G. T. Herman

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A prospective sample of 69 healthy adults, age range 18-80 years, was studied with magnetic resonance imaging scans (T2 weighted, 5 mm thick) of the entire cranium. Volumes were obtained by a segmentation algorithm that uses proton density and T2 pixel values to correct field inhomogeneities ("shading"). Average (+/- SD) brain volume, excluding cerebellum,(More)
A computerized system was developed to process standard spin-echo magnetic resonance (MR) imaging data for estimation of brain parenchyma and cerebrospinal fluid (CSF) volumes. In phantom experiments, the estimated volumes corresponded closely to the true volumes (r = .998), with a mean error less than 1.0 cm3 (for phantom volumes ranging from 5 to 35 cm3),(More)
Relationships were examined between clinical features of schizophrenia and cerebrospinal fluid (CSF) volume in brain obtained by magnetic resonance imaging (MRI) in a sample of 59 patients. The volumes of the cerebral hemispheres and CSF were measured with a computer program designed to separate reliably neural tissue from CSF. The CSF to cranial volume(More)
PURPOSE To determine if simple renal cysts may be accurately characterized with helical computed tomography (CT) during peak levels of renal enhancement. MATERIALS AND METHODS Water-filled "cysts" were suspended in varying concentrations of iodine solution, meant to simulate varying levels of renal enhancement, within an abdominal phantom.(More)
Roentgenographic evaluation of maxillofacial trauma is an integral component in the management of the acutely injured patient. Recent developments in computerized software permit three-dimensional computed tomographic (CT) reconstructions of complex anatomic parts. Five examples of complex maxillofacial trauma were demonstrated by conventional plain films,(More)
After a brief discussion of the algebraic reconstruction techniques (ART), we introduce the attenuation problem in positron emission tomography (PET). We anticipate that a generalization of ART, the so-called cyclic subgradient projection (CSP) method, may be useful for solving this problem. This, however, has not been successfully realized, due to the fact(More)
In this paper we propose a method to overcome the effects of cardiac and respiratory motion in coronary subtraction imaging. We present the ideas of retrospective gating of masks, where both cardiac and respiratory phases are measured for a set of masks, and are subsequently used in a functional decomposition of motion. Through retrospective gating of(More)
The computed tomographic studies obtained routinely in the examination of patients with congenital or acquired defects of the skull and facial bones can be utilized as a substrate to provide an accurate three-dimensional representation of osseous abnormalities. The total dose of x-irradiation is reduced as other means of radiological examination are(More)