9:30-9:45. First Pass FDG Measured Blood Flow in Tumors: A Comparison with O-15 Labeled Water Measured Blood Flow

Area of Science:

• Oncology
• Nuclear Medicine
• Radiochemistry

Background:

• Assessing tumor blood flow is crucial for evaluating treatment response to antiangiogenic agents.
• Positron Emission Tomography (PET) is a key imaging modality for tumor perfusion and metabolism.
• Current methods often rely on specific perfusion tracers, limiting broader application.

Purpose of the Study:

• To investigate the utility of the initial uptake phase of fluorodeoxyglucose (FDG) for measuring regional tumor blood flow.
• To determine if FDG first-pass imaging can serve as a surrogate for established perfusion tracers.
• To evaluate FDG's potential in scenarios lacking dedicated perfusion imaging.

Main Methods:

• PET scans were acquired in patients undergoing a Phase I trial of Endostatin.
• Simultaneous O-15 labeled water (perfusion tracer) and FDG scans were performed.
• Blood flow was calculated using a one-compartment model for both tracers.
• Linear regression analysis compared FDG-derived blood flow with O-15 water-derived blood flow.

Main Results:

• FDG first-pass blood flow showed a strong linear correlation with O-15 water blood flow (R=0.86).
• The correlation yielded an intercept of 0.01 and a slope of 0.86.
• This association was significant for blood flow values up to 0.6 ml/min/gm.

Conclusions:

• The first pass of FDG provides a reliable estimate of tumor blood flow in the absence of specific perfusion tracers.
• FDG first-pass imaging is a feasible method for assessing tumor perfusion within certain limitations.
• This technique enhances the utility of standard FDG PET scans for evaluating tumor vascularity.