Reduction of Metal Artifact around Titanium Alloy-based Pedicle Screws on CT Scan Images: An Approach using a Digital Image Enhancement Technique / 대한척추외과학회지

ABSTRACT

STUDY DESIGN: A study on the development of an algorithm to enhance computed tomographic images. OBJECTIVE: The purpose of this study was to develop an approach to reduce the metal artifact that appears around pedicle screws, and thus to facilitate the evaluation of pedicle screw positions on CT scan images. SUMMARY OF LITERATURE REVIEW: Metal artifact caused by pedicle screws significantly reduces the interpretability of computed tomography images. MATERIALS AND METHODS: We describe the development of an algorithm that processes CT scan images on a personal computer using a digital image enhancement technique. The algorithm improves CT images by transforming image pixel values using a proper transformation curve that takes into account the characteristic distribution pattern of metal artifact caused by pedicle screws made of titanium alloys. We implemented this algorithm in a program that reconstructs the resulting images in arbitrary planes and in axial, coronal, and sagittal planes. The software was tested with spiral CT scan images of 38 patients containing 190 pedicle screws. RESULTS: In all test cases, our algorithm generated images with less metal artifact, better soft tissue visualization and clearer screw outlines than conventional bone setting. In addition, images reconstructed in arbitrary planes increase the convenience and confidence of localizing screw positions. CONCLUSIONS: The algorithm effectively decreases metal artifact and improved pedicle screw localization.