Measuring response to therapy using FDG PET: semi-quantitative and full kinetic analysis

Area of Science:

• Oncology
• Nuclear Medicine
• Pharmacodynamics

Background:

• Positron emission tomography (PET) with (18)F-2-fluoro-2-deoxy-D-glucose (FDG) is crucial for assessing cancer treatment response.
• Various semi-quantitative and quantitative methods exist for analyzing FDG PET data.

Purpose of the Study:

• To compare simplified FDG PET quantification methods against full kinetic analysis for response assessment.
• To evaluate the reliability of different measures in novel therapy trials.

Main Methods:

• Utilized dynamic FDG PET data from two studies involving lung and gastrointestinal cancer patients undergoing targeted therapies.
• Quantification included full kinetic methods (nonlinear regression, Patlak) and simplified measures (SKM, SUV).
• An image-derived input function was employed for kinetic modeling.

Main Results:

• Excellent correlation was observed between Patlak and nonlinear regression (NLR) analyses (R² > 0.96).
• Standardized uptake value (SUV) showed significant differences compared to Patlak analysis.
• Correcting SUV for plasma glucose improved agreement in one study, but differences persisted in another due to variations in arterial input functions.

Conclusions:

• Simplified FDG PET quantification methods may not always align with full kinetic analysis.
• Discrepancies, particularly in novel therapy assessments, can arise from variations in input functions and method choice.