Nuclear Cardiology: Nuclear Cardiology:

162 Nuclear Cardiology, The BasicsFig. 14-23. Quantification of the SPECT slices in Fig. 14-22. The yellow curvesrepresent the count distribution on the stress images and the red curves representthe rest images. The white curve represents the lower limit of normal radiotracerdistribution. The stress and rest curves are below the lower limit of normal in theinferolateral walls in the apical, midventricular, and basal short axis slices. Notethat the yellow and red curves are virtually identical, indicating a fixed myocardialperfusion abnormality due to either scar or attenuation. In the table at thetop the results of computer quantification are shown. The total stress and restdefect size is moderate and involves 8% of the left ventricle.Fig. 14-24. (Top right) Movie display of ECG-gated SPECT of images shown inFig. 14-22. Note that the wall motion and thickening of the inferior wall (locationof fixed defect) is normal. This suggests that the fixed defect may be artifactualand due to attenuation.Fig. 14-25. (Bottom right) Planar left-lateral images of the patient whose reconstructedSPECT images were shown in Fig. 14-22. Planar images were acquiredin supine position (top) and in right side decubitus position (bottom). One canappreciate that the planar images on the bottom are normal with good visualizationof the inferior wall, whereas on the supine images, in the position thatSPECT was acquired, the inferior wall is practically absent due to attenuation.The constellation of findings on rotating images, gated images, and planarimages all confirm the presence of inferior attenuation.