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  • 1
    Book
    Book
    Boston :Birkhäuser,
    Title: Sampling, wavelets, and tomography /
    Contributer: Benedetto, John , Zayed, Ahmed I.
    Publisher: Boston :Birkhäuser,
    Year of publication: 2003
    Pages: p. cm
    Series Statement: Applied and computational harmonic analysis
    ISBN: 0-8176-4304-4 , 3-7643-4304-4
    Type of Medium: Book
    Language: English
    Keywords: Hamonic analysis ; Wavelets (Mathematics) ; Fourier analysis ; Sampling (Statistics) ; Tomography
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Skeletal radiology 29 (2000), S. 409-412 
    ISSN: 1432-2161
    Keywords: Key words Tarsal bones ; abnormalities ; Tomography ; X-ray computed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Objective. To determine the findings of calcaneonavicular coalition on coronal CT. Design. We retrospectively reviewed the CT scans of 14 calcaneonavicular coalitions in eight patients. All coalitions were visible on the axial scans, and the diagnosis was confirmed by surgery in five patients. These CT scans were compared with scans of ten normal feet. Results. We identified two features of calcaneonavicular coalition on coronal CT: lateral bridging (an abnormal bony mass lateral to the head of the talus) and rounding of the talus. All eight patients demonstrated at least one of these two findings. Conclusion. Although calcaneonavicular coalition is best seen on axial CT scans of the feet, there are two abnormalities, lateral bridging and rounding of the head of the talus, which should suggest the diagnosis on coronal CT scans.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1619-7089
    Keywords: Key words: Behçet’s disease ; Tomography ; emission computed ; Acetazolamide ; Diaschisis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The purpose of this study was to characterise the nature of the baseline perfusion defects found in patients with Behçet’s disease using hexamethylpropylene amine oxime single-photon emission tomography in conjunction with acetazolamide test (Acz SPET). Eleven patients underwent both baseline and Acz SPET. Regions of interest (ROIs) were drawn on the areas with decreased perfusion (D-ROI) and, in the same section, on areas with normal perfusion (N-ROI). The ROIs were then repositioned on the corresponding section on Acz SPET. The mean ROI counts were then transformed into a perfusion index value (PIV) with reference to the global brain counts. In total we found 24 D-ROIs (17 in the cortical and 7 in subcortical grey matter). The influence of Acz infusion was selectively registered in the D-ROIs, where PIVs changed from 1.23±0.17 (baseline SPET) to 1.63±0.23 (Acz SPET) (P〈0.001). No significant difference was seen in the N-ROIs (1.46±0.21 and 1.40±0.17, respectively, on baseline SPET and Acz SPET). Our results demonstrate that Acz infusion increases the regional cerebral blood flow within baseline grey matter perfusion defects. This finding suggests that baseline perfusion abnormalities could reflect a disconnection rather than local vasculitic involvement.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1619-7089
    Keywords: Key words: Arrhythmias ; Imaging ; Tomography ; Infarct size ; Defibrillator
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Infarct size as determined by perfusion imaging is an independent predictor of mortality after implantable cardioverter defibrillator (ICD) implantation in patients with coronary artery disease (CAD) and life-threatening ventricular arrhythmias (VA). However, its value as a predictor of VA recurrence and hospitalisation after ICD implantation is unknown. Therefore, the objective of this study was to evaluate whether infarct size as determined by perfusion imaging can help to identify patients who are at high risk for recurrence of VA and hospitalisation after ICD implantation.We studied 56 patients with CAD and life-threatening VA. Before ICD implantation, all patients underwent a uniform study protocol including a thallium-201 stress-redistribution perfusion study. A defect score as a measurement of infarct size was calculated using a 17-segment 5-point scoring system. Study endpoints during follow-up were documented episodes of appropriate anti-tachycardia pacing and/or shocks for VA and cardiac hospitalisation for electrical storm (defined as three or more appropriate ICD interventions within 24 h), heart failure or angina. After a mean follow-up of 470±308 days, 22 patients (39%) had recurrences of VA. In univariate analysis, predictors for recurrence were: (a) ventricular tachycardia (VT) as the initial presenting arrhythmia (86% vs 59% for patients without ICD therapy, P=0.04), (b) treatment with β-blockers (36% vs 68%, P=0.03) and (c) a defect score (DS) ≥20 (64% vs 32%, P=0.03). In multivariate analysis, VT as the presenting arrhythmia (χ2=5.51, P=0.02) and a DS ≥20 (χ2=4.22, P=0.04) remained independent predictors. Cardiac hospitalisation was more frequent in patients with a DS ≥20 (44% vs 13% for patients with DS 〈20, P=0.015) and this was particularly due to more frequent hospitalisations for electrical storm (24% vs 3% for patients with DS〈20, P=0.037). The extent of scarring determined by perfusion imaging can separate patients with CAD into high- and low-risk groups for recurrence of VA and cardiac hospitalisation after ICD implantation.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Applied composite materials 1 (1994), S. 325-331 
    ISSN: 1573-4897
    Keywords: Composite ; Percolation ; Chemical vapor infiltration (CVI) ; Porosity ; Tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Three-dimensional x-ray microtomography has been used to visualize porosity in ceramic matrix composites during chemical vapor infiltration processing. The topology of percolating pores was determined in both 0°/90° and 0°/45° architectures. At densities greater than 75%, consolidation can be described with percolation theory.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1613-9674
    Keywords: Tomography ; Temporomandibular joint ; Longitudinal study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract For patients with TMJ dysfunction, operators often change the condylar position by various methods. The aim of this study is to investigate how much the changes with time of condylar positions are related to the changes of clinical signs. The subjects were 584 joints of 127 patients with TMJ dysfunction to whom the serial lateral TMJ tomography was performed more than twice. In the most of cases where the condylar position had moved downward, inter-incisal distance had increased and TMJ noise had ameliorated. Furthermore, in many cases where the condylar position had moved forward, the amelioration of the TMJ pain was observed. It was considered that those ameliorations occurred because the positional relationship between the condylar head and the articular disk or posterior attachment had been improved.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 31 (1993), S. 157-164 
    ISSN: 1741-0444
    Keywords: Laser ; Scattering ; Time resolution ; Tomography ; Transillumination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Time-resolved tomography is performed in transillumination by using 527 nm picosecond pulses from a passively mode-locked doubled Nd/glass laser and a streak camera to select photons according to their flight time. This work reports on the increase in contrast of a time-resolved profile of a 2 mm radius opaque object embedded in a scattering medium, constituted of diluted milk in a 30 mm thick cell. For spatial analysis, the emerging photons are detected through a 6 mm slit at the outlet face of the cell. Transmission profiles obtained as a function of time show that the contrast is enhanced for the shortest flight times, while the ‘shadow’ of the object is no longer detected after about 100 ps. Moreover, improvements in contrast are studied for different configurations of the model, to analyse separately the role of collimated and scattered photons. It is expected that such a tomographic method based on time-resolved absorption could be applied to imaging for more complex biological structures in the red and near-infra-red range.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1084
    Keywords: Right ventricle ; Tomography ; Gated blood pool ; Phase analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Gated tomography of the cardiac blood pool has been found to be useful for detecting regional wall motion abnormalities of the left ventricle. We have applied this technique to study regional wall motion of the right ventricle. Twenty normal controls and 38 patients with previous myocardial infarction underwent tomography of the right ventricle following in vivo labelling of the blood pool. Three dimensional images were produced using a transputer based display system. These images were oriented into a right anterior oblique projection, and phase maps of the right ventricle superimposed onto them. The phase maps from the controls showed contraction to begin in the region of the apex and spread laterally and superiorly up the free wall of the right ventricle. Normal right ventricular phase was found to lie in a 200 degree range. In one of 20 patients with anterior and in 11 of 18 patients with inferior myocardial infarction, there were focal areas of right ventricle with phase angles outside this range. These results suggest that the contraction phase pattern of the right ventricle may be used to detect right ventricular contraction abnormalities after myocardial infarction.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1613-9674
    Keywords: Tomography ; Temporomandibular joint ; Temporomandibular joint syndrome ; Osteoarthritis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract One hundred and twenty two patients with temporomandibular joint (TMJ) disorders were examined by lateral and frontal tomograms. A comparison between clinical and radiographic findings was performed to confirm the clinical characteristics of TMJ osteoarthritis. The patients with radiographic abnormal or suspicious findings showed a significantly higher frequency of TMJ pain and limitation of mouth opening less than 29mm than the patients with normal findings. The TMJs with surface erosion also showed a significantly higher frequency of TMJ pain than the TMJs with normal findings. Therefore, these findings were thought to be one of the distinctive feature of TMJ osteoarthritis. However, 22 patients with unilateral clinically primary symptoms presented bilateral abnormal or suspicious findings and 7 patients with unilateral clinically primary symptoms presented abnormal or suspicious findings only in the TMJ opposite to the clinically primary symptomatic site. Therefore, the necessity of radiographic examination of the clinically unaffected TMJ was concurrently indicated for the treatment planning and for the further research.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Clinical rheumatology 11 (1992), S. 376-381 
    ISSN: 1434-9949
    Keywords: Sternoclavicular Joint ; Clavicle ; Dislocation ; Condensing Osteitis ; Tomography ; X-ray Computed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Eight middle-aged women with spontaneous atraumatic subluxation of the sternoclavicular joint were evaluated with radiography and computed tomography. All patients were employed in occupations involving moderate to heavy physical labour, and no patients could recall a specific traumatic incident associated with onset of symptoms. In seven of the eight patients, the displacement of the medial clavicle was in a cranial direction; in four of the eight patients, there was an associated anterior subluxation, and in one patient, the subluxation was purely anterior. All five patients with an anterior component to the sternoclavicular subluxation had associated condensing osteitis of the clavicle. The sclerosis of the medial clavicle is possibly the result of chronic abrasion on the sternum and first costal cartilage in association with normal respiration and with upper extremity motion.
    Type of Medium: Electronic Resource
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  • 11
    ISSN: 1435-1463
    Keywords: Tomography ; monkey ; L-DOPA ; aromatic L-amino acid decarboxylase ; catechol-O-methyltransferase ; Parkinson's disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Positron emission tomography (PET) following intravenous administration of β-[11 C]-L-DOPA provides a method of assessing regional cerebral uptake and utilization of levodopa. Cerebral levodopa kinetics in the rhesus monkey were investigated after the inhibition of catechol-O-methyltransferase (COMT) with RO 40-7592, and after coadministration of the peripheral aromatic L-amino acid decarboxylase (AADC) inhibitors benserazide and carbidopa. Pretreatment with RO 40-7592 (10 mg/kg), benserazide (10 mg/kg) or carbidopa (3.5 mg/kg) did not change striatal k3, which mainly reflects the ability for the brain tissue to convert [11C]-L-DOPA to [11C]-dopamine, although the brain's uptake of radioactivity increased substantially after pretreatment with the AADC inhibitors. When benserazide was coadministered with RO 40-7592 (10 mg/kg) a dose-dependent decrease in striatal k3 was measured with an apparent ED50 of 3 mg/kg. No such effect was indicated after pretreatment with the combination of RO 40-7592 (10 mg/kg) and carbidopa (3.5 mg/kg). The possible negative interactions of coadministration with COMT inhibitors and predominantly peripherally acting AADC inhibitors must be considered when used in the therapy of Parkinson's disease.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 133 (1990), S. 305-315 
    ISSN: 1420-9136
    Keywords: Tomography ; seismic inversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract In this paper, linearized tomography and the Herglotz-Wiechert inverse formulation are compared. Tomographic inversions for 2-D or 3-D velocity structure use line integrals along rays and can be written in terms of Radon transforms. For radially concentric structures, Radon transforms are shown to reduce to Abel transforms. Therefore, for straight ray paths, the Abel transform of travel-time is a tomographic algorithm specialized to a one-dimensional radially concentric medium. The Herglotz-Wiechert formulation uses seismic travel-time data to invert for one-dimensional earth structure and is derived using exact ray trajectories by applying an Abel transform. This is of historical interest since it would imply that a specialized tomographic-like algorithm has been used in seismology since the early part of the century (seeHerglotz, 1907;Wiechert, 1910). Numerical examples are performed comparing the Herglotz-Wiechert algorithm and linearized tomography along straight rays. Since the Herglotz-Wiechert algorithm is applicable under specific conditions, (the absence of low velocity zones) to non-straight ray paths, the association with tomography may prove to be useful in assessing the uniqueness of tomographic results generalized to curved ray geometries.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Acta applicandae mathematicae 18 (1990), S. 251-260 
    ISSN: 1572-9036
    Keywords: 44A15 ; Tomography ; radon transform
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract The exponential Radon transform on the plane arises in single photon emission computed tomography. It differs from the usual Radon transform by an exponential weight along the line of integration. The full description of the image of the transform in the space of compactly supported smooth functions is given. This description is connected with some curious identities for the sin function.
    Type of Medium: Electronic Resource
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