Nuclear Cardiology: Nuclear Cardiology:

144 Nuclear Cardiology, The BasicsFig. 14-1. Cine display of rotating planar projection images. In this, and allfollowing movies of projection images, the stress study is on the left and the reststudy is on the right. The horizontal white line serves as a reference mark andis placed by the technologist approximately at the level of the left ventricularapex. The most convenient display speed for inspecting these images is at 10frames/second. The lung/heart ratio (L/H) is displayed, as is the maximal countdensity/pixel within the left ventricle. Studies with maximal cardiac counts/pixel < 100 are of suboptimal quality. The rotating projection images shouldalways be viewed before analysis of reconstructed tomographic slices. Theimages should be inspected for patient motion, breast shadow and overall quality.Fig. 14-2. Cine display of rotating planar projection images. The count densityof the rest study as measured by maximal count/pixel within the left ventricleis low (73 counts). The stress study in contrast has excellent count density. Onecan expect the reconstructed tomographic slices of the rest study to be of suboptimalquality.heart is poorly visualized. Software developed in our laboratory displaysmaximal counts/pixel in the left ventricle on the rotating images screen.Good quality SPECT images (Fig. 14-4) usually have > 150 maximalcounts/pixel in the heart. Low count studies are often caused by patientobesity. It is helpful if the imaging worksheet for technologists contains