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  • 2000-2004  (4)
  • 1985-1989  (10)
  • 1920-1924
  • 1915-1919
  • Tomography
  • 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
    ISSN: 1432-1106
    Keywords: Tomography ; Dopamine ; Striatum ; MPTP ; Monkey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Positron emission tomography following intravenous administration of 6-[18F]-L-fluorodopa was used to investigate the usefulness of PET for the assessment of normal and abnormal dopaminergic function. For this purpose, the incracerebral distribution of 6-[18F]-L-fluorodopa and its metabolites was evaluated in normal control and asymptomatic MPTP-treated rhesus monkeys. MPTP is a neurotoxic compound which destroys selectively the dopaminergic neurons of the nigrostriatal pathways in primates. The 18F accumulation was found to be significantly reduced in the striatum, putamen more than caudate, of the MPTP-treated animals compared to the normal controls. The 18F accumulation in dopamine-poor areas did not differ between the two groups. The ratios of striatum to dopamine-poor brain area were highly correlated to the concentrations of the dopamine metabolite, homovanillic acid, in the cerebrospinal fluid of the same animals. The findings are consistent with the hypothesis that “silent damage” to the dopaminergic nigral neurons may precede the onset of parkinsonism by many years and that PET scanner examination using 6-[18F]-L-fluorodopa may be useful in the detection of subtle dopaminergic dysfunctions as may exist in DA-related motor syndromes and neuropsychiatric disorders.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nuclear medicine 15 (1989), S. 189-193 
    ISSN: 1619-7089
    Keywords: SPECT ; Computers ; Tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A new method is described to allow interactive selection of the reconstruction filter at the time of interpretation of images from single-photon tomography. In the filtered back projection algorithm, the only part of the reconstruction process requiring user interaction is the selection of the window function. Since the ramp and window filters have different purposes, they can be separated, placing the window at the end of the reconstruction process as a three-dimensional filter. All stages of reconstruction except the window filtering are performed before the physician begins to interpret the study. The three-dimensional filtering is performed very rapidly with use of the Chebyshev convolution algorithm. A 64×64×64 pixel cube of data is filtered in 13–33 s using filters of 3–11 lengths. Smaller volumes of image data can be filtered in less than 1 s; thus, the user can interactively choose any desired filter for a given tomographic study at the time of interpretation of the images.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Oral radiology 5 (1989), S. 11-22 
    ISSN: 1613-9674
    Keywords: Temporomandibular joint ; Tomography ; Blurred image
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary For this study, seven different types of phantom were made simulating the condyle. The phantoms attached to a human dry skull were tomographed using the Polytome-U, under identical conditions to those of tomography for patients. There was no significant difference of the images between tube side and film side of the mandible. The images of the medial part of the TMJ were clearer than that of the lateral part. A discrepancy of contours on the focal plane between the phantom and the tomographic image occurred when the inclination of the phantom surface was larger than the maximum exposure angle. Concerning the influence of focal movements to image quality, the images obtained from hypocycloidal movements were superior with minimum superimposition, although the contrast of the image varied when the phase of the hypocycloidal movements were altered. Any sectional images were not manifested with the phantoms when the inclination of the phantom surface was larger than 23 degrees. Furthermore, 106 condyles from human dry skull were examined on the area of which the inclination of the condylar surface was less than 23 degrees. The mean latero-medial distance of the area was 14.1mm, which corresponded to 75% of whole latero-medial distance of the condyle.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Oral radiology 5 (1989), S. 31-38 
    ISSN: 1613-9674
    Keywords: Panoramic radiography ; Tomography ; Scanography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In this report, basic principles of panoramic tomography are suggested. According to this principle, the effective rotation center doesn't have the importance as was considered before, the tomographic factor of panoramic tomography and the scanographic factor of panoramic tomography are clearly separated, and the relationship between these two factors are mentioned. Exposure angle and section thickness are related to the tomographc factor, and projection angles and image distortion and characteristics of formation of superimposed blurred structures are related to the scanographic factor. There are no machines satisfying the new principle, but the new panoramic tomograph can be designed according to and as an extension of this new principle.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 11 (1989), S. 33-40 
    ISSN: 0741-0581
    Keywords: High-voltage electron microscopy ; Thick specimens ; Tomography ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Optimal imaging of complex structures requires proper alignment relative to the optic axis of the electron microscope. This is especially important for high-voltage and intermediatevoltage microscopes, which form an in-focus image throughout the entire thickness of the object. As a result, structures at different specimen heights form overlapping and confused images that severely curtail the usefulness of these instruments.The work described here provides a generalized, flexible method for optimizing specimen orientation and eliminating or limiting image overlap by means of a commonly used double-tilt stage. Analysis of the motion about the two axes provides accurate tilting for any azimuthal direction whether or not it corresponds to a mechanical axis of the stage. An object can be positioned to minimize image overlap, to record stereopairs for any parallax axis, and to record three-dimensional data sets by the conical collection geometry.Images of muscle paracrystals are shown after tilting about an axis perpendicular to a symmetry direction. The tilted image displays higher-order symmetry, which is altered by changes of one degree. Precision double-tilting for optimizing stereopairs is shown for a desmosome recorded using different parallax axes and pretilts. A tomographic conical data-collection scheme is demonstrated by imaging a microtubule axoneme for a specific cone half-angle and arbitrary azimuthal angles.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1613-9674
    Keywords: Tomography ; Adaptive changes ; Temporomandibular joint
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary It is important for planning the treatment of patients with TMJ dysfunctions to know the location and the distribution of remodeling on the articular surfaces so that the direction of the load may be assessed. The aim of this study is to radiologically clarify the location and the distribution of articular remodeling, in order to investigate the correlation between joint morphology and oral function. The material used in this study was selective lateral tomograms of 110 arthritic patients ranging in age from 12 to 78 years. Three tomograms indicating the lateral, medial and central portion of the condylar heads were selected from 10 simultaneous serial tomograms. The incidence of flattening, concavity and irregularity of articular surfaces was examined on each anterior and posterior surfaces of both condylar heads and articular eminences. Articular remodeling occurred most frequently on the central portion of the condylar heads on the lateral tomograms. A number of flattened surfaces with or without concavity were unexpectedly found on the posterior surfaces of the condylar heads.
    Type of Medium: Electronic Resource
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nuclear medicine 12 (1987), S. 578-579 
    ISSN: 1619-7089
    Keywords: Liver ; Radionuclide imaging ; Tomography ; Emission computed ; Hepatic veins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract An area of photon deficiency in both planar and single photon emission computed tomography (SPECT) images of the liver using 99mTc-Sulfur Colloid was found to be due to a dilated hepatic vein.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Plasma chemistry and plasma processing 6 (1986), S. 127-141 
    ISSN: 1572-8986
    Keywords: Tomography ; emission coefficients ; nonsymmetric plasmas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The technique of reconstructive tomography (RT) is a powerful method of obtaining local, spatially resolved volumetric emission coefficients from line integral data. The applicability of this technique as a diagnostic for nonuniform sources is studied using simulated data with and without noise. The major advantage of RT techniques is that they may be applied, without restriction, to highly asymmetric data as well as symmetric data. When applied to symmetric data, the technique appears to be less susceptible to noise than Abel inversion techniques. Also examined is a method of accounting for self-absorption under certain circumstances.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nuclear medicine 12 (1986), S. S36 
    ISSN: 1619-7089
    Keywords: Myocardial metabolism ; Fatty acid ; Positron emission ; Tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Positron emission tomography with 11C-palmitate and single photon imaging with terminally radioiodinated fatty acid analogues (123I-FFA) were evaluated for the non-invasive assessment of regional myocardial fatty acid metabolism during ischaemia. Decreased uptake of tracer and delayed clearance of activity in the ischaemic myocardium were reported for both 11C-and 123I-labelled compounds. However, since during ischaemia both myocardial blood flow and oxidative metabolism are reduced concomitantly, either factor can be responsible for the changes observed. Experimental preparations in which fatty acid metabolism can be modified independently of flow are helpful for the characterization of the relationship between metabolism and myocardial kinetics of labelled fatty acids. Results obtained during flow-independent inhibition of fatty acid oxidation include the following observations: - In dogs with controlled coronary perfusion the rate of clearance of 11 C-palmitate activity is decreased during diminished delivery of oxygen, regardless of whether myocardial perfusion is concomitantly reduced or not. - In isolated rabbit hearts perfused at normal flow, the extraction of 123 I-FFA is decreased during hypoxia. - During pharmacological inhibition of fatty acid oxidation the deiodination of 123 I_FFA is markedly reduced in rat hearts in vivo and in vitro.
    Type of Medium: Electronic Resource
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  • 14
    ISSN: 1573-9686
    Keywords: Renal cortex ; Perfusion ; X-ray ; Tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The three-dimensional image data generated by the Dynamic Spatial Reconstructor (DSR) enables measurement of the three-dimensional distribution of blood supply in organs. We have applied this imaging technique to evaluate renal cortical blood flow distribution and compare it with distribution of radiolabeled microspheres. The DSR, a high temporal resolution volumetric roentgenographic computed tomographic scanner, was used to scan the volume containing a kidney in 0.13–0.26 s and repeating this scan 8–4 times per s for six s during a renal arteriogram. Five anesthetized dogs were studied in the prone position with the left kidney exteriorized through a flank incision. An electromagnetic flowmeter was placed around the renal artery and a needle placed retrograde into the artery for injection of a 2 cc bolus of contrast agent. During the scan the contrast agent was injected over a four s period during which radioactively labelled microspheres were injected into the left atrium. The tomographic images of approximately 10 parallel, 5 mm thick sagittal slices corresponding to the slices of the kidney used for counting microspheres in the cortical layers were displayed and analyzed. The time point chosen for analysis was the one in which peak brightness (i.e., concentration of contrast agent) was detected in the cortex. The spatial distribution of peak brightness values was compared to the number of microspheres at the same sampling locations. The microsphere-based value of regional cortical blood flow fell below the regression line for the juxtamedullary cortex and above for the outer cortex. This result is consistent with the preferential distribution of microspheres to the outer cortex whereas the contrast agent distributed more uniformly throughout the cortex.
    Type of Medium: Electronic Resource
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