三维增强磁共振血管造影(60例临床应用分析)

目的　探讨三维增强磁共振血管造影 ( 3DDCEMRA)技术及其临床应用价值。方法60例 3DDCEMRA包括 4 4例病变血管和 16例正常血管。选用三维快速梯度回波 ( 3DFFE)序列 ,行3DDCEMRA检查 ,主要参数为TR 9毫秒 ,TE 3毫秒 ,翻转角 3 0° ,矩阵 12 8× 2 5 6,快速注射 0 2mmol/kg钆 喷替酸葡甲胺 (Gd DTPA) ,注射速度 1 5～ 2 0ml/s ,延迟时间依据病情而定 ,其中 3 6例 (病变组 3 4例和正常组 2例 )经数字减影动脉血管造影 (IADSA)或 (和 )手术证实 ;图像质量采用优、良、差 3级评价 ,并计算出敏感性、特异性和准确性。结果　 60例 3DDCEMRA图像质量优良者 5 7例 ,占 95 %。5 0例 ( 16例正常组与经手术、IADSA证实的 3 4例病变组 ) 3DDCEMRA的敏感性、特异性和准确性分别为 94 1%、87 5 %和 92 0 % ;假阳性 ,假阴性各 2例 ,病变程度高估 3例。 3 4例各类血管和相关病变的 3DDCEMRA结果与IADSA或 (和 )手术符合率为 85 3 % ,主动脉及其主支病变则分别为 10 0 0 %和77 3 %。结论　 3DDCEMRA是一种有效、微创技术 ,评价主动脉病变可与IADSA媲美 ,对主动脉主支病变与IADSA尚有一定差距 ,通过提高扫描速度和改善重建技术 ,有望能逐步替代IADSA。     

三维动态增强磁共振血管造影在肝移植中的初步应用

目的　探讨三维动态增强磁共振血管造影 (threedimensionaldynamiccontrast -enhancedMRangiography ,3DDCEMRA)技术 ,初步评估其在肝移植术前准备中的应用价值。方法　对 8例患严重肝脏疾病 ,临床上拟行肝移植的患者 ,术前行MRI平扫及 3DDCEMRA检查 ,对所得图像进行综合评价。所有病例均行多普勒超声 (DUS)检查 ,4例成功行肝移植手术。结果　所有病例均获得了满意的血管图像 ,肝动脉可显示 2～ 3级分支 ,门静脉可显示 2～ 5级分支 ,肝静脉可显示 1～ 2级分支。其中 3例肝硬化显示胃底食道静脉曲张 ,1例多囊肝显示肝动脉、门静脉受压移位。结论　 3DDCEMRA是一种有效的、无创的技术 ,对临床医师进行肝移植病人术前血管评估有很大的帮助     

Tim技术三维动态增强磁共振血管造影的临床应用

目的:探讨Tim(total image matrix)技术行三维动态增强磁共振血管造影(3D DCE MRA)的临床应用价值。方法:采用Avanto 1.5T MR,Tim外周血管线圈,自动移床及无缝连接技术,行3D DCE-MRA检查(3D-FLASH自减影序列,TR 2~4ms,TE 1~2ms,层厚1.5~2.0mm);通过双筒高压注射器经肘正中静脉注射对比剂Gd-DTPA,浓度0.5mmol/ml,总量30ml,流量2.5ml/s;扫描延迟时间195例采用Test-bolus法,40例采用Care-bolus法;后处理对靶血管作最大信号强度投影(MIP)重建。共235例行3D DCE MRA,包括颈动脉63例,胸、腹主动脉34例,肺动脉21例,肾动脉25例,肝动脉24例,双下肢动脉56例,全身动脉12例。其中45例经数字减影动脉血管造影(IADSA)或(和)手术证实;图像质量采用优、良、差三级评价。结果:235例3D DCE MRA图像质量优良者225例,占95.4%。45例经手术I、ADSA证实的3D DCE MRA的敏感性、特异性和准确性分别为93.5%、78.6%和88.9%;假阳性3例,假阴性2例;病变程度低估、高估各1例。3D DCEMRA结果与IADSA或(和)手术符合率为88.9%,主动脉及其主要分支病变符合率为92.9%,较细分支病变符合率为87.1%。结论:Tim线圈、自动移床及无缝连接技术3D DCE MRA是一种全新、无创或微创性血管显像技术,正确掌握延迟时间是3D DCE MRA成功的关键,评价主动脉及其主要分支病变有较高的可靠性,但对动脉较细分支的分辨率尚有待于进一步提高。     

三维显示增强磁共振血管造影

目的:探讨应用两种公式计算三维对比血管造影(3D CEMRA)的延时时间对改善头部和体部血管影像质量的价值。方法:86例分为两组:头颈组65例使用3D CEMRA检查头颈时间计算公式,即延迟时间=对比剂达峰时间-采集中心时间-1/2对比剂团注时间。体部组21例使用3D CEMRA经典计算公式,即延迟时间=对比剂达峰时间-采集中心时间 1/2对比剂团注时间。结果:86病例3D CEMRA图像中各级血管显示的总优良率达到96%。结论:头部和体部采用不同的公式计算扫描延迟时间可得到良好的3D CEMRA影像。     

三维增强磁共振血管造影技术和临床应用

随着磁共振成像技术的进展,磁共振血管造影(MRA)技术已从研究阶段转变成为临床应用,越来越多的医生已经应用MRA 来筛查血管病变.三维增强磁共振血管造影(3D CE-MRA)是目前用于体部血管检查的最先进MR技术之一,而且其本身的技术也在不断改进.本文根据我院的应用经验并结合文献对此技术做一介绍.     

三维增强磁共振肺动脉血管造影诊断肺动脉血栓栓塞

目的 探讨三维增强ＭＲ肺动脉血管造影（３Ｄ ｃｏｎｔｒａｓｔ－ｅｎｈａｎｃｅｄ ＭＲ ｐｕｌｍｏｎａｒｙ ａｎｇｉｏｇｒａｐｈｙ,３Ｄ ＣＥＭＲＰＡ）诊断肺动脉血栓栓塞的价值。方法 肺动脉栓塞患者１２例,共行１７次３Ｄ ＣＥＭＲＰＡ,其中４例５次于３Ｄ ＣＥＭＲＰＡ当天进行了选择性肺动脉ＤＳＡ。静脉注射钆喷替酸葡甲胺０．２ｍｍｏｌ／ｋｇ后,屏气获得２４层肺血管连续冠状面像,以最大强度投影法（ＭＩＰ     

三维动态增强磁共振腹部血管造影

目的：探讨三维动态增强磁共振腹部血管造影（3D-CE-MRA）成像技术和临床应用毒义。材料和方法：回顾性的分析了30例腹部3D-CE-MRA的成像技术和MRI表现。结果：全部病例显示良好。可以从不同的角度和位置上观察血管的整体形态。结论：三维动态增强磁共振腹部血管造影是腹部血管病变诊断的准确，快速，无创和首选的影像学检查方法，具有较高的临床应用价值。     

重视三维增强磁共振血管造影在诊断肺栓塞中的价值

肺动脉血栓栓塞 (ｐｕｌｍｏｎａｒｙｅｍｂｏｌｉｓｍ ,ＰＥ)是一种严重危害人民健康的疾病 ,由于ＰＥ的临床表现多样 ,医生对其认识不足 ,经常导致误、漏诊 ,患者的病死率较高 (通常认为可达2 0 %～ 30 % )。尽管本病在我国尚不属于常见病和多发病 ,但也并非少见。如果ＰＥ能得到及时的诊断和正确的治疗 ,患者的死亡率可降低至 8%。所以 ,人们一直在寻求快速、准确的诊断方法。影像学检查在ＰＥ的诊断上占有重要地位 ,无论急诊还是平常门诊 ,临床上通常首先行胸部Ｘ线平片检查 ,由于ＰＥＸ线征象多在 12ｈ以后才出现 ,而且其敏感性和特异…     

三维增强磁共振肺动脉血管造影诊断急性肺栓塞的实验研究

目的 探讨钆喷替酸葡甲胺（Ｇｄ－ＤＴＰＡ）三维增强共振肺动脉血管造影成像（３ＤＣＥＭＲＰＡ）在急性肺栓塞（ｐｕｌｍｏｎａｒｙ ｅｍｂｏｌｉｓｍ,ＰＥ）中的诊断价值。方法 对１７只自体血栓引发的犬急性肺栓塞模型,利用３Ｄ快速扰相梯度回波序列（ＦＳＰＧＲ）行３Ｄ ＣＥＭＲＰＡ检查和Ｘ线肺动脉血管造影（Ｘ－ｒａｙ ｐｕｌｍｏｎａｒｙ ａｎｇｉｏｇｒａｐｈｙ,ＸＰＡ）检查,并与病理解剖对照。     

三维动态增强磁共振血管造影诊断肺隔离症的价值

目的：评估三维动态增强磁共振血管造影（3D DCE MRA）对显示肺隔离症异常血管的价值。方法：5例肺隔离症患者作了胸部正侧芯片，CT和MRI检查后，均行胸部和上腹部3D DCE MRA检查，并进行最大信号强度投影（MIP）和多平面重建（MPR）。结果：5例肺隔离症均为肺叶内型，位于左肺下叶。胸片表现隔离的肺组织均位于左下叶，呈圆形或椭圆形，密度较均匀的团块影。CT示降主动脉后方软组织密度肿块，2例肿块周围伴有肺气肿。增强CT显示2例供血动脉。平扫MRI示隔离肺组织在T1WI和T2WI较正常肺组织信号高的软组织块影，并显示3例供血动脉，但未能显示其作貌，行程，分支及引流静脉。另2例异常供血动脉未能显示，而3D工DCE MRA均显示了其异常供血动脉和引流静脉，并清楚显示了其分支和行程，与术中所见完全一致。结论：3D DCE MRA较能较好地显示肺隔离症的异常供血动脉和引流静脉，有利于确诊此病和制订手术治疗方案。     

Vessel enhancement filtering in three-dimensional MR angiography

For a variety of reasons, small vessels have low signal intensity in magnetic resonance angiography. When the vessel signal Intensity is lower than the signal intensity of background tissues, these vessels tend not to be visible on maximum-intensity-projection images. The authors developed a nonlinear second-difference spatial filtering technique that enhances the details of small vessels while suppressing both noise and uniform background tissue. Two similar nonlinear second-difference filters are presented and compared with the linear Laplacian second-difference filter. To evaluate the performance of these filters, they were applied to intracranial three-dimensional time-of-night MR angiographic data and the results compared with the vessel enhancement obtained with a simple second-difference Laplacian filter and with magnetization transfer contrast (MTC) techniques. The comparisons demonstrated that nonlinear filtering and MTC techniques result in similar improvement in small-vessel visibility and apparent continuity. A quantitative comparison demonstrated that the improvement in the contrast-to-noise ratio is much greater with the nonlinear filters than the Laplacian filter.     

Vessel enhancement filtering in three-dimensional MR angiography

For a variety of reasons, small vessels have low signal Intensity in magnetic resonance angiography. When the vessel signal intensity is lower than the signal intensity of background tissues, these vessels tend not to be visible on maximum-intensity-projection images. The authors developed a nonlinear second-difference spatial filtering technique that enhances the details of small vessels while suppressing both noise and uniform background tissue. Two similar nonlinear second-difference filters are presented and compared with the linear Laplacian second-difference filter. To evaluate the performance of these filters, they were applied to intracranial three-dimensional time-of-flight MR angiographic data and the results compared with the vessel enhancement obtained with a simple second-difference Laplacian filter and with magnetization transfer contrast (MTC) techniques. The comparisons demonstrated that nonlinear filtering and MTC techniques result in similar Improvement in small-vessel visibility and apparent continuity. A quantitative comparison demonstrated that the improvement in the contrast-to-noise ratio is much greater with the nonlinear filters than the Laplacian filter.     

Three-phase gadolinium infusion in moving-table three-dimensional MR angiography

Moving-table three-dimensional (3D) MR angiography provides images of long segments of arteries. However, deep veins are sometimes superimposed on the arteries below the knee, and peripheral arteries sometimes fail to be visualized. We have developed an imaging method with three-phase gadolinium infusion according to the mean blood flow velocity of the leg. Nineteen patients with various blood flow velocities were studied. Eighteen of the patients had no venous superimposition. All 19 patients showed good configuration of peripheral arteries with 16-18 ml of gadolinium. This method is useful for better visualization of peripheral arteries without venous superimposition.     

Rapid three-dimensional angiography with undersampled MR imaging

Techniques for subtraction angiography with magnetic resonance imaging have been extended from two to three dimensions, and a novel method that reduces the expected data acquisition time by at least an order of magnitude is presented. Electrocardiogram-gated three-dimensional (3D) images are acquired by Fourier transform technique, and flow contrast is obtained by subtracting pairs of images acquired at different points in the cardiac cycle. The vascular tree is shown in 3D perspective by means of a surface detection and a 3D display program. Isotropic 3D angiography requires determining the disposition of the blood vessels in a matrix of cubical voxels. Using orthodox Fourier transform technique, for an image matrix with 256 voxels to the edge, a data acquisition with 256 X 256 = 65 K phase-encodings would be needed. If gated, this would require approximately 1 day. In this study we abbreviate the data acquisition by doing only 1/64 of the usual set of phase-encoding gradient pulses. Spatial resolution is undiminished, but aliasing or "wraparound" results in each of the two phase-encoded coordinates of the 3D image. This aliasing is rectified in a two stage process. First, 64 copies of the undersampled 3D arteriogram are juxtaposed in a two-dimensional grid pattern. This assembles many copies of the complete vascular tree. Because they occupy only a small fraction of ambient volume, these copies are unlikely to overlap or collide with one another. Second, a single copy of the vascular tree is isolated by a surface detection program that takes advantage of the fact that the vascular tree is topologically connected. Studies of the abdominal aorta are presented.     

Partial fat-saturated contrast-enhanced three-dimensional MR angiography compared with non-fat-saturated and conventional fat-saturated MR angiography

Abdominal three-dimensional magnetic resonance angiography was performed in 35 patients in the equilibrium phase without fat saturation, with conventional fat saturation, and with fast partial fat saturation. Qualitative and quantitative evaluation demonstrated significantly better vessel visualization with both fat-saturated techniques. The partial fat-saturated technique provided water-specific images within a breath hold, reducing motion artifacts significantly.     

Nonlinear excitation profiles for three-dimensional inflow MR angiography

An RF excitation pulse for three-dimensional (3D) time-of-flight (TOP) MR angiography (MRA) with a nonlinear excitation profile was numerically calculated under the condition of uniform vessel signal across the excitation volume (slab), and the superiority of the optform pulse as compared with conventional RF pulses and TONE pulses was demonstrated. For this purpose we acquired MRA of the lower leg and of the carotid and vertebral arteries in a 30-year-old healthy volunteer. Although the flow velocity ranges in these two anatomic locations are different by about a factor of 10, in both cases the corresponding optform pulse provided the best signal homogeneity at the highest level.     

TRICKS扫描在糖尿病下肢血管病变诊断中的应用

目的:探讨TRICKS(时间决定对比剂动态成像法)扫描技术在诊断糖尿病下肢血管病变诊断中的应用。方法:对20例糖尿病下肢动脉病变患者行动态增强(TRICKS)扫描,原始数据传到ADW4.3工作站,利用多平面重建及最大密度投影技术对原始图像处理进行血管重现。感兴趣血管分为6个节段,依次对腘动脉、胫腓主干动脉、胫前动脉、胫后动脉、腓动脉、足背动脉狭窄程度进行评价。并利用图像原始数据对小腿肌肉作时间-信号强度分析。结果:20例患者中下肢血管各节段符合诊断要求。静脉混染率低不影响诊断。两下肢血管节段对比狭窄严重的小腿组织强化最大上升斜率较对侧为低,信号值也有差异。结论:TRICKS能清晰显示下肢各节段血管且能评价血管狭窄程度,为临床医生提供准确的诊断定位及治疗依据。TRICKS成像结合组织灌注分析能够评价下肢软组织的血供状况。     

Examination of susceptibility artifact in three-dimensional gadolinium-enhanced chest MR angiography

Signal loss that is sometimes found in the subclavian artery during chest MR angiography is thought to be caused by the susceptibility effect of highly concentrated contrast medium. In our research project, we examined the conditions under which signal loss occurs. We made vessel phantoms (artery phantom, vein phantom) that contained different concentrations of Gd-DTPA water solutions, and placed them in a 0.5 mmol/l Gd-DTPA water solution. We examined signal loss when the vein phantom was parallel to the magnetic field and when it was perpendicular to the magnetic field. We found that there was no signal loss in the artery phantom when the vein phantom was parallel to the magnetic field. In contrast, signal loss occurred in the artery phantom when the vein phantom was perpendicular to the magnetic field. The higher the concentration in the vein phantom, the closer the distance to the vessel phantom, and the longer the echo time (TE), the greater was the signal loss. Thus, the cause of signal loss in the subclavian artery was found to be the perpendicular orientation of the subclavian vein (through which the highly concentrated contrast medium flows) to the magnetic field. With the MRI devices currently in use, perpendicular orientation of the subclavian vein to the magnetic field cannot be avoided. Furthermore, the subclavian vein and subclavian artery are anatomically in close proximity to one another. These factors cause the susceptibility artifact, which is thought to result in signal loss in the subclavian artery.     

磁共振三维血流成像在小儿腹部疾病诊断中的价值

目的：探讨对比剂增强自动触发磁共振三维血流成像(3D CE MRA)技术在小儿腹部疾病诊断中的价值。方法：2001年3月～2003年6月对临床拟诊腹部实体肿瘤和腹腔大血管病变的46例患儿行常规MRI扫描和3D CEMRA检查，年龄生后1天～14岁，平均4．8岁。腹部实体肿瘤40例，腹腔大血管病变6例。全部患者检查前行肘静脉穿刺并保留静脉通道．镇静睡眠后注射2～3倍剂量非离子型对比剂。扫描采用Smart Prep Angio。对比剂智能捕捉技术。结果：本组检查成功率97．83％。40例实体肿瘤中,3D CEMRA显示肿瘤起源2例，肿瘤侵犯和包绕腹主动脉11例，下腔静脉闭塞3例，肾动静脉受侵蚀闭塞6例，肾蒂受肿瘤牵拉变细3例，腹腔动脉干、肠系膜上动静脉及睥静脉移位共12例，门静脉及其左右肝内分支受侵犯3例。腹部大血管病变6例。结论：3D CEMRA技术对巨大腹膜后肿瘤的起源定位具有诊断价值。结合多方位的断面图像不仅可以了解腹腔重要大血管被肿瘤浸润包裹和推挤移位情况，而且可对肾脏受浸润破坏情况进行术前评估，从而为临床制定恰当的治疗方案提供比较可靠的影像学依据。3D CEMRA是无创显示体腔大血管病变的有效方法。