膝关节损伤的MRI分析与临床

目的:探讨膝关节损伤的MRI特征、病理基础、诊断依据及临床意义。方法:对240例手术或关节镜证实的膝关节损伤的MRI资料回顾分析。结果:240例患者中,半月板损伤234例,表现为三角形的低信号影内出现不同形状的高信号;关节软骨损伤142例,表现为关节面线形低信号影内出现点条状高信号或连续性中断;韧带损伤者224例,表现为条带状低信号影增粗、边缘呈波浪状或连续性中断,内可出现高信号,中断处为长T1长T2异常信号组织充填;隐匿性骨折55例,表现为受累骨端内出现高低混杂信号影。结论:MRI在诊断半月板、关节软骨、韧带损伤及隐匿性骨折方面具有优越性,可有效地指导临床治疗。     

Influence of dental materials on dental MRI

Objectives:

To investigate the potential influence of standard dental materials on dental MRI (dMRI) by estimating the magnetic susceptibility with the help of the MRI-based geometric distortion method and to classify the materials from the standpoint of dMRI.

Methods:

A series of standard dental materials was studied on a 1.5 T MRI system using spin echo and gradient echo pulse sequences and their magnetic susceptibility was estimated using the geometric method. Measurements on samples of dental materials were supported by in vivo examples obtained in dedicated dMRI procedures.

Results:

The tested materials showed a range of distortion degrees. The following materials were classified as fully compatible materials that can be present even in the tooth of interest: the resin-based sealer AH Plus^® (Dentsply, Maillefer, Germany), glass ionomer cement, gutta-percha, zirconium dioxide and composites from one of the tested manufacturers. Interestingly, composites provided by the other manufacturer caused relatively strong distortions and were therefore classified as compatible I, along with amalgam, gold alloy, gold–ceramic crowns, titanium alloy and NiTi orthodontic wires. Materials, the magnetic susceptibility of which differed from that of water by more than 200 ppm, were classified as non-compatible materials that should not be present in the patient’s mouth for any dMRI applications. They included stainless steel orthodontic appliances and CoCr.

Conclusions:

A classification of the materials that complies with the standard grouping of materials according to their magnetic susceptibility was proposed and adopted for the purposes of dMRI. The proposed classification can serve as a guideline in future dMRI research.     

MRI及MRS在大脑胶质瘤病诊断中的应用

目的：探讨MRI及MRS在大脑胶质瘤病诊断及鉴别诊断中的意义。方法：回顾性分析经穿刺病理或手术病理证实的5例大脑胶质瘤病患者,所有患者均行常规MRI检查及单体素MRS检查。结果：MRI常规图像显示所有病灶均呈浸润性生长但无明确肿块形成,病变累及区脑回肿胀、脑沟及脑裂变浅。5例患者均累及三个脑叶,其中同时合并单侧基底节区受累4例,合并胼胝体区受累5例。MRI常规图像所有病灶T1WI均呈弥漫性低信号,T2WI呈弥漫性高信号;增强扫描2例病灶内见斑片状强化区,所有病灶内未见明显坏死区或囊变区。MRS谱线显示5例病灶内谱线均表现为不同程度NAA峰降低,Cho峰升高,Cho/Cr比值及Cho/NAA比值升高。结论：MRI及MRS对大脑胶质瘤病的早期诊断及鉴别诊断具有重要作用。     

肾上腺疾病的MR影像诊断

本文对５０例正常肾上腺，４２例共４９个肾上腺病灶的ＭＲ影像进行分析，结果表明：（１）正常肾上腺信号均匀，显示率与ＣＴ相似；（２）ＭＲ可清晰显示大于１．０ｃｍ的病灶及其与周围结构的关系；（３）ＭＲ对腺瘤与转移瘤的鉴别有较大的帮助，Ｔ＿２ＷＩ腺瘤类似于肝脏的信号强度，转移瘤与脂肪的信号强度相似；（４）嗜铬细胞瘤的ＭＲ影像有特异性，Ｔ＿２ＷＩ呈明显高信号，４５％见散在点状短Ｔ＿２低信号区。     

Contrast between white and grey matter: MRI appearance with ageing

MRI contrast between white and grey matter appears to be higher in young normal subjects than in older patients. The aim of the present study was to investigate the possible relationships between these changes in contrast and ageing. It consisted of two parts. In the first part we retrospectively evaluated 140 MRI brain examinations of healthy subjects, 20 per decade (age range 20–90 years), in whom the contrast was subjectively scored. In the second part we prospectively measured the actual T1, spin density (SD) and T2 values of white and grey matter in another 22 healthy subjects (age range 20–80 years). In the first group of subjects a progressive decrease in white/grey matter contrast was observed with ageing. In the second group of subjects the T1, SD and T2 values of white matter were always shorter than those of grey matter. There is a close relation among T1, SD and T2 values of white and grey matter with ageing. We suggest that there is a progressive loss of white/grey matter contrast with ageing. Such a phenomenon is possibly due to an increased water content in the white matter and the progressive neuronal loss in the grey matter that occurs with age. Correspondence to: S. Magnaldi     

Protocol error artifacts in MRI: Sources and remedies revisited

PurposeThe objective of this article is to review the sources, effects and remedies of the artifacts that are controlled by operator variable parameters. Protocol error artifacts include susceptibility, ferromagnetic, truncation, aliasing, chemical shift, black boundary, cross-talk, partial volume averaging, and saturation artifacts. All these artifacts are simulated/developed in-house along with a few uncommonly seen artifacts. Also, the effectiveness of various remedial measures for all these artifacts has been demonstrated.ResultsSusceptibility, ferromagnetic, and black boundary artifacts can be reduced by using spin echo (SE) pulse sequence. Susceptibility and ferromagnetic artifacts are minimized by altering time-to-echo (TE), though chemical shift artifact (CSA) may turn into black boundary artifact and vice versa when TE is varied. By employing three-dimensional (3D) volume acquisitions susceptibility, ferromagnetic and partial volume averaging (PVA) artifacts can be reduced. Field of view (FOV) has an effect on aliasing, CSA and PVA artifacts, whereas by proper selection of phase encoding and frequency-encoding axes, susceptibility, ferromagnetic, aliasing and CSA can be overcome.ConclusionsThese artifacts can usually be ameliorated or avoided by altering parameters that are under operator control and employing remedial measures, thus maintaining good image quality and avoiding diagnostic errors, thereby enhancing the usefulness of MRI in clinical practice.     

MRI of patients with cerebral palsy and normal CT scan

Summary Three children with clinical evidence of cerebral palsy (CP) and normal cerebral computed tomography (CT) scans were evaluated by magnetic resonance imaging (MRI) to identify CT-undetectable white matter lesions in the watershed zones of arterial territories. The two patients with spastic diplegia showed bilateral lesions either in the subcortical regions or in the occipital periventricular regions. The patient with congenital hemiplegia exhibited unilateral lesions in the periventricular region. We conclude that MRI is more informative than CT for the evaluation of patients with CP.     

蛛网膜下腔出血MRI诊断价值与进展

蛛网膜下腔出血(SAH)是临床最常见的危急病之一,准确及时地诊断十分必要.随着现代医学影像技术的飞速发展,尤其是MRI新技术的临床应用,其对SAH诊断的敏感性不断增加,但对蛛网膜下腔少量出血的早期确诊仍是影像学检查的一个挑战.简述CT与MRI各序列的成像原理,对比了CT和MRI对急性、亚急性、慢性SAH诊断的敏感性,并总结SAH在CT和MRI影像表现上的各种假阳性情况.旨在提高本病的诊断率,为临床确定治疗方案提供依据,探讨最合适的影像学检查方法.     

先天性右室流出道狭窄及其合并畸形的MRI

目的：研究MRI诊断小儿先天性右室流出道狭窄及其合并畸形的可靠性及限度。材料和方法：回顾分析15例小儿先天性右室流出道狭窄及其合并畸形的MRI表现，与二维超声心动图．心血管造影和手术对照比较．结果：MRI定性诊断的正确率与心血管造影一致。对其合并畸形的显示，MRI和二维超声心动图各有优缺点，而心血管造影则仍为最佳显示方法．结论：MRI对小儿先天性右室流出道狭窄的定性确诊率为100％，对合并畸形——体肺侧支，冠状动脉的显示随着MRI设备(硬件和软件)的改进，可望进一步提高而替代超声和心血管造影．     

MRI对肥厚性心肌病解剖及功能评价

目的：探讨MRI对肥厚性心肌病(HCM)解剖及功能评价的临床应用价值。方法：对18例经病史、临床表现、心电图及超声心动图检查(UCG)诊断为HCM的患者，进行MRI扫描，并用ARGUS专用心功能分析软件计算左室心肌质量、左室舒张末期容积和射血分数等参数。比较UCG和MRI检测心脏解剖和功能的作用。结果：①HCM主要累及室间隔及左室前、侧壁，呈非对称性分布。②MRI和UCG在检测左室心肌质量、左室舒张末期容积及射血分数时，2种技术无显著性差异。结论：MRI能全面了解心脏解剖和功能异常，有重要的临床应用价值。     

增强MRI诊断乳腺良恶性病变的价值

目的评价增强ＭＲＩ对乳腺良、恶性病变的诊断价值。方法对４８例乳腺病变患者进行ＭＲＩ平扫和增强扫描，并对照Ｘ线、Ｂ超及手术病理结果，分析比较了病变强化后形状、边界、内部信号、强化速度与程度以及强化消失快慢等特征。结果４８例乳腺病变患者８１个病灶的良、恶性诊断准确率为９２．６％。结论增强ＭＲＩ是鉴别乳腺良、恶性病变的一种有效的影像学诊断方法     

MR脂肪抑制技术在肌肉骨骼系统的临床应用进展

肌肉骨骼系统磁共振成像(MRI)常应用脂肪抑制技术，抑制背景脂肪信号，清楚显示病变及其信号特征，减少伪影，提高图像质量。本文综述了脂肪抑制技术在肌肉骨骼系统疾病诊断中的应用进展。     

恶性脑膜瘤MRI表现与病理对照研究

目的：研究ＭＲＩ诊断恶性脑膜瘤特征性表现的可靠性及限制。材料和方法：回顾性分析５０例恶性脑膜瘤的ＭＲＩ表现，与手术病理相对照，同时随机抽取同期５０例良性脑膜瘤加以比较研究。结果：５０例恶性脑膜瘤中，男女之比为１．５：１；ＭＲＩ显示恶性脑膜瘤多呈不规则形（３５／５０），轮廓常呈分叶状（１５／５０），结节状（１２／５０）和锯齿状（８／５０），包膜常不完整（２８／５０），瘤内信号多不均匀（２１／５０），造影后瘤内不均匀强化多见（２６／４０），脑膜尾征以粗短不规则为特征（９／１３），与良性组比较有统计学意义（ｘ２检验：Ｐ＜０．０５）。病灶部位、大小、边缘及瘤周水肿良、恶性者比较无统计学意义。结论：本组术前定位诊断正确率为１００％，定性诊断正确者仅１例，回顾性分析定性诊断正确率可达８６％。因此提高认识、足够重视，恶性脑膜瘤的术前定性诊断正确率将明显提高。     

磁共振成像对颅内脑膜瘤水肿分析

目的：探讨脑膜瘤周围脑水肿的程度和肿瘤的生长部位．质地．组织学亚型的相关性．研究其瘤周水肿的形成原因．材料和方法：使用经手术和病理证实的65例脑膜瘤MRI和临床病理资料．观察分析脑膜瘤的瘤周水肿的程度．肿瘤的质地，组织学亚型等．结果：发生于大脑颅盖部或／和有矢状窦受累的脑膜瘤有明显的脑水肿．而发生于其它部位(颅底，丘脑、小脑、脑池等)无或只有轻度脑水肿．结论：轻度脑水肿主要是脑膜瘤对脑组织的直接压迫，而中，重度脑水肿主要是脑膜瘤对大脑表面引流静脉尤其是矢状窦的压迫或阻塞．脑水肿和肿瘤的发生部位有关，面和肿瘤的质地、组织学亚型无关．     

Evaluation of an equilibrium phase free-breathing dynamic contrast-enhanced MRI prototype sequence compared to traditional breath-held MRI acquisition in liver oncology patients

IntroductionMagnetic Resonance Imaging (MRI) is a commonly used for diagnosing metastatic liver disease. When patients are unable to achieve the necessary arrested respiration required during image acquisition, image artefacts occur that affect image quality and diagnostic value. The main contribution of this study is the evaluation of a novel prototype technique that allows a specific sub-group of patients to breathe freely throughout the acquisition of dynamic contrast enhanced equilibrium phase MRI of the liver.MethodsThe study compared a traditional single phase of arrested respiration T1-weighted (T1W) fat saturated (FatSat) volumetric interpolated breath-hold sequence (VIBE) with a novel free-breathing T1W 3D Radial VIBE prototype sequence. A cohort of patients (n = 30) with known hepatic metastases who demonstrated difficulty in complying with the instructions for arrested inspiration were scanned. Both sets of data were compared for diagnostic quality using a Likert scale questionnaire by specialist Oncology Radiologists (n = 2).ResultsHigher scores for all image quality criteria, including the presence of artefact (2.6 ± 0.57; p < 0.001), lesion conspicuity (2.9 ± 0.35; p < 0.001) and visibility of intra-hepatic vessels (2.8 ± 0.37; p < 0.001) were found using the free-breathing sequence (13.5 ± 1.94; p < 0.001 t = 13.31; df 29; p < 0.001) than the breath hold phase (8.1 ± 2.06), confirmed with kappa (k-0.023; p-0.050).ConclusionsThe results demonstrated a 39.5% improvement in overall image quality using the T1W 3D Radial VIBE prototype sequence, and have the potential to improve patient experience and reduce image artefacts during MRI imaging of this sub-group of patients.     

儿童白质消融性脑白质病的MRI表现

目的 探讨白质消融性脑白质病(VWM)的MRI特征表现.方法 回顾性分析2008年至2013年间经本院儿科基因确诊为VWM的10例患儿的临床及MR资料.由2名资深的神经放射医师进行阅片,对白质病变部位(大脑、小脑、脑干、胼胝体及内外囊)、范围、信号特点、有无囊变、脑萎缩及基底节受累等进行分析.结果 10例大脑中央白质均弥漫受累,9例部分皮层下白质受累,7例伴U形纤维受累;7例伴有囊变;8例内囊后肢受累,7例外囊受累,8例胼胝体内缘(透明隔缘)受累.2例丘脑和苍白球出现异常信号,6例脑干白质受累,7例小脑白质受累.结论 大脑中央白质出现弥漫对称的异常信号伴囊变是VWM特征性的MRI表现,对该病的诊断具有重要价值.     

脑静脉性血管畸形的MRI表现

目的 探讨脑静脉性血管畸形的MRI表现。方法对17例脑静脉性血管畸形病例的临床和MRI资料进行总结、分析。结果所有病例均表现为管状或条带状流空信号,增强扫描病灶明显均匀强化。其中额叶5例,颢叶4例,小脑半球4例,顶叶3例,脑干1例,均为单发,畸形血管向浅部静脉引流。1例合并海绵状血管瘤。结论脑静脉性血管畸形临床症状轻微,常为偶然发现,在MRI上具有特征性表现,可据此做出诊断。     

Brain infarcts due to scorpion stings in children: MRI

We report two children with severe neurological complications after having been stung by a scorpion. Clinical and MRI findings suggested brain infarcts. The lesions seen were in pons in one child and the right hemisphere in the other. The latter also showed possible hyperemia in the infarcted area. No vascular occlusions were observed and we therefore think the brain infarcts were a consequence of the scorpion sting. The cause of the infarct may be hypotension, shock or depressed left ventricular function, all of which are frequent in severe poisoning by scorpion sting. Received: 20 January 1999/Accepted: 13 May 1999     

小儿长骨骨髓炎的MRI表现

目的：探讨不同年龄组间小儿长骨骨髓炎的MRI表现。方法：在我院确诊为血源性骨髓炎并行MRI检查者38例;按年龄分成A组（年龄≤18个月）和B组（年龄〉18个月）。分析比较两组患者的临床表现、部位、病灶在长骨中的部位（骨骺、干骺端或骨干）、病灶信号、骨膜下脓肿、关节积液等。采用SPSS19．00软件进行统计学分析。结果：本研究中病变最常累及的部位：A组为股骨（52．3％）,B组为胫骨（50．0％）,两组间差异无统计学意义（P〉0．05）。A组中累及干骺及骨骺者占81．0％,在B组中累及千骺端及骨骺者占50．0％,累及干骺端及骨干者占30．0％,两组间差异无统计学意义（P〉O．05）。低年龄组中炎症累及骨骺的发生率与高年龄组间的差异有统计学意义（P％0．05）。A组中合并关节炎者占81．0％,B组中为45．0％,两组间差异有统计学意义（P〈O．05）。结论：小儿长骨骨髓炎的主要MRI表现为病变多位于干骺端,常合并软组织炎症;小于18个月的幼儿骨髓炎易向骺侧扩散而并发关节炎,而大于18个月的儿童骨髓炎更易于向骨干延伸。     

兔坐骨神经挤压伤的MRI与SEP对比研究

目的:探讨磁共振成像和体感诱发电位以及两者结合在坐骨神经急性挤压伤中的诊断价值。方法:24只兔按钳夹力的不同随机分为A、B两组,左后肢为损伤侧,右后肢为对照侧,建立坐骨神经急性挤压伤模型,于伤后1、2、4、8周行MR扫描,同时行双侧体感诱发电位检查。结果:损伤侧24条神经,有23条MR显示异常,诊断正确率95.8%,假阴性率4.17%(1/24);24条损伤侧坐骨神经,有22条SEP显示异常,诊断正确率91.6%,假阴性率8.3%(2/24)。MRI与SEP对神经损伤的正确诊断率无统计学差异(P>0.05)。MRI与SEP结合起来,24条损伤神经均显示异常,诊断正确率100%。结论:MR与SEP检查可无创、准确地判断神经损伤,两者结合可明显提高神经损伤的正确诊断率,重复性好,可作为神经损伤的较好诊断手段。