A comparison of the overall first-pass kinetics of thallium-201 and technetium-99m MIBI in normoxic and low-flow ischaemic myocardium

Abstract

The specific impact of ischaemia on the myocardial kinetics of thallium-201 and technetium-99m 2-methoxy-2-isobutylisonitrile (MIBI) remains a matter of debate. Using an isolated heart model perfused with red blood cell-enhanced perfusate, we compared the overall first-pass kinetics of 201Tl and MIBI under haemodynamically stable conditions of low-flow ischaemia (> 50% reduction in normal coronary flow and a > or = 20 mmHg fall in systolic contraction pressure, n = 10) and normoxia (n = 11). For both 201Tl and MIBI, we found that under ischaemic conditions (as compared with normoxia) there was a higher initial net extraction fraction (201Tl: 0.78 +/- 0.03 vs 0.72 +/- 0.06, P = 0.006; MIBI: 0.49 +/- 0.10 vs 0.39 +/- 0.11, P = 0.03), a lower clearance rate in the 30 min following extraction (% decrease in cardiac uptake: 201Tl: 30 +/- 12 vs 47 +/- 14, P = 0.02; MIBI: 5 +/- 5 vs 13 +/- 11, P = 0.02) and a higher retention fraction at 30 min (20lTl: 0.54 +/- 0.10 vs 0.39 +/- 0.12, P = 0.004; MIBI: 0.46 +/- 0.08 vs 0.33 +/- 0.12, P = 0.01). Multivariate analyses, however, revealed that all myocardial kinetic parameters of both tracers were dependent only on coronary flow rates, without any additional significant impact of the presence of ischaemia or states of contractility or oxidative metabolism. We conclude that the myocardial fractional retention of both 201Tl and MIBI is strongly correlated with the decrease in coronary flow during ischaemia. This inverse relationship with coronary flow derives from both the flow-dependent increase in the initial myocardial extraction and the decrease in the subsequent myocardial washout of the tracers.

Compared Performance of High-Sensitivity Cameras Dedicated to Myocardial Perfusion SPECT: A Comprehensive Analysis of Phantom and Human Images

“…This low percentage can be explained by several factors: that only about 5% of the injected activity is likely to pass through coronary vessels (coronary flow expressed as percentage of cardiac flow) (30), that less than 40% of this amount will be retained within the myocardial tissue (retention fractions of sestamibi under high-flow conditions (31,32)), and that the addition of body attenuation further decreases the number of detected photons.…”

Changes in First-Pass Interstitial Kinetics of DTPA in Myocardium Submitted to Low-Flow Ischemia

“…8,10,14,15 Final perfusate contained 30% of bovine red blood cells, 5 g/l Ϫ1 bovine serum albumin (A-6003; Sigma Chemica Co., St. Louis, MO), and the following electrolytes and substrates: NaCl (127 mM), MgSO 4 (0.9 mM), CaCl 2 (2.5 mM), NaHCO 3 (25 mM), KH 2 PO 4 (1.17 mM), glucose (11 mM), and lactate (0.9 mM). Bovine red blood cells were supplied by a regional slaughterhouse (Socopa SA, Mirecourt); before use, they were washed twice with a 0.9% NaCl solution.…”

Fleming-Harrington Redistribution Wash-in Washout (FHRWW): The Platinum Standard for Nuclear Cardiology

“…Furthermore, comparisons of the initial 5-minute imaging with the 60-minute imaging demonstrated different results from the simple "uptake/retention" rest-stress model. Other investigators have noted similar differences between 5 minute and 60 minute imaging of the heart (Hurwitz 1993, Saha 1994, Giubbini 1995, Pace 2005) allowing for enhanced detection of congestive heart failure (Hurwitz 1998, Kumita 2002, Sugiura 2006, Matsuo 2007, cardiomyopathies (Meissner 2002, Ikawa 2007), Prinzmetal 's angina (Ono 2002(Ono , 2003 and underlying coronary artery disease (Meerdink 1990, Richter 1995, Shin 1995, Takeishi 1996, Takahashi 1996, Fujiwara 1998, Hurwitz 1998, Ayalew 2000, Liu 2001, Kumita 2002, Tanaka 2006, Fukushima 2007, VanBrocklin 2007 including evidence of wash-in (Meerdink 1990, Richter 1995 indicative of critical lesions not detected by conventional MPI. In the same way that thrombolysis in myocardial infarction (TIMI) flow is used to look for changes (sometimes subtle, sometimes not) in coronary blood flow in the catch lab, multiple imaging following pharmacologic or EST allows us to take a more advanced look at the physiologic function of the heart, unmasking ischemic heart disease missed by rest-stress imaging.…”