Search results for "PHOTON"
showing 10 items of 3171 documents
Dynamic image denoising for voxel-wise quantification with Statistical Parametric Mapping in molecular neuroimaging.
2018
Purpose PET and SPECT voxel kinetics are highly noised. To our knowledge, no study has determined the effect of denoising on the ability to detect differences in binding at the voxel level using Statistical Parametric Mapping (SPM). Methods In the present study, groups of subject-images with a 10%- and 20%- difference in binding of [123I]iomazenil (IMZ) were simulated. They were denoised with Factor Analysis (FA). Parametric images of binding potential (BPND) were produced with the simplified reference tissue model (SRTM) and the Logan non-invasive graphical analysis (LNIGA) and analyzed using SPM to detect group differences. FA was also applied to [123I]IMZ and [11C]flumazenil (FMZ) clinic…
Decreased benzodiazepine receptor binding in panic disorder measured by IOMAZENIL-SPECT. A preliminary report.
1994
Single photon emission tomography (SPECT) imaging of the central benzodiazepine receptor (BZr) became possible with the newly developed ligand 123I-IOMAZENIL. The BZr binding was investigated in ten patients with panic disorder (PP) compared to ten epileptic patients (EP). Panic patients had lower IOMAZENIL uptake rates in the frontal, occipital and temporal cortex than EP indicating the involvement of the BZr complex in panic disorder.
Loading modalities and bone structures at nonweight-bearing upper extremity and weight-bearing lower extremity: a pQCT study of adult female athletes.
2005
This cross-sectional study of adult female athletes assessed whether the apparent loading-related differences in bone structure are primarily associated with the loading type or the muscle performance-related joint moments. Several structural variables at shaft sites of the tibia, radius and humerus, and distal sites of the tibia and radius were measured with peripheral quantitative computed tomography (pQCT) among 113 female national level athletes (representing hurdling, volleyball, soccer, racket-sports and swimming) and their 30 nonathletic referents. For the weight-bearing lower extremities, the loading modalities of the above sports were classified into high-impact (hurdling, volleyba…
Association between long-term exercise loading and lumbar spine trabecular bone score (TBS) in different exercise loading groups
2015
Objective: To examine whether different exercise loading is associated with lumbar vertebral texture as assessed with Trabecular Bone Score (TBS). Methods: Data from 88 Finnish female athletes and 19 habitually active women (reference group) were analyzed. Participants’mean age was 24.3 years(range 17-40 years).Athletes were divided into five specific exercise loading groups according to sport-specific training history: high-impact (triple jumpers and high jumpers), odd-impact (soccer players and squash players), high-magnitude (power lifters), repetitive impact (endurance runners), and repetitive non-impact (swimmers). TBS-values were determined from lumbar vertebral L1-L4 DXA images. Body…
Correlation of cerebral blood flow and treatment effects of repetitive transcranial magnetic stimulation in depressed patients.
2002
The aims of this study were to: (1) assess the effects of repetitive transcranial magnetic stimulation (rTMS) on brain activity in depressed patients as measured by single photon emission tomography (SPECT); (2) evaluate the predictive value of brain SPECT on the antidepressant efficacy of rTMS. Patients (n=17) received 1600 rTMS stimuli at a rate of 10 Hz, 5 days per week for 2 weeks to the left dorsolateral prefrontal cortex. Whole brain SPECT data were acquired using Tc99m-Bicisate. Regional cerebral blood flow (rCBF) was correlated with the % change in the 28-item Hamilton Depression Rating Scale Score (Δ-HDRS) and a semiquantitative region of interest (ROI) analysis was conducted. Prio…
A custom image-based analysis tool for quantifying elastin and collagen micro-architecture in the wall of the human aorta from multi-photon microscopy
2014
The aorta possesses a micro-architecture that imparts and supports a high degree of compliance and mechanical strength. Alteration of the quantity and/or arrangement of the main load-bearing components of this micro-architecture - the elastin and collagen fibers - leads to mechanical, and hence functional, changes associated with aortic disease and aging. Therefore, in the future, the ability to rigorously characterize the wall fiber micro-architecture could provide insight into the complicated mechanisms of aortic wall remodeling in aging and disease. Elastin and collagen fibers can be observed using state-of-the-art multi-photon microscopy. Image-analysis algorithms have been effective at…
Somatostatin-receptor scintigraphy in Graves' disease: reproducibility and variance of orbital activity.
2000
Somatostatin-receptor (SSTR) scintigraphy using the single photon emission computed tomography (SPECT) technique allows the assessment of orbital inflammation in patients with Graves' disease. Previous studies showed differences in orbital octreotide uptake already 4 hr after injection. In this study, analysis of inter-/intra-observer variance and reproducibility in the evaluation of orbital SPECT images was performed. First, SPECT data of one representative female patient with clinically active Graves' ophthalmopathy (GO), obtained 4 hr after intravenous injection of 110 MBq 111In-pentetreotide and processed by filtered backprojection, were analyzed. Transverse SPECT images were reconstruc…
Within-Day Energy Deficiency and Metabolic Perturbation in Male Endurance Athletes.
2018
Endurance athletes are at increased risk of relative energy deficiency associated with metabolic perturbation and impaired health. We aimed to estimate and compare within-day energy balance in male athletes with suppressed and normal resting metabolic rate (RMR) and explore whether within-day energy deficiency is associated with endocrine markers of energy deficiency. A total of 31 male cyclists, triathletes, and long-distance runners recruited from regional competitive sports clubs were included. The protocol comprised measurements of RMR by ventilated hood and energy intake and energy expenditure to predict RMRratio (measured RMR/predicted RMR), energy availability, 24-hr energy balance a…
Three-dimensional distribution of trabecular bone density and cortical thickness in the distal humerus
2008
One major barrier to osteosynthesis in distal humeral fractures is poor bone quality. This study was an attempt to measure the bone quality in the distal humerus.We measured the distribution of total bone mineral density (BMD), trabecular BMD (tBMD), and cortical thickness (CTh) in the distal humerus using peripheral quantitive computed tomography. Four slices in the infracondylar, supracondylar, and distal disphyseal regions of 25 human cadaver humeri were investigated.Total BMD decreased continuously from the distal diaphysis to the trochlea. Within the infracondylar region, the capitellum was the region of lowest tBMD and CTh (P.001). Measurements in anterior regions were higher than in …
Mass spectroscopic analysis of excimer laser ablated material from human corneal tissue.
1988
The clinical feasibility of photorefractive keratectomy depends on the surface structure of the ablated cornea. Two factors that influence the remodeled surface are the homogeneity of the energy distribution and the properties of the laser source (energy and wavelength). Currently, the homogeneity of the beam is difficult to control. The second factor, laser source properties, was the focus of this study. We investigated the effect of laser wavelength and energy by analyzing the reaction products of photoablation. We monitored the fragments produced by UV-laser ablation of human corneas using mass spectroscopy in the range of 0 to 100 atomic mass units. At 248 nm (KrF), average photon energ…