MR imaging of hepatic metastases

MR imaging is an excellent diagnostic tool for the detection and characterization of liver metastases. The most characteristic finding is peripheral ring enhancement on immediate postgadolinium images.     

MR imaging evaluation of the hepatic vasculature

Assessment of the hepatic vasculature is essential for tumor staging, surgical planning, and understanding of liver disease. Technological advances have made contrast-enhanced magnetic resonance (MR) imaging comparable to multidetector-row computed tomography for diagnostic vascular imaging with respect to spatial resolution. Unenhanced MR angiographic sequences enable reasonable clinical assessment of vessels without contrast agents in patients with contraindications or renal insufficiency. Furthermore, MR angiography may be used to provide directional information through manipulation of the signal intensity of flowing blood. A major limitation to consistent contrast-enhanced MR angiography is the timing of MR image acquisition with arrival of the contrast bolus in the structures of interest. In this article, the authors discuss currently available techniques for imaging of the hepatic vasculature.     

MRI评价乳腺癌脑膜转移

目的探讨乳腺癌脑膜转移的MRI表现特点及转移途径。方法回顾性分析21例经临床病理证实的乳腺癌脑膜转移患者的临床及MRI资料。结果 MRI表现:平扫仅3例表现为条片状或结节状异常信号。增强后18例表现为硬脑膜-蛛网膜型,3例为软脑膜-蛛网膜型。12例伴有颅骨骨质破坏,6例伴有脑内转移。乳腺癌脑膜转移途径:11例经邻近颅骨转移灶直接侵犯邻近硬脑膜;5例脑实质表浅部位的转移瘤侵犯邻近硬脑膜;4例经血行直接转移至硬脑膜和(或)柔脑膜,1例经血行转移至脑脊液后播散至柔脑膜。结论 MR增强扫描是乳腺癌脑膜转移的重要检查方法。经颅骨转移瘤侵犯邻近硬脑膜是乳腺癌脑膜转移的主要途径和特点。     

两次激发SE-EPI在肝脏MRI的应用

目的比较两次激发SE-EPI与呼吸门控FSE及SSFSET2WI在肝脏的应用。方法对14名志愿者及21名肝病患者行上腹部呼吸门控FSE及SSFSE和屏气2次激发SE-EPI(TR=5999ms和1999ms)扫描。所有T2WI序列均运用脂肪抑制技术。定量分析肝脏,病灶的信噪比及肝脏-病灶的对比度噪声比,评价各序列的图像质量及伪影。结果两次激发SE-EPI与SSFSE及FSE在肝脏及病灶信噪比,肝脏-病灶对比度噪声比和图像质量方面无明显差别(P>0.05)。SE-EPI的磁敏感伪影及化学位移伪影均较FSE及SSFSE重,其运动伪影较FSE轻(P<0.05)。结论两次激发SE-EPI能够在较短时间里提供较高质量的上腹部T2WI。被检查者在扫描时可自由平静呼吸或屏气,可作为肝脏T2WI选择序列之一。     

椎体转移瘤扩散加权成像与MRI增强扫描的比较研究

目的比较扩散加权成像(DWI)与MRI增强扫描对MRI增强扫描有强化的椎体转移病灶的诊断价值.方法搜集恶性肿瘤合并脊柱转移病例57例,行常规MRI(T1WI,T2WI,STIR,MR增强扫描)及DWI扫描,113个病灶有强化;测量DWI与MR增强扫描对比噪声比(CNR),计算病灶表观弥散系数(ADC)值和骨髓对比率,比较病变椎体在DWI和MR增强扫描的信号,进行统计学分析.结果DWI和MR增强扫描序列的CNR无显著差异;椎体转移灶ADC值平均为(1.37±0.56)×10-3 mm2/s,正常椎体ADC值(0.64±0.22)×10-3 mm2/s,两者ADC值具有显著性差异(P＜0.05).DWI和MR增强扫描病灶骨髓对比率平均为(1.54±1.39)和(0.64±0.54),二者有良好相关性(P=0.01),DWI骨髓对比率高于MR增强扫描.结论DWI在显示病灶方面有一定优势,病灶骨髓对比率高于MR增强扫描.临床上应用DWI结合ADC值,可以提高对椎体转移病灶的诊断.     

MR imaging in hepatic transplantation.

This article reviews the utility of MR imaging in the evaluation of liver transplantation. Issues related to the prospective transplant donor and recipient, such as inclusion and exclusion criteria, indications and contraindications, and imaging of donor anatomy and recipient pathology, are discussed. Post-transplantation complications and their imaging features are reviewed, with emphasis on the use of MR arteriography, venography, and cholangiography. MR is a single, noninvasive examination that allows a comprehensive investigation of anatomic and pathologic features in pre- and postoperative liver transplant patients, and may eventually replace many, if not all, of the numerous diagnostic examinations performed in this patient population.     

Percutaneous MR imaging-guided laser-induced thermotherapy of hepatic metastases

Background: Many primary tumors may cause liver metastases, which are generally treated with surgical resection and/or chemotherapy. After resection of liver metastases in patients with colorectal carcinoma, 5-year survival rates are achieved in 25–38%, and two-thirds of patients will experience recurrent metastases. We examined percutaneous, minimally invasive, laser-induced thermotherapy (LITT) as an alternative outpatient procedure. Local tumor control rate and survival data were analyzed prospectively. Methods: Between June 1993 and August 2000, 7148 laser applications were performed in 1981 lesions in 705 consecutive patients and 1653 treatment sessions. The complications of the procedure were evaluated by clinical examination and magnetic resonance imaging (MRI) and computed tomography. Local tumor control was evaluated by plain and contrast-enhanced follow-up MRI using T1- and T2-weighted spin-echo and gradient-echo sequences every 3 months after treatment. Cumulative survival times were calculated using the Kaplan–Meier method. Results: The overall rate of complications and side effects was 7.5%. The rate of clinically relevant complications was 1.3%. Local tumor control rate after 3 months was 99.3%; 6 months after laser treatment, plain and contrast-enhanced MRI documented a local tumor control rate of 97.9%. In patients treated with MR-guided LITT for unresectable colorectal liver metastases, the mean survival was 41.8 months (95% confidence interval = 37.3–46.4 months). The 1-year survival rate was 93%, the 2-year survival rate was 74%, the 3-year survival rate was 50%, and the 5-year survival was 30%. In patients treated with LITT for liver metastases from breast cancer, the mean survival was 4.3 years (95% confidence interval = 3.6–5.0 years). Conclusion: In patients with liver metastases, local tumor destruction using minimally invasive, percutaneous LITT under local anesthesia results in improved clinical outcomes and survival rates and can be a potential alternative to surgical resection.     

MR imaging of benign hepatic tumors

Use of a state-of-the-art pattern recognition approach and the combination of various MR sequences and contrast enhancement techniques makes it possible to diagnose most benign hepatic tumors with confidence.     

肝脏血管平滑肌脂肪瘤的MRI诊断

目的：描述肝脏血管平滑肌脂肪瘤的MR表面,探讨MRI对该肿瘤的诊断价值。材料与方法：回顾性分析经病理证实的5例肝脏血管平滑肌脂肪瘤的MRI平扫、多时相动态增强表现和术前诊断。结果：5例均为单发肿块,术前3例正确诊断为肝脏血管平滑肌脂肪瘤,1例诊断为肝腺瘤,1例误诊为恶性肿瘤。T1WI：4例低信号伴斑片状高信号,1例为低信号,用脂肪抑制后T1WI高信号3例完全消失,1例大部分消失伴多囊状改变;T2WI：5例为不均匀高信号。多时相动态增强发现：动脉期4例明显强化,1例中度强化,门脉期及延迟期2例中度强化,3例轻度强化。结论：MRI能显示肝脏血管平滑肌脂肪瘤的特征性表现,多种肿瘤术前正确诊断是可能的。     

MR imaging evaluation of the adnexa

MR imaging has become an important tool in the evaluation of patients with adnexal disease, and its role continues to evolve. Some benign entities can be diagnosed by MR imaging with a high grade of confidence, such as teratomas, endometriomas, simple and hemorrhagic cysts, fibromas, and hydrosalpinx. In cases of malignant lesions, MR imaging may be more accurate than other modalities for lesion characterization, staging, and follow-up.     

肝脏MR灌注成像技术方法的优化研究

目的优化肝脏MR灌注成像的扫描技术方案.方法采用单层2D FSPGR序列对40例无肝脏疾病和30例肝硬化行MR肝脏灌注扫描.将受检者随机分为4组.A、B组各含5例无肝脏病变受检者,快速团注对比剂(3.5 ml/s)后连续扫描100 s,A组采用经肝门单层横断面扫描,平静呼吸,B组采用单层斜冠状层面(同时包含门静脉主干、腹主动脉、肝实质),屏气状态扫描;C、D组各包含15例无肝脏病变受检者及15例肝硬化患者,均采用单层斜冠状层面扫描,平静呼吸,C组于注射对比剂后连续扫描60 s;D组则连续扫描100 s.分析各组受检者的时间信号强度曲线、峰值时间和肝脏灌注指数.结果A、D组比较,采用单层斜冠位扫描方位可以避免呼吸运动导致的扫描层面的上下移动,并且避免腹主动脉的流入增强效应;B、D组比较,显示采用平静呼吸可以避免屏气后大幅度换气导致的时间信号强度曲线(TIC)大幅度波动.C、D两组正常肝脏及肝硬化患者门静脉和肝实质峰值的时间比较均无统计意义的组间差异(P＞0.05);C组肝实质TIC未显示峰段.D组正常肝脏与硬化患者的TIC峰值时间和肝脏灌注指数之间均有统计意义差异(P＜0.05).结论采用单层2D FSPGR行动态增强MR肝灌注成像时,选用斜冠状层面,平静呼吸,团注对比剂后连续扫描100s更有利于肝脏疾病患者MR灌注量化评估.     

真实稳态进动快速成像脉冲序列在肝脏病变中的应用

目的探讨MR稳态采集快速成像(FIESTA)在肝脏病变中的应用价值。方法对121例拟诊肝脏疾病患者分别行轴位、冠状位FIESTA T2*W及FSE T2W成像,对其中经病理或临床证实的80例患者(244个病灶)进行评价,包括病灶检出率、图像质量分级及定量分析。结果①FIESTA序列对富水性病灶的检出率略高于FSE序列(P>0.05),对实性病灶的检出率明显低于FSE序列(P<0.05);②在病灶对比和伪影方面,FSE序列优于FIESTA序列(P<0.05);FI-ESTA序列则在腹部脏器边界及间隙解剖显示和肝静脉及门静脉系统显示中有明显优势(P<0.05);③FIESTA序列的SNR高于FSE序列(P<0.001),而肝脾CNR则低于FSE序列(P<0.001);FIESTA序列的实性病灶CNR低于FSE序列(P<0.05),而富水性病灶CNR与FSE序列相近(P>0.05)。结论 FIESTA脉冲序列的优点:①具有很好的图像SNR;②能清楚显示腹部脏器边界及间隙解剖、门静脉肝静脉结构及受侵情况、胆管内外病灶范围;③成像速度快,几乎无运动伪影。缺点:①检出实性病灶的能力差,尤其对于实性小病灶;②易出现磁化率伪影。     

MRI评价心功能

心血管疾病的诊断需要对心脏形态和功能作出准确评价，MRI可满足上述要求。传统电影法和屏气电影法MRI能够对左右室的整体和局部功能进行准确和可重复性测量，MRI流速编码电影（velocity－encodedcine，VEC）技术能测量心脏大血管内的血流速度，快速梯度回波序列和团注对比剂能够观察造影剂的首次通过情况，显示心肌的血流灌注。最近，应用屏气VEC技术可显示冠状动脉的主干和大分支，它提供了一种确定冠状动脉通畅性的无创方法，使早期发现无症状冠状动脉疾病患者成为可能。本文全面探讨MRI心功能评价能力，并介绍几种具有潜在应用…     

MR imaging in intracystic hemorrhage of simple hepatic cysts

Intracystic hemorrhage of simple hepatic cysts is one of the most frequent complications. Ul-trasonography (US) and computed tomography (CT) may show abnormal findings and mimic other diseases. We describe magnetic resonance (MR) imaging in four patients with intracystic hemorrhage confirmed by surgery or percutaneous aspiration. In all cases the lesions were hyperintense on both T1- and T2-weighted sequences. In three of the four cases the signal was heterogeneous on T1-weighted sequences. Two cases of a thickened wall and one case of a fluid-fluid level were also observed. We suggest that MR imaging may be helpful to differentiate intracystic hemorrhage from other cystic lesions by showing high signal on T1- and T2-weighted sequences.     

肝脓肿的磁共振弥散加权成像量化分析初探

肝脓肿是肝脏较常见的感染性病变,可单发或多发,早期病理学改变为肝脏局部的炎症,然后形成脓腔,不同的个体、不同病理时期,其影像学表现形式复杂多样,临床易发生误诊.MRI具有多序列成像及功能成像的优势,有较高的软组织对比度,可较敏感地反映肝组织充血、水肿、坏死、液化、脓腔及脓壁形成等多种病理学信息,是目前诊断肝脓肿最佳的检查手段.MRI弥散加权成像(DWI)作为MRI功能成像的重要组成部分,以往主要应用于中枢神经系统病变的诊断.近年来,随着MRI超快速成像序列的开发,机器硬、软件的升级,尤其是回波平面成像序列的应用,DWI已逐渐用于腹部病变影像诊断中.本文旨在分析肝脓肿各成分DWI的影像学特点.     

肝囊肿的弥散加权成像研究

目的 分析不同b值肝囊肿弥散加权像(DWI)的信号特点,并测量ADC值,为DWI对其他肝脏疾病的研究提供方向.方法 50例肝囊肿112个病灶进行磁共振DWI,分析b值为300、500、1000 s/mm2肝囊肿的DWI信号表现,并测量ADC值,分析b值为300、500 s/mm2时ADC值的分布情况.结果 肝囊肿在3种b值(300、500、1000 s/mm2)的DWI表现为低信号分别占79.5%、83.0%、92.0%,等信号分别占13.4%、11.6%、7.1%,高信号分别占7.1%、5.4%、0.9%;平均ADC值分别为(4.10±0.11)×10-3、(4.09±0.14)×10-3、(3.85±0.12)×10-3 mm2/s;b值＝300、500 s/mm2时;ADC值＝4.10×10-3 mm2/s分别为91例(占81.3%)、61例(占54.5%).结论 肝囊肿在DWI主要表现为低信号,且ADC值较稳定,选b=300、500 s/mm2时,ADC值接近一固定值4.10×10-3 mm2/s,结合DWI及ADC值可确诊肝囊肿.     

Magnetic resonance (MR) imaging and MR angiography for evaluation and follow-up of hepatic artery banding in patients with hepatic involvement of hereditary hemorrhagic telangiectasia

Background We describe findings obtained by magnetic resonance angiography (MRA) and magnetic resonance imaging (MRI) for evaluation and follow-up after hepatic artery banding in patients with hepatic involvement of hereditary hemorrhagic telangiectasia (HHT). Methods Abdominal MRA and liver MRI were performed in three patients with HHT as clinically defined by Curacao criteria. One patient underwent MRA and MRI twice for preinterventional evaluation and follow-up, one patient for preinterventional evaluation, and one patient for postinterventional evaluation. Hepatic vascular involvement of the disease and postinterventional vascular anatomy were evaluated by two radiologists by consensus. Results Hepatic vascular involvement with perfusion disorders and arteriosystemic shunts was found in all three patients. MRA and MRI allowed diagnostic characterization of hepatic vascular disease (three of three), preinterventional evaluation of complex vascular anatomy and variants (two of two), and postinterventional follow-up of hepatic artery banding (two of two). Conclusion In preinterventional evaluation and postinterventional follow-up, MRA and MRI allows characterization of complex hepatic vascular alterations of HHT and, hence, is an alternative to other imaging modalities in the diagnosis, clinical decision making, and follow-up of HHT.     

原发性肝癌的MR功能成像研究进展

原发性肝癌是世界上最常见恶性程度最高的肿瘤之一,我国原发性肝癌患病率高于欧美及其他发达国家,严重影响了患者及其家庭的生活质量。目前,原发性肝癌的影像学检查主要有B超、CT、DSA及MR。B超价格便宜、操作简单及对软组织病变灵敏度高,但容易受到检查者经验和细致程度的限制且对早期小肝癌（直径<1 cm）诊断的准确率较低;CT有较高的空间和密度分辨率,缺点是有辐射,且时常出现假阳性;DSA为有创检查。MR成像为无创检查,且无辐射、软组织分辨率较高,可进行多参数、多方位成象及各种功能成像,在临床中应用越来越广泛,本文就MR成像技术在原发性肝癌的诊断、鉴别诊断及评价治疗疗效的应用进行综述。     

肝脏常见占位性病变的磁共振扩散成像的量化研究

目的探讨磁共振扩散成像的量化分析在肝脏占位性病变诊断和鉴别诊断中的价值。方法对100例磁共振检查发现的肝脏占位性病变,进行扩散成像并测量表面扩散系数(ADC值),其中:29例肝细胞癌,24例肝转移癌,28例肝血管瘤,19例肝囊肿。结果各种病变的平均ADC值分别为:肝细胞癌:(0.99±0.26)×10-3mm2/sec,肝转移瘤:(1.17±0.32)×10-3mm2/sec,肝血管瘤:(1.81±0.42)×10-3mm2/sec,肝囊肿:(3.11±0.38)×10-3mm2/sec,肝囊肿与肝血管瘤、肝细胞癌及肝转移瘤之间存在显著性差异P<0.001;b值(扩散敏感系数)差大,测得ADC值较准确。结论磁共振扩散成像的量化分析对肝脏占位性病变的诊断和鉴别诊断有一定价值,可与常规检查一起综合分析。