MR-driven metal artifact reduction in PET/CT.

Area of Science:

• Medical Imaging
• Radiology
• Biomedical Engineering

Background:

• Tri-modality systems combining PET/MR offer synergistic advantages over standalone systems.
• Metal artifacts, particularly dental streak artifacts, pose challenges in CT-based attenuation correction for PET/CT.
• Assessing the frequency and severity of these artifacts is crucial for accurate imaging in oncology patients.

Purpose of the Study:

• To investigate the feasibility of correcting dental streak artifacts in CT images using complementary MR data.
• To develop and test an algorithm for automatic localization and editing of metal artifact regions.
• To evaluate the impact of artifact correction on radiotracer uptake measurements in PET/CT scans.

Main Methods:

• A prospective correction algorithm was developed, utilizing both CT and MR information.
• The algorithm was retrospectively tested on PET/CT data from 15 oncology patients with metal artifacts.
• Artifact correction efficacy was assessed by measuring uptake variations in specific regions (Waldeyer's ring) and in lesions near implants.

Main Results:

• The developed algorithm successfully located and edited regions affected by metal artifacts.
• In non-malignant datasets, the correction reduced bias, with measured variations ranging from 10% to 30%.
• In datasets with malignancies, artifact correction resulted in minimal lesion uptake variations (<1% to 6.1% depending on distance from the implant).

Conclusions:

• Complementary MR data can effectively correct dental streak artifacts in CT attenuation correction images.
• The proposed correction algorithm demonstrates feasibility and minimizes the impact of artifacts on quantitative PET measurements.
• This technique holds promise for improving the accuracy of PET/CT imaging in oncology patients with dental implants.