Efficient Delay Correction for Total-Body PET Kinetic Modeling Using Pulse Timing Methods.

Area of Science:

• Nuclear medicine
• Medical imaging
• Quantitative imaging

Background:

• Quantitative kinetic modeling in PET relies on accurate input functions.
• Image-derived input functions (IDIFs) can be affected by time delays between the IDIF and tissue, especially in total-body PET.
• Standard joint estimation (JE) for delay correction is computationally intensive.

Purpose of the Study:

• To investigate the efficiency and accuracy of pulse timing methods, specifically leading edge (LE), for estimating and correcting time delays in total-body PET.
• To compare LE delay correction with JE and no delay correction in simulations and human studies.

Main Methods:

• Simulation studies evaluated LE and constant fraction discrimination methods under various delay, frame length, and noise conditions.
• LE (10% threshold) and JE methods were applied to dynamic total-body 18F-FDG PET data from 21 subjects.
• Kinetic analysis and parametric imaging were performed to compare delay correction methods.

Main Results:

• Simulations showed LE (10% threshold) provided tolerable bias and SD with 2-s frames across tested noise levels.
• Pooled ROI analysis demonstrated strong agreement between LE and JE for delay estimation and kinetic parameters (v, K, K1).
• Parametric images showed improved lesion contrast with LE and JE delay correction compared to no correction or Patlak analysis.

Conclusions:

• Delay correction is crucial for accurate total-body PET parametric imaging.
• LE delay correction is an efficient and effective surrogate for JE, significantly reducing computational time.
• This method enables rapid delay correction for large total-body PET datasets.