A comparison of MR-based attenuation correction in PET versus SPECT

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Biomedical Engineering

Background:

• Attenuation correction (AC) is crucial for quantitative accuracy in positron emission tomography (PET) and single photon emission computed tomography (SPECT) imaging.
• Magnetic resonance (MR)-based AC algorithms are established for hybrid PET/MR systems but require validation for SPECT/MR.

Purpose of the Study:

• To evaluate the applicability of MR-based AC algorithms, validated for PET, to SPECT imaging.
• To compare the performance of MR-based AC in PET versus SPECT reconstructions.
• To assess the sensitivity of MR-based AC reconstructions to variations in attenuation maps for both modalities.

Main Methods:

• Anthropomorphic chest phantom and canine studies (n=4 per group) were conducted using PET/CT and MR, and SPECT/CT and MR.
• MR-based attenuation maps were generated and applied to reconstruct PET and SPECT images.
• Quantitative and qualitative comparisons of image fidelity and sensitivity to attenuation map variations were performed.

Main Results:

• SPECT reconstructions using MR-based attenuation maps exhibited higher fidelity compared to PET reconstructions.
• SPECT reconstructions demonstrated lower sensitivity to variations in the MR-based attenuation map.
• The findings suggest MR-based AC algorithms are robust for SPECT/MR applications.

Conclusions:

• MR-based AC algorithms designed for PET/MR systems are expected to perform effectively, with potentially improved results, in SPECT/MR systems.
• The study validates the use of MR-based AC for emerging SPECT/MR hybrid imaging technologies.
• Further development and application of these algorithms can enhance quantitative accuracy in SPECT imaging.