Magnetic resonance imaging of fetal thoracic abnormalities

Fetal thoracic abnormalities are increasingly being detected using prenatal ultrasound. Prenatal magnetic resonance imaging is an important adjunct in evaluation of fetal chest lesions. It can help differentiate different masses and is most helpful in evaluation of large or atypical masses. It also is very important in planning in utero interventional procedures, delivery, and immediate postnatal surgery.     

Magnetic resonance imaging of fetal developmental anomalies

Fetal developmental anomalies consist of central nervous system malformations, brain injury, and tumors. Overlap is often seen especially between malformation and injury because malformation may be genetically determined or related to external causative agent, whereas brain injury may be, on one hand, caused by malformation as with intracranial vascular malformation and, on another, can cause brain malformation when cerebral insult occurs during organogenesis and histogenesis. The goal of this review was not to describe by magnetic resonance imaging (MRI) all fetal developmental anomalies encountered in utero; it is most likely to focus on fetal brain anomalies that either are most commonly seen in fetal tertiary care facility or are extremely challenging for MRI. Consequently, the potential of advanced MR techniques such as proton MR spectroscopy and diffusion tensor imaging is also described especially when a challenge is highlighted. This review is therefore organized in subchapters as follows. The first section gives the place of MRI in prenatal development and cites the standard protocol and the advanced techniques. The rules of fetal brain MRI, the challenge and pitfalls, and the selection of MRI cases follow as 3 subchapters. Also, abnormalities are described as 3 separate subchapters entitled ventriculomegalies (hydrocephalus), malformations, and brain injury.     

Magnetic resonance imaging of cerebral hemorrhagic stroke

Despite a traditional perception of reliance on computed tomography and lack of acceptance of magnetic resonance imaging (MRI) for detecting acute hemorrhage, MRI appears to be used increasingly in hemorrhagic stroke. This review addresses the MRI findings of acute hemorrhagic stroke obtained using relatively new imaging techniques. These new techniques have resulted in more acute stroke patients undergoing MRI examination. New information about the frequency and appearance of hemorrhage is emerging: for example, approximately 15-26% of cases of acute cerebral infarctions appear to be complicated by intracerebral hemorrhage. The MRI appearances of hemorrhagic transformation of ischemic infarction, as well as acute hypertensive intracerebral hemorrhage, are discussed based on clinical, biochemical, and technical aspects.     

Magnetic resonance imaging of abdominal pain during pregnancy

The objective of this review is to demonstrate magnetic resonance imaging as an important adjunct to ultrasound and computed tomography in the evaluation of the pregnant patient with abdominal pain. With the advent of ultrafast T2-weighted pulse sequences, fetal and bowel motion cause minimal artifact on the images. An accurate diagnosis can often be made in a few minutes based on these high-contrast images performed in 2 or 3 planes. T1-weighted gradient echo images with and without fat saturation are useful for identifying blood and fat, especially in the case of adnexal masses. Gadolinium-diethylenetriamine pentaacetic acid is rarely used to diagnose inflammatory or obstructive disease and is reserved for those patients with suspected malignancies.     

Magnetic resonance imaging.

Magnetic Resonance Imaging is the latest diagnostic tool to have a significant impact on patient management. Magnetic Resonance Imaging, or MRI, has been available for over six years but has only in the last 18 months become readily available to many more hospitals in Great Britain. MRI scanners have been purchased by large specialist hospitals but the arrival of mobile MRI scanners has made the technology available to smaller hospitals and groups. The impact of MRI for all clinicians and especially surgeons is great and the following text will outline the advantages of MRI and mobile MRI.     

Magnetic resonance imaging of the intrauterine fetal genitourinary tract

Although ultrasonography (US) remains the most widely used diagnostic imaging modality for routine evaluation of the fetus, magnetic resonance (MR) imaging has become an invaluable complement to US in all cases in which additional information is desirable. While the ability of US to detect fetal abnormalities is limited in cases such as maternal obesity, oligohydramnios, and in certain fetal positions, MR using fast and ultrafast pulse sequences enables high-quality fetal images to be acquired regardless of the mothers physical condition or fetal position. Fetal genitourinary disorders are the most common intrauterine abnormalities detected by US, accounting for approximately 30% of all antenatally detected anomalies. Although they usually occur in isolation, these defects can form part of more complex syndromes or chromosomopathies, and MR is indicated to rule out associated abnormalities. In some severe genitourinary disorders, there is a severe deficit of amniotic fluid; these cases are associated with other fetal anomalies such as pulmonary hypoplasia and very poor prognosis. In other cases, the amniotic fluid is not compromised, yet the further detection, localization, and characterization of prenatal disorders will have an impact on postnatal follow-up. This article reviews the role of fetal MR in urogenital tract disorders.     

磁共振影像联合带厚度指标与T2WI高信号对子宫腺肌症的诊断价值

目的:探讨磁共振成像(MRI)中联合带厚度指标和病灶区T_2WI高信号灶联合应用对子宫腺肌症的诊断价值。方法:回顾性分析56例经手术和病理证实为子宫腺肌症患者及35例正常对照组的MRI资料,在观察子宫腺肌症MRI病灶特征的基础上,测量联合带厚度最大值(JZ_(max))、最大值与最小值差(JZ_(dif))、联合带与肌层厚度比(JZ_(rat))。子宫腺肌症组和对照组JZ_(max)、JZ_(dif)、JZ_(rat)比较采用Mann-Whitney U检验。联合带增厚和高信号灶单独应用与联合应用诊断子宫腺肌症的差异采用Pearsonχ2检验。结果:弥漫性子宫腺肌症35例,局限性21例。弥漫性子宫腺肌症中,3例联合带测量困难;另外32例中,JZ_(max)、JZ_(dif)和JZ_(rat)三者平均值分别为20.6mm、12.8mm和70.1%。局限性子宫腺肌症中,3例联合带显示欠清,其他18例JZ_(max)、JZ_(dif)和JZ_(rat)平均值分别为16.4mm、10.2mm和61.0%。子宫腺肌症组和正常对照组JZ差异有统计学意义(P0.05)。子宫腺肌症48例(85.7%)见T_2WI高信号灶。JZ_(max)、JZ_(dif)和T_2WI高信号3个参数联合应用诊断子宫腺肌症的灵敏度、特异度和准确度分别为92.9%、97.1%、94.5%,其中敏感度和准确度高于JZ_(max)、JZ_(dif)单独应用(P0.05)。结论:JZ_(max)、JZ_(dif)、JZ_(rat)联合T_2WI高信号有助于提高子宫腺肌症诊断价值。     

Magnetic resonance imaging of cerebral fat embolism: A case report

Fat embolism syndrome (FES) is one of the most important causes of morbidity and mortality following multiple fractures. Neurological involvement (cerebral fat embolism) has been reported frequently. A case of cerebral fat embolism is reported. While CT scan revealed no abnormalities, MRI, performed in this patient 8 days after trauma, showed relative lowintensity areas on T1-weighted images and high intensity areas on T2-weighted images involving cerebral white matter, corpus callosum and basal ganglia. MRI follow-up (1 and 3 months post-trauma) showed nearly complete resolution of the abnormal signal. MRI seems to be a useful diagnostic tool for detecting and quatifying lesions in fat embolism syndrome.     

Magnetic resonance imaging: historical perspective.

Since Paul Lauterbur and Peter Mansfield independently published in 1974 the technique that later became known as magnetic resonance imaging (MRI), this technology has become an invaluable clinical and research tool. Their Nobel Prize-winning discovery, however, was preceded by a series of seminal contributions by scientists from the fields of mathematics, physics, and chemistry dating back to the 19th century and subsequently followed by rapid developments in clinical MRI. This article provides a brief overview of the key developments that have led to today's MRI and its application to the cardiovascular system.     

Magnetic resonance imaging of fibropolycystic liver disease: the spectrum of ductal plate malformations

Abdominal Radiology - Fibropolycystic liver diseases, also known as ductal plate malformations, are a group of associated congenital disorders resulting from abnormal development of the biliary...     

Magnetic resonance imaging of the kinked fetal brain stem: a sign of severe dysgenesis.

OBJECTIVE: Magnetic resonance imaging (MRI) allows visualization of the fetal brain stem in a manner not previously possible. A "kinked" brain stem is a sign of severe neurodysgenesis. The purpose of this series was to describe cases of a kinked brain stem detected on prenatal MRI and to discuss the possible genetic and syndromic etiologies. METHODS: Seven cases of a kinked brain stem on fetal MRI (gestational age range, 18-34 weeks) were reviewed and correlated with other clinical, genetic, imaging, and autopsy findings. RESULTS: In all cases, there was associated cerebellar hypogenesis. Additional findings were ventriculomegaly (4 cases), cerebral hypogenesis (3 cases), microcephaly (4 cases), schizencephaly (1 case), cephalocele (1 case), hypogenesis of the corpus callosum (1 case), and hydrocephalus (1 case). In 2 cases, prenatal sonography misidentified the kinked brain stem as the cerebellum. CONCLUSIONS: A kinked brain stem is an indicator of severe neurodysgenesis arising early in gestation. Magnetic resonance imaging provides the necessary resolution to detect this sign and delineate any associated anomalies in utero to assist with further genetic evaluation, management, and counseling.     

Magnetic resonance imaging of meningiomas.

MRI with gadolinium enhancement is the imaging modality of choice in the diagnosis of meningiomas. Various MRI features are described. MRI signal intensity characteristics in meningiomas contain information that could be correlated with the histopathology of the tumor. Hyperintensity on T2-weighted images indicates soft tumor consistency and microhypervascularity and is more often seen in aggressive, angioblastic, or meningothelial meningiomas. MRI is useful in demonstrating dural sinus involvement. Meningiomas in unusual locations and their mimics are also presented.     

磁共振静脉成像诊断静脉窦栓塞的实验研究

目的探讨磁共振静脉成像对静脉窦栓塞的诊断价值,并以DSA检查结果和解剖标本为标准,评价其有效性。方法采用经静脉插管的介入方法将弹簧圈和/或明胶海绵放置在猪脑静脉窦的不同位置制作静脉窦完全或不完全栓塞的动物模型。对所有模型进行磁共振静脉成像和DSA检查,比较两种检查方法对静脉窦栓塞的显示能力。2周后处死动物,开颅取脑,观察大体标本的形态和色泽,剥开硬脑膜观察弹簧圈等栓塞材料在硬脑膜内的准确位置。结果磁共振静脉成像成功的显示上矢状窦中后1/3Rolandic静脉前矢状窦栓塞1例,Rolandic静脉处栓塞3例,Rolandic静脉后1~2cm处栓塞2例,直窦栓塞1例,窦汇和直窦栓塞1例。结论磁共振静脉成像方法可以清晰的显示脑静脉窦栓塞的情况并对其作出正确的诊断。     

Magnetic resonance imaging of metabolic diseases of the cerebral white matter

Metabolic diseases of the brain are a rare occurrence. They may be either occurring as inherited diseases causing a destruction of myelin, or they may be the result of toxicity. Neuroimaging, especially magnetic resonance imaging, plays an important role in the detection and classification of these rare diseases. Magnetic resonance spectroscopy is an important tool in the characterization and diagnosis of inherited metabolic diseases.     

Magnetic resonance imaging of the kidney.

High tissue contrast, multiplanar image capabilities, and tissue characterization render MR into an ideal imaging modality for effective evaluation of a wide range of renal disorders. It provides high details of anatomy and can suggest the composition of lesions. Improvements of MRI technology during the last years have made MRI increasingly attractive for body imaging. Fast imaging sequences and parallel imaging techniques have proved to be useful in minimizing artifacts from respiratory motion and magnetic susceptibility differences providing superior imaging quality. Additionally, the use of renally eliminated paramagnetic contrast agents permits assessment of parenchymal perfusion and visualization of the excretion of the contrast medium providing information on renal function.