Longitudinal magnetic resonance imaging study of rhesus monkey brain development

To examine early brain development, T1-weighted structural MRI scans of seven rhesus monkeys (Macaca mulatta) were obtained longitudinally between the ages of 1 week and 4 years at 12 age points. Total brain volume, calculated at each age point, increased significantly, by 56%, between 1 week and 4 years. The greatest increase of 22% occurred between 1 week and 1 month, followed by further significant increases between 1 and 2 months, and 3 and 4 months. Gradually smaller increases continued up to 3 years with no further significant changes thereafter. A robust maturation of white matter occurred between 1 week, at which the only easily identifiable fibre tracts were internal capsule and optic radiations, and 3 months, at which most large fibre tracts were visible; only at this age reproducible measurements were possible for all cases. White matter volume increased by 126% between 3 months and 4 years, with the biggest increase between 3 and 4 months (32%) followed by smaller but significant increases up to 4 years. The macaque brain development parallels that of humans by reaching the maximum in total brain volume around the age of sexual maturity (in macaques 3-4 years) and by the increases in white matter continuing beyond this age. The most rapid growth in both total brain volume and white matter from birth to approximately 4 months is consistent with the emergence of various cognitive abilities in macaques at that age.     

Direct visualization of Parkinson's disease by in vivo human brain imaging using 7.0T magnetic resonance imaging

Parkinson's disease (PD) is a neurodegenerative disorder resulting from progressive loss of dopaminergic neurons in the substantia nigra (SN) pars compacta. Therefore, imaging of the SN has been regarded to hold greatest potential for use in the diagnosis of PD. At the 7.0T magnetic resonance imaging (MRI), it is now possible to delineate clearly the shapes and boundaries of the SN. We scanned eight early and two advanced PD patients, along with nine age‐matched control subjects, using a 7.0T MRI in an attempt to directly visualize the SN and quantify the differences in shape and boundaries of SN between PD subjects in comparison with the normal control subjects. In the normal controls, the boundaries between the SN and crus cerebri appear smooth, and clean “arch” shapes that stretch ventrally from posterior to anterior. In contrast, these smooth and clean arch‐like boundaries were lost in PD subjects. The measured correlation analyses show that, in PD patients, there is age‐dependent correlation and substantially stronger UPDRS motor score‐dependent correlation. These results suggest that, by using 7.0T MRI, it appears possible to use these visible and distinctive changes in morphology as a diagnostic marker of PD. © 2011 Movement Disorder Society     

3-Dimensional visualization of lesions in rat brain using magnetic resonance imaging microscopy

High-resolution (< 50 microm) magnetic resonance imaging microscopy (MRM) has been used to identify brain regions and localization of excitotoxin-induced lesions in fixed rat brains, subsequently confirmed using standard histology. The anatomical extent of lesions identified by MRM was identical to that seen in histological sections and various histopathological changes could be visualized. In contrast to the time involved in preparing and examining histological sections, lesions in intact brains could be rapidly identified and visualized in three dimensions by examining digitally generated sections in any plane. This study shows that MRM has tremendous potential as a prescreening tool for neurotoxicity and neuropathology. These observations suggest that MRM has the potential to affect pathology much as conventional MRI has influenced clinical imaging.     

Gadolinium-loaded liposomes allow for real-time magnetic resonance imaging of convection-enhanced delivery in the primate brain

Drug delivery to brain tumors has long posed a major challenge. Convection-enhanced delivery (CED) has been developed as a drug delivery strategy to overcome this difficulty. Ideally, direct visualization of the tissue distribution of drugs infused by CED would assure successful delivery of therapeutic agents to the brain tumor while minimizing exposure of the normal brain. We previously developed a magnetic resonance imaging (MRI)-based method to visualize the distribution of liposomal agents after CED in rodent brains. In the present study, CED of liposomes was further examined in the non-human primate brain (n = 6). Liposomes containing Gadoteridol, DiI-DS, and rhodamine were infused in corona radiata, putamen nucleus, and brain stem. Volume of distribution was analyzed for all delivery locations by histology and MR imaging. Real-time MRI monitoring of liposomes containing gadolinium allowed direct visualization of a robust distribution. MRI of liposomal gadolinium was highly accurate at determining tissue distribution, as confirmed by comparison with histological results from concomitant administration of fluorescent liposomes. Linear correlation for liposomal infusions between infusion volume and distribution volume was established in all targeted locations. We conclude that an integrated strategy combining liposome/nanoparticle technology, CED, and MRI may provide new opportunities for the treatment of brain tumors. Our ability to directly monitor and to control local delivery of liposomal drugs will most likely result in greater clinical efficacy when using CED in management of patients.     

Intraoperative magnetic resonance imaging and magnetic resonance imaging-guided therapy for brain tumors

Since their introduction into surgical practice in the mid 1990s, intraoperative MRI systems have evolved into essential, routinely used tools for the surgical treatment of brain tumors in many centers. Clear delineation of the lesion, "under-the-surface" vision, and the possibility of obtaining real-time feedback on the extent of resection and the position of residual tumor tissue (which may change during surgery due to "brain-shift") are the main strengths of this method. High-performance computing has further extended the capabilities of intraoperative MRI systems, opening the way for using multimodal information and 3D anatomical reconstructions, which can be updated in "near real time." MRI sensitivity to thermal changes has also opened the way for innovative, minimally invasive (LASER ablations) as well as noninvasive therapeutic approaches for brain tumors (focused ultrasound). Although we have not used intraoperative MRI in clinical applications sufficiently long to assess long-term outcomes, this method clearly enhances the ability of the neurosurgeon to navigate the surgical field with greater accuracy, to avoid critical anatomic structures with greater efficacy, and to reduce the overall invasiveness of the surgery itself.     

Multimodal magnetic resonance imaging of brain tumors

Magnetic resonance imaging arose as a reference for diagnosis, pre-therapeutic and follow-up of brain tumors. Among parameters obtained from standard MRI (of low specificity), only volumetric growth allows prognostic information. The multiple “advanced” sequences have leaded to increase both sensitivity and specificity of brain MRI. Yet, perfusion-weighted imaging and spectroscopy provide metabolic information, and diffusion tensor imaging and cortical activation provide functional information. Characterization, grading, therapeutic management and follow-up have improved, with prognostic information.     

术中磁共振实时影像导航下穿刺活检术的临床初步应用

目的 探讨术中磁共振(iMRI)影像导航应用于穿刺活检术的临床初步经验、优势与不足.方法 在0.15T PoleStar N-20 iMRI实时影像引导下,对6例颅内占位性质不明患者进行穿刺活检术.结果 6例均获得组织病理学诊断,活检阳性率为100%;1例颅内多发占位患者术后并发左基底节活检区域局限性血肿.结论 iMRI影像导航能及时纠正术中脑移位,即只有当iMRI确定穿刺针已位于病灶内才进行活检,从而有利于提高活检阳性率,减少术后并发症.     

Diffusion-weighted magnetic resonance imaging in brain death

BACKGROUND; Traditionally the diagnosis of brain death is established on the basis of a combination of clinical signs and paraclinical methods. Diffusion-weighted MRI is a new method sensitive to cerebral ischemia. Its value in brain death has not been demonstrated until now. CASE DESCRIPTION: A patient was referred to MRI with suspicion of a brain stem stroke. Echo-planar whole-brain, multislice, diffusion-weighted MRI was performed in addition to conventional sequences and MR angiography sequences. In addition to the extensive bilateral hyperintensities observed on T2-weighted images, diffusion-weighted MRI showed diffuse hyperintensities involving both hemispheres as well as a severe drop in the apparent diffusion coefficient in both affected hemispheres. There was also transtentorial herniation with compression of the brain stem as well as absence of flow voids on the T2-weighted images and absence of intracranial vessels on MR angiography. On the basis of the clinical and imaging findings, it was concluded that the patient was in a state of brain death. The patient died the same day. CONCLUSIONS: With the use of new fast techniques such as diffusion-weighted imaging, now MRI can not only display anatomic changes associated with severe brain suffering but can also demonstrate ultrastructural changes secondary to brain death and differentiate them from edematous changes seen on T2-weighted images.     

17O magnetic resonance imaging of the human brain

Here we show the first example of in vivo oxygen-17 (17O) magnetic resonance imaging of the human in natural abundance. Two-dimensional fast multi-planar gradient recalled 90 deg echo (FMPGR/90) pulse sequence and three-dimensional projection reconstruction pulse sequence methods were used.     

New developments in magnetic resonance imaging of the brain

Magnetic resonance imaging (MRI) continues to have a large impact on the diagnosis and management of a number of diseases, especially diseases associated with brain injury. The strengths of MRI are the unique contrast that can be obtained, and the fact that it is not harmful and that it can be readily applied to human and animal models. The past decade has seen development of functional MRI techniques that measure aspects of hemodynamics and water diffusion that are playing an important role. Indeed, these techniques are having a major impact on management of brain injury. The development of MRI continues at a rapid pace and a renewed push to increased spatial and temporal resolution will extend the applicability of anatomical and functional MRI. Increased interest in molecular imaging using MRI is increasing the number of processes that can be imaged in the brain. This work reviews some new developments that are being made in anatomical, functional, and molecular MRI of the brain, with comments about usefulness for work in the area of neuroprotection.     

17O magnetic resonance imaging of the human brain

Abstract

Here we show the first example of in vivo oxygen-17 (¹⁷O) magnetic resonance imaging of the human in natural abundance. Two-dimensional fast multi-planar gradient recalled 90 deg echo (FMPGR/90) pulse sequence and three-dimensional projection reconstruction pulse sequence methods were used.     

精神分裂症脑萎缩的MRI研究

目的 了解精神分裂症患者的脑萎缩是疾病初期即已发生，还是随病程逐渐进展。方法 研究对象选取符合DSM-Ⅲ精神分裂症诊断标准的住院患者95例，正常对照组20例，按规定序列作头颅核磁共振扫描，测定第三脑室宽度、两侧第三脑室距脑岛面距离及两侧尾状核头部宽度。并以病程5年为限，分为短病程组和长病程组。结果 ①病例组第三脑室显著增宽，尾状核头部缩小。②短病程组与长病程组各组值无显著性差异。③病程与第三脑室宽度、两侧第三脑室距脑岛面距离及两侧尾状核头部宽度均无显著相关性。结论 精神分裂症患者脑萎缩明显，且与病程、服药无关，在疾病早期即已发生。     

Three-dimensional tracking of axonal projections in the brain by magnetic resonance imaging

The relationship between brain structure and complex behavior is governed by large-scale neurocognitive networks. The availability of a noninvasive technique that can visualize the neuronal projections connecting the functional centers should therefore provide new keys to the understanding of brain function. By using high-resolution three-dimensional diffusion magnetic resonance imaging and a newly designed tracking approach, we show that neuronal pathways in the rat brain can be probed in situ. The results are validated through comparison with known anatomical locations of such fibers. Ann Neurol 1999;45:265–269     

Structural brain magnetic resonance imaging of pediatric twins

To explore the relative impact of genetic and nongenetics factors on human brain anatomy during childhood and adolescence development, a collaborative team from the Child Psychiatry Branch of the National Institute of Mental Health and Virginia Commonwealth University is applying structural equation modeling to brain morphometric data acquired via magnetic resonance imaging from a large sample of monozygotic and dizygotic pediatric subjects. In this report, we discuss methodologic issues related to pediatric neuroimaging twin studies and synthesize results to date from the project. Current sample size from the ongoing longitudinal study is approximately 150 twin pairs. Consistent themes are: (1) heritability is high and shared environmental effects low for most brain morphometric measures; (2) the cerebellum has a distinct heritability profile; (3) genetic and environmental factors contribute to the development of the cortex in a regional and age specific manner; and (4) shared genetic effects account for more of the variance than structure specific effects. Understanding of influences on trajectories of brain development may shed light on the emergence of psychopathology during childhood and adolescence and ultimately may guide therapeutic interventions.     

精神分裂症脑结构的核磁共振研究

目的：采用核磁共振技术（MRI）分析精神分裂症患者的脑结构改变。方法：以精神分裂症住院患者101例为对象,正常30例为对照,作头颅核磁共振扫描。结果：病例组第三脑室显著增宽,尾状核体积较大,海马增厚,各部位海马信号强度减弱。结论：精神分裂症患者脑萎缩明显,尾状核增大。     

Prenatal diagnosis of periventricular hemorrhage by fetal brain magnetic resonance imaging

Following the incidental diagnosis of triventricular hydrocephalus in a fetus 34 weeks after the mother's last menstrual period, during an uneventful pregnancy, 1.5-T brain magnetic resonance (MR) was carried out. A subependymal hemorrhage, which had not been revealed by transabdominal ultrasound, was found; this finding was confirmed by neonatal brain ultrasound and MR. Fetal MR allowed identification of the hemorrhage as the cause of the hydro-cephalus and also established its time of occurrence. Unexplained hydrocephalus should be included among the indications for fetal MR. Received: 15 June 1998