Combination of Iterative Metal Artifact Reduction and Virtual Monoenergetic Reconstruction Using Split-Filter Dual-Energy CT in Patients With Dental Artifact on Head and Neck CT.

Background: Head and neck CT may be limited by dental hardware artifact. Both post-processing based iterative metal artifact reduction (iMAR) and virtual monoenergetic reconstruction (VMR) from dual-energy CT (DECT) can reduce metal artifact. Their combination is poorly described for single-source DECT systems. Objective: To compare metal artifact reduction between VMR, iMAR, and their combination, using split-filter single-source DECT in patients with severe dental hardware artifact. Methods: This retrospective study included 44 patients (9 female, 35 male; mean age 66.0±10.4 years) who underwent head and neck CT exhibiting severe dental hardware artifact. Standard images, VMR, iMAR, and VMRi-MAR were reconstructed; VMR and VMRiMAR used 40, 70, 100, 120, 150, and 190 keV. ROIs were placed to measure corrected attenuation in pronounced hyperattenuating and hypoattenuating artifacts and artifact-impaired soft tissue, as well as corrected artifact-impaired soft tissue noise. Two radiologists independently assessed soft tissue interpretability (1-5 scale); pooled ratings were analyzed. Readers selected the preferred reconstruction for each patient. Results: Mean hyperattenuating artifact corrected attenuation was 521.0 for standard, 496.4-892.2 for VMR, 48.2 for iMAR, and 32.8-91.0 for VMRiMAR. Mean hypoattenuating artifact corrected attenuation was -455.1 for standard, -408.5 to -679.9 for VMR, -37.3 for iMAR, and -17.8 to -36.9 for VMRiMAR. Mean artifact-impaired soft tissue corrected attenuation was 10.8 for standard, -0.6 to 24.9 for VMR, 4.3 for iMAR, and -2.0 to 7.8 for VMRiMAR. Mean artifact-impaired soft tissue corrected noise was 58.7 for standard, 38.2-129.7 for VMR, 11.0 for iMAR, and 5.8-45.6 for VMRiMAR. Median soft tissue interpretability was 1.2 for standard, 1.1-1.2 for VMR, 3.7 for iMAR, and 2.0-3.8 for VMRiMAR. Artifact-impaired soft tissue corrected attenuation and soft tissue interpretability were significantly improved (p<.05) for VMRiMAR versus iMAR only at 100 keV. Readers preferred VMRiMAR at 100 keV in 56.8% and 59.1% of examinations. Conclusion: For reducing severe dental material artifact, iMAR has greater impact than VMR. Though iMAR and VMRiMAR were overall similar, VMRiMAR exhibited small benefit at 100 keV. Clinical Impact: VMR and iMAR techniques, using split-filter DECT, may be combined for clinical head and neck imaging to reduce artifact from dental hardware and improve image quality.