have long been known, other unusual signs are continually reported in the medical literature. We reviewed the classic and less common CT findings, correlating them with pathophysiology, timing and management options, to achieve a definite and timely diagnostic and therapeutic definition.     

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.     

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.