肝内门静脉和肝静脉的解剖与变异(三维动态增强磁共振血管成像分析)

目的用三维动态增强磁共振血管成像（３ｄｉｍｅｎｔｉｏｎａｌｄｙｎａｍｉｃｃｏｎｔｒａｓｔｅｎｈａｎｃｅｄＭＲＡ,３ＤＤＣＥＭＲＡ）前瞻性地观测肝内门静脉（简称门脉）和肝静脉的解剖和变异。方法共进行１４２例门脉和肝静脉３ＤＤＣＥＭＲＡ检查。对肝内门脉和肝静脉的解剖和变异做分型,计算每一型所占总调查人数的比例,并计算右后下肝静脉的显示率。结果１４２次成像中,８例（５．６％）显示门脉呈三分叉状,７例（４．９％）门脉先分出右后支,然后上行分为左支和右前支,４例（２．８％）门脉右前支源于左支,未发现有门脉左支水平段或右支缺如,余下１２３例（８６．６％）显示正常门脉分支。绝大多数情况下（９５．１％）肝中、肝左静脉合并,而三大支肝静脉单独汇入下腔静脉仅占４．９％。右后下肝静脉的显示率为７．７％。结论肝内门脉变异并不少见。肝中和肝左静脉多合并后汇入下腔静脉。部分病人有较为粗大的右后下肝静脉。３ＤＤＣＥＭＲＡ能方便而清楚地显示上述血管的解剖和变异     

门静脉磁共振血管成像技术和临床应用

本文阐述了门静脉磁共振血管成像（ＭＡＲ）的几种主要技术，各自的优缺点和它在临床上的使用价值。     

肝内门静脉和肝静脉的解剖与变异

目的 用三维动态增强磁共振血管成像（３－ｄｉｍｅｎｔｉｏｎａｌ ｄｙｎａｍｉｃ ｃｏｎｔｒａｓｔ ｅｎｈａｎｃｅｄ ＭＲＡ,３Ｄ ＤＣＥ ＭＲＡ）前瞻性地观测肝内门静脉（简称门脉）和肝静脉的解剖和变异。方法 共进行１４２例门脉和肝静脉３ＤＤＣＥ ＭＲＡ检查。对肝内门脉和肝静脉的解剖和变异做分型,计算每一型所占总调查人数的比例,并计算右后下肝静脉的显示率。结果 １４２次成像中,８例（５．６％）显示     

门静脉系统的MR血管成像

本文简述了门静脉系统的两种基本ＭＲ血管成像方法（时间飞越法和相位相对法）,并概括介绍了门静脉ＭＲ血管成像的临床应用和局限性。     

经动脉磁共振门静脉成像的实验研究

目的在犬模型上评价不同的造影动脉、对比剂剂量及血管扩张剂应用与否对经动脉磁共振门静脉成像(MR imaging during arterial portography,MRAP)图像的影响,总结出MRAP的最佳技术参数,为下一步的临床应用做准备.方法健康成犬16条,通过随机化分组表法分配到造影动脉、对比剂剂量及有无血管扩张剂3个研究组中.每条犬行腹腔麻醉后,在X线监视下经股动脉穿刺插管至肠系膜上动脉或脾动脉,行MRAP检查.计算增强前后肝实质信号强度的相对增强值,比较各因素不同水平间的相对增强值之间差异有无统计学意义.分析时间-增强曲线,总结MRAP的最佳技术参数.结果在16条犬上均获得了较为理想的MRAP图像.肠系膜上动脉组肝实质相对增强峰值为29.3%～106.0%,脾动脉组为29.5%～105.0%,肠系膜上动脉组达到肝实质相对增强峰值的时间为24～27 s,而脾动脉组为24～28 s,两组间差异无显著性意义(F=0.03,P>0.05).0.025 mmol/kg组的相对增强峰值为29.3%～30.9%,与0.050 mmol/kg组的95.5%～98.8%,0.100 mmol/kg组的102.0%～106.0%和0.200 mmol/kg组的104.0%～105.0%比较,除后两组之间差异无显著性意义(P>0.05)外,其他各组间差异均有非常显著性意义(P<0.01).有血管扩张剂组达到肝实质相对增强峰值的时间为21～27 s,早于无血管扩张剂组的24～28 s(P<0.05),但两组肝实质相对增强峰值差异无显著性意义(P>0.05).结论 (1)MRAP是一项新的安全可行的肝脏影像学检查技术,20 ml 钆喷替酸葡甲胺(Gd-DTPA)混合液(0.050～0.100 mmol/kg)以1 ml/s注射速度经造影动脉注入,在注射开始后21～28 s即可获得实验动物肝实质的最佳门静脉增强MRAP图像.(2)肠系膜上动脉或脾动脉作为造影动脉,在MRAP影像和时间-增强曲线上无差别.(3)0.050～0.100 mmol/kg的Gd-DTPA剂量完全可以引起肝实质足够的增强(95.5%～106.0%).(4)血管扩张剂的应用并不影响MRAP图像肝实质增强峰值达到的时间和峰值的大小.     

磁共振门静脉成像技术探讨

目的：通过改变翻转角试图优选出一种最佳翻转角的快速准确的磁共振门静脉血流成像方法，并尽可能消除呼吸运动的影响。材料与方法：采用Ｓｉｇｎａ１．５Ｔ磁共振仪随机对５８例上腹部ＭＲ检查者进行门脉血流成像，其中快速梯度回波间断闭气扫描１８例，采用２０°、３０°和４５°三种不同翻转角。梯度回波加呼吸门控法共扫描４０例，均采用３０°翻转角。所有图像均经三维处理，并采用双盲法评价门脉显示效果。结果：间断闭气ＭＲ门脉成像选择３０°翻转角，图像信噪比、对比度及血管亮度比２０°或４５°为优，此技术受呼吸影响较大，而呼吸门控技术的运用可大大消除呼吸运动的影响。结论：选择３０°翻转角并加用呼吸门控的门脉血流成像技术是较为有效的门脉成像方法之一，它能较好地显示门脉主干及分支，对诊断和手术治疗方案的制定有一定的帮助     

动态增强磁共振门静脉成像及临床应用

目的　探讨动态增强磁共振门静脉成像 (DCE -MRP)技术要点及临床应用优势。方法　 3 1例进行腹部常规扫描时疑有门静脉异常的患者接受了动态增强磁共振门静脉成像扫描 ,其中正常 8例 ,异常 2 3例。使用高压注射器将Gd -DTPA造影剂经手背静脉注入血管 ,应用透视触发造影技术确定扫描延迟时间 ,所有图像分别进行数字减影、最大信号强度投影 (MIP)重建。结果　3 1例患者均获得了清晰、立体的门静脉图像。 8例无肝脏疾患者 ,DCE -MRP均能完整显示门静脉主干及肝内 5级以上的分支。 2 3例异常 ,其中肝硬化门静脉高压 13例 ,均显示门静脉扩张迂曲 ,2例显示门静脉主干闭塞 ;肝癌 9例 ,其中门静脉主干和 (或 )其主分支闭塞 3例 ;肝右叶巨大血管瘤 1例。结论　动态增强磁共振门静脉成像为新的磁共振血管成像技术 ,成像效果与传统的血管造影相仿 ,具有明显的临床应用优势     

《三维增强磁共振血管成像》出版

第二军医大学长海医院陆建平教授主编的《三维增强磁共振血管成像》一书，已由上海科学技术出版社于2005年3月正式出版（书号为ISBN7-5323-7613-3）。该书为国内第1本系统阐述增强磁共振全身血管成像（CE-MRA）的专著，全书共分总论、颅内血管、颈部血管、肺部动脉、主动脉、下肢动脉、门静脉系统、腔静脉系统等8个章节。全书以4500余例次临床资料为背景，     

《三维增强磁共振血管成像》出版

第二军医大学长海医院陆建平教授主编的《三维增强磁共振血管成像》一书，已由上海科学技术出版社于2005年3月正式出版（书号为ISBN7-5323-7613．3）。该书为国内第1本系统阐述增强磁共振全身血管成像（CE-MRA）的专著，全书共分总论、颅内血管、颈部血管、肺部动脉、主动脉、下肢动脉、门静脉系统、腔静脉系统等8个章节。全书以4500余例次临床资料为背景，     

间接门静脉数字减影造影对肝癌血供的研究

目的 研究肝癌有无门脉供血。材料与方法 １１６例经临床及影像学资料证实的肝癌,采用经腹腔动脉或肠系膜上动脉行间接门静脉ＤＳＡ方法,观察肝癌有无门脉供血。结果 １１６例肝癌中１０３例仅有肝动脉而无门静脉供血,只有１３例有肝动脉和门静脉双重供血（占１１．２％）。门脉供血表现为环状或少量染色。９７例原发性肝癌和１９例转移性肝癌有门脉供血者分别有１０例（占１０．３％）和３例（占１５．８％）,两者无显著性差     

Streamlined flow in the portal vein: demonstration with MR angiography

PURPOSE: To demonstrate whether streamlining of the portal vein flow exists by evaluating the relative distribution of blood flowing from the superior mesenteric vein (SMV) and splenic vein (SV) into the portal venous system. MATERIALS AND METHODS: Fifteen healthy adult volunteers underwent MR angiography of the main portal vein (PV) and portal vein branches after an overnight fast. Transverse two dimension time-of-flight gradient echo sequences were obtained three times, in suspended expiration and inspiration, respectively, as follows: 1) No presaturation slab, 2) presaturation slab across the SMV, 3) presaturation slab across the SV. Signal intensity (SI) measurements were obtained for all acquisitions. using regions of interest traced manually within the PV and portal branches. RESULTS: After presaturation of the SMV and SV during expiration, the overall SI average in the PV decreased by 47% +/- 8 (mean +/- SD) and 17% +/- 9, respectively. Right to left portal branch SI ratio and right-anterior to left-posterior SI ratio in the PV were 0.91 +/- 0.09 and 1.02 +/- 0.08 at baseline, respectively. They decreased significantly (P < 0.05) to 0.87 +/- 0.09 and to 0.95 +/- 0.09 after saturation of the SMV, and increased significantly to 0.95 +/- 0.08 and to 1.07 +/- 0.10 after saturation of the SV. CONCLUSION: MR angiography with selective saturation of the SMV and SV provided reproducible assessment of the respective contributions of the SMV and SV to portal flow, and allows demonstration that streamlining of splanchnic blood occurs in the portal vein of normal subjects.     

Noncontrast SSFP pulmonary vein magnetic resonance angiography: impact of off-resonance and flow

Purpose

To investigate pulmonary vein (PV) off‐resonance and blood flow as causes of signal void artifacts in noncontrast steady‐state‐free‐precession (SSFP) PV magnetic resonance angiography (MRA).

Materials and Methods

PV blood off‐resonance was measured on 11 healthy adult subjects and 10 atrial fibrillation (AF) patients. Noncontrast PV MRA was performed using a 3D slab‐selective SSFP sequence at 1.5T on seven healthy subjects with signal profile shifts of 0–125 Hz. The time‐resolved blood flow velocity of the PVs was measured on five healthy subjects. The impact of flow was studied on six healthy subjects, on whom SSFP PV MRA was acquired twice with the electrocardiogram (ECG) trigger delay corresponding to low and high flow, respectively.

Results

The PV off‐resonances were 97 ± 27 Hz, 65 ± 20 Hz, 74 ± 25 Hz, and 52 ± 17 Hz for right inferior, left inferior, right superior, and left superior PVs, respectively, on healthy subjects, and 74 ± 20 Hz, 38 ± 9 Hz, 51 ± 20 Hz, and 28 ± 11 Hz on AF patients (P<0.01 for all). The off‐resonance caused severe signal voids in the PVs. Signal acquired during mid‐diastole with high PV flow caused additional signal voids in the left atrium, which was reduced by setting the ECG trigger delay to late‐diastole.

Conclusion

PV off‐resonance and flow causes signal void artifacts in noncontrast 3D slab‐selective SSFP PV MRA. J. Magn. Reson. Imaging 2010;32:1255–1261. © 2010 Wiley‐Liss, Inc.     

First-line investigation of acute intracerebral hemorrhage using dynamic magnetic resonance angiography

Purpose: To report the initial experience of magnetic resonance (MR) digital subtraction angiography (MR-DSA) in the dynamic assessment of the cerebral circulation in acute non-traumatic intracerebral hemorrhage (ICH).

Material and Methods: Twelve patients with acute ICH were investigated within 6 days of the ictus using a dynamic contrast-enhanced 2-D MR angiogram that produces subtracted images with a temporal resolution of 1-2 frame/s. The MR-DSA examinations were assessed for evidence of an intracranial vascular abnormality and were compared with (i) the routine MR sequences, (ii) non-dynamic time-of-flight MR angiography, and (iii) catheter angiogram performed during the same admission.

Results: All 12 MR-DSA examinations were considered to be technically satisfactory. MR-DSA detected an intracranial vascular abnormality in 7 patients (3 arteriovenous malformations, 2 aneurysms, 1 dural arteriovenous fistula, and 1 venous thrombosis). All abnormalities were confirmed by catheter angiography with the exception of one patient with venous sinus thrombosis found on MR imaging that did not undergo catheter angiography. All four arteriovenous shunts were detected by MR-DSA by virtue of early venous filling.

Conclusion: MR-DSA can be performed satisfactorily in the setting of acute ICH and provides an alternative method to catheter angiography for identifying shunting vascular abnormalities such as arteriovenous malformations and fistulae, as well as large aneurysms and venous occlusions. MR-DSA is a contrast-medium-based technique that does not suffer from the T1 shortening effects of acute hemorrhage that can obscure abnormalities on conventional flow-based non-dynamic techniques.     

Intra-arterial magnetic resonance angiography of the iliac arteries: clinical experience using two different protocols

Purpose: To assess the feasibility of intra-arterial magnetic resonance angiography (iaMRA) with two different protocols.

Material and Methods: Twenty patients were prospectively examined after digital subtraction angiography. Contrast-enhanced iaMRA was performed using a 1.5T magnetic resonance imaging (MRI) system. Contrast agent (gadodiamide) was injected through a conventional angiography catheter placed in the abdominal aorta. The patients were randomized into two groups each comprising 10 patients. Group 1 was examined with a FLASH-3D (fast low-angle shot) sequence, allowing the center of the k-space to be acquired 0.5 s after initiation of the measurement. Group 2 was examined with the identical sequence, but the center of the k-space was acquired after 8.7 s. The increase in the intravascular signal intensity was determined and the diagnostic value of the angiograms was independently scored by 4 investigators using a 5-point scale.

Results: Nineteen of 20 MRAs were scored as diagnostic; only 1 was scored as non-diagnostic by 2 observers. The diagnostic value of the angiograms of group 2 was judged superior to that of group 1 owing to a more homogeneous intravascular contrast distribution.

Conclusion: Intra-arterial MRA is feasible. The diagnostic value of angiograms using a flash sequence with center of the k-space acquisition after 8.7 s ranged from good to excellent. This sequence is appropriate for iaMRA of iliac arteries to support MR guided intervention.     

Hypogenetic lung syndrome: Functional and anatomic evaluation with magnetic resonance imaging and magnetic resonance angiography

A case of hypogenetic lung syndrome is described in which anatomic and functional information was obtained with use of ECG-triggered turbo (fast) spin-echo, cine, velocity-encoded cine, and contrast-enhanced magnetic resonance angiography (MRA) sequences. To the best of our knowledge, a complete functional and anatomic study of hypogenetic lung syndrome with MRI has not been previously reported.     

磁共振门静脉血流动力学改变与肝功能相关性

目的：通过磁共振相位对比法成像测量慢性肝病患者门静脉主干的平均血流速度及每分血流量,并将其与肝功能终末期肝病模型（MELD）评分进行相关性研究,探讨磁共振相位对比法成像在评价慢性肝病肝功能的应用价值。方法：60例慢性肝病患者行肝脏磁共振相位对比法成像（包括15例治疗前后的随访复查）,测量病例组60例及15例治疗前、后门静脉主干的平均血流速度及每分血流量,分析它们与MELD评分的相关性。结果：病例组60例门静脉主干的平均血流速度与MELD评分有显著性负相关（R=-0.40,P〈0.05）,每分血流量与MELD评分无显著性相关（R=-0.22,P〉0.05）。治疗前后15例门静脉主干的平均血流速度变化量与MELD评分变化量有显著性负相关（R=-0.69,P〈0.01）,每分血流量变化量与MELD评分变化量也有显著性负相关（R=-0.51,P〈0.05）。结论：门静脉主干的平均血流速度及每分血流量与MELD评分有较密切的相关性,对慢性肝病患者的肝功能评估及疗效观测有较高的临床应用价值。