SPECT Imaging of 2-D and 3-D Distributed Sources with Near-Field Coded Aperture Collimation: Computer Simulation and...

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Biomedical Engineering

Background:

• Near-field coded aperture (CA) imaging is challenging for single-photon emission computerized tomography (SPECT).
• Traditional pinhole collimation in SPECT faces limitations with distributed sources.

Purpose of the Study:

• To propose and evaluate a novel CA SPECT reconstruction approach for distributed sources.
• To assess the feasibility of near-field CA collimation for imaging hot sources and cold lesions.
• To compare CA collimation with pinhole collimation in SPECT.

Main Methods:

• Computer simulations comparing CA and pinhole collimation in 2D radionuclide imaging.
• Reconstruction of digital phantom and ex vivo rat heart images using maximum likelihood expectation maximization (MLEM) algorithm.
• Evaluation of image quality, contrast-to-noise ratio (CNR), resolution, and artifacts.

Main Results:

• CA SPECT demonstrated improved image quality, lower root-mean-squared error, and higher CNR compared to pinhole SPECT in phantom studies.
• Both CA and pinhole methods provided similar resolution, but CA exhibited fewer noise artifacts.
• 3D CA SPECT successfully visualized myocardial perfusion defects in a rat heart, outperforming pinhole SPECT with reduced noise artifacts.

Conclusions:

• The proposed 3D CA SPECT imaging and reconstruction methods are feasible and effective.
• Near-field CA collimation offers potential for high-sensitivity and high-resolution SPECT imaging.
• CA SPECT shows promise for overcoming limitations of traditional SPECT systems, particularly for distributed sources.