Myocardial clearance of technetium-99m-teboroxime in reperfused injured canine myocardium.

Background: Recent technical developments using solid-state technology have enabled rapid image acquisition with single photon emission computed tomography (SPECT) and have led to a renewed interest in technetium-99m-teboroxime (Tc-99m-teboroxime) as a myocardial imaging agent. Tc-99m-teboroxime has demonstrated high myocardial extraction, linear myocardial uptake relative to flow even at high flow rates, rapid uptake and clearance kinetics, and differential clearance in the setting of ischemia. However, the myocardial clearance kinetics of Tc-99m-teboroxime in a model of myocardial injury has not been previously reported.

Beta adrenergic receptor blockade causing severe left ventricular systolic dysfunction during dobutamine stress echocardiography in a patient with no structural heart disease.

A 41-year-old woman with a history of neurocardiogenic syncope treated with beta-blockers was admitted with chest pain. Dobutamine echocardiogram images demonstrated decreased global LV systolic wall motion and thickening. Coronary angiograms were normal.

99mTc-glucarate kinetics differentiate normal, stunned, hibernating, and nonviable myocardium in a perfused rat heart model.

Purpose: (99m)Tc-glucarate is an infarct-avid imaging agent. However, patients may have mixtures of normal, irreversibly injured, stunned, and hibernating myocardium. The purposes were to determine (99m)Tc-glucarate uptake and clearance kinetics in these four conditions, and its ability to determine the extent of injury.

Monocationic radiotracer kinetics and myocardial infarct size: a perfused rat heart study.

Objective: To compare the myocardial kinetics of three (99m)technetium-labeled monocationic tracers [methoxy-isobutylisonitrile (MIBI), tetrofosmin, and Q12] in a model of ischemia-reperfusion (IR) to determine their abilities to assess myocardial viability.

Methods: Isolated perfused rat hearts (n = 30) were studied in control and IR groups for each tracer. IR hearts were treated with 120 min global no-flow followed by 5 min reflow, then 60 min tracer uptake/clearance.

99mTc-sestamibi kinetics predict myocardial viability in a perfused rat heart model.

Introduction: (99m)Tc-sestamibi has been proposed as a viability imaging agent. The purposes of this study were: (1) to determine the relationship between myocardial viability and (99m)Tc-sestamibi kinetics using perfused rat heart models across a full spectrum of viability, (2) to do so under conditions where myocardial flow was controlled and held constant, and (3) to do so using multiple quantitative methods to assess myocardial viability.

Methods: Twenty-three isolated rat hearts were perfused retrogradely with a modified Krebs-Henseleit (KH) solution.

(99m)Tc-glucarate imaging for the early detection of infarct in partially reperfused canine myocardium.

Purpose: (99m)Tc-glucarate is an imaging agent developed for the detection of acutely infarcted myocardium. The purposes of the current study were to (1) determine whether (99m)Tc-glucarate can detect acute infarct in the setting of only partial minimal reperfusion, (2) study the persistence and time course of scan positivity following coronary occlusion and intravenous tracer injection, (3) assess the ability of (99m)Tc-glucarate to determine infarct size, and (4) compare these data with previous results obtained using a 100% reperfusion model.

Methods: Six dogs underwent left circumflex (LCx) coronary occlusion for 90 min, followed by 10% epicardial blood flow reperfusion.

Early detection of infarct in reperfused canine myocardium using 99mTc-glucarate.

Unlabelled: 99mTc-Glucarate is an infarct-avid imaging agent with the potential for very early detection of myocardial infarction. The purposes of this study using a canine model were to determine (a) the time course of (99m)Tc-glucarate uptake and clearance from necrotic and normal myocardium; (b) the (99m)Tc-glucarate necrotic-to-normal activity ratio over time; (c) the time course of detectable scan positivity after intravenous administration of the tracer; and (d) the relationship of infarct size determined by triphenyltetrazolium chloride (TTC) staining versus (99m)Tc-glucarate imaging ex vivo.

Methods: A 90-min left circumflex coronary artery (LCx) occlusion was followed by 270 min of reperfusion at 100% baseline flow in 6 open-chest, anesthetized dogs.