CT diagnosis of acute aortic dissection; clinical importance of acute aortic dissection with non-opacified false lumen

Sixteen (47.5%) of 35 patients with acute aortic dissection showed a non-opacified crescent in the aorta on an initial contrast CT. Seven of these 16 patients underwent cineangiography soon after the initial CT, and in all 7 patients, neither an intimal tear nor an intimal flap was obtained. All but one of above 16 patients were followed by CT. Mean duration of follow-up was 9.6 months. In 10 of 15 patients with non-opacified false lumen, the false lumen remained non-opacified until the last examination. Moreover, in 6 of these 10 patients, the false lumen shrunk, and in the other 3, it disappeared completely on follow-up CT. On the other hand, in remaining 5 of these 15 patients who were initially diagnosed to have non-opacified false lumen, the false lumen became opacified and enlarged in size on follow-up CT performed in the first 14 weeks. Moreover, in 4 of these 5 patients, the false lumen became opacified in the only first 6 weeks. No matter how intensive care should be paid at least for the first 6 weeks, it seems that patients with aortic dissection which have non-opacified false lumen had good prognosis in comparison to patients with ordinary aortic dissections which have opacified false lumen. We believe aortic dissection with non-opacified false lumen may consist of two type of aortic dissection, one has no intimal tear, the other has some intimal tears and a thrombosed false lumen. In conclusion, CT is the most useful modality in diagnosing acute aortic dissection. The reasons are the incidence of acute aortic dissection with non-opacified false lumen was high, patients with non-opacified false lumen had good prognosis, and it was difficult to diagnose aortic dissection with non-opacified false lumen by conventional cineangiography and/or DSA.     

MR evaluation of chronic aortic dissection

Thirty patients with suspected or known chronic aortic dissection were imaged with magnetic resonance (MR), CT, and angiography. Five of these patients had previously undergone surgical repair of the ascending aorta for a type A dissection. Magnetic resonance demonstrated an intimal flap and a double lumen in 25 cases. In four cases with a thrombosed false lumen, proved angiographically, an intimal flap and double channel were not seen. In two of four aortic dissections with a thrombosed false lumen, CT made the diagnosis by showing displaced intimal calcifications not visualized on MR. In one case the aortic dissection was made on CT and angiography but was not supported by MR which showed an aortic aneurysm, subsequently confirmed at surgery. Magnetic resonance, CT, and aortography differentiated between type A (nine patients) or B (20 patients) dissection in all cases and demonstrated extension into the abdominal aorta. Extension into the iliac arteries was seen on MR in three patients but missed in nine patients. Magnetic resonance differentiated the true and false lumen in all but one case. Thrombosis of the false channel was identified in four cases by a decrease in signal intensity on the second echo image. Cardiac gating and longitudinal contiguous sections seemed to be more suitable for appreciation of the relationships with arch vessels. Transverse contiguous slices allowed determination of the origin of celiac, mesenteric, and renal arteries from either the true or the false lumen. This study confirms that MR is an accurate and noninvasive method for the evaluation and follow-up of chronic aortic dissection, obviating the need for iodinated contrast media.     

Imaging appearances and management of isolated spontaneous dissection of the superior mesenteric artery

OBJECTIVE: The objective of our study was to report the clinical and imaging features of isolated dissection of the superior mesenteric artery (SMA) and describe our imaging classification of this disease entity. SUBJECTS AND METHODS: We retrospectively analyzed clinical presentation, imaging appearances and outcome of the 12 patients who were diagnosed as having spontaneous dissection of the SMA from 1991 to 2005 in our institution or its affiliated two hospitals. There were 11 males and 1 female with a mean age of 50 years (range, 43-61 years). The diagnosis of isolated dissection was established with CT within 24h of the onset. RESULTS: We categorized SMA dissection into the following four types based on imaging appearances: type I, patent false lumen with both entry and re-entry (four patients), type II, 'cul-de-sac' shaped false lumen without re-entry (one patient), type III, thrombosed false lumen with ulcer like projection (ULP), which is defined as a localized blood-filled pouch protruding from the true lumen into the thrombosed false lumen (five patients) and type IV, completely thrombosed false lumen without ULP (two patients). One patient with type II underwent urgent surgery because of small bowel ischemia. One patient with type III underwent urgent embolotherapy for the treatment of rupture of a branch of the SMA. The remaining 10 patients were initially managed conservatively. In one of the conservatively treated patient, ULP had progressively dilated, and it was treated with stent placement and coil packing 22 months after the onset. The remaining nine patients were conservatively managed without any event during the follow-up period of 7-72 months. CONCLUSION: Most of the patients with isolated SMA dissection can initially be managed conservatively if there are no clinical and imaging signs indicating ruptured SMA branches or bowel ischemia.     

64层螺旋CT血管成像在主动脉夹层诊断中的临床价值

目的:探讨64层螺旋CT血管成像(CTA)在主动脉夹层(AD)诊断及术前评价中的应用价值。方法:58例连续性AD患者行64层螺旋CTA,对所有数据进行MPR、MIP、VR等重建分析。结果:CTA结果显示依据DeBakey分类法,Ⅰ型夹层14例,Ⅱ型2例,Ⅲ型42例。所有患者均存在明确的撕裂内膜片及真假腔,动脉期真腔平均CT值较假腔高,差异有统计学意义(P=0.000<0.05)。所有患者均明确显示了初始破口的位置,55例显示了一个或多个再破口,3例Ⅲ型患者未显示再破口。39例Ⅲ型患者初始破口位于主动脉弓降部或降胸主动脉近端,其近端瘤颈长度、宽度分别为0.4～10.8cm(平均3.5cm)、2.2～3.6cm(平均2.8cm),瘤体最大径为3.2～9.2cm(平均5.4cm)。图像准确显示了所有患者主动脉重要分支受累以及假腔内血栓形成情况。结论:64层螺旋CT血管成像具有无创、快速、准确性高等优点,是主动脉夹层诊断及术前评价的可靠影像学检查方法之一。     

MR imaging of the aorta after surgery for aortic dissection

MR imaging is known to be an effective technique for the noninvasive diagnosis of thoracic aortic disease, but it has not been used to monitor the appearance of the aorta or the fate of the false lumen after surgery for aortic dissection. This study describes our initial experience with postsurgical MR imaging of aortic dissection (nine type A and two type B) to evaluate prognostically important features, including the status of residual false lumen. The most notable findings were (1) aneurysmal dilatation beyond the interposed graft (11/11 cases), (2) residual intimal flap (10/11 cases) with at least partial patency of the false lumen (10/10 cases), and (3) origin of a visceral vessel from the false lumen in persistently dissected abdominal aorta (6/9 cases). Evaluation of residual false lumen by double-spin-echo-intensity and phase-display techniques showed evidence of slow blood flow with variable amounts of thrombus in eight of 10 cases. Differentiation between signal within the false lumen due to slow flow and signal due to thrombus was facilitated by phase display. MR imaging can be used for noninvasive monitoring of the aorta after surgical repair of aortic dissection. Since the false lumen usually remains patent after surgical repair, such follow-up of its status seems necessary for identifying potential complications of the original dissection and/or the therapy.     

Dissecting aneurysm of thoracic aorta: reappraisal of radiologic diagnosis.

In a series of 24 cases of acute dissecting aneurysm of the aorta (not including Marfan's disease) the diagnosis was usually suspected on the basis of the clinical picture and plain chest roentgenograms. The most consistent clinical sign was severe pain. Absent pulses and a neurological deficit were each noted in only five patients. In many cases there was no correlation between the clinical picture and the type or the extent of the dissection. Widening of the aortic arch and obliteration of the aortic knob with displacement of the trachea to the right are the most common signs in plain chest roentgenograms. A barium swallow examination in these cases reveals an elongated compression and displacement of the esophagus by the aortic arch. Calcification in the area of the aortic arch is the exception rather than the rule in dissecting aneurysms. Angiography is essential for the definitive diagnosis of dissecting aneurysms. The diagnosis is based on the demonstration of two channels, either by the presence of a linear radiolucency separating the two lumens, or by differences in flow that present as delayed opacification or delayed washout. If only the true lumen is opacified, widening of the outer extraluminal border of the aorta or narrowing of the lumen indicates the presence of a dissection. Abnormal catheter recoil and position were helpful in only two cases, and are not informative when the false lumen is catheterized. Failure to visualize main aortic branches was not always due to involvement by the dissection. It can also be caused by reduced flow due to severe proximal compression of the main lumen. The exact location of the intimal tears is usually not demonstrated unless additional injections are made in the area assumed to contain the tear. If only the false lumen is opacified in the ascending aorta, this can be recognized by the demonstration of a blind end, by failure to visualize the sinuses of Valsalva, from flattening of the medial border of the opacified channel, and from delayed washout in the blind end.     

Thoracic aortic dissections: magnetic resonance imaging

Six patients with documented dissections of the thoracic aorta (two Type A, four Type B) were examined by magnetic resonance (MR) imaging using a 0.6-Tesla superconductive magnet. Cardiac gating was applied in five cases. Correlation was made with CT and angiography. MR imaging demonstrated the dissection in all six cases and accurately differentiated Type A from Type B dissections. Coronal and sagittal MR sections were advantageous in establishing the relationship of the three arch vessels to the dissection. In addition, cardiac-gated MR was useful in demonstrating mural thrombus and in distinguishing the true from the false lumen based on differences in signal intensity resulting from different flow rates. In five cases, the information obtained by MR was equal to or surpassed that obtained by CT. In the one case of a completely thrombosed dissection, the CT scan was more helpful. MR should become an important imaging modality in the evaluation of aortic dissections.     

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.     

Thrombosis of the false lumen in acute aortic dissection. CT diagnosis

Three cases are reported of acute aortic dissection with complete thrombosis of the false channel, which is a very uncommon event in De Bakey's I and II type aortic dissections. The 3 patients entered hospital because of severe thoracic pain without any ECG sign of myocardial infarction. Emergency CT showed evidence of pericardial effusion suggesting hemopericardium, enlargement of the ascending aorta and a peripheral semilunar filling defect which caused a slight deformation of the true channel. On precontrast scans, only one case showed inward displacement of peripheral intimal calcifications and high-density aortic wall. No typical signs of aortic dissection were reported, except in the first patient--where a double contrast filled lumen, separated by an intimal flap was seen. CT findings are individually discussed. It is emphasized that in all patients more than one CT sign was present at a time. The correct evaluation of these signs together with the clinical data could lead to the right diagnosis of aortic dissection in spite of the lack of a filled false channel.     

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.     

Aortic dissection: magnetic resonance imaging

Fifteen patients with suspected or known aortic dissection were imaged with magnetic resonance (MR). Thirteen of these patients were eventually shown to have dissection. In most instances the diagnosis was established by aortography and/or computed tomography (CT) prior to the MR study. Surgical proof (6/13) and/or aortographic proof (10/13) were available in 11/13 patients with aortic dissection. MR demonstrated the intimal flap and determined whether the dissection was type A or type B. In addition, MR: differentiated between the true and false lumens; determined the origins of the celiac, superior mesenteric, and renal arteries from the true or false lumen in the cases where the dissection extended into the abdominal aorta (8/12); allowed post-surgical surveillance of the dissection; and identified aortoannular ectasia in the three patients who had Marfan syndrome. In addition to the 13 cases with dissection, there were two cases in whom the diagnosis of dissection was excluded by MR. Our early experience suggests that MR can serve as the initial imaging test in clinically suspected cases of aortic dissection and that the information provided by MR is sufficient to manage many cases. Additionally, MR obviates the use of iodinated contrast media.     

CT follow-up of medically treated type-B aortic dissection: a case report

The fate of the false lument of a type-B aortic dissection was studied using computed tomography (CT) in a 64-year-old woman with hypertension. The CT follow-up showed the disappearance of the false lumen in the thoracic aorta, shrinkage and thrombosis of the false channel in the proximal abdominal aorta (in these sections no major vesel arose from the false lumen), and persistence of the false lumen in the distal abdominal aorta, where the right common iliac artery arose from the false lumen. Such different findings at the various levels of dissection have not been described previously, and confirm the presumption that the fate of dissection depends on the blood flow in the false channel. Correspondence to: M. Heman     

CT virtual angioscopy in the study of thoracic aortic dissection]

PURPOSE: Virtual endoscopy is a technique in which helical-CT and MR data sets are processed by a special software creating a three-dimensional viewing of the inner surface of hollow viscera that simulates the endoscopic view. We report our 2.5-year experience with virtual intraluminal endoscopy (VIE) in the study of the thoracic aorta in patients with aortic dissection and in patients with normal aorta. MATERIAL AND METHODS: From December 1997 to June 2000, CT angiography (CTA) data sets of the thoracic aorta obtained in a series of 43 patients were retrospectively evaluated. Our series included 23 patients with clinical or radiological suspicion of aortic dissection and 20 patients in whom the study of the thoracic aorta was carried out as a necessary completion of an abdominal aortic disease. CTA data sets were processed with a dedicated software (Navigator); the view point and view direction could be set arbitrarily in the vessel, obtaining an intraluminal endoscopic view of the inner surface of the vessel. Multiple views were obtained and visualised consecutively through a cine-loop technique. The entire thoracic aorta was studied. RESULTS: VIE enabled correct visualisation of the intimal flap in all cases of aortic dissection (=23) and of its origin at the level of the ascending aorta in 16 cases (Stanford A) and in the descending aorta in the remaining 7 patients (Stanford B). In the control group (=20) no signs of intimal flap were identified with the VIE. In all patients with aortic dissection false and true lumen were entirely visualised. VIE allowed the understanding of the relation between false lumen and supraaortic vessels that originated from the true lumen in all cases and were found to be dissected in 6 patients. In 16 cases the dissection included thoracic and abdominal aorta. In some cases the endoscopic view was altered by artifacts related to the selected threshold levels and represented by pierced surface and floating shape artifacts. A correlation with axial and multiplanar (MPR) images allowed the correct interpretation of such artifacts. CONCLUSIONS: According to our experience, virtual endoscopy represents a useful tool in the evaluation of the dissection of the thoracic aorta, allowing a better definition of anatomical details. A correlation with axial images and multiplanar views remains compulsory for a better understanding of VIE findings, which is nevertheless significantly influenced by the operator's experience.     

The spontaneous regression of a dissection of the descending aorta

The outcome of an aortic dissection is either endothelialisation of the false lumen forming a so-called double aorta, or thrombosis of the sack leading to fibrosis. Healing of an aortic dissection, particularly if thrombosis and organisation have obliterated the dissected segment, is rare and there are only a few case reports on this finding. We report on a case where spontaneous resolution of the false lumen of Type B aortic dissection was demonstrated by serial contrast enhanced computed tomography after antihypertensive medical treatment.     

Coronary artery aneurysm and type-A aortic dissection demonstrated by retrospectively ECG-gated multislice spiral CT

The case of a 40-year-old male patient with a coronary aneurysm of the proximal left descending artery (LAD) combined with circumferential type-A dissection of the ascending aorta is reported. Computed tomography angiography of the coronary arteries was performed using multislice spiral computed tomography (MSCT) with retrospective ECG gating. Anatomical relations of the LAD aneurysm as well as the origin of the left coronary artery from the false lumen of the dissection were well depicted for planning of the surgical intervention using this new noninvasive imaging modality.     

Stanford B型主动脉夹层腔内修复术后早期死亡患者术前多层螺旋CT特征分析

目的探讨术前多层螺旋CT(MSCT)对Stanford B型主动脉夹层血管腔内修复术后早期死亡的预测价值。方法回顾性分析2014年1月至2018年12月采用腔内修复术治疗的158例急性期和亚急性期Stanford B型主动脉夹层患者临床随访资料和术前MSCT图像。测量和记录破口位置、破口大小、降主动脉最大直径、气管分叉平面主动脉直径、气管分叉平面假腔面积占该平面主动脉管腔总面积百分比、重要分支血管受累情况、假腔状态、腹主动脉是否受累等CT参数。分析术前CT各参数与患者术后30 d死亡的关系。结果腔内修复术紧急干预88例,非紧急干预70例,术后30 d死亡率为9.5%(15/158)。术后30 d死亡单因素分析显示,紧急干预患者术后30 d死亡率显著高于非紧急干预患者[13.6%(12/88)对4.3%(3/70),χ2=3.967,P=0.046];术后30 d死亡组患者气管分叉平面假腔面积占该平面主动脉管腔总面积≥50%患者[93.3%(14/15)对0.7%(1/143),χ2=135.581,P<0.001]和重要分支血管受累患者[66.7%(10/15)对32.9%(47/143),χ2=6.725,P=0.010]显著高于术后30 d生存组患者;两组患者破口位置、破口大小、降主动脉最大直径、气管分叉平面主动脉直径、假腔状态、腹主动脉是否受累比较,差异无统计学意义(P>0.05)。Logistic回归多因素分析显示,紧急干预(OR=1.31,95%CI=1.08~3.53,P=0.026)和气管分叉平面假腔面积占该平面主动脉管腔总面积≥50%(OR=9.53,95%CI=3.69~12.47,P<0.001)是Stanford B型主动脉夹层腔内修复术后30 d死亡的独立危险因素。结论术前MSCT对预测Stanford B型主动脉夹层腔内修复术后患者早期死亡具有重要价值,紧急干预和气管分叉平面假腔面积占主动脉管腔总面积≥50%是术后30 d死亡的独立危险因素。     

Diagnosis of acute thoracic aortic dissection using combined echocardiography and computed tomography.

Acute dissection of the thoracic aorta is a life-threatening emergency requiring a diagnosis which is rapid, accurate and safe, and which will distinguish between dissections involving the ascending and descending aorta. In the absence of any general agreement on the best method of making this diagnosis we studied the use of combined echocardiography and contrast-enhanced computed tomography (CT) to diagnose acute aortic dissection. Over a 3 year period 23 patients were investigated in this way. Aortic dissection was demonstrated in 18 cases, involving the ascending aorta in 15, and the descending aorta alone in three. The diagnosis of aortic dissection was confirmed in 13 patients at surgery, in one at aortography and in one at autopsy. Three patients died without surgery or autopsy being performed to confirm the diagnosis and the subsequently which accounted for their symptoms. This combined approach has proved a valuable and safe means of investigating aortic dissection.     

Spiral CT angiography of aortic dissection

Spiral CT angiography (CTA) is one of the newest imaging techniques used for the evaluation of aortic dissection. Current spiral CT scanners with high-performance tubes and subsecond scanning allow increased regions of coverage. Large volumes of data are rapidly acquired through the aorta during maximum contrast enhancement. Multiplanar reformat (MPR), curved planar reformat (CPR), and 3-D rendering techniques including shaded surface display (SSD) and maximum intensity projection (MIP) are then applied to the data to generate CT angiographic images of the aorta. Emergent spiral CTA may be performed in patients with suspected aortic dissection who are hemodynamically stable. Postprocessing is performed immediately following data acquisition and can provide additional information for aortic dissection diagnosis and clinical management. The technique, applications, and limitations of spiral CTA for the evaluation of aortic dissection will be discussed relative to the role of other imaging modalities.     

64层螺旋CT对主动脉夹层的应用价值

目的:探讨64层螺旋CT诊断主动脉夹层的临床价值。方法:39例拟诊为主动脉病变的患者作为本组研究对象,对所有患者行CT平扫及增强扫描。CT平扫图像上观察内膜钙化的移位、主动脉直径扩大、心包和/或纵隔积血、胸腔积液/血。并对A型和B型主动脉夹层的平扫征象进行统计学比较。CT增强图像上观察低密度的内膜瓣、破口(入口和再入口)、真假腔及主要动脉分支受累情况。结果:21例主动脉夹层中,CT平扫观察到钙化的内膜瓣移位9例(42.9%),主动脉直径增宽8例(38.1%),心包和/或纵隔积血8例(38.1%),胸腔积液/血5例(19.0%)。CT增强扫描对主动脉夹层内膜瓣的显示率达100%(21/21),对真、假腔的显示率为100%(21/21),对破口的显示率为85.7%(18/21)。8例(38.1%)弓上血管受累,5例(19.0%)内脏血管受累。结论:64层螺旋CT对主动脉夹层有较高的诊断价值,能较好的显示夹层的真假腔、内膜瓣及破口,并且可以显示主要动脉受累情况,为外科的手术治疗提供重要信息。     

Imaging of aortic dissection: a retrospective study of 27 patients]

Aortic dissection can be a life threatening condition which requires an early diagnosis. As initial signs and symptoms may be nonspecific and confusing, reliable imaging techniques are requested for immediate and accurate diagnosis. This retrospective study of 27 patients with proven aortic dissection assesses the relative value of angiography, CT, and MR imaging. Contribution of these imaging modalities is discussed and illustrated. Aortic dissection was correctly identified by angiography and CT respectively in 100% and 83% of the cases. MRI was diagnostic in all six examined cases. Both angiography and CT proved to be reliable imaging modalities; in addition, they can be easily performed in the critically ill patient. We consider MRI useful in the evaluation of suspected dissection in stable patients and follow-up of medical or surgical therapy.