It was the aim of this study to implement an algorithm, modifing Dixon-based magnetic resonance imaging (MRI) datasets for attenuation correction in hybrid PET/MRI with a Multi-Acquisition Variable Resonance Image Combination (MAVRIC) sequence to reduce metal artifacts.
METHODS: After ethics approval, in eight oncological patients with dental implants data were acquired in a trimodality setup with PET/CT and MRI. The protocol included a whole-body 3D dual gradient-echo sequence (Dixon) used for MRI based PET attenuation correction (AC), and a high resolution MAVRIC sequence, applied in the oral area compromised by dental implants. An algorithm was implemented correcting the Dixon-based µMaps by using the MAVRIC in areas of Dixon signal voids. Artifact size of the corrected µMaps was compared to the uncorrected MRI µMaps.
RESULTS: The algorithm was robust in all patients. There was a significant reduction in mean artifact size of 70.5% between uncorrected and corrected µMaps from 697±589mm(2) to 202±119mm(2) (P = 0.016).
CONCLUSION: The proposed algorithm could improve MRI based attenuation correction in critical areas, when standard AC is hampered by metal artifacts, using a MAVRIC.