Pareto optimization of SPECT acquisition and reconstruction settings for ¹⁷⁷Lu activity quantification

Area of Science:

• Nuclear Medicine
• Medical Imaging
• Radiopharmaceutical Therapy

Background:

• Quantitative SPECT imaging with Lutetium-177 (¹⁷⁷Lu) is crucial for dosimetry in targeted radiopharmaceutical therapy.
• Understanding the impact of acquisition and reconstruction parameters on image quality is essential for accurate quantification.

Purpose of the Study:

• To investigate the influence of projection angles, subsets, and iterations on noise and bias in ¹⁷⁷Lu-SPECT.
• To evaluate these properties across different total acquisition times for OS-EM reconstruction.

Main Methods:

• Experimental SPECT phantom studies with ¹⁷⁷Lu and Monte Carlo simulations of ¹⁷⁷Lu-DOTA-TATE in an anthropomorphic phantom.
• Bootstrapping and noise realizations were used to simulate varying projection numbers (20-120) and acquisition times (10, 20, 40 min).
• OS-EM reconstruction with parameter variation (subsets, iterations) and Pareto front analysis of CV vs. mean relative error.

Main Results:

• Reconstructions with a low number of subsets yielded Pareto front points with low coefficient of variation (CV) but high mean error.
• High numbers of subsets resulted in high CV but low mean error.
• The number of projection angles demonstrated a limited impact on noise and bias.

Conclusions:

• For precise ¹⁷⁷Lu activity concentration estimation in SPECT, the number of projection angles is of minor importance.
• Total acquisition time, number of subsets, and iterations are critical parameters for optimizing quantitative accuracy.