RT Journal Article
SR Electronic
T1 <sup>201</sup>Tl and <sup>99m</sup>Tc-MIBI Retention in an Isolated Heart Model of Low-Flow Ischemia and Stunning: Evidence of Negligible Impact of Myocyte Metabolism on Tracer Kinetics
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 566
OP 574
VO 43
IS 4
A1 Ayalew, Adey
A1 Marie, Pierre-Yves
A1 Menu, Patrick
A1 Mertes, Paul-Michel
A1 Audonnet, Sandra
A1 Jouan, Valérie
A1 Olivier, Pierre
A1 Karcher, Gilles
A1 Ungureanu-Longrois, Dan
A1 Bertrand, Alain
YR 2002
UL http://jnm.snmjournals.org/content/43/4/566.abstract
AB It is not known whether cellular metabolic disorders play a role in the decreased tracer uptake that is documented by conventional SPECT during low-flow ischemia or stunning. This study sought to determine the impact of low-flow ischemia and stunning on the kinetics of 201Tl and MIBI across the plasma membrane of myocytes. Methods: The global myocardial retention (Rf) of 201Tl and MIBI was determined in isolated working hearts from rabbits, perfused with red blood cell–enhanced solution. Experiments were performed in normoxia, with physiological values of coronary flow (N; n = 16); in low-flow ischemia, with a &gt;50% reduction of coronary flow and a ≥ 20-mm Hg fall in systolic left ventricle pressure (L; n = 15); and in stunning, with 15 min of acute ischemia followed by reperfusion (S; n = 15). Concentration ratios across the plasma membrane of myocytes were also determined for both tracers and expressed as Ci/Cc, where Ci is interstitial activity determined with microdialysis, and Cc is activity from cellular space determined from Rf and Ci values. Results: There was a slight increase in average values of Ci/Cc in ischemia, but not in stunning, for 201Tl (L, 0.011 ± 0.006 vs. N, 0.006 ± 0.004 [P &lt; 0.05]; S, 0.007 ± 0.004 vs. N [not significant]) and for MIBI (L, 0.011 ± 0.008 vs. N, 0.005 ± 0.004 [P &lt; 0.05]; S, 0.005 ± 0.003 vs. N [not significant]). Moreover, ischemia and stunning had no deleterious effects on the average values of global myocardial retention for 201Tl (L, 0.63 ± 0.09 vs. N, 0.50 ± 0.14 [P &lt; 0.05]; S, 0.59 ± 0.10 vs. N [P &lt; 0.05]) or for MIBI (L, 0.45 ± 0.10 vs. N, 0.31 ± 0.09 [P &lt; 0.05]; S, 0.41 ± 0.12 vs. N [P &lt; 0.05]). In fact, these values were significantly enhanced in the 2 situations. Conclusion: The kinetics of 201Tl and MIBI across the plasma membrane of myocytes were affected only poorly by low-flow ischemia and not at all by stunning, without any deleterious effects on myocardial retention of both tracers. During low-flow ischemia or stunning, therefore, the information provided by 201Tl or MIBI SPECT is expected to depend on myocardial perfusion but not on cellular metabolic disorders.