Image derived input functions: effects of motion on tracer kinetic analyses

Area of Science:

• Nuclear medicine
• Medical imaging analysis
• Pharmacokinetics

Background:

• Accurate tracer kinetic analysis in dynamic positron emission tomography (PET) relies on precise image-derived input functions (IDIFs).
• Patient motion during PET scans is a common issue in clinical settings.
• Motion can introduce significant artifacts into dynamic PET data, potentially compromising quantitative results.

Purpose of the Study:

• To quantify the impact of motion-affected image-derived input functions (IDIFs) on tracer kinetic analysis outcomes.
• To evaluate how rotational and translational motion affects the accuracy of V(T) calculations.

Main Methods:

• Two simulation studies were conducted, one with high and one with low cortical uptake.
• Rotational and axial translational motion artifacts were introduced into simulated dynamic PET scans.
• Image-derived input functions (IDIFs) were extracted from motion-affected scans and compared to original IDIFs and resulting V(T) values.

Main Results:

• Motion-affected IDIFs showed deviations up to 239% in later frames.
• Patient motion exceeding 6° or 5 mm led to at least 10% changes in V(T) for high cortical uptake tracers.
• Significant discrepancies were observed in tracer kinetic parameters due to motion.

Conclusions:

• The simulated motion levels are representative of those encountered in clinical PET studies.
• Motion significantly hinders the accurate extraction of IDIFs, leading to unreliable kinetic analyses.
• Minimizing and correcting for patient motion is crucial for obtaining accurate quantitative PET data.