625,535 research outputs found
Methods and Approaches for Characterizing Learning Related Changes Observed in functional MRI Data — A Review
Brain imaging data have so far revealed a wealth of information about neuronal circuits involved in higher mental functions like memory, attention, emotion, language etc. Our efforts are toward understanding the learning related effects in brain activity during the acquisition of visuo-motor sequential skills. The aim of this paper is to survey various methods and approaches of analysis that allow the characterization of learning related changes in fMRI data. Traditional imaging analysis using the Statistical Parametric Map (SPM) approach averages out temporal changes and presents overall differences between different stages of learning. We outline other potential approaches for revealing learning effects such as statistical time series analysis, modelling of haemodynamic response function and independent component analysis. We present example case studies from our visuo-motor sequence learning experiments to describe application of SPM and statistical time series analyses. Our review highlights that the problem of characterizing learning induced changes in fMRI data remains an interesting and challenging open research problem
Tensor Regression with Applications in Neuroimaging Data Analysis
Classical regression methods treat covariates as a vector and estimate a
corresponding vector of regression coefficients. Modern applications in medical
imaging generate covariates of more complex form such as multidimensional
arrays (tensors). Traditional statistical and computational methods are proving
insufficient for analysis of these high-throughput data due to their ultrahigh
dimensionality as well as complex structure. In this article, we propose a new
family of tensor regression models that efficiently exploit the special
structure of tensor covariates. Under this framework, ultrahigh dimensionality
is reduced to a manageable level, resulting in efficient estimation and
prediction. A fast and highly scalable estimation algorithm is proposed for
maximum likelihood estimation and its associated asymptotic properties are
studied. Effectiveness of the new methods is demonstrated on both synthetic and
real MRI imaging data.Comment: 27 pages, 4 figure
Statistical Image Reconstruction for High-Throughput Thermal Neutron Computed Tomography
Neutron Computed Tomography (CT) is an increasingly utilised non-destructive
analysis tool in material science, palaeontology, and cultural heritage. With
the development of new neutron imaging facilities (such as DINGO, ANSTO,
Australia) new opportunities arise to maximise their performance through the
implementation of statistically driven image reconstruction methods which have
yet to see wide scale application in neutron transmission tomography. This work
outlines the implementation of a convex algorithm statistical image
reconstruction framework applicable to the geometry of most neutron tomography
instruments with the aim of obtaining similar imaging quality to conventional
ramp filtered back-projection via the inverse Radon transform, but using a
lower number of measured projections to increase object throughput. Through
comparison of the output of these two frameworks using a tomographic scan of a
known 3 material cylindrical phantom obtain with the DINGO neutron radiography
instrument (ANSTO, Australia), this work illustrates the advantages of
statistical image reconstruction techniques over conventional filter
back-projection. It was found that the statistical image reconstruction
framework was capable of obtaining image estimates of similar quality with
respect to filtered back-projection using only 12.5% the number of projections,
potentially increasing object throughput at neutron imaging facilities such as
DINGO eight-fold
A framework for the statistical analysis of mass spectrometry imaging experiments
Mass spectrometry (MS) imaging is a powerful investigation technique for a wide range of biological applications such as molecular histology of tissue, whole body sections, and bacterial films , and biomedical applications such as cancer diagnosis. MS imaging visualizes the spatial distribution of molecular ions in a sample by repeatedly collecting mass spectra across its surface, resulting in complex, high-dimensional imaging datasets. Two of the primary goals of statistical analysis of MS imaging experiments are classification (for supervised experiments), i.e. assigning pixels to pre-defined classes based on their spectral profiles, and segmentation (for unsupervised experiments), i.e. assigning pixels to newly discovered segments with relatively homogenous and distinct spectral profiles. To accomplish these goals, this research provides both statistical methods and statistical computing tools. First, we propose a novel spatial shrunken centroids framework for performing classification and segmentation of MS imaging experiments with feature selection. Spatial shrunken centroids combines spatial smoothing with statistical regularization in a model-based framework appropriate for both supervised and unsupervised settings. Second, we provide Cardinal, a free and open-source R package for processing, visualization, and statistical analysis of MS imaging experiments. Cardinal is the first R package designed specifically for MS imaging, and the first software for MS imaging that focuses specifically on experiments and statistical analysis. In addition to providing tools for statistical analysis, it also provides infrastructure to enable other statisticians to more easily develop new methods for MS imaging experiments. Lastly, to enable scalability of Cardinal to larger-than-memory datasets, we provide matter, a free and open-source R package for statistical computing with structured datasets-on-disk, such as MS imaging data files. Together, spatial shrunken centroids, Cardinal, and matter aim to allow scalable statistical analysis for high-resolution, high-throughput MS imaging experiments
Learning associations between clinical information and motion-based descriptors using a large scale MR-derived cardiac motion atlas
The availability of large scale databases containing imaging and non-imaging
data, such as the UK Biobank, represents an opportunity to improve our
understanding of healthy and diseased bodily function. Cardiac motion atlases
provide a space of reference in which the motion fields of a cohort of subjects
can be directly compared. In this work, a cardiac motion atlas is built from
cine MR data from the UK Biobank (~ 6000 subjects). Two automated quality
control strategies are proposed to reject subjects with insufficient image
quality. Based on the atlas, three dimensionality reduction algorithms are
evaluated to learn data-driven cardiac motion descriptors, and statistical
methods used to study the association between these descriptors and non-imaging
data. Results show a positive correlation between the atlas motion descriptors
and body fat percentage, basal metabolic rate, hypertension, smoking status and
alcohol intake frequency. The proposed method outperforms the ability to
identify changes in cardiac function due to these known cardiovascular risk
factors compared to ejection fraction, the most commonly used descriptor of
cardiac function. In conclusion, this work represents a framework for further
investigation of the factors influencing cardiac health.Comment: 2018 International Workshop on Statistical Atlases and Computational
Modeling of the Hear
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