Quantitative gated PET for the assessment of left ventricular function in small animals

Area of Science:

• Nuclear Medicine
• Cardiology
• Small Animal Imaging

Background:

• 18F-FDG PET identifies myocardial viability and necrosis, crucial for evaluating treatments.
• Assessing left ventricular volume (LVV) and ejection fraction (LVEF) in small animals is vital for preclinical research.
• High-resolution avalanche photodiode (APD) PET scanners enable in vivo small animal cardiac imaging.

Purpose of the Study:

• To evaluate the utility of 18F-FDG PET for measuring LVV and LVEF in normal and diseased rats.
• To compare in vivo PET-derived cardiac parameters with echocardiography and phantom data.
• To assess the effectiveness of experimental cardiac interventions using small animal PET.

Main Methods:

• List-mode gated 18F-FDG PET studies were performed on 30 rats (11 healthy, 4 septic shock, 15 heart failure).
• PET images were analyzed using standard clinical cardiac software after resizing to human-scale pixels.
• Echocardiography was used to evaluate LVV and LVEF in the same animals.

Main Results:

• Excellent agreement was found between PET and phantom volumes (r² = 0.96).
• Agreement between PET and echocardiography for LVV was good in healthy rats (r² = 0.89) and fair in diseased rats (r² = 0.49).
• Fair agreement was observed for LVEF between PET and echocardiography (r² = 0.56), with comparable values in normal and heart failure groups.

Conclusions:

• Both PET and echocardiography effectively differentiate normal from heart failure rats.
• Echocardiography is rapid and convenient for assessing cardiac function.
• List-mode PET provides additional valuable information on defect size, myocardial viability, and metabolism.