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Paramagnetic and superparamagnetic substances are used as contrast agents to enhance proton relaxation in magnetic resonance imaging. This review summarizes the physics of contrast agents, specifically the mechanisms by which contrast agents enhance T1 and T2 relaxation. The purpose is to provide a background for understanding the behavior of existing(More)
Three-dimensional (3D) MR imaging of the knee is useful to detect cartilage abnormalities, although the tissue contrast in 3D gradient-recalled echo (GRE) sequences such as gradient-recalled acquisition in the steady state (GRASS) or fast low-angle shot (FLASH) is poor. T2 contrast can be added to a GRASS sequence by combining the signals from the first and(More)
Fast spin-echo (FSE) sequences are becoming popular for T2-weighted clinical imaging because they result in a severalfold reduction in imaging time and because they provide conventional spin-echo contrast for most tissues. Fat, however, has been observed to have anomalously high signal intensity on FSE images. The present study shows that the brighter fat(More)
Functional imaging of the non-human primate brain in awake animals is now feasible because of recent methodological advances. Here we detail our procedures for conducting functional MRI (fMRI) studies in rhesus monkeys. Our emphasis has been on analyzing drug-evoked responses within and across test groups, meaning that techniques have had to be developed(More)
Speed of visual word recognition is an important variable affecting linguistic competence. Although speed of visual word recognition varies widely between individuals, the neural basis of reaction time (RT) differences is poorly understood. Recently, a magnetic resonance technique called diffusion tensor imaging (DTI) has been shown to provide information(More)
We have analyzed female-sterile mutations at the X-linked loci fs(1)Nas and fs(1)ph which show allele-specific effects on egg shell structure and embryonic pattern formation. The majority of mutant alleles at both loci lead to a collapsed egg phenotype. The maternal effect lethal phenotype is characterized by cuticle defects resembling those found in three(More)
The segmental plan of the Drosophila embryo is already established at the blastoderm stage through the action of maternal effect genes which determine the polarity of the embryo and zygotically active genes involved in segmentation. We have analyzed the first example of a group of maternally acting genes which are necessary for establishing the(More)
A comparative double blind trial was undertaken of the efficacy of cephradine, amoxycillin and phenoxymethylpenicillin in the treatment of acute dentoalveolar abscesses. Patients were admitted to the trial with acute dentoalveolar abscesses with systemic involvement and assessments were made of pain, swelling, temperature and lymphadenopathy. After(More)
PURPOSE To test the hypothesis that the T2 shortening observed on MR images of the brain in patients with Parkinson and Huntington diseases is due to tissue iron deposition. METHODS Tissue iron and ferritin assays were performed on postmortem putamen and globus pallidus samples from subjects with Huntington and Parkinson disease. The assays were(More)
Magnetic resonance (MR) imaging with a whole-body imager was performed in 10 fresh, unfixed whole human brains selected randomly from cadavers. All subjects were neurologically intact before death. T2 time constants were measured within the caudate nucleus, putamen, globus pallidus, cortical gray matter, subcortical white matter, and optic radiation. These(More)