Inflammatory abdominal aortic aneurysm: a cause of urinary obstruction and acute renal failure

Abdominal aortic aneurysms are rare causes of ureteric obstruction. We report three cases of inflammatory abdominal aortic aneurysm producing hydronephrosis. In two patients acute renal failure preceded this presentation. The diagnosis can be established by computed tomography when mural thrombus, wall calcification, and an enhancing periaortic soft-tissue mantle are present. It is important to recognize this disease preoperatively.     

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.     

MSCT在腹主动脉瘤临床诊疗中的价值

目的：评估 MSCT在腹主动脉瘤(AAA)诊断和预后评价的价值。方法前瞻性收集本院经 MSCT 检查的26例疑似AAA患者,分析 MSCT检查的准确性和特点。结果26例患者经 MSCT诊断为 AAA,其中17例真性 AAA,9例假性 AAA。真性AAA的MSCT显示腹主动脉呈梭形扩张并向左前方膨出,瘤破裂患者残余瘤腔周围可见血栓和瘤壁钙化;假性AAA的MSCT显示腹主动脉旁偏心的膨大肿块,肿块可在血管钙化边界之外。手术诊断结果为25例 AAA,MSCT 与手术病理结果的符合率为96.1%(25/26);本组患者均出现动脉壁钙化的现象,其中17例伴有附壁血栓。结论 MSCT是一种安全、有效和无创性的诊断技术,对于AAA的早期发现,病情判断和指导治疗有较高的临床应用价值。     

Unstable abdominal aortic aneurysms: a review of MDCT imaging features

Abdominal aortic aneurysms are commonly encountered during abdominal CT imaging, and size-based parameters for surgical or endovascular repair are well established. Aneurysms greater than 5 cm in diameter are recognized as representing an increased rupture risk and meriting intervention. Increasingly, additional interest has been generated in recognizing imaging features which may herald instability and portend a higher chance for potentially catastrophic rupture. This article will review and illustrate such signs, including hyperattenuation of mural thrombus, rapid expansion, low thrombus to lumen ratio, intimal calcification disruption, posterior mural draping, and saccular outpouching. Other features of complicated abdominal aneurysms including perianeurysmal inflammation, aortocaval and aortoenteric fistula formation will also be addressed. Heightened awareness of these features and their prognostic implications, as well as timely communication with the clinical service, is critical for the interpreting radiologist.     

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.     

主动脉病变螺旋CT三维成像的临床应用

目的　探讨螺旋CT在主动脉疾病诊断中的临床应用及其价值。　材料与方法　22例主动脉疾病（11例主动脉瘤、1例胸主动脉假性动脉瘤、7例主动脉夹层动脉瘤、1例大动脉炎、2例主动脉缩窄）者行螺旋CT增强检查,以表面覆盖显示(SSD)、多平面重建(MPR)、最大密度投影(MIP)、血管CT仿真内窥镜成像(CTVE)等多种方式重建。　结果　SSD均能很好显示病变的全貌,动脉瘤的大小、范围,夹层内膜片及与分支血管的关系等;MPR可较好显示附壁血栓,真假腔和内膜片;MIP可清楚显示管壁钙化和动脉瘤形态;CTVE可清晰显示内膜片、真假腔及血管的狭窄。　结论　诊断主动脉疾病综合应用螺旋CT的各种技术可基本取代X线血管造影,其为临床提供了一种可靠的诊断手段。     

The fate of infrarenal abdominal aortic aneurysms after stent grafting: influence of thrombosis at side branch ostia

PURPOSE: To evaluate the effect of postoperative thrombosis of the side branch ostia on the shrinkage of endoluminally treated abdominal aortic aneurysms with patent side branch vessels. MATERIALS AND METHODS: Thirty-three patients were followed up with serial computed tomography (CT). Special attention was paid to presence or absence of retrograde enhancement of the side branch ostia after the covering of the patent side branch vessels by the stent graft and aneurysm diameter change on postoperative CT. Preoperative CT was also reviewed to assess the number of patent side branch vessels, degree of aneurysm wall calcification, and thickness of the mural thrombus. The patients with type 2 endoleak were excluded from this evaluation. The patients were divided into 2 groups, the nonthrombosed and thrombosed groups, based on presence or absence of retrograde enhancement of the side branch ostia as depicted on all postoperative CT. RESULTS: Type 1 endoleak was not seen in all patients. Preoperative diameter of the aneurysm was 4.75 +/- 0.18 cm in the thrombosed group (n = 12) and 4.98 +/- 0.35 cm in the nonthrombosed group (n = 8). There were no significant differences in follow-up periods, preoperative diameter of the aneurysm, number of patent side branch vessels, degrees of aneurysm wall calcification, and thickness of the mural thrombus between the 2 groups. The mean diameter of the aneurysm in the nonthrombosed group did not change at 3 and 6 months then first decreased at 12 months after the stent grafting. However, in the thrombosed group, the mean diameter of the aneurysm had decreased at 3 months after stent grafting. Thereafter, the aneurysms continuously shrank. CONCLUSIONS: Postoperative thrombosis of the side branch ostia may predict favorable shrinkage of endoluminally treated aneurysms.     

A mural thrombus of an infrarenal aortic aneurysm demonstrated as photon deficiency in a radionuclide study

Radionuclide angiogram (RNA) and aortogram may underestimate external aneurysmal diameter. Photon deficient areas are not uncommon along the abdominal aortic aneurysm (AAA) on RNA. To determine whether or not photon deficient areas along the aneurysm could represent a large thrombus, we studied radionuclide aortic angiography in thirty-eight patients during a preoperative cardiac gated study. All the patients (men, ages from 60 to 78) had CT, US, and/or aortogram for comparison. The presence of a thrombus was determined by CT, US, and/or surgical findings. Twelve of 38 (32%) patients’ RNA and blood pool images showed photon deficient areas along the aneurysmal walls having a large concentric or eccentric thrombus of the AAA. A large photon deficient area could be detected along the narrowing calibre of the aorta lumen. This finding results from a large mural thrombus being interposed between the left or right bowel/mesentery activity and the activity of the aneurysms functioning patent lumen. We concluded that a photon deficient area along an inferorenal aortic aneurysm may indicate a large thrombus of either eccentric or concentric type within an AAA.     

Accessory retrograde aneurysmal aortic lumen supplying the inferior mesenteric artery

We report the case of a patient with infrarenal abdominal aortic aneurysm with mural thrombus covering the ostium of a patent inferior mesenteric artery (IMA). The IMA was supplied via flow from an accessory aneurysmal lumen within the mural thrombus that filled retrogradely from the aorta. This unusual pattern, associated with calcifications within the thrombus, raised the possibility of chronic aortic dissection.     

Computed tomographic evaluation of aortic aneurysms.

Applications of computed tomography are being extended from the brain to other body parts. This report describes CT scanning of abdominal and thoracic aortic aneurysms in 30 patients. CT shows greatest promise in abdominal aortic scanning, where reliable identification of the aorta can be achieved even in the absence of enlargement or calcification. However, current limitations prevent visualization of internal detail such as intimal plaques or mural thrombi. Technical advances are described which should have an important bearing on this.     

多层螺旋CT诊断主动脉瘤的价值探讨

目的:探讨多层螺旋CT及后处理技术诊断主动脉瘤的价值。方法:使用美国GElightspeed QX/I型多层螺旋CT(MSCT)对疑有或有主动脉疾病的21例患者行轴位容积扫描,扫描条件:120 kV、300 mA,5 mm准直,7.5 mm/sec进床速度,HQ或HS扫描模式。重建层厚2.5 mm,重建间隔1.25 mm。用MEDRAD ENVISION高压注射器,经静脉团注非离子型造影剂100 ml,注射流率为2.8-3.5 ml/s。将横断面图像传至GE advantagewindows 4.0工作站进行二维和三维重建,包括多平面重建(MPR)、最大密度投影(MIP)、表面遮盖法重建(SSD)、容积再现(VR)、CT、仿真内窥镜重建(CTVE)及电影分析成像。结果:21例中主动脉瘤6例,主动脉夹层13例,其中Ⅰ型4例,Ⅱ型1例,Ⅲ型8例,马凡氏综合征2例。13例主动脉夹层在轴位图像均可见高密度的真腔和假腔,真腔小而密度略高于假腔,真假两腔之间的低密度弧型影为撕破的内膜。MIP、CTVE重建发现6例主动脉夹层破口,附壁血栓6例,发现主动脉外壁溃疡破口2例,主动脉内膜钙化并内移>5 mm7例。结论:MSCT成像技术作为一种非创伤性的血管成像方法,具有安全、可靠的优越性。     

Hypointense boundary layer between slow flow and mural thrombus on spin-echo MR.

To evaluate the ability of spin-echo MRI to differentiate between slow flow and mural thrombus in aortic diseases, we reviewed the spin-echo MRI of 10 patients with intraaortic thrombus that had been documented by CT in 8 patients and aortography in 2 patients. Six patients had aortic aneurysms with mural thrombi, and four had aortic dissections with adherent mural thrombi within the false lumen. Five of seven gated oblique sagittal or coronal T1-weighted studies demonstrated hyperintense slow flow signal within the residual lumen. This hyperintense slow flow signal was accompanied by a parallel hypointense rim due to a boundary layer dephasing phenomenon. Eight axial T2-weighted MR studies demonstrated a hypointense zone due to fresh clot at the edge of a mural thrombus on even-echo images consistently. The hypointense boundary layer between slow flow and mural thrombus on either gated T1-weighted MRI or second-echo T2-weighted MRI not only predicted the presence of flow within the residual lumen but also clearly separated the area of slow flow from that of mural thrombus in 9 of 10 patients. Proper interpretation of spin-echo images may obviate the need for phase display imaging or gradient-echo imaging in differentiating between slow flow and mural thrombus.     

主动脉夹层动脉瘤的MR序列研究

目的评价MRI动态增强三维血管造影(3D DCE MRA)及增强后梯度回波(CE—FFE)序列对主动脉夹层的诊断价值。方法84例主动脉夹层病例均进行上述两种序列检查。结果84例病例中,3D DCE MRA及CE—FFE两种序列图像的表现为：内膜片和真假腔的显示分别为82及82例,内膜破口分别显示79、76例,主动脉分支受累分别显示85及80条,血栓形成分别显示58及60例。结论MRI是诊断主动脉夹层的最佳影像学方法之一,3D DCE MRA及CE—FFE技术能给临床提供主动脉夹层的全面信息：夹层范围、内膜破口、分支受累及血栓形成。     

多层螺旋CT血管造影在腹主动脉瘤诊断中的价值

目的:评价多层螺旋CT血管造影在腹主动脉瘤诊断中的价值。材料和方法:24例腹主动脉瘤病人行多层螺旋CT血管造影,其中17例经DSA证实,7例经手术证实,采用容积再现(VR)、最大密度投影(MIP)、表面遮盖显示(SSD)和曲面重建(CPR)对原始数据进行重建。结果:所有行CT血管造影的病人,都能清晰显示瘤体,与周围血管的关系和附壁血栓,能准确测量动脉瘤的相应数据,其中Ⅰ型5例(20.8%),ⅡA型7例(29.2%),ⅡB型2例(8.3%),ⅡC型5例(20.8%),Ⅲ型5例(20.8%)。7例腹主动脉支架置入术后复查能清晰显示支架的位置、范围和管腔通畅情况,4例手术后复查均清晰显示桥血管。结论:多层螺旋CT血管造影是一种无创、快速的检查方法,作为腹主动脉瘤的诊断已可取代DSA。     

平板旋转血管造影及三维重组在主动脉病变中的应用

目的:评价平板旋转血管造影及三维重组在主动脉病变临床应用的价值.方法:对比分析31例主动脉病变患者的CT或MR、二维血管造影、旋转血管造影及三维重组影像学资料,并对其结果对比分析.31例均为男性,年龄18～81岁,平均56.5岁.结果:行胸主动脉造影28例,发现主动脉夹层25例,动脉瘤1例,假性动脉瘤1例,主动脉弓畸形1例.行腹主动脉造影3例,发现动脉瘤2例,1例为腹主动脉动脉硬化性改变并主动脉钙化.所有主动脉夹层、真性及假性动脉瘤造影与CT或MRI对比,病变的形态、大小、位置均相符.其中有2例夹层的造影提示CT诊断破口位置错误.1例主动脉弓畸形,CT误诊为动脉瘤,而造影则可以清晰显示扩张纡曲的畸形主动脉弓.其中23例主动脉夹层和3例真性动脉瘤造影后进行支架主动脉腔内隔绝术的介入治疗,术后均行二维血管造影,支架位置准确,隔绝效果良好,没有出现并发症.结论:平板旋转血管造影及三维重组对主动脉病变的诊断和治疗有较高的临床应用价值,可以提高介入治疗的安全性和成功率.     

多层螺旋CT血管成像在腹主动脉瘤中的诊断应用

目的探讨多层螺旋CT血管成像在腹主动脉瘤（AAA）中的诊断价值。方法30例临床疑诊AAA患者均经16层螺旋CT血管成像（MSCTA）。采用最大密度投影（M1P）、多平面重组（MPR）、容积再现（VR）技术对传送至AW4.1工作站的原始数据进行重建,获得二维或三维的立体图像。结果30例疑诊AAA患者中有7例真性腹主动脉瘤,15例假性动脉瘤,8例主动脉夹层。MPR能准确显示瘤体位置、形态、范围及附壁血栓。MIP能较好地显示瘤壁及附壁血栓内的钙化。VR技术能立体精确显示腹主动脉、瘤体及周围组织结构的空间关系。结论多层螺旋CT血管成像是一种无创、快速的检查方法,为临床诊断、治疗腹主动脉瘤提供重要信息。     

The role of gadolinium-enhanced MR imaging in the preoperative evaluation of inflammatory abdominal aortic aneurysm

Inflammatory abdominal aortic aneurysm is an uncommon variant of abdominal aortic aneurysms. Thorough preoperative imaging of the extent of the aneurysm and inflammation and the associated complications are crucial in the management of this condition. We report a case of inflammatory abdominal aortic aneurysm where, after the initial contrast-enhanced CT, gadolinium-enhanced MR imaging was used to define the true extent of the inflammation and differentiate inflammation from mural thrombus at the iliac extension of the aneurysm. The imaging appearances are presented and the impact of MR imaging on further surgical management options including endovascular repair are discussed.     

64层螺旋CT血管成像对主动脉病变的诊断价值

目的 探讨64层螺旋CT血管成像技术对主动脉病变的诊断及临床应用价值.方法 32例主动脉病变患者行64层螺旋CT扫描,并对原始数据采用多平面重组(MPR)、曲面成像(CPR)、最大密度投影(MIP)、容积再现(VR)、高级血管分析(AVA)处理.32例主动脉病变均经临床、手术证实.结果 32例主动脉病变中,主动脉夹层16例、假性动脉瘤7例、真性动脉瘤4例、主动脉弓缩窄3例、主动脉离断2例.MPR对内膜破口、附壁血栓显示较佳.内膜片及初始破口显示率为81%(13/16),7例假性动脉瘤周围血栓,显示率100%(7/7);CPR简单、直观显示病变全程,显示率100%(32/32);MIP对钙化及管径精确测量颇有价值,显示率84%(27/32);VR能明确病变的范围和周围血管关系,显示率100%(32/32);AVA对测量血管管径、血管横截面积具有意义,显示率44%(14/32).结论 64层螺旋CT血管成像技术对主动脉病变的诊断具有重要意义.     

Infected aortic aneurysms: CT appearance

Three patients with infected (mycotic) aortic aneurysms were diagnosed primarily by CT. In two patients findings included the presence of a saccular aneurysm with an irregular lumen, perianeurysmal fluid, gas and/or hematoma, osteomyelitis in adjacent vertebral bodies, and disruption of intimal calcification. In one patient with sepsis there was rapid development of an aortic aneurysm. Computed tomography is of substantial benefit in the identification and characterization of infected aortic aneurysms. Certain features may strongly suggest the diagnosis without use of aortography.     

Spared flow tract within the mural thrombus of an aortic aneurysm: its pathogenesis and clinical importance

The purpose of this case report is to determine the unique pathogenesis of a "spared flow tract" through a thick mural thrombus of an aortic aneurysm mimicking the penetrating or dissecting tract of an impending or acute rupture of an abdominal aortic aneurysm (AAA) and to discuss its clinical importance. Three blood flow tracts (i.e., spared flow tracts) penetrating to aortic major branches (inferior mesenteric arteries in two and left renal artery in one) through thick mural thrombi of three aortic aneurysms were found on thin section spiral CT scans. Histopathological examination revealed that the tracts were formed by thrombi and partially covered with endothelial cells. In conclusion, spared flow tracts may be pathways continuing to the aortic major branches through thick mural thrombi of aortic aneurysms and are spared from thrombogenesis because of relatively high blood flows. Their pathogenesis is definitely different from penetrating or dissecting tracts within mural thrombi of ruptured AAAs. Spared flow tracts should not be misinterpreted as penetrating or dissecting tracts of impending or acute rupture.