Myocardial activation patterns (MAP) applied to patients with CAD using multi-pinhole SPECT during dobutamine stress

1447 Objectives Visual interpretation of LV contraction following stress can be difficult. Multi-Pinhole SPECT (MP-SPECT) allows rapid serial measurement of LV contractility, both during the stages of dobutamine stess and during recovery. We investigated analysis and display techniques to maximize information obtained from MAP. Methods List-mode gated MP-SPECT data was acquired during dobutamine stress using 300 MBq of Tc followed by injection of either 150 MBq of Tl or 900 MBq of Tc. LVEF, segmental motion and thickening were measured during each 8 min stress stage and serially during recovery from stress in 2-4 minute segments. Following equilization of cardiac cnts/frm, the MAP were displayed as dynamic polar maps of thickening, radial distance to the mid-wall and activation of contraction for each stress stage and each segment during recovery. Results The MAP correlated with visual segmental thickening in all patients (n=~80). In normals, MAP were not altered by dobutamine stress. In patients with myocardial ischemia, dobutamine caused an intial increase in segmental contraction followed by a decrease at peak stress, wherein the MAP also demonstrated a biphasic response. Dobutamine stress did not induce motion or thickening abnormalities in the MAP of normal patients, patients with non-ischemic flow differences or patients with a non-viable infarction. Conclusions The application of MAP to MP-SPECT cardiac images allows serial measurement of abnormal LV contractility, can be used to increase certainty and confirm visual impressions. High count images from MP-SPECT support MAP quantification as a tool to enhance the identification of LV contractional abnormalities.