Rb-82 PET/CT left ventricular mass-to-volume ratios

Area of Science:

• Cardiovascular Imaging
• Nuclear Cardiology
• Cardiac Physiology

Background:

• Left ventricular (LV) mass:volume ratios indexed to body size (Mi/Vi) are established predictors of cardiac events.
• Rubidium-82 (Rb-82) Positron Emission Tomography (PET) is utilized for myocardial perfusion imaging.

Purpose of the Study:

• To compare Rb-82 PET derived LV mass and volume indices with established MRI normal values in patients with low likelihood of coronary artery disease (CAD).
• To investigate the relationship between abnormal LV mass and volume indices and myocardial blood flow (MBF) abnormalities.

Main Methods:

• Retrospective analysis of 194 patients undergoing rest/stress Rb-82 PET.
• Calculation of LV ejection fraction (EF), volumes, and mass; indexed Mi/Vi ratios.
• Computation of MBF from dynamic PET data.

Main Results:

• PET derived Mi/Vi in low CAD likelihood subjects (1.35 ± 0.27) were consistent with MRI literature values (1.0-1.5).
• Abnormally high indexed LV volume (Vi) was associated with significantly lower rest and stress MBF (p < 0.0001).
• Low indexed Mi/Vi (<1.0) correlated with reduced rest EF and rest MBF (p < 0.0001).

Conclusions:

• Rb-82 PET derived LV mass and volume indices are comparable to MRI normal values.
• Abnormal LV volume and mass indices are associated with reduced MBF and EF.
• These findings suggest that abnormal LV indices in this population are linked to more extensive obstructive CAD.