The application of spectral CT imaging in reducing artifacts caused by metallic implants / 中华放射学杂志

ABSTRACT

Objective To assess the capability of monochromatic energy images of Gemstone spectral imaging(GSI) in reducing artifacts caused by metallic implants. Methods Twelve subjects with metallic implants underwent GSI (Discovery CT750 HD, GE Healthcare, Milwaukee ). The metallic orthopedic implants included 3 patients of dentures, 2 patients of cervical spinal vertebraplasty, one clavicle fracture fixation, one lumbar spinal vertehraplasty, 3 patients of artificial femoral head, one iliac fracture fixation and one tibial fracture fixation. GSI was performed by using a single source ultra-fast dual energy X-ray switching (80 kVp and 140 kVp). Following GSI scanning, thin slice images were reconstructed into 1.25 mm slice thickness. The monochromatic energy images were set to the same window width and level (window width 1500 HU,window level 500 HU). The artifact indexes (AI) at different kiloelectronvolts (keV) images were measured and compared. 3D reconstruction was performed using images with minimal AI. Result The artifacts index on monochromatic energy images varied with the change of keV. Of the images from 12 subjects, the maximal AI ranged between 145-225 at 40 keV, and minimal AI ranged between 15-90 at the 95-140 keV. The artifacts are clearly visible on polychromatic energy images and the artifacts are reduced markedly on the monochromatic energy images with minimal AI. Conclusion The artifacts caused by metallic implants can be reduced significantly by GSI with high keV monochromatic energy images.