PET/MR brain imaging: evaluation of clinical UTE-based attenuation correction

Area of Science:

• Medical Imaging
• Radiology
• Nuclear Medicine

Background:

• Accurate attenuation correction (AC) is crucial for PET/MR imaging.
• MR-based AC presents a significant challenge for PET/MR systems.

Purpose of the Study:

• To evaluate the performance of Siemens' VB20P MR-based AC for head PET data.
• To compare MR-based AC against CT-based AC in PET/MR imaging.

Main Methods:

• Utilized (18)F-FDG PET data from lymphoma and lung cancer patients on a Biograph mMR system.
• Reconstructed PET data using both CT-based and MR-based AC.
• Quantitatively compared SUV in brain regions and analyzed attenuation maps for bone segmentation.

Main Results:

• MR-based AC (UTE μ maps) overestimated neck bone and underestimated cranial bone.
• MR-based AC struggled with tissue classification at air/tissue interfaces (sinuses, ears).
• PET activity showed overestimation (0.5-3.6%) and underestimation (2.7-5.2%) in the brain due to inaccurate bone segmentation.

Conclusions:

• The UTE MRAC method in VB20P performs near optimally in the brain.
• The method is unsatisfactory for the neck and face/nasal regions due to bone segmentation issues.
• Improvements in UTE MRAC or bone segmentation methods are necessary for better PET/MR accuracy.