三维动态增强磁共振血管成像在肝移植术前的应用

 目的探讨三维动态增强磁共振血管成像(3D DCE MRA)三期扫描技术,评价其在肝移植术前的诊断价值.方法对拟进行肝移植的183例患者进行术前3D DCE MRA成像扫描,采用Siemens Symphony 1.5T超导MRI扫描机,圆形极化相控阵体线圈,3D DCE MRA三期(动脉期、门脉期和静脉期)扫描技术,即对所得图像进行综合评价.结果全部病例均获得了满意的血管成像图像,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.183例肝移植患者,5例显示肝动脉变异,其中2例起自肠系膜上动脉,2例直接起自腹腔干,1例起自胃左动脉.单纯肝硬化门脉高压103例,其中,冠状静脉和食道胃底静脉曲张23例、脐周静脉曲张5例、肠系膜静脉曲张2例、脾门周围静脉曲张30例,门静脉玻璃样变性1例;原发性肝癌79例,5例肝动脉包埋、僵直、推移,2例肝内动-静脉瘘,门静脉右支癌栓23例,门静脉左支癌栓7例,门静脉主干癌栓3例,同时发生门静脉左右支癌栓的2例,MRA表现为门静脉呈半月形或杯口形缺损或不显影.7例肝静脉出现栓塞,5例下腔静脉受压推移,1例下腔静脉瘤栓.结论 3D DCE MRA三期扫描能很好的显示肝动脉、门静脉、肝静脉及下腔静脉系统病变,肝移植术前应用3D DCE MRA,基本达到临床要求,是术前血管评估的有效方法.     

单次屏气三维对比增强磁共振门静脉造影

目的探讨中次收气三维对比增强门静脉造影（3DCEMRP）方法并初步评价其临床应用价值。方法39例病人接受3DCEMBP检查及三维时间飞越法（2DTOF）门静脉成像，其中无肝脏疾患者8例，肝硬化18例，肝癌12例，脾静脉血栓形成1例，Gd-DTPA用量为每公斤体重0.1～0.2mmol，用团注实验剂量确定门静脉峰值通过时间及扫描延迟时间，所有图像分别经最大信号强度投影（MIP）重建，评价门静脉成像质量、开放程度、侧支血管及从静脉曲张的情况。结果门静脉内造影剂峰值通过时间为17～45秒，所有病例3DCE哑MRP成像质量明显优于2DTOF门静脉成像。8例无肝脏疾病者，CEMRP均完整显示门静脉主干及肝内4级以上的分支；18例肝硬化中有17例显示门、脾静脉扩张迂曲，其中10例显示食管胃底静脉曲张，1例门静脉主干近段闭塞，12例肝癌中，5例门静脉主干和（或）其主分支闭塞，6例显示肝内门静脉分支受压、移位；1例脾静脉血栓形成，见脾静脉闭塞及广泛的侧支血管。结论3DCEMRP为一快速、有效评价门静脉系统的检查方法。     

三维动态增强磁共振门静脉造影

目的　探讨三维动态增强磁共振门静脉造影 (3DDCE -MRP)的方法及其临床应用价值。方法　共对 35例临床上疑有肝脏疾患的病人进行了 3DDCE -MRP检查 ,用TEST -BOLUS序列测定循环时间 ,然后根据公式 :延时时间 =造影剂循环时间 -1 /4采集时间 ,推算出延时时间。从肘静脉快速推注Gd-DTPA 0 .2mmol/kg,用 3DFLASH序列 (TR/TE 4 .6ms/1 .8ms)屏气冠状位扫描获得 3组三维原始图像 ,行最大信号投影处理。观察 3DDCE -MRP对门静脉正常结构和病理状况的显示情况。结果　35例中 1 0例MRP表现为正常 ,原发性肝癌 1 4例 ,门静脉高压 8例 ,肝血管瘤 3例。 3DDCE -MRP能清晰显示门静脉系正常解剖结构 ,门静脉肝内分支能显示至 4～ 6级 ,能较满意显示门脉内瘤栓及门脉高压症患者的侧枝循环情况 ,并能直观地显示门静脉、肝静脉和下腔静脉的立体关系 ,为临床提供全面的肝脏血管结构。结论　 3DDCE -MRP能很好地显示门静脉结构 ,并能准确地评价门静脉病变     

3D CE-MRA在评价腹部静脉系统中的应用

目的探讨三维增强磁共振血管成像（3DCE—MRA）技术在腹部静脉系统中的应用价值。方法收集具有完整资料的16例病例，先行常规MRI检查，随后经静脉注射Gd—DTPA20—30mL后连续三次行3DCE—MRA采集数据，对静脉系统原始图像进行MIP重建。主要观察指标为下腔静脉、脾静脉、肝静脉、肠系膜上静脉、门静脉形态变化。结果16例患者中，门腔静脉正常者9例，3DCE—MRA清晰显示下腔静脉、肝静脉、脾静脉、肠系膜上静脉、门静脉结构；门静脉高压3例，示脾静脉增宽迂曲，门静脉主干增宽及明显侧支循环形成；2例布加氏综合征；1例下腔静脉血栓形成；1例门静脉海绵样改变。结论3DCE—MRA是一种安全、敏感性高的血管造影技术，可提高腹部静脉系统疾病的术前诊断。     

动态增强磁共振血管成像对主动脉疾病的诊断价值

目的的：评价动态增强磁共振血管成像对主动脉疾病的诊断价值及对临床治疗的指导作用。方法：82例怀疑有主动脉疾病的患者，应用动态增强磁共振血管成像技术扫描，并与手术结果和血管造影对照，分析DCEMRA的图像质量及其对血管的显示情况。结果：82例均获得满意图像。DCE、EMRA可清晰地显示主动脉疾病的位置以及血流动态情况。结论：动态增强磁共振血管成像是诊断主动脉疾病准确、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。     

3D DCE MRA在原发性肝癌诊断中的临床应用

目的：探讨单次屏气三维对比增强磁共振造影(3D DCE MRA)在原发性肝癌中的检查技术及临床应用。方法：回顾性分析23例原发性肝癌的3D DCE MRA表现。对原发性肝癌肝动脉期、门静脉期分别进行扫描和重建。结果：肝动脉期可显示肝癌供血动脉血管7例，动静脉瘘6例，肝动脉受挤压变形6例。门静脉期显示门静脉高压18例。门静脉癌栓13例，肝内门静脉受压移位3例。结论：有效地抓住对比剂在各靶血管中的有效浓度，可分别显示肝癌的血供情况、血管破坏情况、门静脉开放程度，为临床治疗提供有价值的影像参考。     

动态增强磁共振门静脉造影在门脉高压症诊断中的价值

目的:探讨动态增强磁共振门静脉造影(DCE MRP)在门脉高压症诊断中的价值。方法:对门脉高压症组23例和正常对照组15例行DCE MRP检查。观察23例门静脉高压症在DCE MRP上的表现。结果:对照组15例均清楚显示门静脉。门脉高压症表现为门静脉增粗(21例)、脾静脉迂曲扩张(23例);门静脉分支级数减少(18例);门静脉延迟显影(7例);显示侧枝循环静脉(6例);门静脉血栓形成(3例)。结论:DCE MRP是评价门静脉的一项快速无创的技术,可准确显示门静脉高压症门静脉系统的病理改变。     

动态增强磁共振血管成像技术及应用优势

目的 探讨动态增强磁共振血管成像(DCE MRA)技术要点及临床应用优势。资料与方法 对35例疑有血管性病变的患者，行DCEMRA扫描，最大信号强度投影(MIP)重建。结果35例均获得了清晰的血管图像，其中8例正常，27例异常。结论 DCE MRA为新的MRA技术，克服了常规MRA及对比增强MRA的缺点，成像效果与DSA相仿，因此具有极大的临床应用价值。     

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     

LAVA结合ASSET技术在肝门静脉成像的应用价值

目的 探讨应用LAVA结合ASSET技术进行门静脉成像的可行性.资料与方法 对60例肝病患者应用LAVA结合ASSET进行门静脉成像,并与20例门静脉CE-MRA进行对照,分析两者对肝内门静脉及其分支的显示.结果 应用LAVA结合ASSET扫描获得的门静脉成像显示全部60例的门脉主干及肝内1、2级分支、32例3级分支、4级18例和10例4级以下分支.门静脉CEMRA20例显示全部门脉主干及肝内1、2级分支、10例3级分支,7例4级分支和3例4级以下显示.两种方法显示门静脉的差异无统计学意义(P>0.05).结论 LAVA结合ASSET技术可完全替代常规的CE-MRA获得门静脉图像.     

Hepatic blood supply: comparison of optimized dual phase contrast-enhanced three-dimensional MR angiography and digital subtraction angiography

PURPOSE: To optimize and determine the value of dual-phase contrast material-enhanced three-dimensional (3D) magnetic resonance (MR) angiography for preoperative evaluation of the blood supply to the liver. MATERIALS AND METHODS: Dual phase 3D MR angiography of the hepatic arteries and portal vein was performed in 140 patients. In 80 patients, the value of fat saturation, digital image subtraction, an anticholinergic agent, and a high-caloric meal were evaluated. In the next 60 patients, MR angiographic and digital subtraction angiographic (DSA) image quality and diagnostic value were compared. RESULTS: Fat-saturated images were of significantly better quality (P < .01) than non-fat-saturated images. Digital image subtraction was useful in only 23 of 40 patients. The injection of an anticholinergic agent was superfluous, whereas administration of a high-caloric meal helped in demonstration of the superior mesenteric artery and portal vein. Classification on MR angiograms of the arterial blood supply was correct in 57 of 60 patients. All arterial and portal venous lesions were seen on MR angiograms, and MR angiograms had a significantly higher subjective image-quality ranking than did DSA images in the evaluation of the portal vein (P < .05). CONCLUSION: Fat saturation and use of a high-caloric meal improve the results of MR angiography of hepatic vessels. MR angiography was comparable to DSA for evaluation of the arterial system and was superior for demonstration of the portal vein; therefore, MR angiography could replace intraarterial DSA.     

MR portal venography: preliminary results of fast acquisition without contrast material or breath holding

RATIONALE AND OBJECTIVES: The authors performed this study to evaluate the feasibility of using the steady-state free precession (SSFP) sequence to perform magnetic resonance (MR) venography of the portal venous system without the use of contrast material or breath holding. MATERIALS AND METHODS: Eleven patients underwent MR venography with the SSFP technique. Coronal three-dimensional images were obtained with respiratory triggering. Contrast material and respiratory suspension were not used. All patients had recently undergone at least one other imaging study (conventional angiography, transhepatic portal venography, ultrasound, or contrast-enhanced computed tomography), and these findings were correlated with those from MR venography. The structures evaluated were the main portal vein, right portal vein, left portal vein, superior mesenteric vein, and splenic vein. RESULTS: MR venography with SSFP accurately depicted the status of these veins in all cases except one. In this patient, MR venography depicted portal vein thrombus but could not indicate that it was tumor thrombus. CONCLUSION: MR venography with SSFP accurately depicted the portal venous system in 10 of 11 patients without the use of respiratory suspension or contrast material.     

Detection of thrombosis in the portal venous system: comparison of contrast-enhanced MR angiography with intraarterial digital subtraction angiography

PURPOSE: To determine whether intraarterial digital subtraction angiography (DSA) can be replaced by contrast material-enhanced magnetic resonance (MR) angiography in the assessment of patency or thrombosis of the portal venous system in patients with portal hypertension. MATERIALS AND METHODS: Thirty-six patients with portal hypertension underwent contrast-enhanced MR angiography and intraarterial DSA for assessment of the portal venous system. The images were evaluated for vessel patency or thrombosis of the portal, splenic, or superior mesenteric vein. RESULTS: Of the 101 vessels evaluated, 42 were thrombosed. Overall sensitivity, specificity, and accuracy for the detection of thrombosis were 100%, 98%, and 99%, respectively, for MR angiography and 91%, 100%, and 96%, respectively, for DSA; differences between the imaging methods were not statistically significant. Only in four patients with six vessels (6%) were there discordant findings between MR angiography and DSA. CONCLUSION: Noninvasive contrast-enhanced MR angiography has the potential to replace intraarterial DSA as the standard method to assess the whole portal venous system.     

肝癌合并动-静脉分流一种DSA新分型法的临床应用

目的探讨并总结肝癌合并动-静脉分流的DSA表现和以分流速度为基础的新分型方法及其在栓塞治疗中的临床意义。方法根据分流速度将中晚期肝癌动-静脉分流分为3型,即:快速型、慢速型和中速型。对32例肝癌合并动-静脉分流患者经DSA检查进行分型,选择相应的栓塞材料进行栓塞封堵治疗。结果 32例中,快速型6例(19%),慢速型16例(50%),中速型10例(31%)。23例(72%)一次封堵成功,4例(13%)二次封堵瘘口消失,3例(9%)因分流口较大,同时伴有门静脉癌栓,未行封堵,2例(6%)因分流口较多且分散仅行部分分流口封堵及栓塞化疗。32例中20例DSA同时显示合并门静脉癌栓(与CT所示相符),超声仅检出16例;栓塞治疗后患者临床症状均有不同程度改善。结论中晚期肝癌患者栓塞术前DSA检查可准确显示动-静脉分流和癌栓情况,以分流速度快慢为依据的分型法简便、实用,在栓塞治疗中有重要的临床意义。     

Magnetic resonance angiography with three-dimensional dynamic technique after contrast media administration for the study of the portal system ]

PURPOSE: To evaluate the feasibility of a contrast enhanced MR angiography (MRA) technique, using the latest 1.5 T MR tomoscan, to obtain optimal imaging of the portal system and compare the angiographic images with those obtained by color-Doppler and DSA. MATERIAL AND METHODS: Thirty patients (9 women and 21 men: average 53 years old) underwent contrast MRA of the portal vein, after portal hypertension had been diagnosed on the basis of clinical and chemical data and by color-Doppler. We used a dynamic 3D FFE T1-weighted breath - hold sequence during the arterial and venous phase after administering. 0.2 mmol/Kg of gadolinium-DTPA were at the rate of 2 ml/s. The contrast bolus was monitored using a 2D FFE T1-weighted sequence on a coronal plane. A FFE T1-weighted sequence was performed on axial plane before and after the dynamic sequence to obtain evaluate the a hepatic parenchyma. In the post processing phase MIP (maximum intensity projection) were reconstructed. We considered the patency of the portal venous system and the presence of cavernomatous and collateral circles; portal thrombosis was classified as partial or complete and as proximal or distal. RESULTS: Good quality MR angiographic images were obtained in 28 of the 30 cases examined; in 2 patients movement artefacts compromised the image quality. We observed a concordance between MRA and Doppler ultrasound in 79 vessels out of 84 (94%). A 97.5% concordance was found between MRA and DSA (82 vessels out of 84) with a sensitivity of 100% and a specificity of 97.3%. MRA was superior to DSA and Doppler ultrasound for evaluating large collateral shunts, above all gastro-esophageal and paraumbilical shunts, and complex anatomical conditions. CONCLUSIONS: Where available, advanced MRA technology with contrast enhancement should be used as a routine modality to study the anatomy and pathology and the portal system in all patients in whom Doppler ultrasound has yielded doubtful information. MRA is well-suited to obtain good vascular imaging before surgical or interventional procedures.     

Failing hemodialysis access grafts: evaluation of complete vascular tree with 3D contrast-enhanced MR angiography with high spatial resolution: initial results in 10 patients

Ten patients with failing hemodialysis access underwent contrast material-enhanced magnetic resonance (MR) angiography within 7 days before digital subtraction angiography (DSA). MR angiography was performed at 1.5 T by using a multistation multiinjection three-dimensional technique, and contrast material was injected via intravenous cannula. In all patients, MR angiographic images displayed the complete arterial inflow tract from the subclavian artery and access proper. The complete venous outflow tract up to the superior caval vein could be evaluated in all but one patient. DSA showed hemodynamically significant stenoses in 13 segments. MR angiography depicted all 13 stenoses and two false-positive findings, resulting in sensitivity of 100% and specificity of 94%.     

MR imaging of portal vein thrombosis

MR imaging is emerging as a potential means of detecting portal venous thrombosis (PVT). Therefore, we attempted to establish specific criteria with which to diagnose PVT on conventional spin-echo images. In a retrospective review of 342 consecutive abdominal MR scans performed with a 0.5-T magnet, we identified nine patients with persistent signal in the portal vein and used the findings in these patients to establish criteria with which to diagnose PVT. We subsequently applied these criteria to 109 additional consecutive abdominal MR scans performed with the same magnet. Fifteen cases were found in which all images showed either (1) signal involving the entire width of the portal vein lumen, which approximated (with T1 weighting) and exceeded (with T2 weighting) the intensity of the hepatic parenchyma in images in which the hepatic veins showed a complete flow void or (2) complete nonvisualization of the portal vein and its major branches in images that showed a flow void in portal venous collaterals and hepatic veins. All patients had unequivocal findings of PVT on at least one other imaging study (CT or sonography) or at surgery. Although the sensitivity of these signs could not be calculated, their specificity was 100%. We conclude that in the presence of these signs, the diagnosis of PVT can be made with confidence.     

Portal hypertension evaluated by MR imaging

Thirteen patients with portal hypertension were examined by magnetic resonance (MR) imaging, using spin-echo sequences, and by visceral angiography. Data from this group were compared with the MR images and angiograms of 20 patients without portal hypertension. MR imaging demonstrated two of three cases of portal vein occlusion and four of five cases of occlusion of the retropancreatic portion of the superior mesenteric vein. Two thirds of the patients with portal hypertension and patent portal veins had marked MR signal within the main portal vein on MR images. Little or no signal was present in the portal veins of the 20 patients without portal hypertension. Our experience indicates that marked intraportal MR signal can be seen in patients with portal hypertension with or without venous occlusion. In some cases the size and distribution of venous collaterals allow one to distinguish between venous occlusion and other causes of portal hypertension. MR images confirmed the patency of distal splenorenal shunts in two patients studied.