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Biomedical subjects

H Sůrová

Publications and source records attributed to H Sůrová.

14 recordsLinked to original sources
PubMed1993

Three-dimensional cold spot volume rendering.

Three-dimensional volume rendering enhances the perception of radiopharmaceutical distribution within organs. Formerly, a maximum activity projection method was developed for hot spot rendering, which increases the contrast between hot spots and normal tissue. This method can only render cold spots at organ edges; a decrease in uptake within organs is not displayed. In this contribution, it is shown that the projection technique developed for hot spot imaging also can be used for cold spot rendering after suitable transformation of the tomographic data format.

Brain↗
PubMed1989

Determination of left ventricular wall motility injury by factor analysis in patients with advanced ischemic heart disease.

Left ventricular phase and amplitude images (Fourier analysis, PAI) and factor analysis images (FAI) from gated radionuclide ventriculography were obtained in 235 patients after myocardial infarction (MI) and in 44 patients with well documented ischemic heart disease (IHD) in order to assess areas of regional left ventricular motility injury (LVMI). The sensitivity of FAI for LVMI detection was higher than with PAI (36.3% vs 22.7% in patients without MI; 76.6% vs 68% in those after anterior MI; and 53.2% vs 31.9% after posterior MI, respectively). In 2.9% of all patients PAI were unclear due to small time activity amplitudes and heart rate irregularity, whereas FAI could be easily assessed. Significantly decreased left ventricular ejection fraction was observed predominantly after anterior MI in connection with distinct signs of LVMI in a large area of anterior wall or in the anteroseptal and/or apical region. Areas of LVMI could be sharply delineated in FAI; however, in contrast to PAI, FAI is unable to distinguish between dyskinetic and akinetic regions. The use of both PAI and FAI is recommended for more detailed detection of regional LVMI in patients with IHD.

Coronary Disease↗
PubMed1989

On the existence of an unambiguous solution in factor analysis of dynamic studies.

Achievement of an unambiguous solution in factor analysis of dynamic radionuclide studies depends on constraints reflecting the known properties of factors. The constraints should be tight enough to prevent ambiguity but sufficiently general in order to ensure the data-based derivation of factors. In dynamic scintigraphy, the non-negativity of factors is their essential property which is implied by the physical nature of measured quantities. Considering factors as the images of compartments in the distribution space of a radiopharmaceutical (i.e. performing the factor analysis in the spatial domain), a powerful additional constraint can be applied. This constraint is based on the presence of segments in the image matrix where the subtotal number of compartments is projected. Using this constraint, the existence of physiologically related unique solution in factor analysis can be proved providing the number of factors is chosen properly.

Factor Analysis, Statistical↗
PubMed1987

Rotation to simple structure in factor analysis of dynamic radionuclide studies.

The physiological interpretation of factors in the factor analysis of dynamic radionuclide studies is dependent on the proper solution of the problem of factor rotation. A new solution suitable for scintigraphic data is suggested using a generalised concept of simple structure in data configurations. The method is described in detail, its efficiency is demonstrated on a phantom and its relationship to existing methods is discussed.

Factor Analysis, Statistical↗
PubMed1986

Enhancement of physiological factors in factor analysis of dynamic studies.

Factor analysis of dynamic radionuclide studies provides their decomposition into the images and time-activity curves corresponding to the underlying dynamic structures. The method is based on the analysis of study variance and on the subsequent differential imaging of its principal components into a simplified factor space. By changing the amount and the composition of the variance processed in the analysis it is possible to enhance the factors that are important for diagnosis while the less important factors can be suppressed. In our report, a short theoretical review of the problem is given and illustrated by the analysis of dynamic cholescintigraphy. It is shown that a suitable choice of region and/or the temporal interval of interest enables the differential evaluation of such intrahepatic compartments, which could not be observed without enhancement.

Calculi↗
PubMed1984

Immunoscintigraphy and distribution study of experimental tumours using 131I-labelled anti-fibrinogen antibodies.

131I-labelled antibodies to the fragment E of human fibrin, anti-rat fibrinogen, non-immune rabbit IgG and 67Ga-citrate were used for scintigraphy and distribution studies in experimental tumours in rats. The best visualisation was achieved with 131I-labelled anti-rat fibrinogen antibodies at intervals longer than 48 h after administration. Tumour to tissue ratios found in distribution studies performed formed more than 48 h after administration were higher in most examined tissues when using 131I-labelled antibodies than those obtained with 67Ga-citrate.

Animals↗