Journal of nuclear medicine : official publication, Society of Nuclear Medicine
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In this study, first-pass radionuclide angiography (FPRNA) was performed using a digital single-crystal gamma camera. Twenty-nine men and six women (ages 43-80, mean 61 yr) underwent FPRNA in the supine position immediately prior to cardiac catheterization. Total counts/sec in the whole field-of-view in the right ventricular phase were 150,352 +/- 26,006. ⋯ Analyses of intra- and interobserver variability gave r = 0.99 and 0.98 and an s.e.e. of 0.02 and 0.03, respectively. Spearman-Rank correlation coefficients between FPRNA and contrast angiographic wall-motion scores were greater than 0.8 for all walls, while sensitivity/specificity were 0.86/0.90, 0.76/1.00, 0.76/1.00 for anterior, apical, and inferior wall-motion abnormalities, respectively. We conclude that satisfactory counting statistics for FPRNA can be obtained with a digital gamma camera, and that accurate and reproducible measurements of global and regional left ventricular function can be obtained with this technique.
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A rotating cardiac phantom with three possible ejection fraction (EF) values was used in conjunction with a scintillation camera employing energy correction and count skim arithmetic for uniformity correction. Studies were collected with and without any correction, with the energy window of the analyzer set properly, and with the camera properly tuned. The uniformity was then degraded in one experiment by off-setting the analyzer window both high and low with respect to the primary photopeak and in another experiment by de-tuning a selected photomultiplier tube. ⋯ If either energy correction alone, or energy correction combined with count skim correction is used, the ejection fraction values return to more acceptable values. Asymmetric windows, improper setting of the energy window or a badly tuned photomultiplier will likely result in poor analog images before the effect on ejection fraction measurements becomes evident. Uniformity correction devices do not adversely affect the numerical results obtained from these phantom studies, but should, nevertheless, be used with caution.
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Mucociliary clearance mechanisms were evaluated in 17 normal subjects visually and qualitatively by radioaerosol inhalation cinescintigraphy of the lung, and quantitatively by calculating the following indices: (a) overall or regional lung retention ratio; (b) airway deposition ratio; (c) airway retention ratio; (d) airway clearance efficiency; and (e) alveolar deposition ratio. The inhaled aerosol deposited homogeneously throughout the lungs, and mucus transport was always cephalad in direction and constant in velocity, although a temporary stasis of mucus was seen in smokers. ⋯ There was an inverse relationship between alveolar deposition ratio and cigarette consumption. Mucociliary clearance mechanisms were well maintained in the normal subjects, but in the smokers inhaled aerosol tended to deposit more proximally.
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An experimental model was developed using ellipsoidal balloons of different volumes to derive an empirical formula linking the "normalized" total count rates on gamma-camera images to volume. The normalized total count rate (NTC) is defined as the total count rate divided by the maximum count density. ⋯ The distance from the left ventricle to the collimator was estimated from the patient's height and weight. The volumes calculated by the radionuclide method were compared with angiographic volumes obtained at cardiac catheterization, and good correlation was found (r = 0.95).
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Comparative Study
A comparison of bone imaging with Tc-99m DPD and Tc-99m MDP: concise communication.
Bone to soft tissue (ST) ratios for both high-uptake bone (sacrum) and low-uptake bone (femoral diaphysis) were obtained with a derivative of phosphonic acid, TC-99m 2,3-dicarboxypropane-1, 1-diphosphonate (DPD), in 26 normal subjects and 177 patients with malignant disease but without metastases. Tests were run 2 hr after tracer injection. Similar ratios were obtained with Tc-99m methylene diphosphonate (MDP) in 220 normal subjects and 451 patients. ⋯ DPD was superior to MDP for both ratios. With MDP, prolonged incubation time yielded significantly enhanced ratios; however, the ratios for the DPD were still higher. With either agent and preparation, sacrum-to-ST ratios decreased with increasing subject age, and in patients with malignant disease the ratios tended to be higher than those obtained from normals.