Lester Kwock

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Colloid cysts are relatively rare intracranial lesions located in the rostral aspect of the third ventricle. They may produce acute hydrocephalus, brain herniation, and lead to death. Although the clinical and imaging features of colloid cysts are well known, their etiology and the factors responsible for their imaging features continue to be a subject of(More)
Magnetic resonance (MR) spectroscopy has received little attention from the clinical radiology community. Indeed, most MR spectroscopic studies are performed by a small and dedicated group of individuals, mostly basic scientists. This behavior is partly because MR spectroscopy does not produce “pictures” but results in “graphs,” and until lately, it could(More)
BACKGROUND AND PURPOSE In a limited number of patients, the level of myo-inositol (MI), as seen by proton magnetic resonance spectroscopy (HMRS), has been shown to differ for gliomas of different histologic grades. We sought to determine if MI levels correlate with cerebral astrocytoma grade. METHODS Five control subjects, 14 patients with low-grade(More)
Conveying data uncertainty in visualizations is crucial for preventing viewers from drawing conclusions based on untrustworthy data points. This paper proposes a methodology for efficiently generating density plots of uncertain multivariate data sets that draws viewers to preattentively identify values of high certainty while not calling attention to(More)
We present a user study quantifying the effectiveness of Scaled Data-Driven Spheres (SDDS), a multivariate three-dimensional data set visualization technique. The user study compares SDDS, which uses separate sets of colored sphere glyphs to depict variable values, to superquadric glyphs, an alternative technique that maps all variable values to a single(More)
BACKGROUND AND PURPOSE Decreases in N-acetyl aspartate (NAA) as seen by proton MR spectroscopy are found in hippocampal sclerosis, and elevated levels of lipids/lactate have been observed after electroconvulsive therapy. Our purpose was to determine whether increased levels of lipids/lactate are found in patients with acute seizures of hippocampal origin.(More)
Proton magnetic resonance spectroscopy (MRS) and neuropsychological testing were conducted on 8 children with attention-deficit/hyperactivity disorder (ADHD-H), with no learning disabilities or comorbidities and 8 controls. Magnetic resonance spectroscopy revealed increased Glutamate/Glutamine in both frontal areas, and increased N-acetyl aspartate and(More)
BACKGROUND AND PURPOSE Bipolar affective disorder (BPAD) can have its onset during childhood, but the diagnosis may be difficult to establish on the basis of clinical findings alone. Our purpose was to determine whether proton MR spectroscopy can be used to identify abnormalities in the brain of children with BPAD. METHODS Ten children, ages 6 to 12(More)
The basic principles of proton MR spectroscopy as well as newer and more advanced related techniques are reviewed. Spectroscopy is capable of differentiating normal from pathologic brain and provides tissue specificity greater than that of imaging in many instances. Spectroscopic mapping allows for the visualization of the concentration of different(More)