Abstract:Multi-subject functional magnetic resonance imaging (fMRI) data has been increasingly used to study the population-wide relationship between human brain activity and individual biological or behavioral traits. A common method is to regress the scalar individual response on imaging predictors, known as a scalar-on-image (SI) regression. Analysis and computation of such massive and noisy data with complex spatio-temporal correlation structure is challenging. In this article, motivated by a psychological study on… Show more
“…Recent studies of scalar‐on‐image regression models in neuroimaging data applications incorporated the entire image (see, for example, Reiss and Ogden (), Li et al . () and Goldsmith et al . ()); such methods are not applicable in the current setting since MRIs of GBM tumours cannot even be coregistered.…”
Summary.
We propose a curve-based Riemannian geometric approach for general shape-based statistical analyses of tumours obtained from radiologic images. A key component of the framework is a suitable metric that enables comparisons of tumour shapes, provides tools for computing descriptive statistics and implementing principal component analysis on the space of tumour shapes and allows for a rich class of continuous deformations of a tumour shape. The utility of the framework is illustrated through specific statistical tasks on a data set of radiologic images of patients diagnosed with glioblastoma multiforme, a malignant brain tumour with poor prognosis. In particular, our analysis discovers two patient clusters with very different survival, subtype and genomic characteristics. Furthermore, it is demonstrated that adding tumour shape information to survival models containing clinical and genomic variables results in a significant increase in predictive power.
“…Recent studies of scalar‐on‐image regression models in neuroimaging data applications incorporated the entire image (see, for example, Reiss and Ogden (), Li et al . () and Goldsmith et al . ()); such methods are not applicable in the current setting since MRIs of GBM tumours cannot even be coregistered.…”
Summary.
We propose a curve-based Riemannian geometric approach for general shape-based statistical analyses of tumours obtained from radiologic images. A key component of the framework is a suitable metric that enables comparisons of tumour shapes, provides tools for computing descriptive statistics and implementing principal component analysis on the space of tumour shapes and allows for a rich class of continuous deformations of a tumour shape. The utility of the framework is illustrated through specific statistical tasks on a data set of radiologic images of patients diagnosed with glioblastoma multiforme, a malignant brain tumour with poor prognosis. In particular, our analysis discovers two patient clusters with very different survival, subtype and genomic characteristics. Furthermore, it is demonstrated that adding tumour shape information to survival models containing clinical and genomic variables results in a significant increase in predictive power.
“…To avoid the phase transition boundary, we adopt an analytical approach similar to Li et al . () to quantify the value for the bounds of both β 0 p and β 1 p . An outline of the bound derivation is given below in Section .…”
Section: The Spatially Varying Auto‐regressive Order Modelmentioning
confidence: 97%
“…Here, we adopt an approach that is similar to that considered in Li et al . () and construct some theoretical bounds to prevent phase transition. The resulting hyperparameter values are then chosen as fixed values within the estimated bounds.…”
Section: The Spatially Varying Auto‐regressive Order Modelmentioning
confidence: 99%
“…To avoid the phase transition problem that is associated with the Ising model, we derive theoretical bounds as in Li et al . () and use these bounds to prevent critical slowing of the algorithm. We compare our model with the GLM–AR model of Penny et al .…”
Summary
Statistical modelling of functional magnetic resonance imaging data is challenging as the data are both spatially and temporally correlated. Spatially, measurements are taken at thousands of contiguous regions, called voxels, and temporally measurements are taken at hundreds of time points at each voxel. Recent advances in Bayesian hierarchical modelling have addressed the challenges of spatiotemporal structure in functional magnetic resonance imaging data with models incorporating both spatial and temporal priors for signal and noise. Whereas there has been extensive research on modelling the functional magnetic resonance imaging signal (i.e. the convolution of the experimental design with the functional choice for the haemodynamic response function) and its spatial variability, less attention has been paid to realistic modelling of the temporal dependence that typically exists within the functional magnetic resonance imaging noise, where a low order auto‐regressive process is typically adopted. Furthermore, the auto‐regressive order is held constant across voxels (e.g. AR(1) at each voxel). Motivated by an event‐related functional magnetic resonance imaging experiment, we propose a novel hierarchical Bayesian model with automatic selection of the auto‐regressive orders of the noise process that vary spatially over the brain. With simulation studies we show that our model is more statistically efficient and we apply it to our motivating example.
“…Many existing supervised learning and variable selection methods (Hastie et al, 2009; Clarke et al, 2009; Fan and Fan, 2008; Bickel and Levina, 2004; Buhlmann et al, 2012; Tibshirani, 1996), however, can be sub-optimal for high-dimensional prediction problem considered here, since the effect of high dimensional data x (e.g., image biomarker) on y is often non-sparse (Li et al, 2015; Zhou et al, 2013; Friston, 2009; Hinrichs et al, 2009). First, the existing unstructured regularization methods can suffer from diverging spectra and noise accumulation in high dimensional feature space (Reiss and Ogden, 2010; Bickel and Levina, 2004; Buhlmann et al, 2012; Fan and Fan, 2008), whereas the structured ones (e.g., fused Lasso or Ising prior) can be computationally challenging for high-dimensional imaging predictor (Vincent et al, 2011; Cuingnet et al, 2012; Fan et al, 2012; Goldsmith et al, 2014).…”
We propose a multiscale weighted principal component regression (MWPCR) framework for the use of high dimensional features with strong spatial features (e.g., smoothness and correlation) to predict an outcome variable, such as disease status. This development is motivated by identifying imaging biomarkers that could potentially aid detection, diagnosis, assessment of prognosis, prediction of response to treatment, and monitoring of disease status, among many others. The MWPCR can be regarded as a novel integration of principal components analysis (PCA), kernel methods, and regression models. In MWPCR, we introduce various weight matrices to prewhitten high dimensional feature vectors, perform matrix decomposition for both dimension reduction and feature extraction, and build a prediction model by using the extracted features. Examples of such weight matrices include an importance score weight matrix for the selection of individual features at each location and a spatial weight matrix for the incorporation of the spatial pattern of feature vectors. We integrate the importance score weights with the spatial weights in order to recover the low dimensional structure of high dimensional features. We demonstrate the utility of our methods through extensive simulations and real data analyses of the Alzheimer’s disease neuroimaging initiative (ADNI) data set.
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