磁共振仿真内镜在胆总管梗阻性病变中的应用

目的：评价MR仿真内镜（MRVE）对胆总管梗阻性病变的诊断作用。方法：将61例行3D TSE MRCP检查的胆总管梗阻病例的原始图像资料传送至工作站，利用专用的仿真内镜软件进行仿真内镜，观察不同病变的仿真内镜表现。结果：所有61例均得到较好的仿真内镜图像，32例结石及7例壶腹癌基础上合并结石、壶腹癌11例、十二指肠乳头炎6例、胰头癌6例、胰腺炎4例均得到清楚的显示，同时有12例泥沙样结石MIP图像未见显示而仿真内镜上得到清楚的显示，但有1例胆道乳头状癌的诊断需结合平扫图像；MRVE的空间分辨率低、无法真正显示病变的色彩改变及无法显示粘膜的细微改变为MRVE的应用局限性。结论：MRVE能直观地显示扩张胆总管内表现及病变情况，MRVE结合MRCP可提高胆总管梗阻性病变的诊断准确性。     

多层螺旋CT仿真内镜在主动脉夹层破口显示中的应用

目的 探讨多层螺旋CT仿真内镜（CTVE）在主动脉夹层破口显示中的临床应用价值。资料与方法 31例主动脉夹层患者行多层螺旋CT血管造影（MSCTA）,利用螺旋CT扫描的容积数据行仿真内镜成像,并与表面遮盖显示（SSD）、容积显示（VR）、多平面重建法（MPR）进行比较。结果 27例CTVE清楚地显示了主动脉夹层的真假腔及内膜片,4例由于伪影干扰图像质量欠佳;21例直观、清晰地显示了腔内破口的位置、大小、形态及其与周围主动脉分支血管开口的关系,分支血管受累情况。结论 多层螺旋CT仿真内镜为主动脉夹层破口的显示提供了一种全新的视觉影像,CTVE结合轴位及SSD、VR、MPR图像,能为临床术前评估及手术方案的制定提供更全面、更有价值的信息。     

电子束CT血管造影及三维重建在主动脉病变诊断中的临床应用

目的建立电子束ＣＴ血管造影（ＥＢＣＴ－Ａｎｇｉｏｇｒａｐｈｙ）常规扫描及三维重建方法，探讨其临床应用价值。材料与方法回顾分析了自１９９５年７月至１９９６年１２月经ＥＢＣＴ诊断的各种主动脉病变共１８９例，男１５２例，女３７例，其中６８例与手术结果作了对照。胸主动脉扫描采用单层增强扫描方法（ＳＳＭ），心电门控采像；腹主动脉扫描采用连续容积扫描方法（ＣＶＳ），无心电门控。三维重建方法采用表面阴影显示法（ＳＳＤ）、多层面或曲面重建法（ＭＰＲ／ＣＰＲ）及最大密度投影法（ＭＩＰ）。结果１８９例主动脉病变包括各型夹层动脉瘤９７例，真性动脉瘤２６例，假性动脉瘤８例，马凡综合征３９例，大动脉炎５例，各种先天性主动脉发育异常１４例。６８例与手术对照，ＥＢＣＴ诊断符合率为９７％。结论ＥＢＣＴ血管造影图像时间分辨率高，消除了呼吸及运动伪影，可以明确诊断各种主动脉病变；三维重建图像利于整体直观地显示病变，帮助明确诊断并指导手术；在主动脉病变的诊断方面，可望取代有创的常规血管造影。     

螺旋CT仿真血管内镜的临床应用

目的 :探讨螺旋CT仿真血管内镜 (VIE)成像方法及其临床应用价值。方法 :对 5 6例临床怀疑血管病变的患者进行螺旋CT增强扫描。容积扫描所得原始数据在同机工作站重建横断面图像 ,使用内镜导航软件进行仿真血管内镜(VIE)成像 ,并采用多平面重组 (MPR)、表面遮盖显示 (SSD)、最大密度投影 (MIP)等后处理技术显示并观察靶血管。结果 :VIE能显示主动脉夹层内膜片、真假腔 ,可显示或推测破口位置是否累及重要分支 ;能直观的显示假性动脉瘤破口大小及位置 ;能清晰显示时主动脉炎时不规则的血管内壁和狭窄 ;可显示术后血管支架位置及有无支架外渗漏 ;显示血管壁钙化情况 ;判断上腔静脉狭窄程度 ;观察动静脉瘘之间的异常血管连接。结论 :螺旋CT仿真血管内镜成像技术能获得血管管腔内表面的仿真内镜图像 ,可直观、立体地观察血管病变 ,有利于显示血管全貌 ,结合其它三维重组方法 ,可为临床提供更多的诊断信息 ,但敏感性和特异性有待提高。     

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。     

MRI对主动脉瘤的诊断价值(附49例分析)

目的　探讨MRI对主动脉真性动脉瘤、主动脉夹层及假性动脉瘤的诊断价值。方法　 49例主动脉瘤 ,其中真性动脉瘤2 0例 ,主动脉夹层 2 6例 ,假性动脉瘤 3例。全部病例均采用MRISE常规序列 ,9例采用FFE序列电影成像。结果　本组病例均直观显示病变的部位、范围、形态 ,可直接测量主动脉瘤瘤体大小。 2 6例主动脉夹层均显示特有的双腔征 ,18例显示内膜片 ,7例显示内膜撕裂口。 9例患者 (真性动脉瘤 1例 ,主动脉夹层 8例 )共 2 0支分支血管受累。结论　MRI能清晰显示主动脉瘤和瘤体内结构 ,是诊断主动脉病变的最佳影像学方法之一     

螺旋CT上似夹层动脉瘤的主动脉运动伪影

螺旋CT血管成像作为一种无创性血管成像技术已常用于主动脉夹层动脉瘤的诊断,但升主动脉的运动伪影除了损害影像质量外,还极似内膜片或假腔,文献上已有将其误诊为夹层动脉瘤的报道。作者对171例曾行主动脉增强螺旋CT扫描者作了回顾性分析。目的是了解此种伪影的发生率、幅度和范围,以及不同的采集方式和重建算法对它的影响。其中87例采用360°线状内插法重建,84例采用180°线     

螺旋CT在主动脉夹层动脉瘤诊断中的应用

目的：探讨螺旋CT在夹层主动脉瘤诊断中的作用。方法：对13例夹层动脉瘤患者分别行CT平扫和增强扫描后行血管重建，对比发现。结果：行增强扫描可清晰显示主动脉双腔．行血管重建可更直观地了解病变范围。结论：螺旋CT增强扫描在动脉早期扫描后行多维重建是早期、准确发现夹层动脉瘤的重要检查方法。     

多层螺旋CT血管成像技术诊断主动脉夹层的临床价值

目的:评价多层螺旋CT血管成像对主动脉夹层的临床诊断价值。方法:对29例主动脉夹层患者行多层螺旋CT平扫和增强扫描,将获得的容积数据进行表面覆盖法(SSD)、实时3D(RT-3D)、多平面重组(MPR)及曲面重组(CPR)等多种方式重组。16例经手术证实,8例经造影证实,其中2例术后进行了复查。结果:SSD能直观地显示主动脉夹层的全貌,病变与分支血管的关系,但显示管腔内的情况欠佳;RT-3D图像优于其它方法的重组图像,可清楚显示主动脉壁的钙化、测量各径线参数以及多角度动态观察病变,但重组时间较长。MPR能保留有助于定性诊断的密度CT征象,多方位地显示附壁血栓、真假腔,并能显示主动脉旁血肿等合并症,但缺乏病变与周围解剖结构的立体观。CPR可连续地显示主动脉夹层的范围,弥补MPR的不足。结论:多层螺旋CT血管造影可直观地显示主动脉夹层的特异性征象,综合应用多层螺旋CT的各种重组技术,为临床提供了一种安全可靠的诊断手段。     

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.     

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.     

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.     

Magnetic resonance imaging of aortic aneurysm

Magnetic resonance (MR) imaging in 16 patients with aortic aneurysm used a field of 5,000 Gauss and spin echo multisection imaging with two echos. Results were compared retrospectively with those of echotomography, computed tomography and angiography. Surgical exploration allowed correlation with histopathology in 13 patients. The external diameter of aneurysm and of its residual lumen and length of aneurysm were in each case evaluated precisely by MR. In patients with abdominal aneurysm, MR images identified the limits of the aneurysm in relation to renal and iliac arteries. In aneurysms of thoracic aorta, synchronization of signal with an ECG and longitudinal imaging provided data on relations of aneurysm with supraaortic trunks. In 2 patients with extensive, partially thrombosed thoracic and abdominal aorta aneurysm, MR imaging could not eliminate a diagnosis of aortic dissection with thrombosed false lumen. Finally, aortic wall calcifications were never apparent on MR images.     

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.     

Automatic vessel wall contour detection and quantification of wall thickness in in-vivo MR images of the human aorta

PURPOSE: To develop an automated technique to trace the contours of the lumen and outer boundary of the aortic wall, and measure aortic wall thickness in axial MR images. MATERIALS AND METHODS: The algorithm uses prior knowledge of vessel wall morphology. A geometrical model (ellipse) is deformed, translated and rotated to obtain a rough approximation of the contours. Model-matching is based on image gradient measurements. To enhance edges, the images were preprocessed using gray-level stretching. Refinement is performed by means of dynamic programming. Wall thickness is computed by measuring the distance between inner and outer contour of the aortic wall. RESULTS: The algorithm has been tested on high-resolution axial MR images from 28 human subjects of the descending thoracic aorta. The results demonstrate: High correspondence between automatic and manual area measurements: lumen (r = 0.99), outer (r = 0.96), and wall thickness (r = 0.85). CONCLUSION: Though further optimization is required, our algorithm is a powerful tool to automatically draw the boundaries of the aortic wall and measure aortic wall thickness in aortic wall devoid of major lesions. J. Magn. Reson. Imaging 2006. (c) 2006 Wiley-Liss, Inc.     

3-dimensional magnetic resonance angiography in apnea with the rapid infusion of a paramagnetic contrast medium in studying the thoracic aorta

INTRODUCTION: We investigated the diagnostic accuracy of gadolinium-enhanced 3D MRA in the assessment of thoracic aortic diseases. MATERIAL AND METHODS: Thirty-eight patients with diagnosed or suspected conditions of thoracic aorta were examined with contrast-enhanced MRA. All the examinations were performed with a 1.5 T superconductive magnet acquiring breath-hold 3D fast Gradient-Echo (GE) sequences (TR = 5.9 ms; TE = 1.2 ms; FA = 45 degrees; FOV = 48 cm; thickness = 2-2.5 mm; locs = 30-32; TA = 22-24 s; MA = 512) on the coronal plane. The contrast agent was injected bolus after a bolus-test to evaluate circulation time. RESULTS: Three-dimensional gadolinium-enhanced MRA permitted to correctly diagnose aneurysm in 18 patients, dissection in 13 patients and coarctation in 3 patients. In the former the size and extent of the aneurysmal lumen and its relationship to aortic side branches was demonstrated. As for dissections we evaluated the following parameters: 1) type; 2) presence of intimal flap; 3) thrombosis of the false lumen; 4) dilatation of the aorta; 5) assessment of great vessel origins. MRA data were correlated with those of biplane transesophageal esophageal echocardiography, conventional MRI and spiral CT. In the three patients with aortic coarctation the site of coarctation was correctly identified, the degree of aortic narrowing evaluated and the collateral vessels demonstrated. CONCLUSIONS: In our opinion contrast-enhanced three-dimensional MR angiography should be the screening technique of choice in the evaluation of thoracic aorta thanks to its low invasiveness, short acquisition time, large field of view and morphologic resolution. ECG gating is not needed. Limitations are found in the study of wall and periaortic region which are better evaluated with conventional MR imaging.     

Follow-up of aortic dissection: Contribution of MR angiography for evaluation of the abdominal aorta and its branches

Spin-echo MR is an established method to evaluate thoracic aortic dissections, but is not well suited to study the abdominal aorta. In this study we evaluated whether MR angiography could provide a complete examination of the abdominal aorta. In 28 patients (40 MR studies) with suspected (n=6) or known (n=34) aortic dissection, MR studies were performed. Thoracic aorta was evaluated with spinecho and gradient-recalled-echo MR imaging. Axial two-dimensional time-of-flight MR angiography with thin overlapping slices was used to study the abdominal aorta. Intermediate and high signal intensity on MR angiography was interpreted as patent flow, and low signal was interpreted as thrombus. The presence of an intima flap and the re-entry site could be depicted in all MR studies. Thrombus in the false channel was seen in 8 studies. The origin of the abdominal visceral branches and their relation to the false-true channel could be depicted, except in 4 of 80 renal arteries studied. Extension of the dissection into the coeliac trunk was seen in 2 and in the superior mesenteric artery in 10 studies. Dilatation of the suprarenal abdominal aorta was seen in 20 studies, and of the infrarenal aorta in 9 studies. MR angiography provides valuable information about the abdominal aorta and its branches in patients with aortic dissection. This makes MR imaging appealing as the preferred imaging modality for the diagnosis and follow-up of aortic dissection.     

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.     

MR virtual angioscopy of thoracic aortic atherosclerosis in homozygous familial hypercholesterolemia

PURPOSE: The thoracic aorta is an important site of atherosclerotic disease in patients with homozygous familial hypercholesterolemia (HFH). Thoracic aortic atherosclerosis in patients with HFH was assessed with contrast-enhanced MR angiograms using exoscopic and endoscopic virtual angioscopy reconstructions and maximum intensity projections (MIPs). METHOD: Contrast-enhanced MR angiograms of the thoracic aorta of 15 patients with HFH and 8 normal volunteers were obtained. Perspective surface reconstructions of the MR angiograms including virtual angioscopy views were evaluated by three radiologists blinded to the diagnosis. RESULTS: Thoracic wall irregularity was depicted on 8 of 15 (53%) patient scans and only 1 of 8 (13%) normal subject scans using surface reconstructions. Wall irregularity scores of patients with HFH were significantly increased compared with controls (2.0 +/- 0.9 vs. 1.0 +/- 0.6; p = 0.008). There was excellent interobserver agreement (weighted kappa = 0.82 +/- 0.12). Virtual endoscopy views added diagnostic confidence compared with exoscopic surface renderings alone. MIP reconstructions were unable to depict wall irregularity. CONCLUSION: MR angiography with virtual angioscopy of the thoracic aorta depicts nonstenotic wall irregularity of thoracic aortic atherosclerosis in patients with HFH. This may be important for assessing disease progression and response to treatment and may be generalizable to routine (non-HFH) atherosclerosis.