[Comparison of OS-EM reconstruction algorithms among different processors using a digital phantom dedicated for SPECT...

Area of Science:

• Medical Imaging
• Nuclear Medicine Technology
• Image Reconstruction

Background:

• Ordered-subset expectation-maximization (OS-EM) algorithms are crucial for image reconstruction in nuclear medicine.
• Variability in OS-EM implementations across different image processors can affect diagnostic accuracy.
• Standardization is needed for reliable research and clinical use of SPECT data.

Purpose of the Study:

• To evaluate differences in OS-EM algorithm performance across four distinct image processors.
• To assess the impact of varying subsets and iterations on image reconstruction quality.
• To compare quantitative metrics like average counts, contrast, %RMSU, and NMSE.

Main Methods:

• Utilized a digital phantom for SPECT data evaluation.
• Reconstructed multiple images using OS-EM with varied subsets and iterations.
• Quantified average counts, contrast, root mean square uncertainty (%RMSU), and normalized mean squared error (NMSE) within regions of interest (ROIs).

Main Results:

• No significant differences in image contrast were observed among the processors.
• Average counts and %RMSU showed significant variations with increasing updates.
• The minimum normalized mean squared error (NMSE) differed across the evaluated algorithms.

Conclusions:

• OS-EM algorithm performance varies between image processors, affecting quantitative metrics.
• Careful evaluation of image processors is essential for research standardization in nuclear medicine.
• Clinical applications require awareness of potential discrepancies in OS-EM reconstructed images.