Implicit brain imaging

We describe how implicit surface representations can be used to solve fundamental problems in brain imaging. This kind of representation is not only natural following the state-of-the-art segmentation algorithms reported in the literature to extract the different brain tissues, but it is also, as shown in this paper, the most appropriate one from the computational point of view. Examples are provided for finding constrained special curves on the cortex, such as sulcal beds, regularizing surface-based measures, such as cortical thickness, and for computing warping fields between surfaces such as the brain cortex. All these result from efficiently solving partial differential equations (PDEs) and variational problems on surfaces represented in implicit form. The implicit framework avoids the need to construct intermediate mappings between 3-D anatomical surfaces and parametric objects such planes or spheres, a complex step that introduces errors and is required by many other cortical processing approaches.     

Fetal brain MR imaging

In the past 10 years, improvements in MR imaging and faster imaging techniques have dramatically increased the use of in-utero fetal brain MR imaging. Challenging abnormalities now can be diagnosed prenatally through a careful analysis of morphology and signal changes. Using illustrations of normal brain development as a starting point, this article illustrates and discusses major brain malformations and specific morphologic changes, destructive lesions, and isolated ventriculomegalies, and the advantages and disadvantages of T1 and T2 sequences are provided.     

Human brain metabolism of morphine and naloxone

The glucuronidation of morphine and naloxone was investigated in several regions of the human brain. Post-mortem brain tissue specimens were obtained from 19 patients 15 of whom had had cancer. With a few exceptions, all cancer patients had been treated with opiates during the terminal stage of their life. The glucuronide formation of morphine and naloxone was studied in vitro after incubation of the brain microsomal fraction with the substrate and uridine diphosphate glucuronic acid (UDPGA). The glucuronides were analyzed by high performance liquid chromatography. Glucuronidation of morphine and naloxone was catalyzed in 6 of the 19 investigated tissue specimens. The rate of formation of naloxone-3-glucuronide (N3G) exceeded that of the morphine-3-glucuronide (M3G). Morphine-6-glucuronide formation was found in only 2 specimens, in which the formation rate was 10% of the formation rate of M3G. When morphine and naloxone were present simultaneously at equal concentrations (3 mM), the N3G/M3G formation rate ratio increased compared to that when the 2 substrates were incubated one by one. Our findings are interesting from a clinical point of view since the pathways studied represent both bioactivation and inactivation steps in the metabolism of opioids.     

Perspective for imaging of tumor metabolism

FDG-PET has become one of the golden standard of oncologic imaging representing glucose metabolism. Recent investigations demonstrated clinical value of several new tracers targeting for brain tumor, hypoxic cell, and proliferative cell where FDG-PET have showed limitation.     

MR imaging and spectroscopy of brain development

MR imaging provides an invaluable tool for the study of brain development in vivo. Current MR imaging techniques allow noninvasive methodologies, without ionizing radiation, that provide a diversity of information on structure, metabolism, and function of the developing brain. This article focuses on the application of conventional and advanced MR imaging techniques, including quantitative morphometric MR imaging, diffusion-weighted, functional MR, and MR spectroscopic imaging to the study of early human brain development.     

脑受体显像研究现状与进展

脑受体显像是21世纪脑科学领域研究的一个开拓性的新领域,在分子医学水平上探讨受体功能及其生物学作用并用于诊断治疗与受体有关的疾病,是近年来国际上医学科学领域研究的前沿.其中受体显像剂制备、生理数学模型的建立及核医学仪器的开发是目前发展的主要方面.     

铁转运刺激因子与脑铁代谢

目的为进一步加深铁转运刺激因子(stimulator of Fetransport,FT)对机体铁代谢以及铁代谢异常(缺乏或超载)的理解,综述了国内外对SFT的研究进展,重点讨论了SFT的表达分布与结构、生理功能、表达调控及其表达异常与脑铁代谢疾病关系.资料来源应用计算机检索http//www.ncbi.nlm.nih.gov/PubMed与SFY相关文献,检索词"stimulator of iron transport"和"stimulator of Fe transport",并限定文献语种为英文.同时计算机检索中文CNKI(中国期刊网全文数据库)1997-01/2004-10相关文献,检索词"脑铁代谢,铁转运刺激因子",并限定文献语种为中文.资料选择对资料进行筛选,以关于SFT的结构及其与脑铁代谢疾病相关的文献作为纳入标准.资料提炼共收集到20篇关于SFT及1300篇关于脑铁代谢的文献,1篇文献符合纳入标准.资料综合从入选的21篇文献中,综述了目前对SFT的表达分布与结构、生理功能、表达调控及其表达异常与脑铁代谢疾病关系等方面的研究进展.结论SFT具有刺激细胞表面的非转铁蛋白结合铁或转铁蛋白结合铁的摄取功能,其基因表达存在转录水平和转录后水平两种调控机制,主要受细胞内铁浓度的负向调控.SFT可能在脑铁代谢中具有重要作用.     

MR brain image analysis in dementia: From quantitative imaging biomarkers to ageing brain models and imaging genetics

MR brain image analysis has constantly been a hot topic research area in medical image analysis over the past two decades. In this article, it is discussed how the field developed from the construction of tools for automatic quantification of brain morphology, function, connectivity and pathology, to creating models of the ageing brain in normal ageing and disease, and tools for integrated analysis of imaging and genetic data. The current and future role of the field in improved understanding of the development of neurodegenerative disease is discussed, and its potential for aiding in early and differential diagnosis and prognosis of different types of dementia. For the latter, the use of reference imaging data and reference models derived from large clinical and population imaging studies, and the application of machine learning techniques on these reference data, are expected to play a key role.     

脑受体显像临床研究现状与进展

目前受体显像已从长期实验室基础研究进入临床应用研究阶段,脑受体显像更是得到了长足的发展.利用放射性核素进行人脑受体显像,是分子生物学和核医学结合产生的新医学示踪技术的分子医学,即分子核医学将用于脑科学研究的新技术,是分子影像学技术在脑科学研究及应用的一个重要组成部分,具有广阔的应用前景.     

Phenotype discovery from population brain imaging

Neuroimaging allows for the non-invasive study of the brain in rich detail. Data-driven discovery of patterns of population variability in the brain has the potential to be extremely valuable for early disease diagnosis and understanding the brain. The resulting patterns can be used as imaging-derived phenotypes (IDPs), and may complement existing expert-curated IDPs. However, population datasets, comprising many different structural and functional imaging modalities from thousands of subjects, provide a computational challenge not previously addressed. Here, for the first time, a multimodal independent component analysis approach is presented that is scalable for data fusion of voxel-level neuroimaging data in the full UK Biobank (UKB) dataset, that will soon reach 100,000 imaged subjects. This new computational approach can estimate modes of population variability that enhance the ability to predict thousands of phenotypic and behavioural variables using data from UKB and the Human Connectome Project. A high-dimensional decomposition achieved improved predictive power compared with widely-used analysis strategies, single-modality decompositions and existing IDPs. In UKB data (14,503 subjects with 47 different data modalities), many interpretable associations with non-imaging phenotypes were identified, including multimodal spatial maps related to fluid intelligence, handedness and disease, in some cases where IDP-based approaches failed.     

基于知识库的脑功能成像诊断模型初探

本文根据脑功能成像的特点,引入知识工程的知识表示理论,通过一种基于知识的树状表示法描述该问题,并在此基础上表示辅助诊断中的规则,从而形成问题的知识库.本文提出一种基于Prolog语言表示的知识库建立的方法,从而实现脑功能成像辅助诊断模型.     

Perfusion MR imaging of brain tumors

Brain tumors rank second as the cause of cancer-related deaths in children and adults younger than 34 years old, and they are seen in adults of all ages. Primary malignant brain tumors are associated with the third highest cancer-related mortality rate and a disproportionate level of disability and morbidity. Considering this, accurate diagnosis and grading of brain tumors are critical to determining prognosis and therapy. Equally important is to evaluate for tumor status during therapy to assess for therapeutic response and treatment-related complications. Brain tumors can be characterized as a heterogeneous group of neoplasm with a correspondingly wide variation in malignant phenotype and a diverse array of imaging features. Magnetic resonance (MR) imaging with intravenous contrast agent is the test of choice to diagnose and monitor brain tumors before, during, and after therapy. Recent advances in imaging methods such as diffusion-weighted imaging, perfusion imaging, and spectroscopic imaging all have in common the ability to provide quantitative cellular, hemodynamic, and metabolic information that may enhance our understanding of brain tumor biology, help us to better assess treatment response, more accurately determine tumor activity during therapy, and differentiate recurrent tumor and treatment related complications. In this article, we will review the basics of brain tumor imaging and focus on the role of perfusion MR imaging in improving accurate diagnosis and monitoring brain tumors during therapy. Both strengths and shortcomings of perfusion MR imaging over standard anatomic MR imaging will be discussed as will important pitfalls of the technique.     

MR imaging of neonatal brain infections

Infections of the brain in the postnatal period differ from those in older children as a result of a combination of distinct epidemiologic factors in general, and immaturity of neonatal brain and immunologic host response in particular. It has been recognized that clinical and neurologic signs are often nonspecific, sometimes scarce, and seldom correlate with the extent of neuroimaging findings, thus warranting an early MR imaging examination in the course of the disease, enabling rapid therapy institution and better clinical outcome. This article reviews most of postnatal pathogen agents involved in neonatal brain infections, related physiopathology, and neuroimaging findings.     

Functional brain imaging of trigeminal neuralgia

We used functional magnetic resonance imaging (fMRI) to analyze changes in brain activity associated with stimulation of the cutaneous trigger zone in patients with classic trigeminal neuralgia (CTN). Fifteen consecutive patients with CTN in the second or third division of the nerve, were included in this study. The fMRI paradigm consisted of light tactile stimuli of the trigger zone and the homologous contralateral area. Stimulation of the affected side induced pain in seven patients, but was not painful in eight patients on the day of the experiment. Painful stimuli were associated with significantly increased activity in the spinal trigeminal nucleus (SpV), thalamus, primary and secondary somatosensory cortices (S1, S2), anterior cingulate cortex (ACC), insula, premotor/motor cortex, prefrontal areas, putamen, hippocampus and brainstem. Nonpainful stimulation of the trigger zone activated all but three of these structures (SpV, brainstem and ACC). After a successful surgical treatment, activation induced by stimulation of the operated side was confined to S1 and S2. Our data demonstrate the pathological hyperexcitability of the trigeminal nociceptive system, including the second order trigeminal sensory neurons during evoked attacks of CTN. Such sensitization may depend on pain modulatory systems involving both the brainstem (i.e. periaqueductal gray and adjacent structures) and interconnected cortical structures (i.e. ACC). The fact that large portions of the classical ‘pain neuromatrix’ were also activated during nonpainful stimulation of the trigger zone, could reflect a state of maintained sensitization of the trigeminal nociceptive systems in CTN.