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  • Single-photon emission tomography  (2)
  • Polymer and Materials Science  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Cardiac phase-synchronized myocardial thallium-201 single-photon emission tomography using list mode data acquisition and iterative tomographic reconstruction (1997)
    Springer
    European journal of nuclear medicine 24 (1997), S. 276-280 
    Details
    ISSN: 1619-7089
    Schlagwort(e): Myocardium ; Coronary artery disease ; Myocardial contraction ; Single-photon emission tomography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The purpose of this study was to determine whether data acquisition in the list mode and iterative tomographic reconstruction would render feasible cardiac phase-synchronized thallium-201 single-photon emission tomography (SPET) of the myocardium under routine conditions without modifications in tracer dose, acquisition time, or number of steps of the a gamma camera. Seventy non-selected patients underwent201Tl SPET imaging according to a routine protocol (74 MBq/2 mCi201Tl, 180° rotation of the gamma camera, 32 steps, 30 min). Gamma camera data, ECG, and a time signal were recorded in list mode. The cardiac cycle was divided into eight phases, the end-diastolic phase encompassing the QRS complex, and the end-systolic phase the T wave. Both phase- and non-phase-synchronized tomograms based on the same list mode data were reconstructed iteratively. Phase-synchronized and non-synchronized images were compared. Patients were divided into two groups depending on whether or not coronary artery disease had been definitely diagnosed prior to SPET imaging. The numbers of patients in both groups demonstrating defects visible on the phase-synchronized but not on the non-synchronized images were compared. It was found that both postexercise and redistribution phase tomograms were suited for interpretation. The changes from end-diastolic to end-systolic images allowed a comparative assessment of regional wall motility and tracer uptake. End-diastolic tomograms provided the best definition of defects. Additional defects not apparent on non-synchronized images were visible in 40 patients, six of whom did not show any defect on the non-synchronized images. Of 42 patients in whom coronary artery disease had been definitely diagnosed, 19 had additional defects not visible on the non-synchronized images, in comparison to 21 of 28 in whom coronary artery disease was suspected (P〈0.02; χ2). It is concluded that cardiac phase-synchronized201Tl SPET of the myocardium was made feasible by list mode data acquisition and iterative reconstruction. The additional findings on the phase-synchronized tomograms, not visible on the non-synchronized ones, represented genuine defects. Cardiac phase-synchronized201Tl SPET is advantageous in allowing simultaneous assessment of regional wall motion and tracer uptake, and in visualizing smaller defects.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01728763
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Cardiac phase-synchronized myocardial thallium-201 single-photon emission tomography using list mode data acquisition and iterative tomographic reconstruction (1997)
    Springer
    European journal of nuclear medicine 24 (1997), S. 276-280 
    Details
    ISSN: 1619-7089
    Schlagwort(e): Key words: Myocardium ; Coronary artery disease ; Myocardial contraction ; Single-photon emission tomography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. The purpose of this study was to determine whether data acquisition in the list mode and iterative tomographic reconstruction would render feasible cardiac phase-synchronized thallium-201 single-photon emission tomography (SPET) of the myocardium under routine conditions without modifications in tracer dose, acquisition time, or number of steps of the a gamma camera. Seventy non-selected patients underwent 201Tl SPET imaging according to a routine protocol (74 MBq/2 mCi 201Tl, 180° rotation of the gamma camera, 32 steps, 30 min). Gamma camera data, ECG, and a time signal were recorded in list mode. The cardiac cycle was divided into eight phases, the end-diastolic phase encompassing the QRS complex, and the end-systolic phase the T wave. Both phase- and non-phase-synchronized tomograms based on the same list mode data were reconstructed iteratively. Phase-synchronized and non-synchronized images were compared. Patients were divided into two groups depending on whether or not coronary artery disease had been definitely diagnosed prior to SPET imaging. The numbers of patients in both groups demonstrating defects visible on the phase-synchronized but not on the non-synchronized images were compared. It was found that both postexercise and redistribution phase tomograms were suited for interpretation. The changes from end-diastolic to end-systolic images allowed a comparative assessment of regional wall motility and tracer uptake. End-diastolic tomograms provided the best definition of defects. Additional defects not apparent on non-synchronized images were visible in 40 patients, six of whom did not show any defect on the non-synchronized images. Of 42 patients in whom coronary artery disease had been definitely diagnosed, 19 had additional defects not visible on the non-synchronized images, in comparison to 21 of 28 in whom coronary artery disease was suspected (P〈0.02; χ2). It is concluded that cardiac phase-synchronized 201Tl SPET of the myocardium was made feasible by list mode data acquisition and iterative reconstruction. The additional findings on the phase-synchronized tomograms, not visible on the non-synchronized ones, represented genuine defects. Cardiac phase-synchronized 201Tl SPET is advantageous in allowing simultaneous assessment of regional wall motion and tracer uptake, and in visualizing smaller defects.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01728763
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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    Artikel (Nationallizenzen)
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  • 3
    Digitale Medien
    Digitale Medien
    Characterization and promotion of dilatation bands in toughenable thermosetting resins (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 2003-2017 
    Details
    ISSN: 0887-6266
    Schlagwort(e): epoxy ; thermosets ; craze-like damage ; dilatation band ; fracture mechanisms ; toughening ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Formation of dilatation bands has been found in a series of moderately crosslinked thermosets with molecular weights between crosslinks, Mc, ranging from 560 to 1000 g/mole. These dilatation bands, although they do not show distinct craze fibrils inside the band, do behave mechanically like the well-known crazing phenomenon observed in polystyrene. Although the cause for the formation of dilatation bands is still largely unknown, the occurrence of the craze-like fracture phenomenon (dilatation bands) is found to be strongly influenced by the stress state the matrix experiences, by the type of loading applied to the specimen, and by the type/size of toughener particles incorporated in the matrix. The tendency for dilatation band formation in engineering thermosets can be greatly enhanced by the use of craze-prone toughener particles, such as nylon particles. The toughening effect via these newly observed dilatation bands is found to be quite impressive, and in some cases, can approach that via the shear-banding process. The potential significance of the present finding for a better design of toughened thermosets for structural applications is discussed. ©1995 John Wiley & Sons, Inc.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/polb.1995.090331403
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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