1. Volume 96, Issue 2, Pages 227-229 (August 1989)
Coronary Steal 
K. Lance Gould, M.D. 
CHEST 
Volume 96, Issue 2, Pages (August 1989)
DOI: /chest
Copyright © 1989 The American College of Chest Physicians Terms and Conditions

2. FIGURE 1
Positron emission tomography of generator produced Rubidium-82 in horizontal (left upper tomographs) and vertical (right upper tomographs) long-axis views. Rest images are shown (upper row) and dipyridamole stress images (bottom row). In the color coding, white is the highest, red next highest, yellow intermediate, and green and blue lowest relative flows. Tomographs are oriented as if looking down from above with the anterior or apex at the top of each image (ANT), the left lateral free wall on the left (LAT), and the muscular septum (SEP) on the right with the atrioventricular ring and/or inferior myocardium at the bottom (INF). Resting tomographs show a small inferior apical defect indicating a small myocardial scar. With dipyridamole stress, myocardial activity increases appropriately in inferolateral areas. The anterior and apical myocardium shows a severe stress defect extending laterally. Tomographic data can be summarized in a polar display as if looking from outside the body at the apex of the left ventricle located at the center of a bullseye, where the outer rim of the bullseye corresponds to the atrioventricular ring. Polar displays (lower left) show the relative defect on a scale from 0 percent to 100 percent, with rest being the upper (Study 1) and the stress the lower (Study 2) of the left polar maps. The numbers beside the polar maps indicate mean activity of each quadrant; A = anterior, S = septal, X = apex, L = lateral, I = inferior. The right polar map labeled S2/S1 absolute ratio (upper right) shows the absolute counts of the stress image divided by the rest image displayed on a scale from 0 to 2. Increase in activity is shown by warm colors indicating ratios >1 or an increase in absolute activity reflecting increased perfusion on the dipyridamole image. Blue areas indicate an absolute fall in activity, a corresponding fall in perfusion during dipyridamole stress consistent with myocardial steal in a large area supplied by collaterals. The lower right polar display labeled S2/S1 percent ratio illustrates the change in the relative distribution of flow at stress normalized to rest (instead of the absolute values).
CHEST  , DOI: ( /chest )
Copyright © 1989 The American College of Chest Physicians Terms and Conditions

3. FIGURE 2
Shows activity outside 2.5 SD compared with normal subjects as blacked out areas. The numbers beside the polar map indicate the percent of the heart outside 2.5 SD. Thus, polar maps demonstrate a small inferior apical resting defect (Study 1) and a severe large stress defect of anterior, apical, and apical lateral myocardium (Study 2) involving 45 percent of the heart. Of this large area of viable myocardium, 31 percent shows collateralized myocardium associated with myocardial steal as seen in the polar display of S2/S1 absolute ratios (upper right). PET imaging therefore correctly demonstrated the extent and severity of coronary artery disease with collaterals, confirmed at arteriography.
(PET scan courtesy of Don Gordon, M.D., Jacksonville Cardiovascular Clinic and Memorial PET Center.)
CHEST  , DOI: ( /chest )
Copyright © 1989 The American College of Chest Physicians Terms and Conditions