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[en] To validate different procedures for determining regurgitant fractions, 224 measurements were made in 104 patients. Results obtained with standard recording conditions (in vivo RBC labeling, 5 minutes acquisition time) were found to be inadequate. When RBCs were labeled in vitro and acquisition time was extended to 10 minutes, the Fourier amplitude ratio and the stroke volume ratio were superior to conventional 2 ROI analysis in terms of range of variation, reproducibility and sensitivity. While a significant correlation was found to exist in 25 patients with regurgitant valvular disease between invasive studies and hemodynamic data, the relation was not very close and the regurgitant index computed from the Fourier amplitude ratio was higher by a factor of 1.3 than that obtained with invasive procedures. Neither radionuclide ventriculography nor hemodynamic data adequately predicted the severity (I-IV) as determined by angiography. (Author)

[en] Gated single-photon emission computed tomography (SPECT) is the current state-of-the-art approach to myocardial perfusion imaging. Initially, major emphasis was given to the improvement in diagnostic accuracy of myocardial perfusion imaging for the detection of coronary artery disease, because the evaluation of wall motion and thickening allows the recognition of attenuation artifacts and increases the observer's confidence. Different processing algorithm's make possible to perform a reproducible and reliable assessment of left ventricular (LV) function, which has been extensively validated against various reference methods. Several articles report the additional value of functional data derived from gated SPECT to increase the accuracy of myocardial perfusion imaging in particular patient groups, such a women, to enhance the detection of multivessel coronary artery disease and to permit the recognition of severe stenosis. An extensive literature indicates that gated SPECT allows a more accurate and reliable prognostic stratification of patients with known coronary artery disease. More recently, the peculiar contribution of gated SPECT in the assessment of myocardial variability has been demonstrated, with the possibility to evaluate in a single myocardial perfusion study the presence of preserved tracer uptake and the amount of contractile reserve through the acquisition of gated SPECT during inotropic stimulation with dobutamine. The most recent advance in the application of gated SPECT is the use of this technique for the reproducible assessment of LV functional changes, at follow-up or during inotropic stimulation, with perfusion data in the background. Various clinical settings, such as assessment of response to medical or re synchronization therapy in dilated or ischemic cardiomyopathy, prediction of outcome in chronic coronary artery disease with LV remodeling, evaluation of different treatment strategies in acute myocardial infarction, could take advantage from the unique combination of perfusion and functional data made possible by the use of gated SPECT. In conclusion, myocardial perfusion imaging with gated SPECT is a convincing reality in the field of cardiac imaging and has a still largely unexplored potential for a wider use of heart disease

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[en] The aim of this study was to compare ⁹⁹Tc^m-teboroxime and ²⁰¹Tl myocardial studies with particular regard to the classification of perfusion defects as reversible or fixed. Twenty patients with a history of previous myocardial infarction and suspected effort ischaemia underwent exercise ²⁰¹Tl scintigraphy with early (4 h) redistribution and reinjection scans, exercise and rest ⁹⁹Tc^m-teboroxime imaging and coronary angiography. Using a qualitative scoring of static planar images, the perfusion defects were classified as reversible or fixed. ²⁰¹Tl and ⁹⁹Tc^m-teboroxime gave comparable results in the evaluation of the individual vessels (sensitivity 65%, specificity 80% and 85%, respectively). The stress-redistribution ²⁰¹Tl sequence classified 45 defects as reversible and 28 as fixed, the stress-rest ⁹⁹Tc^m-teboroxime studies classified 47 as reversible and 26 as fixed (NS). The stress-reinjection ²⁰¹Tl images, however, characterized 64 defects as reversible and nine as fixed (P < 0.005 versus ²⁰¹Tl redistribution, P < 0.0005 versus ⁹⁹Tc^m-teboroxime rest). In conclusion, this study shows that rest ⁹⁹Tc^m-teboroxime and ²⁰¹Tl redistribution give comparable results but that significantly more defects are classified as fixed by ⁹⁹Tc^m-teboroxime than by ²⁰¹Tl if reinjection of the latter tracer is performed. (author)

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[en] In order to evaluate the significance of gated equilibrium radionuclide ventriculography (RNV) for non invasive quantification of valvular regurgitation and follow up, various approaches were tested concerning accuracy and reproducibility. By using in vitro labeling of red blood cells and extending the acquisition time, a clear reduction of dispersion was obtained in patients without valvular insufficiency. Quantification of regurgitation directly from functional images (ventricular amplitude or stroke volume image) was clearly superior compared to the variable region of interest method. Employing functional images, reproducibility between two observers and between two independent measurements was excellent. Correlation to regurgitation values determined by cardiac catheterization was only moderate with all RNV approaches tested. RNV is limited in the absolute quantification of valvular regurgitation due to the variable overlap of right atrium and right ventricle. However, because of its high reproducibility, RNV is a non invasive technique suitable for intraindividual follow up of patients with valvular insufficiency. (orig.)