Potential of advanced MR imaging techniques in the differential diagnosis of parkinsonism

The clinical differentiation of parkinsonian syndromes remains challenging not only for neurologists but also for movement disorder specialists. Conventional magnetic resonance imaging (cMRI) with the visual assessment of T2‐ and T1‐weighted imaging as well as different advanced MRI techniques offer objective measures, which may be a useful tool in the diagnostic work‐up of Parkinson's disease and atypical parkinsonian disorders (APDs). In clinical practice, cMRI is a well‐established method for the exclusion of symptomatic parkinsonism due to other pathologies. Over the past two decades, abnormalities in the basal ganglia and infratentorial structures have been shown especially in APDs not only by cMRI but also by different advanced MRI techniques, including methods to assess regional cerebral atrophy quantitatively such as magnetic resonance volumetry, proton magnetic resonance spectroscopy, diffusion‐weighted imaging, and magnetization transfer imaging. This article aims to review recent research findings on the role of advanced MRI techniques in the differential diagnosis of neurodegenerative parkinsonian disorders. © 2009 Movement Disorder Society     

Automated analysis of seizure semiology and brain electrical activity in presurgery evaluation of epilepsy: A focused survey

Epilepsy being one of the most prevalent neurological disorders, affecting approximately 50 million people worldwide, and with almost 30–40% of patients experiencing partial epilepsy being nonresponsive to medication, epilepsy surgery is widely accepted as an effective therapeutic option. Presurgical evaluation has advanced significantly using noninvasive techniques based on video monitoring, neuroimaging, and electrophysiological and neuropsychological tests; however, certain clinical settings call for invasive intracranial recordings such as stereoelectroencephalography (SEEG), aiming to accurately map the eloquent brain networks involved during a seizure. Most of the current presurgical evaluation procedures focus on semiautomatic techniques, where surgery diagnosis relies immensely on neurologists’ experience and their time‐consuming subjective interpretation of semiology or the manifestations of epilepsy and their correlation with the brain's electrical activity. Because surgery misdiagnosis reaches a rate of 30%, and more than one‐third of all epilepsies are poorly understood, there is an evident keen interest in improving diagnostic precision using computer‐based methodologies that in the past few years have shown near‐human performance. Among them, deep learning has excelled in many biological and medical applications, but has advanced insufficiently in epilepsy evaluation and automated understanding of neural bases of semiology. In this paper, we systematically review the automatic applications in epilepsy for human motion analysis, brain electrical activity, and the anatomoelectroclinical correlation to attribute anatomical localization of the epileptogenic network to distinctive epilepsy patterns. Notably, recent advances in deep learning techniques will be investigated in the contexts of epilepsy to address the challenges exhibited by traditional machine learning techniques. Finally, we discuss and propose future research on epilepsy surgery assessment that can jointly learn across visually observed semiologic patterns and recorded brain electrical activity.     

MR Intracranial Vessel Wall Imaging: A Systematic Review

The purpose of this systematic review is to identify trends and extent of variability in intracranial vessel wall MR imaging (VWI) techniques and protocols. Although variability in selection of protocol design and pulse sequence type is known, data on what and how protocols vary are unknown. Three databases were searched to identify publications using intracranial VWI. Publications were screened by predetermined inclusion/exclusion criteria. Technical development publications were scored for completeness of reporting using a modified Nature Reporting Summary Guideline to assess reproducibility. From 2,431 articles, 122 met the inclusion criteria. Trends over the last 23 years (1995‐2018) show increased use of 3‐Tesla MR (P < .001) and 3D volumetric T1‐weighted acquisitions (P < .001). Most (65%) clinical VWI publications report achieving a noninterpolated in‐plane spatial resolution of ≤.55 mm. In the last decade, an increasing number of technical development (n = 20) and 7 Tesla (n = 12) publications have been published, focused on pulse sequence development, improving cerebrospinal fluid suppression, scan efficiency, and imaging ex vivo specimen for histologic validation. Mean Reporting Summary Score for the technical development publications was high (.87, range: .63‐1.0) indicating strong scientific technical reproducibility. Innovative work continues to emerge to address implementation challenges. Gradual adoption into the research and scientific community was suggested by a shift in the name in the literature from “high‐resolution MR” to “vessel wall imaging,” specifying diagnostic intent. Insight into current practices and identifying the extent of technical variability in the literature will help to direct future clinical and technical efforts to address needs for implementation.     

Neuroimaging of attention deficit hyperactivity disorder: can new imaging findings be integrated in clinical practice?

Recent advances in neuroimaging research have helped elucidate the neurobiology of attention deficit hyperactivity disorder (ADHD) and the mechanisms by which medications used to treat ADHD exert their effects. The complex nature and array of imaging techniques, however, present challenges for the busy clinician in assessing possible clinical uses of brain imaging. Even though currently there are no accepted uses for imaging in diagnosing ADHD (other than ruling out identifiable medical or neurologic conditions that may mimic ADHD), this review introduces the main imaging techniques used to study ADHD, identifies relevant complexities facing psychiatric researchers in implementing neuroimaging techniques for clinical purposes, and provides benchmarks to help determine when imaging modalities have advanced to a point that they are deemed clinically useful.     

Imaging for the Diagnosis and Management of Traumatic Brain Injury

To understand the role of imaging in traumatic brain injury (TBI), it is important to appreciate that TBI encompasses a heterogeneous group of intracranial injuries and includes both insults at the time of impact and a deleterious secondary cascade of insults that require optimal medical and surgical management. Initial imaging identifies the acute primary insult that is essential to diagnosing TBI, but serial imaging surveillance is also critical to identifying secondary injuries such as cerebral herniation and swelling that guide neurocritical management. Computed tomography (CT) is the mainstay of TBI imaging in the acute setting, but magnetic resonance tomography (MRI) has better diagnostic sensitivity for nonhemorrhagic contusions and shear-strain injuries. Both CT and MRI can be used to prognosticate clinical outcome, and there is particular interest in advanced applications of both techniques that may greatly improve the sensitivity of conventional CT and MRI for both the diagnosis and prognosis of TBI.     

Wallerian Degeneration Beyond the Corticospinal Tracts: Conventional and Advanced MRI Findings

Wallerian degeneration (WD) is defined as progressive anterograde disintegration of axons and accompanying demyelination after an injury to the proximal axon or cell body. Since the 1980s and 1990s, conventional magnetic resonance imaging (MRI) sequences have been shown to be sensitive to changes of WD in the subacute to chronic phases. More recently, advanced MRI techniques, such as diffusion‐weighted imaging (DWI) and diffusion tensor imaging (DTI), have demonstrated some of earliest changes attributed to acute WD, typically on the order of days. In addition, there is increasing evidence on the value of advanced MRI techniques in providing important prognostic information related to WD. This article reviews the utility of conventional and advanced MRI techniques for assessing WD, by focusing not only on the corticospinal tract but also other neural tracts less commonly thought of, including corticopontocerebellar tract, dentate‐rubro‐olivary pathway, posterior column of the spinal cord, corpus callosum, limbic circuit, and optic pathway. The basic anatomy of these neural pathways will be discussed, followed by a comprehensive review of existing literature supported by instructive clinical examples. The goal of this review is for readers to become more familiar with both conventional and advanced MRI findings of WD involving important neural pathways, as well as to illustrate increasing utility of advanced MRI techniques in providing important prognostic information for various pathologies.     

Evaluation of gastrointestinal motility with MRI: Advances,challenges and opportunities

Dynamic magnetic resonance imaging (MRI) of gastrointestinal motility has developed rapidly over the past few years. The non‐invasive and non‐ionizing character of MRI is an important advantage together with the fact that it is fast and can visualize the entire gastrointestinal tract. Advances in imaging and quantification techniques have facilitated assessment of gastric, small intestinal, and colonic motility in a clinical setting. Automated quantitative motility assessment using dynamic MRI meets the need for non‐invasive techniques. Recently, studies have begun to examine this technique in patients, including those with IBD, pseudo‐obstruction and functional bowel disorders. Remaining challenges for clinical implementation are processing the large amount of data, standardization and validation of the numerous MRI metrics and subsequently assessment of the potential role of dynamic MRI. This review examines the methods, advances, and remaining challenges of evaluation of gastrointestinal motility with MRI. It accompanies an article by Khalaf et al. in this journal that describes a new protocol for assessment of pan‐intestinal motility in fasted and fed state in a single MRI session.     

颅内血管周细胞瘤的影像学特点及显微外科手术治疗

目的探讨颅内血管周细胞瘤(HPC)的影像学特点及显微外科手术方法。方法回顾性分析显微外科手术治疗的26例颅内HPC患者的临床资料;包括影像学检查、手术方法及手术疗效。结果16例颅内HPC患者术前影像学诊断与术后病理诊断一致,6例患者术前被误诊为脑膜瘤,4例患者误诊为血管母细胞瘤。手术效果:肿瘤全切除者17例,次全切除5例,部分切除4例,无死亡患者。全部患者术后均行局部放疗。术后随访6~42个月,3例患者肿瘤复发。结论颅内HPC的影像学表现具有一定特点,仔细分析其影像学特点可提高术前诊断率。根据肿瘤的影像学表现制定手术方案,以及娴熟的显微外科技术,术中控制好出血,是提高颅内HPC全切除率和提高手术疗效的关键。     

脑膜癌病

目的 探讨脑膜癌病(MC)的临床表现和诊断依据.方法 采用临床病例分析统计方法,对45例MC患者的临床资料进行回顾性研究.结果 MC以颅内高压和脑膜刺激征为主要临床表现,头CT及MRI平扫检查均无异常发现,脑脊液细胞学检查和头MRI增强扫描可有阳性发现.结论 MC临床表现缺乏特异性,早期诊断困难.头MRI增强扫描对诊断MC有一定的指导意义,反复脑脊液检查找到癌细胞是确诊的依据.     

Cerebral revascularization by endovascular techniques

The minimally invasive approach to managing patients with ischemic and hemorrhagic stroke by endovascular intervention has made tremendous progress over the past years. Early recognition of stroke, improved ability to accurately diagnose the site of pathological abnormality with advanced imaging techniques and advances in treatment alternatives have led to better patient outcomes. Endovascular techniques for cerebral revascularization, a leading new therapeutic approach in the treatment of cerebrovascular disease, play a major role in both the management of acute stroke and secondary prevention. Selective intra-arterial thrombolysis for acute stroke has been performed for more than two decades with increasing success. Neurovascular therapies for secondary prevention include angioplasty of extracranial and intracranial vessels, as well as procedures for arterial reconstruction.     

A multimodal diagnostic approach for lateralised rhythmic delta activity in the ictal‐interictal continuum∗

The ictal‐interictal continuum represents a diagnostic challenge even for expert neurrophysiologists, often requiring an additional multimodal diagnostic workup to understand its clinical significance. Lateralised rhythmic delta activity (LRDA) is an ictal‐interictal continuum pattern that has only recently been investigated and recognised as potentially ictogenic or sometimes even ictal. We describe a patient who presented with acute‐onset aphasia, initially suspected of having a stroke; advanced brain imaging with CT‐perfusion showed features suggesting regional left temporo‐parietal hyperperfusion and an EEG revealed LRDA with fluctuations and intermixed sharp waves in the same areas. Treatment with lacosamide caused both clinical and EEG improvement after a few hours, supporting the hypothesis that the EEG pattern represented an ictal/interictal phenomenon. In the literature, a correlation between metabolic/perfusion imaging and ictal‐interictal continuum patterns is described regarding lateralised periodic discharges but less studied for LRDA. In this case, we adopted a multimodal approach, integrating advanced imaging, EEG, clinical features, and response to therapy, to consider the overall clinical presentation as focal NCSE.     

Intraoperative fluorescent imaging of intracranial tumors: A review

A review of fluorescent imaging for intracranial neoplasms is presented. Complete resection of brain cancer is seldom possible because of the goal to preserve brain tissue and the inability to visualize individual infiltrative tumor cells. Verification of histology and identification of tumor invasion in macroscopically normal-appearing brain tissue determine prognosis after resection of malignant gliomas. Therefore, imaging modalities aim to facilitate intraoperative decision-making. Intraoperative fluorescent imaging techniques have the potential to enable precise histopathologic diagnosis and to detect tumor remnants in the operative field. Macroscopic fluorescence imaging is effective for gross tumor detection. Microscopic imaging techniques enhance the sensitivity of the macroscopic observations and provide real-time histological information. Further development of clinical grade fluorescent agents specifically targeting tumor cells could improve the diagnostic and prognostic yield of intraoperative imaging.     

Malformations of cortical development: current concepts and advanced neuroimaging review

Malformations of cortical development (MCD) result from disruptions in the complex process of the human brain cortex formation and are highly associated to severe epilepsy, neurodevelopmental delay and motor dysfunction. Nowadays, magnetic resonance imaging (MRI) is the cornerstone of the work-up of patients with epilepsy and modern advanced imaging techniques have improved not only our ability to detect and characterize cortical malformations, but also in identifying associated functional abnormalities that are far beyond the structural visualized lesions. Herein, we address the most currently used classifications of MCD and make a concise review of the embryological process of cortical development. Our main goal is to summarize recent advances and new trends in diagnostic imaging techniques concerning MCD. Thereafter, follows a brief discussion of specific disorders and their radiological features.     

Endovascular management of acute ischemic stroke: advances in patient and treatment selection

Selection of patients for acute-stroke therapy has traditionally been based on rigid time criteria in clinical trials. Recent advances in radiographic imaging have allowed clinicians to estimate brain physiology and thus utilize radiographic parameters to select patients for acute-stroke therapies. Both a better understanding and the quantification methods of salvageable tissue versus irreversibly injured tissue can help guide clinicians to which treatment modality to utilize. The evolution of endovascular techniques to treat acute stroke has resulted in treatment modalities that include mechanical and chemical methods to revascularize occluded cerebral arteries. Prior technical limitations to accessing distal-cerebral arteries have been partially overcome by modifications in technology. Patient and treatment-modality selection can help reduce hemorrhagic complication rates and also potentially increase revascularization rates, which may translate into improved clinical outcomes. We review the recent advances in radiographic imaging that have advanced patient selection in treating acute ischemic stroke and also consider current endovascular treatment options that are available to interventionalists performing these procedures.     

MRI for identification of progression in brain tumors: from morphology to function

For monitoring of brain tumors, it is crucial to identify progression or treatment failure early during follow-up to change treatment schemes and, thereby, optimize patient outcome. In the past years, several areas within the field of magnetic resonance (MR) have seen considerable advances: modern contrast media, advanced morphologic approaches and several functional techniques, for example, in the visualization of tumor perfusion or tumor cell metabolism. This review presents these recent advances by introducing the different techniques and outlining their benefit for identification of progression in brain tumors, with a focus on gliomas, metastases and meningiomas. After radiotherapy, MR spectroscopy helps to more accurately discriminate between radiation necrosis and glioma progression. In low-grade gliomas, perfusion MR techniques enable a more sensitive detection of anaplastic transformation than conventional MRI. Modern contrast media, as well as diffusion tensor imaging, allow for an improved tumor delineation and assessment of tumor extension. We will also highlight the biological background of these techniques, their applicability and current limitations. In conclusion, modern MRI techniques have been developed that are on the doorstep to be integrated in clinical routine.     

Imaging of intracranial haemorrhage

Intracranial haemorrhage can be a devastating disorder that requires rapid diagnosis and management. Neuroimaging studies are not only required for diagnosis but also provide important insights into the type of haemorrhage, the underlying aetiology, and the accompanying pathophysiology. Historically, CT has been the diagnostic imaging study of choice; however, there is a growing body of data that suggest that MRI is at least as sensitive as CT to detect haemorrhage in the hyperacute setting, and superior to CT in the subacute and chronic settings. Blood has characteristic appearances on both imaging modalities at each stage (acute, subacute, and chronic) and it is important that physicians are familiar with the appearance of various types of intracranial haemorrhage on CT and MRI and their clinical implications. In addition, new imaging applications, such as magnetic resonance spectroscopy and diffusion tensor imaging, are promising research techniques that have the potential to enhance our understanding of the tissue injury and recovery that result from intracranial haemorrhage.