MR-based attenuation correction methods for improved PET quantification in lesions within bone and susceptibility...

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Radiology

Background:

• Hybrid PET/MR systems are increasingly used in clinical practice.
• Accurate attenuation correction is crucial for quantitative PET imaging.
• MR-based attenuation correction methods require validation for simultaneously acquired data.

Purpose of the Study:

• To assess the accuracy of four MR-based attenuation correction methods in hybrid PET/MR imaging.
• To evaluate performance in soft tissue, bone, and MR susceptibility artifact regions.
• To compare methods against CT-based attenuation correction.

Main Methods:

• Four attenuation correction methods were evaluated: SEG1, SEG2, AT&PR, and SEG2wBONE.
• PET/MR datasets from 10 patients were analyzed.
• Volumes of interest were placed on lesions in various locations, and relative differences to CT-based correction were calculated.

Main Results:

• No significant differences were found for soft-tissue lesions across all methods.
• All methods underestimated PET values in bone lesions, with SEG2wBONE showing the smallest error (-4.7% ± 4.4%).
• SEG2wBONE and AT&PR demonstrated accurate results for lesions affected by MR susceptibility artifacts, with errors of 0.6% ± 11.1% and -4.1% ± 11.2%, respectively.

Conclusions:

• SEG1 and SEG2 methods showed significant underestimation for bone lesions.
• MR susceptibility artifacts can lead to substantial quantification errors if uncorrected.
• SEG2wBONE offers accurate PET quantification in diverse lesion types and locations, with improved robustness for bone imaging.