[Estimation of infarct size with 201Tl by multiprojection analysis]

Area of Science:

• Cardiology
• Nuclear Medicine
• Medical Imaging

Background:

• Cardiac arrhythmia mortality has decreased with CCU introduction, making power failure the primary cause of death in acute myocardial infarction (AMI) patients.
• Power failure in AMI is linked to infarct size, necessitating noninvasive methods for infarct size quantification to guide prognosis and treatment.
• Thallium-201 (201Tl) scintigraphy, which localizes to intact myocardium, offers a potential noninvasive approach for assessing myocardial damage.

Purpose of the Study:

• To evaluate two parameters (% area and % loss counts) derived from 5-projection myocardial scintigraphy for noninvasive infarct size quantification in AMI patients.
• To assess the correlation of these infarct size parameters with established clinical markers of cardiac function and myocardial damage.
• To determine the reliability and clinical utility of 201Tl scintigraphy in estimating infarct size and providing prognostic information.

Main Methods:

• Utilized 5-projection myocardial scintigraphy with radionuclide thallium-201 in 56 patients with a first acute myocardial infarction.
• Calculated infarct size using two parameters: % area (defect area/total myocardium) and % loss counts (count decrease/total counts) from planar images.
• Analyzed parameters from uni- and multi-projection (1, 3, and 5 projections) and compared correlations with contrast ventriculography (ejection fraction), pulmonary end-diastolic pressure, and peak/sigma CPK levels.

Main Results:

• Both % area and % loss counts parameters, across different projection analyses, showed clinically acceptable correlations with ejection fraction, pulmonary end-diastolic pressure, and CPK measurements.
• No significant difference was observed in correlation coefficients between the two parameters (% area vs. % loss counts) across the evaluated projection methods.
• Serial scintigraphy in 11 patients indicated a decrease in infarct size correlating with the clinical course, demonstrating the technique's ability to track changes over time.

Conclusions:

• 201Tl scintigraphy provides a reliable noninvasive method for estimating infarct size in patients with acute myocardial infarction.
• The assessed parameters (% area and % loss counts) offer valuable information regarding the extent of myocardial necrosis and its impact on cardiac function.
• This scintigraphic technique aids in the proper assessment of prognosis and guides treatment strategies for AMI patients.