Correlation of Myocardial p-123I-Iodophenylpentadecanoic Acid Retention with 18F-FDG Accumulation During Experimental Low-Flow Ischemia
Cindy Q. Shi, MD1,
Lawrence H. Young, MD1,
Edouard Daher, MD1,
Edward V.R. DiBella, PhD2,
Yi-Hwa Liu, PhD1,
Eliot N. Heller, MD1,
Sami Zoghbi, PhD3,
Frans J.Th. Wackers, MD1,3,
Robert Soufer, MD1,4 and
Albert J. Sinusas, MD1,3
1 Experimental Nuclear Cardiology Laboratory, Division of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
2 Department of Radiology, University of Utah, Salt Lake City, Utah
3 Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, Connecticut
4 Positron Imaging Laboratory, Yale University/Department of Veteran Affairs, West Haven, Connecticut
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FIGURE 1. Surgical instrumentation of heart.
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FIGURE 2. Experimental protocol. After baseline (BASE) measurements, partial coronary stenosis was created and maintained throughout protocol. Arterial and venous samples were obtained for metabolic measurements, and radiolabeled microspheres were injected at times designated. IPPA was injected 60 min after creation of stenosis. 18F-FDG was injected 90 min later.
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FIGURE 3. Myocardial blood flow in endocardial (ENDO), midwall (MW), epicardial (EPI), and transmural (TM) layers of central ischemic region are expressed as percentage of nonischemic region. Normalized flows are shown at baseline and at time of IPPA (stenosis 60 min) and 18F-FDG (stenosis 150 min) injections.
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FIGURE 4. Lactate balance for LAD and LCX was measured during baseline and after 60 min (stenosis 60 min) and 150 min (stenosis 150 min) of partial coronary occlusion. Time points correspond to time of IPPA and 18F-FDG injections.
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FIGURE 5. Ischemic-to-nonischemic ratios of myocardial IPPA activity obtained in 9 dogs from selected IPPA SPECT images. Individual dogs are represented by different symbols. Average ratio is represented by  and thickened line. Significant normalization of ischemic defect ratio occurred within 16 min and nearly complete normalization of defect ratio occurred within 48 min after injection. Data are expressed as mean ± SEM.
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FIGURE 6. (A) Serial short-axis and vertical long (v-long) axis SPECT IPPA images from representative dog displayed in standard format. Time after injection is designated on left margin. Note perfusion defect in anteroseptal and anteroapical regions, which normalizes over time. (B) Myocardial IPPA clearance curves derived from ischemic and nonischemic regions for same dog. (C) Early clearance data for same dog are also displayed as semilogarithmic plot. Early myocardial clearance appears linear on this semilogarithmic plot, suggesting early monoexponential clearance of IPPA. Delayed myocardial IPPA clearance is seen in ischemic region.
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FIGURE 7. Myocardial IPPA and 18F-FDG retained activities expressed as nonischemic percentage for all segments (n = 576). Segments were segregated on basis of normalized flows in segments into 20%-flow increments. Numbers within each bar represent number of segments falling into each flow range.
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FIGURE 8. Correlation between normalized myocardial IPPA and 18F-FDG retained activity for all dogs (n = 6) injected with 18F-FDG. Individual dogs are represented by different symbols.
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Copyright © 2002 by the Society of Nuclear Medicine.
