Quantification of 18F-Fluoride Kinetics: Evaluation of Simplified Methods

Area of Science:

• Nuclear Medicine
• Radiochemistry
• Bone Metabolism

Background:

• Positron Emission Tomography (PET) with Fluorine-18 ((18)F-fluoride) is a key imaging modality for assessing bone metabolism and blood flow.
• Accurate kinetic analysis is crucial for reliable interpretation of PET data.

Purpose of the Study:

• To evaluate the performance of simplified clinical methods (Patlak, SUV) against full kinetic analysis for (18)F-fluoride PET.
• To investigate the validity of using (18)F-fluoride K1 to derive bone blood flow, using Oxygen-15-labeled water ((15)O-H2O) as a reference.

Main Methods:

• Dynamic PET scans with (18)F-fluoride and (15)O-H2O were performed on 22 adults (16 patients, 6 healthy volunteers).
• Arterial blood was continuously monitored.
• (18)F-fluoride data were analyzed using nonlinear regression (NLR), Patlak, and standardized uptake value (SUV) methods.

Main Results:

• Patlak analysis (10-60 min) yielded a mean fluoride influx rate (Ki) highly correlated with NLR-derived Ki (r=0.976).
• Lean body mass-normalized SUV (50-60 min) also showed a strong correlation with Ki (r=0.958).
• (18)F-fluoride K1 demonstrated a low correlation with measured bone blood flow (r=0.35).

Conclusions:

• Both Patlak and SUV methods are suitable for assessing (18)F-fluoride kinetics in human bone.
• (18)F-fluoride PET has limitations in accurately monitoring bone blood flow.