X Zhang1, S Tilley1, S Xu1, A Mathews1, E R McVeigh2, J W Stayman1. 1. Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD USA 21205. 2. Department of Bioengineering, Medicine, Radiology, UC San Diego, La Jolla, CA USA 92093.
Abstract
PURPOSE: Atherosclerosis detection remains challenging in coronary CT angiography for patients with cardiac implants. Pacing electrodes of a pacemaker or lead components of a defibrillator can create substantial blooming and streak artifacts in the heart region, severely hindering the visualization of a plaque of interest. We present a novel reconstruction method that incorporates a deformable model for metal leads to eliminate metal artifacts and improve anatomy visualization even near the boundary of the component. METHODS: The proposed reconstruction method, referred as STF-dKCR, includes a novel parameterization of the component that integrates deformation, a 3D-2D preregistration process that estimates component shape and position, and a polyenergetic forward model for x-ray propagation through the component where the spectral properties are jointly estimated. The methodology was tested on physical data of a cardiac phantom acquired on a CBCT testbench. The phantom included a simulated vessel, a metal wire emulating a pacing lead, and a small Teflon sphere attached to the vessel wall, mimicking a calcified plaque. The proposed method was also compared to the traditional FBP reconstruction and an interpolation-based metal correction method (FBP-MAR). RESULTS: Metal artifacts presented in standard FBP reconstruction were significantly reduced in both FBP-MAR and STF-dKCR, yet only the STF-dKCR approach significantly improved the visibility of the small Teflon target (within 2 mm of the metal wire). The attenuation of the Teflon bead improved to 0.0481 mm-1 with STF-dKCR from 0.0166 mm-1 with FBP and from 0.0301 mm-1 with FBP-MAR - much closer to the expected 0.0414 mm-1. CONCLUSION: The proposed method has the potential to improve plaque visualization in coronary CT angiography in the presence of wire-shaped metal components.
PURPOSE: Atherosclerosis detection remains challenging in coronary CT angiography for patients with cardiac implants. Pacing electrodes of a pacemaker or lead components of a defibrillator can create substantial blooming and streak artifacts in the heart region, severely hindering the visualization of a plaque of interest. We present a novel reconstruction method that incorporates a deformable model for metal leads to eliminate metal artifacts and improve anatomy visualization even near the boundary of the component. METHODS: The proposed reconstruction method, referred as STF-dKCR, includes a novel parameterization of the component that integrates deformation, a 3D-2D preregistration process that estimates component shape and position, and a polyenergetic forward model for x-ray propagation through the component where the spectral properties are jointly estimated. The methodology was tested on physical data of a cardiac phantom acquired on a CBCT testbench. The phantom included a simulated vessel, a metal wire emulating a pacing lead, and a small Teflon sphere attached to the vessel wall, mimicking a calcified plaque. The proposed method was also compared to the traditional FBP reconstruction and an interpolation-based metal correction method (FBP-MAR). RESULTS: Metal artifacts presented in standard FBP reconstruction were significantly reduced in both FBP-MAR and STF-dKCR, yet only the STF-dKCR approach significantly improved the visibility of the small Teflon target (within 2 mm of the metal wire). The attenuation of the Teflon bead improved to 0.0481 mm-1 with STF-dKCR from 0.0166 mm-1 with FBP and from 0.0301 mm-1 with FBP-MAR - much closer to the expected 0.0414 mm-1. CONCLUSION: The proposed method has the potential to improve plaque visualization in coronary CT angiography in the presence of wire-shaped metal components.
Entities:
Keywords:
CT reconstruction; implant imaging; metal artifact reduction; penalized-likelihood estimation
Authors: J Webster Stayman; Yoshito Otake; Jerry L Prince; A Jay Khanna; Jeffrey H Siewerdsen Journal: IEEE Trans Med Imaging Date: 2012-05-16 Impact factor: 10.048
Authors: Yoshito Otake; Adam S Wang; J Webster Stayman; Ali Uneri; Gerhard Kleinszig; Sebastian Vogt; A Jay Khanna; Ziya L Gokaslan; Jeffrey H Siewerdsen Journal: Phys Med Biol Date: 2013-11-18 Impact factor: 3.609