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Neurosurgery Clinics of North America Apr 2011Blood Oxygen Level Dependent (BOLD) functional magnetic resonance imaging (fMRI) depicts changes in deoxyhemoglobin concentration consequent to task-induced or... (Review)
Review
Blood Oxygen Level Dependent (BOLD) functional magnetic resonance imaging (fMRI) depicts changes in deoxyhemoglobin concentration consequent to task-induced or spontaneous modulation of neural metabolism. Since its inception in 1990, this method has been widely employed in thousands of studies of cognition for clinical applications such as surgical planning, for monitoring treatment outcomes, and as a biomarker in pharmacologic and training programs. More recently, attention is turning to the use of pattern classification and other statistical methods to draw increasingly complex inferences about cognitive brain states from fMRI data. This article reviews the methods, challenges, and future of fMRI.
Topics: Animals; Brain; Brain Chemistry; History, 20th Century; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Oxygen
PubMed: 21435566
DOI: 10.1016/j.nec.2010.11.001 -
Frontiers in Bioscience (Elite Edition) Jun 2014In this review article, conventional brain MRI and advanced MRI techniques in Parkinson`s disease (PD) are discussed, with emphasis on clinical relevance. Conventional... (Review)
Review
In this review article, conventional brain MRI and advanced MRI techniques in Parkinson`s disease (PD) are discussed, with emphasis on clinical relevance. Conventional brain MRI sequences generally demonstrate limited abnormalities specific for PD and in clinical practice brain MRI is mainly used to exclude other pathology. Possibly, brain MRI at higher magnetic field strengths could provide new diagnostic markers. In recent years, new imaging techniques such as susceptibility weighted imaging (SWI), diffusion (tensor) MRI, magnetization transfer imaging (MTI), and functional MRI (f-MRI) have been applied to patient cohorts with PD to improve understanding of pathophysiologic changes, including functional connectivity. These advanced MRI techniques hold promise to provide additional diagnostic markers for early stage PD, as demonstrated by diffusional changes in the orbital-frontal region in the pre-motor phase of PD. Whether these advanced MRI techniques provide new diagnostic markers for early stage PD, remains a debate. Standardization of scanning protocols and post-processing methods, and validation of diagnostic criteria is crucial for these advanced MRI techniques. For this, well designed prospective clinical cohort studies are needed.
Topics: Brain; Diffusion Magnetic Resonance Imaging; Humans; Magnetic Resonance Imaging; Parkinson Disease
PubMed: 24896211
DOI: 10.2741/E711 -
Chinese Clinical Oncology Aug 2017Glioblastoma, the most common and most rapidly progressing primary malignant tumor of the central nervous system, continues to portend a dismal prognosis, despite... (Review)
Review
Glioblastoma, the most common and most rapidly progressing primary malignant tumor of the central nervous system, continues to portend a dismal prognosis, despite improvements in diagnostic and therapeutic strategies over the last 20 years. The standard of care radiographic characterization of glioblastoma is magnetic resonance imaging (MRI), which is a widely utilized examination in the diagnosis and post-treatment management of patients with glioblastoma. Basic MRI modalities available from any clinical scanner, including native T1-weighted (T1w) and contrast-enhanced (T1CE), T2-weighted (T2w), and T2-fluid-attenuated inversion recovery (T2-FLAIR) sequences, provide critical clinical information about various processes in the tumor environment. In the last decade, advanced MRI modalities are increasingly utilized to further characterize glioblastomas more comprehensively. These include multi-parametric MRI sequences, such as dynamic susceptibility contrast (DSC), dynamic contrast enhancement (DCE), higher order diffusion techniques such as diffusion tensor imaging (DTI), and MR spectroscopy (MRS). Significant efforts are ongoing to implement these advanced imaging modalities into improved clinical workflows and personalized therapy approaches. Functional MRI (fMRI) and tractography are increasingly being used to identify eloquent cortices and important tracts to minimize postsurgical neuro-deficits. A contemporary review of the application of standard and advanced MRI in clinical neuro-oncologic practice is presented here.
Topics: Brain Neoplasms; Diffusion Magnetic Resonance Imaging; Diffusion Tensor Imaging; Glioblastoma; Humans; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Prognosis; Sensitivity and Specificity
PubMed: 28841802
DOI: 10.21037/cco.2017.06.28 -
NeuroImage Aug 2012The rapid development of fMRI was paralleled early on by the adaptation of MR spectroscopic imaging (MRSI) methods to quantify water relaxation changes during brain... (Review)
Review
The rapid development of fMRI was paralleled early on by the adaptation of MR spectroscopic imaging (MRSI) methods to quantify water relaxation changes during brain activation. This review describes the evolution of multi-echo acquisition from high-speed MRSI to multi-echo EPI and beyond. It highlights milestones in the development of multi-echo acquisition methods, such as the discovery of considerable gains in fMRI sensitivity when combining echo images, advances in quantification of the BOLD effect using analytical biophysical modeling and interleaved multi-region shimming. The review conveys the insight gained from combining fMRI and MRSI methods and concludes with recent trends in ultra-fast fMRI, which will significantly increase temporal resolution of multi-echo acquisition.
Topics: Brain; Brain Mapping; History, 20th Century; History, 21st Century; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy
PubMed: 22056458
DOI: 10.1016/j.neuroimage.2011.10.057 -
Sensors (Basel, Switzerland) Mar 2022Simultaneous EEG-fMRI has developed into a mature measurement technique in the past 25 years. During this time considerable technical and analytical advances have been... (Review)
Review
Simultaneous EEG-fMRI has developed into a mature measurement technique in the past 25 years. During this time considerable technical and analytical advances have been made, enabling valuable scientific contributions to a range of research fields. This review will begin with an introduction to the measurement principles involved in EEG and fMRI and the advantages of combining these methods. The challenges faced when combining the two techniques will then be considered. An overview of the leading application fields where EEG-fMRI has made a significant contribution to the scientific literature and emerging applications in EEG-fMRI research trends is then presented.
Topics: Electroencephalography; Magnetic Resonance Imaging
PubMed: 35336434
DOI: 10.3390/s22062262 -
NeuroImage Feb 2020Functional magnetic resonance imaging (fMRI) studies in animal models provide invaluable information regarding normal and abnormal brain function, especially when...
Functional magnetic resonance imaging (fMRI) studies in animal models provide invaluable information regarding normal and abnormal brain function, especially when combined with complementary stimulation and recording techniques. The echo planar imaging (EPI) pulse sequence is the most common choice for fMRI investigations, but it has several shortcomings. EPI is one of the loudest sequences and very prone to movement and susceptibility-induced artefacts, making it suboptimal for awake imaging. Additionally, the fast gradient-switching of EPI induces disrupting currents in simultaneous electrophysiological recordings. Therefore, we investigated whether the unique features of Multi-Band SWeep Imaging with Fourier Transformation (MB-SWIFT) overcome these issues at a high 9.4 T magnetic field, making it a potential alternative to EPI. MB-SWIFT had 32-dB and 20-dB lower peak and average sound pressure levels, respectively, than EPI with typical fMRI parameters. Body movements had little to no effect on MB-SWIFT images or functional connectivity analyses, whereas they severely affected EPI data. The minimal gradient steps of MB-SWIFT induced significantly lower currents in simultaneous electrophysiological recordings than EPI, and there were no electrode-induced distortions in MB-SWIFT images. An independent component analysis of the awake rat functional connectivity data obtained with MB-SWIFT resulted in near whole-brain level functional parcellation, and simultaneous electrophysiological and fMRI measurements in isoflurane-anesthetized rats indicated that MB-SWIFT signal is tightly linked to neuronal resting-state activity. Therefore, we conclude that the MB-SWIFT sequence is a robust preclinical brain mapping tool that can overcome many of the drawbacks of conventional EPI fMRI at high magnetic fields.
Topics: Anesthetics, Inhalation; Animals; Artifacts; Echo-Planar Imaging; Electroencephalography; Fourier Analysis; Functional Neuroimaging; Isoflurane; Magnetic Resonance Imaging; Male; Movement; Noise; Rats; Rats, Wistar; Unconsciousness; Wakefulness
PubMed: 31730923
DOI: 10.1016/j.neuroimage.2019.116338 -
Biological Psychiatry Mar 2023Altered or atypical functional connectivity as measured with functional magnetic resonance imaging (fMRI) is a hallmark feature of brain connectopathy in psychiatric,... (Review)
Review
Altered or atypical functional connectivity as measured with functional magnetic resonance imaging (fMRI) is a hallmark feature of brain connectopathy in psychiatric, developmental, and neurological disorders. However, the biological underpinnings and etiopathological significance of this phenomenon remain unclear. The recent development of MRI-based techniques for mapping brain function in rodents provides a powerful platform to uncover the determinants of functional (dys)connectivity, whether they are genetic mutations, environmental risk factors, or specific cellular and circuit dysfunctions. Here, we summarize the recent contribution of rodent fMRI toward a deeper understanding of network dysconnectivity in developmental and psychiatric disorders. We highlight substantial correspondences in the spatiotemporal organization of rodent and human fMRI networks, supporting the translational relevance of this approach. We then show how this research platform might help us comprehend the importance of connectional heterogeneity in complex brain disorders and causally relate multiscale pathogenic contributors to functional dysconnectivity patterns. Finally, we explore how perturbational techniques can be used to dissect the fundamental aspects of fMRI coupling and reveal the causal contribution of neuromodulatory systems to macroscale network activity, as well as its altered dynamics in brain diseases. These examples outline how rodent functional imaging is poised to advance our understanding of the bases and determinants of human functional dysconnectivity.
Topics: Animals; Humans; Rodentia; Brain; Brain Mapping; Magnetic Resonance Imaging; Schizophrenia
PubMed: 36517282
DOI: 10.1016/j.biopsych.2022.09.008 -
NeuroImage Mar 2018Functional MRI (fMRI) benefits from both increased sensitivity and specificity with increasing magnetic field strength, making it a key application for Ultra-High Field... (Review)
Review
Functional MRI (fMRI) benefits from both increased sensitivity and specificity with increasing magnetic field strength, making it a key application for Ultra-High Field (UHF) MRI scanners. Most UHF-fMRI studies utilize the dramatic increases in sensitivity and specificity to acquire high-resolution data reaching sub-millimeter scales, which enable new classes of experiments to probe the functional organization of the human brain. This review article surveys advanced data analysis strategies developed for high-resolution fMRI at UHF. These include strategies designed to mitigate distortion and artifacts associated with higher fields in ways that attempt to preserve spatial resolution of the fMRI data, as well as recently introduced analysis techniques that are enabled by these extremely high-resolution data. Particular focus is placed on anatomically-informed analyses, including cortical surface-based analysis, which are powerful techniques that can guide each step of the analysis from preprocessing to statistical analysis to interpretation and visualization. New intracortical analysis techniques for laminar and columnar fMRI are also reviewed and discussed. Prospects for single-subject individualized analyses are also presented and discussed. Altogether, there are both specific challenges and opportunities presented by UHF-fMRI, and the use of proper analysis strategies can help these valuable data reach their full potential.
Topics: Brain; Functional Neuroimaging; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging
PubMed: 28461062
DOI: 10.1016/j.neuroimage.2017.04.053 -
ELife Apr 2022Combining techniques that track blood oxygenation and biochemicals during neuronal activity reveals how the brain computes perceived and unperceived stimuli.
Combining techniques that track blood oxygenation and biochemicals during neuronal activity reveals how the brain computes perceived and unperceived stimuli.
Topics: Brain; Brain Mapping; Magnetic Resonance Imaging
PubMed: 35467531
DOI: 10.7554/eLife.78327 -
Drug Discovery Today Feb 2018Functional magnetic resonance imaging (fMRI) has been known for over a decade to have the potential to greatly enhance the process of developing novel therapeutic drugs... (Review)
Review
Functional magnetic resonance imaging (fMRI) has been known for over a decade to have the potential to greatly enhance the process of developing novel therapeutic drugs for prevalent health conditions. However, the use of fMRI in drug development continues to be relatively limited because of a variety of technical, biological, and strategic barriers that continue to limit progress. Here, we briefly review the roles that fMRI can have in the drug development process and the requirements it must meet to be useful in this setting. We then provide an update on our current understanding of the strengths and limitations of fMRI as a tool for drug developers and recommend activities to enhance its utility.
Topics: Animals; Drug Discovery; Humans; Magnetic Resonance Imaging; Pharmaceutical Preparations
PubMed: 29154758
DOI: 10.1016/j.drudis.2017.11.012