Scintigraphic images are strongly affected by Poisson noise. This article presents the results of a comparison between denoising methods for Poisson noise according to different criteria: the gain in signal-to-noise ratio, the preservation of resolution and contrast, and the visual quality. The wavelet techniques recently developed to denoise Poisson noise limited images are divided into two gr...

The measurement of auditory evoked potentials (AEPs) has proven to be a useful tool for examining the auditory physiology of odontocete cetaceans and there is growing interest in applying this electrophysiological approach to study the hearing of other marine mammals. The aim of the current investigation was to examine some of the basic measurement and response characteristics of the auditory b...

Low-dose CT (computed tomography) sinogram data have been shown to be signal-dependent with an analytical relationship between the sample mean and sample variance. Spatially-invariant low-pass linear filters, such as the Butterworth and Hanning filters, could not adequately handle the data noise and statistics-based nonlinear filters may be an alternative choice, in addition to other choices of...

The purpose of this study was to assess a 3-dimensional (3D)– only PET scanner (ECAT EXACT3D) for its use in the absolute quantification of myocardial blood flow (MBF) using H2O. Methods: Nine large white pigs were scanned with H2O and C15O before and after partially occluding the circumflex (n 4) or the left anterior descending (n 5) coronary artery at rest and during hyperemia induced by intr...

Mathematical models of the muscle excitation are useful in forward dynamic simulations of human movement tasks. One objective was to demonstrate that sloped as opposed to rectangular excitation waveforms improve the accuracy of forward dynamic simulations. A second objective was to demonstrate the differences in simulated muscle forces using sloped versus rectangular waveforms. To fulfill these...

Background: Butterworth, Gaussian, Hamming, Hanning, and Parzen are commonly used SPECT filters during filtered back-projection (FBP) reconstruction, which greatly affect the quality and size accuracy of image. Materials and Methods: This study involved a cardiac phantom in which 1.10 cm thick cold defect was inserted into its myocardium wall and filled with 4.0 μCi/ml (0.148 MBq/ml) 99mTc conc...

background: butterworth, gaussian, hamming, hanning, and parzen are commonly used spect filters during filtered back-projection (fbp) reconstruction, which greatly affect the quality and size accuracy of image. materials and methods: this study involved a cardiac phantom in which 1.10 cm thick cold defect was inserted into its myocardium wall and filled with 4.0 μci/ml (0.148 mbq/ml) 99mtc conc...

INTRODUCTION AND METHODS. Rat barrel cortex undergo plastic changes during sensory experience (3). Twenty four hours o f "pairing" o f untrimmed whiskers leads to short lasting changes in supraand infragranular layers o f corresponding cortical columns. In order to reveal the early dynamics o f this process we studied evoked responses recorded by bipolar electrodes chronically implanted in the ...

UNLABELLED The aim of this study was to compare the performance of filtered backprojection (FBP) and ordered-subset expectation maximization (OSEM) reconstruction algorithms available in several types of commercial SPECT software. METHODS Numeric simulations of SPECT acquisitions of 2 phantoms were used: the National Electrical Manufacturers Association line phantom used for the assessment of...

Soft-tissue detectability in cone-beam computed tomography (CBCT) was evaluated via two-alternative forced-choice (2AFC) tests. Investigations included the dependence of detectability on radiation dose, the influence of the asymmetric three-dimensional (3D) noise-power spectrum (NPS) in axial and sagittal or coronal planes, and the effect of prior knowledge on detectability. Custom-built phanto...