Extra-Mammary Findings Detected on Breast Magnetic Resonance Imaging: A Pictorial Essay

Magnetic resonance imaging (MRI) of the breast is used for various indications. Contrary to computed tomography as a staging tool, breast MRI focuses on the breast parenchyma and axilla. In spite of narrow field of view, many structures such as the anterior portion of the lungs, mediastinum, bony structures and the liver are included which should not be neglected because the abnormalities detected on the above structures may influence the staging and provide a clue to systemic metastasis, which results in the change of treatment strategy. The purpose of this pictorial essay was to review the unexpected extra-mammary findings seen on the preoperative breast MRI.     

Magnetic Resonance Imaging of the Temporal Lobe: Normal Anatomy and Diseases

Objective

This pictorial essay will review the magnetic resonance imaging anatomy of the temporal lobes and describe the major pathologic processes of this complex area.

Conclusions

Magnetic resonance imaging is an essential tool in the investigation of a patient with suspected temporal lobe pathology. Various conditions may affect this anatomic region, and, therefore, classification of imaging findings into specific groups may help provide a more focused differential diagnosis.     

Magnetic Resonance Imaging of Cruciate Ligament Injuries of the Knee

The anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) are important stabilizers of the knee. These ligaments are commonly injured in sports and motor vehicle accidents. An accurate diagnosis of cruciate ligament injuries is vital in patient care. Magnetic resonance imaging (MRI) can diagnose cruciate ligament injuries with high accuracy. The imaging diagnosis should be based on primary signs, although the secondary signs are sometimes useful, particularly in chronic cases. The detection of associated injuries of other structures of the knee, including menisci, collateral ligaments, cartilage, and bone, are also important. Accurate interpretation of the MRI examination requires a meticulous MRI technique, knowledge of the imaging anatomy, and understanding of the lesion appearance. This pictorial essay reviews the MRI appearance of normal and injured cruciate ligaments. Mechanisms of injury, primary and secondary MRI signs, and associated abnormalities are discussed.     

正常胎儿颅脑磁共振层面解剖

目的：探讨磁共振成像对胎儿颅脑主要结构的显示情况。材料与方法：使用超导０．３５Ｔ磁共振成像仪，对４４例孕妇进行ＭＲ成像，观察、分析胎脑各结构在磁共振图像上的显示情况。结果：ＭＲＩ对胎儿颅脑的主要结构如大脑半球的各叶、小脑、脑干（中脑、桥脑、延脑）、脑室、脑池等具有较高的显示率。结论：作者认为３Ｄ ＭＲＩ能较好地显示胎儿颅脑的主要解剖结构。     

Pictorial Review of Mediastinal Masses with an Emphasis on Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) has become a crucial tool for evaluating mediastinal masses considering that several lesions that appear indeterminate on computed tomography and radiography can be differentiated on MRI. Using a three-compartment model to localize the mass and employing a basic knowledge of MRI, radiologists can easily diagnose mediastinal masses. Here, we review the use of MRI in evaluating mediastinal masses and present the images of various mediastinal masses categorized using the International Thymic Malignancy Interest Group''s three-compartment classification system. These masses include thymic hyperplasia, thymic cyst, pericardial cyst, thymoma, mediastinal hemangioma, lymphoma, mature teratoma, bronchogenic cyst, esophageal duplication cyst, mediastinal thyroid carcinoma originating from ectopic thyroid tissue, mediastinal liposarcoma, mediastinal pancreatic pseudocyst, neurogenic tumor, meningocele, and plasmacytoma.     

MR在妊娠中晚期正常胎儿及胎盘检查中的应用价值

目的了解正常胎儿主要器官及胎盘的MRI表现。资料与方法对36例孕20周以上正常胎儿行MRI检查,采用单次激发快速自旋回波序列(SSFSE),从胎儿头颅、躯干轴位、冠状位、矢状位等多体位观察胎儿各系统主要器官,包括脑、肺、心脏、肝、脾、胃肠道等和胎盘的解剖和MRI表现。结果 36例胎儿MRI检查结果表明:中枢神经系统:孕20周以后大脑三层结构在SSFSE上已经可以辨别,皮质与脑室周围的生发层呈稍低信号,中间白质为高信号。双侧侧脑室在25周前呈生理性扩大状态,枕角明显,25周后逐渐缩小;孕20周时,两侧大脑皮层光滑,无明显沟回形成;孕23周时,仅见双侧侧裂池初具形态;23～30周,两侧大脑皮质主要沟回逐渐形成;30～37周,两侧脑皮质脑沟、回形成明显增多。呼吸循环系统:两肺呈高信号,纵隔内心脏、大血管及两肺纹理呈低信号。消化系统:胃泡、胆囊呈高信号,肠管不扩张时呈等低信号,部分肠管内见低信号胎粪影。肝脏、脾脏呈等低信号位于上腹部两侧。泌尿系统:双侧肾脏呈卵圆形等低信号,膀胱呈囊性高信号位于盆腔内。骨骼、肌肉系统:脊柱、四肢呈低信号,肌肉呈等信号。胎盘信号从均匀、稍高信号向不均匀、稍低信号过渡,胎盘边缘也从平滑向分叶状过渡。结论快速MRI能清楚显示胎儿各主要器官正常解剖和发育变化,同时可以对胎盘成熟度进行准确判断。     

Endoclip Magnetic Resonance Imaging Screening: A Local Practice Review

Purpose

Not all endoscopically placed clips (endoclips) are magnetic resonance imaging (MRI) compatible. At many institutions, endoclip screening is part of the pre-MRI screening process. Our objective is to determine the contribution of each step of this endoclip screening protocol in determining a patient's endoclip status at our institution.

正常前列腺外周带的MR测量研究

目的测量正常前列腺外周带宽径及T2信号强度并探讨其与年龄、体重及身高的变化关系。资料与方法选取217例无泌尿系统症状(临床表现为无尿路刺激、无排尿困难、无并发症之一)的成年男性为研究对象。按年龄段分为7组:第1组(20～29岁,n=22),第2组(30～39岁,n=29),第3组(40～49岁,n=47),第4组(50～59岁,n=45),第5组(60～69岁,n=37),第6组(70～79岁,n=22),第7组(80岁及以上,n=15)。MRI测量轴位外周带的五点及七点处宽径;测量闭孔内肌、臀肌、外周带的T2信号强度,并计算外周带的相对信号强度,即外周带分别与闭孔内肌、臀肌的比值。比较分析不同年龄段上述MR测量值的变化特点。结果正常组前列腺的外周带宽径左侧为(1.15±0.25)cm,右侧为(1.16±0.23)cm。不同年龄段前列腺的外周带左右宽径有统计学意义(P<0.000)。外周带分别与闭孔内肌及臀肌的T2信号强度比分别为4.97±1.33、2.80±0.68。结论外周带宽径随年龄的变化有先变大后减小趋势,T2信号强度随年龄增大有先增高后减低趋势,可出现局灶性信号减低。外周带左右宽径、体积及相对T2信号强度与身高、体重无明显相关关系。     

鼻咽癌放疗后放射性脑病的MRI诊断

作者观察了８４例鼻咽癌放疗后放射性脑病（ＲＥＰ）。其ＭＲＩ表现：病变主要位于双侧颞叶、脑干及小脑，Ｔ１ＷＩ病灶以低信号为（８１．３％），Ｔ２ＷＩ均为高信号，占位征象占２７．４％，萎缩征象占９．５％。还讨论了ＲＥＰ与脑梗塞、脑干胶质瘤及脑转移瘤的鉴别诊断。并提出了ＲＥＰ的ＭＲＩ分型，可分为颞叶型、脑干型、小脑型和混合型。作者还强调了ＭＲＩ显示ＲＥＰ，特别是显示脑干、小脑和颞叶底部的病灶，为ＣＴ及其他     

侵蚀性葡萄胎的MRI诊断

目的 探讨侵蚀性葡萄胎的MRI表现及其诊断价值.资料与方法 回顾性分析8例经临床手术和病理证实的侵蚀性葡萄胎患者的MRI表现.结果 所有8例患者MRI表现为宫腔增大,肌层不均匀增厚,宫腔和肌层内可见长T1、长T2信号的囊性影和等信号结节影,外肌层和盆腔内可见大量的血管流空信号.5例宫腔和肌层内见斑点状、条片状高信号出血灶.6例双侧附件出现实性或囊性肿块.增强扫描表现为宫腔、肌层及附件病灶呈环形和结节状强化.结论 侵蚀性葡萄胎MRI表现具有特征性,有助于诊断.     

适于磁共振检测播散性皮层抑制的猫脑解剖研究

目的 寻找适于研究播散性皮层抑制的猫脑表面脑回及磁共振功能成像(fMRI)平面.材料与方法 成年雌性家猫6只,行垂直相交的高分辨力横断面、矢状面、水平面T1WI及T2WI,研究各方位图像显示脑回的解剖特点.灌注固定后取猫脑标本进行大体表面解剖观察,分析各脑回的位置及形态特点.结果 猫脑具有多脑回结构.边缘回内侧紧邻上矢状窦;上侧裂回位置相对表浅,与相邻脑回以脑沟相隔,周围无大血管相邻;外侧裂回位置偏外,长度短,形态复杂.在MRI上每个横断面仅能显示嘴尾侧走行脑回的一个断面,矢状面不能显示相邻脑回间的关系,包括双侧上侧裂回和边缘回的水平面图像既能显示脑回的长轴,又能显示相邻脑回的关系且能提供对侧大脑半球作为对照.结论 上侧裂回是研究播散性皮层抑制最合适的皮层结构;包括双侧上侧裂回和边缘回的水平面是fMRI研究播散性皮层抑制的理想成像层面.     

正常青年人群脑磁共振扩散张量成像的定量研究

目的:运用扩散张量成像(DTI)方法研究正常青年人群不同脑组织及解剖部位的各向异性特点.方法:对40名正常青年人群行DTI成像,分析其表面扩散系数(ADC)图及各向异性分数(FA)图的特点,并对不同脑组织进行ADC及FA值的定量分析,通过统计学分析得出其扩散和各向异性特点.结果:扩散系数ADC不能区分脑灰质与脑白质(ADC分别为807.78±90.29,775.79±115.31×10-6mm2/s,P=0.098).而脑脊液、脑灰质与脑白质间的FA值间差异均具有显著性意义(P<0.05).不同解剖部位的脑白质间具有显著不同的各向异性(P<0.05).胼胝体压部的各向异性程度最高(0.73±0.09),其次为胼胝体膝部与内囊后肢(0.68±0.05,0.67±0.06),半卵圆中心与枕钳最低(0.53±0.09,0.53±0.09).脑灰质中以背侧丘脑具有最高的各向异性(0.31±0.04).结论:FA可准确定量正常青年人群不同脑组织的扩散特点,DTI可清晰显示脑内白质的方向及走行.     

MR Imaging of Central Diabetes Insipidus: A Pictorial Essay

Central diabetes insipidus (DI) can be the outcome of a number of diseases that affect the hypothalamic-neurohypophyseal axis. The causes of the condition can be classified as traumatic, inflammatory, or neoplastic. Traumatic causes include postoperative sella or transection of the pituitary stalk, while infectious or inflammatory causes include meningitis, lymphocytic hypophysitis, and granulomatous inflammations such as sarcoidosis and Wegener''s granulomatosis. Various neoplastic conditions such as germinoma, Langerhans cell histiocytosis, metastasis, leukemic infiltration, lymphoma, teratoma, pituitary adenoma, craniopharyngioma, Rathke cleft cyst, hypothalamic glioma, and meningioma are also causes of central DI. In affected patients, careful analysis of these MR imaging features and correlation with the clinical manifestations can allow a more specific diagnosis, which is essential for treatment.     

低颅压综合征的MRI诊断

目的 分析低颅压综合征的MRI表现,以提高对本病的认识. 资料与方法 搜集经临床证实的低颅压综合征10例,治疗前均行MRI检查,其中3例仅行平扫,7例同时平扫和增强,3例加MRA,1例加MRV. 结果 10例均有硬脑膜增厚、静脉窦和脑静脉扩张;6例可见脑下垂和脑室缩小表现;4例可见侧枝静脉窦显影(基底丛和岩下窦);5例可见垂体增大;4例出现硬膜下积液;增强7例均见硬脑膜均匀性增厚强化,软脑膜无强化,2例见脊膜强化. 结论 低颅压综合征具有特征性的MRI表现,结合脑脊液压力检测,可以明确诊断.     

运动区皮质磁共振脑机能成像

作者用１．５Ｔ磁共振扫描机，观察７例健康志愿乾运动刺激中对应皮质区信号变化，手指运动中对频运动区皮质信号均有增加，ＭＲ值提高２％－１２％。在狗一侧颈总动脉内注入静脉血，用脑机能成像方法扫描对比，注血过程中其供血区皮质下降５％。验证了脑机能成像的基础是局部氧合血红蛋白和脱氧血红蛋白含量的变化。     

Pictorial Essay: Imaging of Peripheral Nerve Sheath Tumours

Peripheral nerve sheath tumours (PNST) may be benign or malignant. Benign PNSTs include neurofibroma and schwannoma. Neurogenic tumours share certain characteristic imaging features, suggested by a fusiform-shaped mass with tapered ends, the “split-fat” sign, atrophy of the muscles supplied by the involved nerve, the “fascicular sign,” and the “target sign”; these imaging features are best demonstrated on magnetic resonance imaging. This pictorial essay emphasizes the characteristic signs and distinguishing features of PNSTs on imaging.     

急性阑尾炎MRI诊断的临床意义

目的 探讨急性阑尾炎的MRI表现及其临床意义.资料与方法 采用MRI SsH/T_2W-DRIVE序列、SsH/T_2WI序列、STIR/TSE序列和B-SPIR-TFE序列对20例临床诊断为急性阑尾炎和21例右下腹疼痛原因待查的患者进行MRI,采用统计学方法比较两组间差异,并与随后的手术结果进行对照.结果 急性阑尾炎在临床明确诊断组中,阑尾腔外径平均为(0.605±0.205)cm、平均壁厚(0.318±0.106)cm;在腹痛原因待查组中,阑尾腔外径平均为(0.613±0.185)cm、阑尾平均壁厚(0.354±0.179)cm,两者间差异无统计学意义.与手术结果对比,急性单纯性阑尾炎主要表现为阑尾壁T_2信号增高和无阑尾周局部积液;化脓性阑尾炎主要表现为阑尾腔扩张、阑尾腔T_2信号增高、阑尾壁增厚、阑尾壁T_2信号增高或有阑尾周围局部积液;而坏疽性阑尾炎表现与化脓性阑尾炎相似;阑尾脓肿则表现为阑尾消失和回盲部包裹性高信号.MR图像能清晰地显示阑尾的具体位置.结论 采用MRI不同序列检查,能在定位与分期诊断上为临床选择治疗方案和采取预防并发症的措施提供重要依据.     

磁共振波谱成像对颅脑肿瘤的鉴别诊断价值

目的:分析脑肿瘤的氢质子磁共振波谱成像(1H-MRSI)改变,评价1H-MRSI对颅内常见肿瘤的诊断和鉴别诊断价值.方法:本组共42例颅内肿瘤患者行1H-MRSI检查,其中胶质瘤17例、脑膜瘤14例、脑转移瘤11例.测量比较3种肿瘤的实质强化区、周围水肿区和对侧正常脑组织的代谢物浓度(包括N-乙酰天门冬氨酸、肌酸和胆碱)并进行分析比较.结果:常规MRI检查T1WI上肿瘤多为等、低信号,T2WI上呈不均匀高信号,伴有不同程度强化和周围水肿.脑肿瘤的主要MRS袁现为NAA/Cho、NAA/Cr下降,Cho/Cr升高;3纽肿瘤周围水肿区的NAA/Cho分别为1.0167±0.314,1.4250±0.326和2.2900±1.186,组间比较差异均有显著性意义(P＜0.05);其它代谢物指标(NAA/Cr和Cho/Cr)在3种肿瘤间的差异无显著性意义(P＞0.05).3组肿瘤实质强化区各代谢物比值间差异无显著性意义(P＞0.05).结论:1H-MRSI可无创地分析脑肿瘤的代谢状况,对脑肿瘤的诊断、鉴别诊断均有很大的价值.