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OBJECTIVE To assess patterns of regional brain activation in response to varying working memory loads shortly after mild traumatic brain injury (MTBI). BACKGROUND Many individuals complain of memory difficulty shortly after MTBI. Memory performance in these individuals can be normal despite these complaints. METHODS Brain activation patterns in response(More)
Wavelet transforms are multiresolution decompositions that can be used to analyze signals and images. They describe a signal by the power at each scale and position. Edges can be located very effectively in the wavelet transform domain. A spatially selective noise filtration technique based on the direct spatial correlation of the wavelet transform at(More)
Accurate characterization of harmonic tissue motion for realistic tissue geometries and property distributions requires knowledge of the full three-dimensional displacement field because of the asymmetric nature of both the boundaries of the tissue domain and the location of internal mechanical heterogeneities. The implications of this for magnetic(More)
Experience suggests the existence of a connection between the contrast of a grayscale image and the gradient magnitude of intensity edges in the neighborhood where the contrast is measured. This observation motivates the development of edge-based contrast enhancement techniques. In this paper, we present a simple and eeective method for image contrast(More)
Many studies of monozygotic (MZ) twins have revealed evidence of genetic influences on intellectual functions and their derangement in certain neurologic and psychiatric diseases afflicting the forebrain. Relatively little is known about genetic influences on the size and shape of the human forebrain and its gross morphologic subdivisions. Using MRI and(More)
The simultaneous multislice technique is a method of imaging multiple parallel slices with the number of echoes normally used to image a single slice. Images of 16 slices have been obtained from a single 128-echo acquisition. The distance between the slices can be decreased to approximately 15% of the field of view in the readout direction with the cost of(More)
Magnetic resonance elastography (MRE) is an important new method used to measure the elasticity or stiffness of tissues in vivo. While there are many possible applications of MRE, breast cancer detection and classification is currently the most common. Several groups have been developing methods based on MR and ultrasound (US). MR or US is used to estimate(More)
Many pathologies alter the mechanical properties of tissue. Magnetic resonance elastography (MRE) has been developed to noninvasively characterize these quantities in vivo. Typically, small vibrations are induced in the tissue of interest with an external mechanical actuator. The resulting displacements are measured with phase contrast sequences and are(More)
Results of recent functional magnetic resonance imaging (fMRI) studies of memory are not entirely consistent with lesion studies. Furthermore, although imaging probes have identified neural systems associated with processing novel visual episodic information, auditory verbal memory using a novel/familiar paradigm has not yet been examined. To address this(More)