EVALUATION OF A MULTICRYSTAL GAMMA-CAMERA ROTATING CHAIR FOR TOMOGRAPHIC STUDIES OF THE HEART

Background. This study evaluates the feasibility of performing tomogra phic studies with a multicrystal gamma camera combined with a rotating chair. Methods and Results. Tomographic acquisitions were performed w ith a cardiac phantom containing eight defects of different sizes. Def ect size was determined from the fraction of counts in the short-axis slices that fell below a fixed threshold value. Image contrast was det ermined from the ratio of minimum/maximum counts. Images of an America n College of Nuclear Physicians cardiac single-photon emission compute d tomographic phantom were acquired and the results were compared with those obtained from 194 centers in the United States. For cardiac stu dies with Tl-201 and (TC)-T-99m, threshold values of 65% to 70% gave t he best correlation (R(2) > 0.94) between true and measured defect siz es, although the slope of the regression line was less than 0.95 for b oth isotopes. Small inferior defects demonstrated poor image contrast, particularly for Tc-99m. Of the three defects in the American College of Nuclear Physicians phantom, the two largest were identified in the tomographic images. Conclusions. A multicrystal gamma camera system c oupled with a rotating chair can be used for tomographic studies of th e heart. Image quality is poorer than that seen on conventional single -photon emission computed tomographic systems, particularly for Tc-99m .