A Novel Metallic Artifact Reduction Technique When Using a Computed Tomography-Guided Percutaneous Metallic Antenna to Ablate Malignant Pulmonary Nodules: A Qualitative and Quantitative Assessment

BACKGROUND: Metallic microwave ablation (MWA) antenna-related artifacts are usually created in conventional CT images, and these artifacts can influence the effect of ablation. The aim of this study was to evaluate a new type of metal artifact reduction (MAR+) technique in CT-guided MWA for lung cancer. MATERIAL/METHODS: This retrospective study enrolled 30 lung cancer patients who received CT-guided MWA treatment from December 2017 to April 2018. Images after microwave antenna insertion into the tumor were reconstructed by the filter back projection (group A) and MAR+ reconstruction (group B). The CT values and standard deviations of the regions of interest (ROIs) on the chosen image were recorded, including the most significantly hypodense artifact (ROI(1)), hyperdense artifacts (ROI(2)), and chest muscles of the same layer (ROI(3)). The metal artifact indexes based on ROI(1) and ROI(2) (AI(1), AI(2)) and the overall metal artifact index (AI) were calculated. Subjective image quality was graded on a five-point scale (1=worst, 5=excellent). RESULTS: The AI(1) (74.14±76.32), AI(2) (13.75±19.02) and AI (54.12±54.82) of group B were lower than those of group A [(153.33±89.04), (30.63±26.42), (112.00±63.10), respectively] (P<0.001 for all). Both radiologists reported that the subjective image value of group B was significantly higher than that of group A (P<0.001). The subjective image quality scores evaluated by 2 observers showed excellent consistency (ICC=0.829). CONCLUSIONS: The MAR+ imaging reconstruction significantly reduced metal artifacts, which helps radiologists to clearly observe the relationship between the ablation antenna and the lesion.