PT - JOURNAL ARTICLE AU - Cindy Q. Shi AU - Lawrence H. Young AU - Edouard Daher AU - Edward V.R. DiBella AU - Yi-Hwa Liu AU - Eliot N. Heller AU - Sami Zoghbi AU - Frans J.Th. Wackers AU - Robert Soufer AU - Albert J. Sinusas TI - Correlation of Myocardial <em>p</em>-<sup>123</sup>I-Iodophenylpentadecanoic Acid Retention with <sup>18</sup>F-FDG Accumulation During Experimental Low-Flow Ischemia DP - 2002 Mar 01 TA - Journal of Nuclear Medicine PG - 421--431 VI - 43 IP - 3 4099 - http://jnm.snmjournals.org/content/43/3/421.short 4100 - http://jnm.snmjournals.org/content/43/3/421.full SO - J Nucl Med2002 Mar 01; 43 AB - Myocardial ischemia is associated with reduced free fatty acid (FFA) β-oxidation and increased glucose utilization. This study evaluated the potential of dynamic SPECT imaging of a FFA analog, p-123I-iodophenylpentadecanoic acid (IPPA), for detection of ischemia and compares retention of IPPA with 18F-FDG accumulation. Methods: In a canine model of regional low-flow ischemia (n = 9), serial IPPA SPECT images (2 min per image) were acquired over 52–90 min. In a subset of dogs (n = 6), 18F-FDG was injected after completing SPECT imaging and allowed to accumulate for 40 min before killing the animals. Flow was assessed with radiolabeled microspheres. Myocardial metabolism was evaluated independently by selective coronary arterial and venous sampling. Results: Serial IPPA SPECT images showed an initial defect in the ischemic region (0.70% ± 0.03% ischemic-to-nonischemic ratio), which normalized within 48 min because of the slower IPPA clearance from the ischemic region (t1/2 = 54.2 ± 3.3 min) relative to the nonischemic region (t1/2 = 36.7 ± 5.6 min) (P &lt; 0.05). Delayed myocardial IPPA and 18F-FDG activities were correlated (r = 0.70; n = 576 segments), and both were maximally increased in segments with a moderate flow reduction (IPPA, 151% of nonischemic; 18F-FDG, 450% of nonischemic; P &lt; 0.05). Conclusion: Serial SPECT imaging showed delayed myocardial clearance of IPPA in ischemic regions with moderate flow reduction, which lead to increased late myocardial retention of IPPA. Retention of IPPA correlated with 18F-FDG accumulation, supporting the potential of IPPA as a noninvasive marker of ischemic myocardium.