Recommended Implementation of Quantitative Susceptibility Mapping for Clinical Research in The Brain: A Consensus of the ISMRM Electro-Magnetic Tissue Properties Study Group

This article provides recommendations for implementing quantitative susceptibility mapping (QSM) for clinical brain research. It is a consensus of the ISMRM Electro-Magnetic Tissue Properties Study Group. While QSM technical development continues to advance rapidly, the current QSM methods have been demonstrated to be repeatable and reproducible for generating quantitative tissue magnetic susceptibility maps in the brain. However, the many QSM approaches available give rise to the need in the neuroimaging community for guidelines on implementation. This article describes relevant considerations and provides specific implementation recommendations for all steps in QSM data acquisition, processing, analysis, and presentation in scientific publications. We recommend that data be acquired using a monopolar 3D multi-echo GRE sequence, that phase images be saved and exported in DICOM format and unwrapped using an exact unwrapping approach. Multi-echo images should be combined before background removal, and a brain mask created using a brain extraction tool with the incorporation of phase-quality-based masking. Background fields should be removed within the brain mask using a technique based on SHARP or PDF, and the optimization approach to dipole inversion should be employed with a sparsity-based regularization. Susceptibility values should be measured relative to a specified reference, including the common reference region of whole brain as a region of interest in the analysis, and QSM results should be reported with - as a minimum - the acquisition and processing specifications listed in the last section of the article. These recommendations should facilitate clinical QSM research and lead to increased harmonization in data acquisition, analysis, and reporting

Seeking the neural basis of grammar : English noun and verb morphological processing investigated with rapid event-related fMRI and intracortical electrophysiology

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Brain and Cognitive Sciences, 2003.Includes bibliographical references (v. 2, leaves 268-271).(cont.) the functionality of the fMRI data analysis and visualization tools used at Massachusetts General Hospital. I analyze and interpret an 18-subject fMRI experiment I ran using the new task design and software tools. Finally, I present preliminary findings on linguistic questions as well as the nature of fMRI signal, using direct Electrophysiological data recorded from electrodes implanted in the brains of two Epilepsy patients. These patients had electrodes implanted through or near classical language areas of their brains, as a necessary clinical step in locating and surgically removing the seizure-causing tissue. The main findings of this thesis are: 1.) Morphology alone can activate Broca's area, 2.) Other areas are involved, including BA47, anterior insula, and SMA, 3.) Broca's area and BA47 respond to application of abstract grammatical features, even without phonological manipulations, 4.) Morphophonological manipulation additionally recruits insula and SMA, 5.) While simply accessing nouns versus verbs may involve separable brain regions, inflectional processing of the two categories may be done by the same process, 6.) Regularly and Irregularly inflected verbs show a double dissociation of activation in frontal and medial regions, 7.) Processing of English noun more than verb morphology may rely on some contribution from number processing brain systems ...Inflectional morphology is the component of language concerned with changing a word's form to reflect context-specific meaning, such as the affixing of"-ed" for English verbs in the past tense, or adding "-s" in order to signal a noun's plural form. Although it is but one part of language, morphology may be useful as a model system for larger issues in language and cognition. Morphological processing touches on: the manipulation of memorized items (the vocabulary of words, and maybe word endings), the application and power of combinatorial rules (to generate correct forms, even of unknown words), and the binding of units of information into meaning. Morphology's relationship with other more traditional facets of language such as syntax (sentence structure) and semantics (meanings of individual words) is debated, as is the objective reality of grammatical categories (e.g. noun/verb) as well as combinatorial rules. Functional Magnetic Resonance Imaging (fMRI) is an exciting technique for peering into the brain and answering questions about its function. However, the technique has limited temporal and spatial resolution, and indexes the brain basis of cognition only indirectly, via blood response to cellular metabolism. In this thesis I propose a task for manipulating morphological production, embedded in a 2*2*3 design simultaneously varying grammatical class (nouns versus verbs), regularity of inflection (e.g. words like "walk" which take the stereotyped or regular ending "-ed", versus those like "bring" and "sing" which have idiosyncratic past tense forms), and three types of morphological task aimed to separate the assignment of grammatical features (e.g. present/past tense) from changes in word sound. I introduce and utilize software to extendby Nedim T. Sahin.S.M