Potential pitfalls of the nuclear stethoscope

Area of Science:

• Cardiology
• Nuclear Medicine
• Medical Imaging

Background:

• Accurate assessment of global left ventricular ejection fraction (LVEF) is crucial for diagnosing and managing cardiovascular diseases.
• Various imaging modalities exist, each with potential limitations in precision and reproducibility.

Purpose of the Study:

• To compare the accuracy of global left ventricular ejection fraction (LVEF) determined by nuclear stethoscope, Tc-99m-labeled-erythrocyte gated nuclear angiocardiography, and contrast left ventriculography.
• To evaluate the determination of global right ventricular ejection fraction (RVEF) using gated nuclear techniques.

Main Methods:

• Eleven patients with diverse cardiac conditions and normal individuals underwent LVEF assessment using three methods within a 6-hour period.
• Techniques included nuclear stethoscope, Tc-99m-labeled-erythrocyte gated nuclear angiocardiography, and single plane RAO contrast left ventriculography.
• Global right ventricular ejection fraction (RVEF) was also assessed via gated nuclear techniques.

Main Results:

• Gamma camera-computer techniques for LVEF showed excellent correlation (r = 0.95) with contrast ventriculography.
• Nuclear stethoscope measurements of LVEF correlated less well (r = 0.59) with contrast ventriculography.
• Two cases demonstrated significant overestimation of LVEF by the nuclear stethoscope due to probe malpositioning, especially in coronary artery disease.

Conclusions:

• Tc-99m-labeled-erythrocyte gated nuclear angiocardiography provides a reliable method for assessing global left ventricular ejection fraction (LVEF), correlating well with contrast ventriculography.
• The nuclear stethoscope may lead to inaccurate LVEF measurements due to potential probe malpositioning, highlighting the importance of precise placement in cardiac imaging.