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  • 1
    ISSN: 1573-0743
    Keywords: ISPECT ; MCG ; Kent bundle ; VT ; non-invasive mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Since catheter or surgical techniques for ablating the arrhythmogenic substrate in patients with SVT due to accessory pathways or those with VT are now available, exact localization of the substrate is mandatory. We report preliminary results of two new non-invasive techniques for localizing either the site of earliest ventricular contraction using ISPECT, or the site of initial ventricular depolarization by magnetocardiography (MCG) in WPW syndrome and in VT patients. Thirteen patients with WPW syndrome and 8 patients with sustained VTs were studied with ISPECT. In 9/13, comparative catheter mapping data were available. Two patients had two Kent bundles. 13/15 Kent bundles could be localized by ISPECT. In 5/9 patients the area of Kent bundle insertion was identical with ISPECT and catheter mapping, in 3 correlation was fair, and in 2 patients with 2 Kent bundles ISPECT failed to localize their insertion. In 3/8 patients with VT catheter mapping could not be performed for hemodynamic reasons. In 2/5 patients the area of VT focus was identical with both methods, in one patient it was adjacent to each other, and in 2/5 patients a larger anatomic distance of the focus was found with both methods. In 3/7 patients with WPW the MCG showed the site of Kent bundle insertion, which was identical to that seen by catheter mapping. In one patient the area was adjacent, and in 3 more distant from the site determined by catheter mapping. In 1/2 patients with 2 Kent bundles, one of these could be detected by MCG. In 1/3 patients with VT, the site of VT focus was identical with both methods, but in the remaining two a distance of 3–4 cm was observed between the area seen with MCG and that with catheter mapping. In 4 further VT patients with stable and uniform ventricular late potentials, ventricular late magnetic activity was found with different QRS lengths within the single MCG channels. From our results we conclude that both ISPECT and MCG seem to become very promising non-invasive techniques for localizing ectopic ventricular depolarization in WPW syndrome and VT patients. However, these methods have to be refined, improved and validated by further systematical studies.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1619-7089
    Keywords: Myocardial imaging ; Upward creep ; Motion artefacts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The upward creep of the heart during myocardial single photon emission tomography (SPET) acquisition has been reported as a frequent source of false-positive results. The aim of this study was to simplify the detection and correction of this upward creep and to estimate its clinical relevance during routine patient care. To recognize the upward heart motion a straight line was fitted to the upper and lower border of consecutively displayed tomographic projection images. In this way, vertical translation of at least 1 pixel in size could be detected easily. On the assumption of a slow but continuous upward motion a fast interpolation correction method was developed. From 100 consecutive, supine, ergometric exercise studies, 1, 2 or 3 pixels of upward creep were found in 16, 4 or 3 patients, respectively. It was found that an upward creep of at least 2 pixels (7/100 cases) led to evident, mostly antero-septal defects on quantitative bull's-eyes, whereas only upward creeps of 3 pixels or more (3/100 cases) produced false-positive diagnostic results. The simple correction method offered a sufficient compensation of image and/or bull's-eye artefacts. These clinical findings could be reproduced in a computer model. Thus, it can be stated that clinically significant upward creep of the heart during stress SPET acquisition is relatively rare; it may have been overestimated in the past, and its artificial effects can be corrected by a quick and simple algorithm.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1619-7089
    Keywords: Orthopantomogram ; Orthopan tomoscintigram ; Dental bone scanning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The exact regional correlation of findings of facial bone scans, planar or SPECT, to dental orthopan X-ray films (OPT) is difficult because of the very different projection techniques. To improve correlative imaging in this regard a projection algorithm was developed that uses SPECT data of the skull for reconstructing an orthopan tomoscintigraphic projection. Fourteen conventional SPECT slices of the upper and lower jaws were obtained during bone scanning. All mandibular slices were superimposed resulting in a horseshoe shaped structure, which was marked by an ROI which was divided into segments. All 14 SPECT slices were then masked by this segmental ROI, thereby marking the teeth-carrying bone in all slices. The information from this horseshoe like ROI is then transformed into lines. Line by line arrangement results in an orthopan projection, the orthopan tomoscintigram. This new display allows 1:1 true scale superimposition with the X-ray OPT and markedly facilitates correlative imaging.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nuclear medicine 5 (1980), S. 333-338 
    ISSN: 1619-7089
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The evaluation of the left ventricular function with the “Nuclear Stethoscope’ was performed on 27 patients with heart diseases. The reproducibility of the measurements was good. Repetitions of EF, ER and EDV estimations yielded errors of 2.63%, 1.45% and 0.31%, respectively. The comparison with the results of camera ventriculography showed a good agreement of EF, contraction velocity parameters and relaxation velocity parameters, with a cor. coeff. of greater or equal to 0.750. An especially high correlation was found between the NS EF and NS ER (r=0.968). It was concluded that the “Nuclear Stethoscope” provides a reliable evaluation of left ventricular function.
    Type of Medium: Electronic Resource
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