Fifty-eighth annual meeting of the american association of physicists in medicine
TU-AB-BRA-04: An Investigation of Metal Artifact Effects in Multi-Modalities: Development of MRI-CT Heterogeneous Head and Neck Phantom for MRI-CT Registration
The purpose of this investigation was to develop an CT-MR head and neck phantom which can investigate dose calculation differences between density-assigned MRI and CT, and to compare non-implant inserted registered MR-CT registered image with artifact reduced image of MR-CT registered image. It is to identify potential limitations related to dental implants of MR image and CT image and maximize the advantages to find interactive method to use registered image.
The phantom comprises half-circled shape which shaped to simulated the anatomical structures of a human head and neck. Through applying various clinical cases, the developed phantom is closely allied to human. Developed phantom can be verified in to opened-mouth and closed-mouth phantom. The case of the phantom was made of acrylic, which introduces a 0.003 parts per million (ppm) phase shift, whereas the Teflon results in a 0.03 ppm shift measured at 3T which represents human bone. Both materials are considered acceptable for MR field measurements. The phantom was filled with a solution of nickel chloride and sodium chloride. The implants and teeth were imaged by means of 3T MRI system.
In MRI image, the metal artifact reduced and the results in improved image quality and reduction of susceptibility artifacts originate in MR images. CT and MR artifact correction method resulted in substantial artifact reduction, both quantitatively and qualitatively. On head and neck CT images, it remained anatomical conformation but it has reduced streak and dark artifact which appeared around the dental restoration. The artifact reduced MR-CT image improved image quality and calculation accuracy for patients with severe CT artifacts.
By using MRI/CT and the artifact-free slice location of the phantom, we demonstrated that the proposed artifact reduction method can effectively remove streak artifacts from a metal object.