Influence of attenuation on radionuclide stroke volume determinations

Area of Science:

• Nuclear medicine
• Cardiovascular physiology
• Medical imaging

Background:

• Accurate measurement of cardiac output and stroke volume is crucial for diagnosing and managing cardiovascular diseases.
• Traditional methods like thermodilution are invasive and can have limitations.
• Radionuclide techniques offer a noninvasive approach but require precise volume determination.

Purpose of the Study:

• To evaluate a radionuclide method for determining absolute left-ventricular volumes, specifically stroke volume (SV) and cardiac output (CO).
• To assess the accuracy of this method by comparing it with thermodilution in human subjects.
• To determine if correcting for attenuation improves the accuracy of radionuclide-derived SV and CO.

Main Methods:

• Simultaneous measurements of cardiac output using thermodilution and multigated equilibrium blood-pool scintigraphy (radionuclide technique) in 20 patients.
• Patients had no evidence of intracardiac shunts or valvular disease.
• The radionuclide method incorporated a correction for attenuation to determine absolute left-ventricular volumes.

Main Results:

• A good correlation was initially observed between attenuated radionuclide stroke volume and thermodilution stroke volume (r = 0.80).
• After correction for attenuation, the correlation significantly improved (r = 0.96), approaching the line of identity.
• The correlation between radionuclide cardiac output (corrected for attenuation) and thermodilution cardiac output was also good (r = 0.89).

Conclusions:

• The developed radionuclide method, with attenuation correction, provides a reliable and noninvasive means to calculate human stroke volume.
• This technique eliminates the need for geometric assumptions or regression equations, enhancing its clinical applicability.
• The findings support the use of this corrected radionuclide method for accurate assessment of cardiac function.