title: Overcoming Nonlinear Partial Volume Effects in Known-Component Reconstruction of Cochlear Implants.
abstract: Nonlinear partial volume (NLPV) effects can be significant for objects with large attenuation differences and fine detail structures near the spatial resolution limits of a tomographic system. This is particularly true for small metal devices like cochlear implants. While traditional model-based approaches might alleviate these artifacts through very fine sampling of the image volume and subsampling of rays to each detector element, such solutions can be extremely burdensome in terms of memory and computational requirements. The work presented in this paper leverages the model-based approach called "known-component reconstruction" (KCR) where prior knowledge of a surgical device is integrated into the estimation. In KCR, the parameterization of the object separates the volume into an unknown background anatomy and a known component with unknown registration. Thus, one can model projections of an implant at very high spatial resolution while limiting the spatial resolution of the anatomy - in effect, modeling NLPV effects where they are most significant. We present modifications of the KCR approach that can be used to largely eliminate NLPV artifacts, and demonstrate the efficacy of the modified technique (with improved image quality and accurate implant position estimates) for the cochlear implant imaging scenario.
authors.affiliation: Dept. of Biomedical Eng., Johns Hopkins University, Baltimore, MD USA 21205.
authors.forename: J W
authors.initials: JW
authors.lastname: Stayman
authors.affiliation: Dept. of Biomedical Eng., Johns Hopkins University, Baltimore, MD USA 21205.
authors.forename: H
authors.initials: H
authors.lastname: Dang
authors.affiliation: Dept. of Biomedical Eng., Johns Hopkins University, Baltimore, MD USA 21205.
authors.forename: Y
authors.initials: Y
authors.lastname: Otake
authors.affiliation: Dept. of Biomedical Eng., Johns Hopkins University, Baltimore, MD USA 21205.
authors.forename: W
authors.initials: W
authors.lastname: Zbijewski
authors.affiliation: Dept. of Electrical Eng. and Computer Science, Vanderbilt University, Nashville, TN USA 37232.
authors.forename: J
authors.initials: J
authors.lastname: Noble
authors.affiliation: Dept. of Electrical Eng. and Computer Science, Vanderbilt University, Nashville, TN USA 37232.
authors.forename: B
authors.initials: B
authors.lastname: Dawant
authors.affiliation: Dept. of Otolaryngology, Vanderbilt University, Nashville, TN USA 37232.
authors.forename: R
authors.initials: R
authors.lastname: Labadie
authors.affiliation: Dept. of Otolaryngology, Johns Hopkins University, Baltimore, MD USA 21205.
authors.forename: J P
authors.initials: JP
authors.lastname: Carey
authors.affiliation: Dept. of Biomedical Eng., Johns Hopkins University, Baltimore, MD USA 21205.
authors.forename: J H
authors.initials: JH
authors.lastname: Siewerdsen