Artifact-free partial volume correction for ¹⁷⁷Lu-PSMA SPECT

Area of Science:

• Nuclear Medicine
• Medical Imaging
• Radiopharmaceutical Therapy

Background:

• Partial volume effect (PVE) in SPECT imaging reduces quantification accuracy.
• Traditional partial volume correction (PVC) methods often use spatially invariant point spread functions (PSFs) and can introduce Gibbs ringing artifacts.

Purpose of the Study:

• To develop a spatially variant PSF (svPSF) enhanced PVC for ¹⁷⁷Lu-PSMA SPECT.
• To achieve improved quantification accuracy without Gibbs ringing or noise amplification.

Main Methods:

• Generated svPSFs via Monte Carlo simulations and linear interpolation.
• Enhanced Reblurred Van Cittert (RVC) and iterative Yang (IY) algorithms with svPSFs, voxel by voxel.
• Implemented non-negativity constraint (NC) in RVC to mitigate artifacts.
• Validated methods using simulated (cylindrical and XCAT phantoms) and real clinical ¹⁷⁷Lu-PSMA-617 SPECT data.

Main Results:

• svPSF-enhanced PVC methods improved recovery coefficients (RC) for phantom spheres.
• Mean absolute errors (MAE) in kidneys, parotid glands, and tumors were significantly reduced, e.g., from 51.8% to 8.8% for tumors.
• The proposed svPSF+NC-RVC method showed improved background uniformity (CoV of 0.082).
• Gibbs ringing artifacts and noise were reduced with NC implementation in RVC.

Conclusions:

• The developed svPSF enhanced PVC methods enhance quantification accuracy in ¹⁷⁷Lu-PSMA-617 SPECT.
• Non-negativity constraint (NC) effectively suppresses Gibbs ringing artifacts and noise in RVC images.