胎儿肾脏积水的MR影像及预后评估

目的利用1．5T高场强扫描机,对胎儿肾脏积水的MR影像及预后进行评估。方法利用B超筛查发现胎儿肾脏积水并进行MR进一步检查的病例34例,胎龄24～37周。结果在34例胎儿中,MR诊断单侧重复肾伴上半肾积水3例（1例产后MR证实,2例引产）,盆腔内囊性病灶致双侧肾脏积水2例（1例产后证实为盆腔巨大畸胎瘤致双肾积水,1例失访）,脑室扩张且单侧肾脏积水2例（1例引产,1例失访）,双侧’肾脏及输尿管扩张积水且肺发育不良1例（产后MR证实,放弃治疗）,双侧肾脏积水伴脐膨出1例（产后证实为脐肠瘘并行手术治疗,双侧肾脏积水随访改善）,双侧肾脏积水伴左肾周积液1例（引产）,单纯性肾脏积水24例（产后确诊左侧UPJ进行手术3例,左侧肾脏积水随访中2例,6例左侧、2例右侧及5例双侧肾脏积水产后超声随访正常,失访6例）;产后确诊UPJ的3例胎儿肾脏皮质厚度平均2mm,随访正常的13例胎儿肾脏皮质厚度平均3．5mm。结论MR影像能够对胎儿肾脏积水的病因进一步评估,有利于胎儿肾脏积水的预后判断。     

Magnetic resonance imaging in fetal anomalies: What does it add to 3D and 4D US?

Objective

The objective of our study is to evaluate the contribution of adding MRI findings to sonographic data when assessing fetal anomalies and to determine how this addition may affect the management of pregnancy.

Study design

We prospectively examined 26 fetuses who had sonographically suspected congenital anomalies over a period of 1 year. 2D/3D and 4D ultrasound, Doppler and magnetic resonant imaging was done for all patients. MRI was done within 1 week following US examination. The maternal age range was 18-39 years. The gestational age range was 15-38 weeks (mean age = 29 weeks). Ultrasound and magnetic resonance findings were compared together.

Results

We reported different types of congenital anomalies including eight cases of isolated central nervous system anomalies, four abdominal, five musculoskeletal anomalies, seven cases of renal anomalies and two cases of Meckel Gruber syndrome. MRI and sonography showed concordant findings in 18 cases. MRI changed the diagnosis in five cases and provided additional information in three cases. Ultrasound was superior to magnetic resonance imaging in three cases.

Conclusion

Our results showed that fetal MR imaging can be used as a complementary modality to US in diagnosing fetal abnormality in which US findings are inconclusive or equivocal.     

Nuclear magnetic resonance of the brain

Recent developments in MRI of the brain are reviewed. Over the past year there has been a general improvement in image quality, a paramagnetic contrast agent has been used in clinical practice, and surface coils have been used more generally in imaging. A wider range of disease has been studied, and there has been considerable agreement about the advantages and disadvantages of MRI at a basic level. As the technique moves into routine clinical use, questions about the economics of the technique are becoming more pressing.     

胎儿后颅窝区畸形的MRI研究

胎儿后颅窝区结构发育情况是常规产前检查的重要内容,产前的准确诊断是产后干预及治疗的关键。MRI较超声可以更全面、直观地显示后颅窝区形态特征及细微结构,通过信号强度的差异辨别病灶的性质,并且能够进一步完善甚至更正超声的诊断。目前MRI已成为产前监测胎儿后颅窝区结构发育情况的主要手段,特别是三维MRI重组、扩散张量成像、扩散张量纤维束成像、磁共振波谱成像皆可提供更丰富的胎儿后颅窝区结构信息。就MRI对胎儿后颅窝区畸形产前诊断的应用予以综述。     

Magnetic resonance imaging of the brain in congenital rubella virus and cytomegalovirus infections

Summary Two children with congenital rubella virus and six with cytomegalovirus (CMV) infections, were examined by magnetic resonance (MR) and CT. Cranial MR imaging (MRI) with T2-weighted spin-echo (SE) and inversion recovery (IR) sequences demonstrated the following: periventricular hyperintensity (4), subcortical hyperintensity (5), delayed myelination (4), oligo/pachygyria (2), cerebellar hypoplasia (2). This study showed that the more-disabled children had more marked abnormal MRI findings. MRI was more effective in the detection of parenchymal lesion than was CT, although intraventricular calcification was better visualized with CT.     

磁共振弥散张量成像在中枢神经系统的应用研究进展

磁共振弥散张量成像（MR-DTI）是一种新的无创性成像方法,它不同于常规T2加权成像和弥散加权成像（DWI）,它可以准确地反映水分子扩散的方向信息,并通过特殊的软件处理,能够实现白质的纤维跟踪与可视化,目前已经成为中枢神经系统临床应用和生命科学研究重要的工具,本文在近年来的文献基础上详述了弥散张量成像的基本原理,并对弥散张量成像在中枢神经系统各个方面的运用现状和研究进展做一综述。     

Magnetic resonance microscopy imaging of posterior interosseous nerve palsy

Posterior interosseous nerve palsy, also called deep radial nerve syndrome, is a neuropathy caused by radial nerve entrapment or compression at the level of the supinator muscle. Although imaging studies are not necessary for diagnosing this syndrome because of its characteristic clinical manifestations, the causes of palsy, which include mass lesions, or precise anatomical findings can sometimes be demonstrated by imaging. Magnetic resonance (MR) findings of posterior interosseous nerve palsy have been described as involving atrophy of related muscles caused by denervation, a common secondary change of this nerve disorder. We present a case in which the swollen posterior interosseous nerve itself could be directly depicted by MR imaging using a 4.7-cm microscopy coil in a patient with neuropathy.     

胎儿颅内异常的超声与 MR对比分析

目的：探讨超声与磁共振在胎儿颅内异常诊断中的应用价值。方法收集21例超声高度怀疑胎儿颅内异常但不能最后确诊的病例。将超声、MR结果与引产后尸体解剖或生后随访结果对照,比较两者诊断正确及漏、误诊率。结果比较两种方法在21例胎儿颅内异常检出方面的差异,MR检出病变并正确诊断20例,超声检出病变并正确诊断18例,两者无统计学差异（ P＞0．05）。但在其伴随畸形方面,MR可检出更多、更微小病变。结论磁共振与超声相比在胎儿颅内异常的检出方面无显著性差异,但MR可为临床提供更多、更详细的信息,超声联合磁共振检查可以发挥更大的作用。     

Quantitative magnetic resonance imaging of the fetal brain in utero: Methods and applications

Application of modern magnetic resonance imaging (MRI) techniques to the live fetus in utero is a relatively recent endeavor. The relative advantages and disadvantages of clinical MRI relative to the widely used and accepted ultrasonographic approach are the subject of a continuing debate; however the focus of this review is on the even younger field of quantitative MRI as applied to non-invasive studies of fetal brain development. The techniques covered under this header include structural MRI when followed by quantitative (e.g., volumetric) analysis, as well as quantitative analyses of diffusion weighted imaging, diffusion tensor imaging, magnetic resonance spectroscopy and functional MRI. The majority of the published work reviewed here reflects information gathered from normal fetuses scanned during the 3^rd trimester, with relatively smaller number of studies of pathological samples including common congenital pathologies such as ventriculomegaly and viral infection.     

Repeatability of estimated fetal weight: Comparison between MR imaging versus 2D ultrasound in at- and near-term patients

IntroductionOur aim was to evaluate the intra- and inter-observer variability and the impact of operator experience on the estimation of fetal weight (EFW) as measured by 2-dimensional ultrasound (2D-US) and magnetic resonance (MR) imaging.Material and methodsWe estimated fetal weight in 46 singleton pregnancies at 35.6–41.4 weeks gestation using 2D-US according to the Hadlock formula and using MR imaging according to the equation developed by Baker. Each examination was performed twice, once by an inexperienced operator and once by an experienced operator. The MR-EFW was derived from the planimetric measurement of fetal body volume (FBV) using an assisted semi-automated method. Intra- and inter-observer variability was evaluated by Bland-Altman analysis. Regression analysis was used to investigate the effect of maternal BMI, delivery weight, diabetes and fetal gender on the differences in US-EFW between the inexperienced and experienced operators.ResultsUS-EFW showed higher intra-observer variability than MR-EFW, irrespective of operator experience. The 95% limits of agreement of MR were narrower compared with those of the US measurements. Similarly, US-EFW showed higher inter-observer variability than MR-EFW. MR-EFW improvement over 2D-US for the limits of agreement was 77.9% for intra-observer variability and 74.5% for inter-observer variability. Regression analysis showed that the differences between US-EFW measurements were not related to any of the tested variables.ConclusionsOperator experience has a marginal impact on the variability of US-EFW and no impact on MR-EFW variability. The variability in US-EFW measurements is unpredictable.     

Magnetic resonance imaging of limbic encephalitis

Summary In two patients with limbic encephalitis serial magnetic resonance (MR) imaging showed evolution of abnormal high-signal intensity in both hippocampal formations on T2-weighted images.     

Magnetic resonance imaging of pyomyositis

Pyomyositis is a relatively rare entity in temperate climates. Because of its rarity and its nonspecific clinical and radiographic findings, pyomyositis may be misdiagnosed and may cause severe morbidity and mortality. We present magnetic resonance imaging findings in two cases of pyomyositis. Magnetic resonance imaging was helpful in differentiating other pathological processes from pyomyositis, outlining the extent of involvement, and localizing the fluid collection.     

快速FLAIR序列像与常规T2WI在中枢神经系统疾病中应用的对比研究

目的：探讨快速液体误减翻转恢复序列（fast fluid attendated inversion recovery，fast FLAIR序列）像在中枢神经系统疾病中的应用价值。方法：本组100例不同中枢神经系统疾病的患者同时行快速FLAIR序列像及常规T2WI检查，并对所得的图像进行对比分析。结果：80例不同中枢神经系统疾病患者中，T2WI显示189个病灶，而fastFLAIR序列像显示244个病灶。20例腔隙性脑梗塞病人中，T2WI显示108个病灶，而fastFLAIR序列像只显示57个病灶。结论：fastFLAIR序列像与常规T2WI在显示不同中枢神经系统疾病方面各具优势，针对不同的病变应选择性地运用fast FLAIR序列像。     

静息状态下帕金森病患者脑部功能连接的MR研究

目的 探讨帕金森病患者在静息状态下脑部功能连接情况.方法 选取9例Ⅱ～Ⅲ级原发性帕金森病患者及8名年龄分布相同的健康志愿者在静息状态下进行MR扫描,选择双侧苍白球作为种子点,分析其脑部功能连接情况,并采用两样本t检验与健康对照组相比较.结果 正常健康对照组中,双侧颞极、双侧海马、双侧丘脑、扣带回后部、右侧枕中区、右侧顶上回等部位存在着功能连接.帕金森病患者的双侧小脑半球、左侧海马、双侧颞上回、后扣带同、左侧额下回、左侧额中回、左侧中央前回、左侧顶下回、左侧顶上回等部位存在功能联系,与对照纽相比,帕金森病患者的双侧小脑、双侧颞叶、左侧额叶、左侧运动前区、左侧顶叶等部位存在着功能连接增强,双侧丘脑的功能连接减弱.结论静息状态下,帕金森病脑部存在着功能连接异常现象.     

MRI联合超声与染色体微阵列分析技术在中枢神经系统异常胎儿产前的应用

目的 探讨核磁共振(MRI)联合超声(US)与染色体微阵列分析技术(chromosomal microarry analysis,CMA)在中枢神经系统异常胎儿产前诊断中的应用.方法 选取我院接受治疗的226例怀疑中枢神经系统异常胎儿的孕妇为此次观察的对象,所有孕妇胎儿均接受MRI联合US与CMA进行相关的检查.比较在...     

产前MRI对胎儿卵巢囊肿的诊断价值

目的探讨产前MRI在胎儿卵巢囊肿中的诊断价值。方法回顾性分析产前诊断及手术确诊的40例胎儿卵巢囊肿的产前、产后MRI影像特征。结果产前MRI检查胎儿卵巢囊肿发生于单侧38例,双侧2例。病灶形态均为类圆形或椭圆形,边界光滑,囊壁较薄。32例病灶内部信号较均匀,T1WI呈均匀低或稍高信号,T2WI呈高信号,DWI扩散不受限,ADC图呈高信号;8例病灶内信号较混杂,T1WI呈稍低及稍高信号,T2WI呈不均匀的稍低信号并夹杂斑片状、点状高信号影,DWI部分扩散受限,ADC图呈低信号。病灶邻近的肠管均受压推移。产后随访发现20例肿块自行消退。有8例行腹腔镜探查手术,病理显示7例为卵巢单纯性囊肿伴出血,1例卵巢囊肿合并蒂扭转。结论产前MRI不仅能清晰显示胎儿卵巢囊肿的发生部位、形态、边界、范围、信号特点,还可评估肿块与邻近组织的结构以及其他合并症,能更好地为临床评估预后和产后治疗提供可靠的诊断依据。     

ForeSee View辅助定位软件在胎儿头部MRI扫描中的价值

目的 探讨ForeSee View辅助定位软件在胎儿头部MRI扫描中的价值。方法 回顾性分析148例接受胎儿头部MRI检查的孕妇的影像资料,根据扫描定位方法将其分为A、B组。A组使用传统方法定位,B组使用ForeSee View软件辅助定位。A组98例,孕妇平均年龄（28.6±4.3）岁,平均孕周（28.4±4.4）周;B组50例,孕妇平均年龄（29.9±4.9）岁,平均孕周（27.3±4.1）周。应用Mann-Whitney U检验分别对A、B组扫描流程时间、初始定位时间、影像质量及影像规范度进行统计学分析。结果 A组全程扫描时间和初始定位时间中位数均高于B组[A组,31.0（25.0,41.3） min、4.1（3.7,4.5） min;B组,24.5（21.0,37.0） min、1.1（1.0,1.2） min;P<0.05],影像切面规范评分低于B组[A组,3（2,3）;B组,3（3,4）,P<0.05]。A组影像质量评分中位数为3（3,4）,B组为3（3,4）,2组间差异无统计学意义（P>0.05）。结论 ForeSee View辅助定位技术可以明显降低胎儿头部扫描的初始定位时间及整个工作流程的扫描时间,使扫描影像更加规范,对影像质量无明显影响。     

Magnetic resonance imaging versus bone scintigraphy in suspected scaphoid fracture

Magnetic resonance imaging (MRI) has become increasingly useful in the evaluation of musculoskeletal problems, including those of the wrist. In patients with a wrist injury, MRI is used mainly to assess vascularity of scaphoid non-union. However, the use of MRI in patients in the acute phase following carpal injury is not common. Three-phase bone scintigraphy is routinely performed from at least 72 h after injury in patients with suspected scaphoid fracture and negative initial radiographs. We evaluated MRI in this patient group. The bone scan was used as the reference method. Nineteen patients were included. Bone scintigraphy was performed in all 19 patients, but MRI could be obtained in only 16 (in three patients, MRI was stopped owing to claustrophobia). In five patients, MRI confirmed a scintigraphically suspected scaphoid fracture. In one patient, a perilunar luxation, without a fracture, was seen on MRI, while bone scintigraphy showed a hot spot in the region of the lunate bone, suspected for fracture. This was confirmed by surgery. In two patients, a hot spot in the scaphoid region was suspected for scaphoid fracture, and immobilization and employed for a period of 12 weeks. MRI was negative in both cases; in one of them a scaphoid fracture was retrospectively proven on the initial X-ray series. In another two patients, a hot spot in the region of MCP I was found with a negative MRI. In both, the therapy was adjusted. In the remaining six patients, both modalities were negative. We conclude that in the diagnostic management of patients with suspected scaphoid fracture and negative initial radiographs, the use of MRI may be promising, but is not superior to three-phase bone scintigraphy.     

Magnetic resonance imaging in glenohumeral instability

The glenohumeral joint is the most commonly dislocated joint of the body and anterior instability is the most common type of shoulder instability.Magnetic resonance (MR) imaging,and more recently,MR arthrography,have become the essential investigation modalities of glenohumeral instability,especially for pre-procedure evaluation before arthroscopic surgery.Injuries associated with glenohumeral instability are variable,and can involve the bones,the labor-ligamentous components,or the rotator cuff.Anterior instability is associated with injuries of the anterior labrum and the anterior band of the inferior glenohumeral ligament,in the form of Bankart lesion and its variants;whereas posterior instability is associated with reverse Bankart and reverse Hill-Sachs lesion.Multidirectional instability often has no labral pathology on imaging but shows specific osseous changes such as increased chondrolabral retroversion.This article reviews the relevant anatomy in brief,the MR imaging technique and the arthrographic technique,and describes the MR findings in each type of instability as well as common imaging pitfalls.     

Magnetic resonance imaging of the liver: New imaging strategies for evaluating focal liver lesions

The early detection of focal liver lesions, particularly those which are malignant, is of utmost importance. The resection of liver metastases of some malignancies (including colorectal cancer) has been shown to improve the survival of patients. Exact knowledge of the number, size, and regional distribution of liver metastases is essential to determine their resectability. Almost all focal liver lesions larger than 10 mm are demonstrated with current imaging techniques but the detection of smaller focal liver lesions is still relatively poor. One of the advantages of magnetic resonance imaging (MRI) of the liver is better soft tissue contrast (compared to other radiologic modalities), which allows better detection and characterization of the focal liver lesions in question. Developments in MRI hardware and software and the availability of novel MRI contrast agents have further improved the diagnostic yield of MRI in lesion detection and characterization. Although the primary modalities for liver imaging are ultrasound and computed tomography, recent studies have suggested that MRI is the most sensitive method for detecting small liver metastatic lesions, and MRI is now considered the pre-operative standard method for diagnosis. Two recent developments in MRI sequences for the upper abdomen comprise unenhanced diffusion-weighted imaging (DWI), and keyhole-based dynamic contrast-enhanced (DCE) MRI (4D THRIVE). DWI allows improved detection (b = 10 s/mm(2)) of small (< 10 mm) focal liver lesions in particular, and is useful as a road map sequence. Also, using higher b-values, the calculation of the apparent diffusion coefficient value, true diffusion coefficient, D, and the perfusion fraction, f, has been used for the characterization of focal liver lesions. DCE 4D THRIVE enables MRI of the liver with high temporal and spatial resolution and full liver coverage. 4D THRIVE improves evaluation of focal liver lesions, providing multiple arterial and venous phases, and allows the calculation of perfusion parameters using pharmacokinetic models. 4D THRIVE has potential benefits in terms of detection, characterization and staging of focal liver lesions and in monitoring therapy.