Value Of Dual-layer Spectral Detector CT In Removing Metal Artifacts From Bone Transport

Objective:To evaluate the efficacy of virtual monoenergetic images(VMIs)from dual-layer spectral detector CT(SDCT)combined with metal artifact reduction algorithm(MAR)for metal artifact reduction caused by orthogonal circular external fixator of bone transport,and to screen the best imaging point.Methods:Twelve patients undergoing bone transport treatment were performed on SDCT scanning.Conventional image(CI)and VMI(40–140 ke V with 10 ke V intervals),MAR and VMI+MAR images were reconstructed.The region of interests was delineated on the images with severe artifacts in the bone extension area and without artifact area.The CT value,standard deviation(SD)were recorded,the,artifact index(AI),hardening artifact removal rate(BAR)were calculated,and the difference between reconstructed setting images were compared.Two radiologists subjectively scored the quality using5-point Likert scale,and they conducted analysis on the score consistency.Results:Compared with CI,the of 110-140 ke V VMI images,MAR image and 40-140 ke V VMI+MAR images were significantly increased(P<0.05).The AI of MAR image and 50-140 ke V VMI+MAR images were significantly reduced(P<0.05).The BAR of40-140 ke V VMI+MAR images were higher than that of 40-140 ke V VMI images,with a highest removal rate of 88.48%.In the same energy level,of VMI+MAR images was higher than that of VMI images,and vice versa for the AI values of the two types of images(P<0.05).The images with a subjective score of 4 points and above were MAR and 110～140 ke V VMI+MAR images.The subjective scoring results that the two doctors obtained were in good agreement.Conclusion:VMI+MAR can effectively reduce the metal artifacts caused by orthogonal circular external fixator of bone transport.In addition,the metal artifacts of 110-140 ke V VMI+MAR images are significantly reduced,and 140 ke V VMI+MAR image has the best subjective and objective image quality.