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Quantification of single-photon emission computed tomographic (SPECT) images is generally based on determination of maximal counts on radial sectors of short-axis slices. We hypothesized that analysis of mean counts may reduce estimation error.We compared quantitative 99mTc-labeled sestamibi (MIBI) SPECT based on maximal myocardial counts with that based on mean myocardial counts for accuracy of quantifying relative regional myocardial perfusion in a canine model of permanent left anterior descending coronary artery occlusion. MIBI and radiolabeled microspheres were injected during left anterior descending coronary artery occlusion. Relative microsphere myocardial blood flow was expressed as a percentage of normal (left circumflex coronary artery territory) blood flow. SPECT imaging was performed in vivo and ex vivo. Relative MIBI uptake on SPECT short-axis slices was quantified with normalized circumferential profiles based on maximal and mean counts. In vivo and ex vivo SPECT relative myocardial count density was compared to relative myocardial blood flow in six dogs. In the comparisons, percent errors in estimating the relative blood flow and relative flow deficit with MIBI SPECT imaging were calculated. There was an excellent correlation between absolute myocardial tissue MIBI activity and regional myocardial blood flow for each of the six dogs (r = 0.90 to 0.98). The correlations between relative myocardial count density on SPECT and relative blood flow for individual sectors were similar for maximal and mean count profiles (maximal, 0.79 to 0.83; mean, 0.77 to 0.82). Comparing the nadirs of in vivo and ex vivo circumferential count profiles, the correlations were slightly better (maximal, 0.82 to 0.91; mean, 0.87 to 0.91). Average percent errors in assessing relative blood flow and relative flow deficit were decreased significantly by use of mean count profiles (p0.05).Relative SPECT count density with either maximal or mean count profiles correlated well with relative myocardial blood flow. Compared with maximal count profiles, quantification with mean count profiles improved estimation of relative flow.

The state of antibody production and the tissue and species specificities together with the sperm immobilizing action of various antibodies in rabbits were examined after immunization with pig's sperm. Before the immunization, the titers of various antibodies against pig's sperm seemed to be generally higher in male than in virgin female, but they became no obvious difference between the two sexes after the immunization. Precipitins of the sera obtained by immunizing rabbits with pig's spermatozoa extract reacted not only with pig's spermatozoa extract but also with heterologous spermatozoa extract to moderate degree, but no cross reaction with pig's serum or heterologous serum was visible, and it was not associated with the sperm immobilization. The sperm-microagglutinin obtained by immunization with pig's spermatozoa showed strong species specificity and moderate tissue specificity. The motility of the sperm was not obviously inhibited by sperm agglutinin. The titer of it was the highest among the immune antibodies, but there are problems in detecting the specific antibody because spontaneous sperm agglutination is common and it is difficult to determine whether the agglutination is due to antisperm antibody or to a nonspecific factor. The evidence that strong tissue and species specific sperm-immobilizing antibody could be produced by immunizing rabbits with heterologous pig's sperm in both sexes gives us the confidence that sperm immobilization by immunization of both sexes with homologous sperm could contribute to human population control in the future.