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9 March 2010 Dual-energy electronic cleansing for non-cathartic CT colonography: a phantom study
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Partial volume effect and inhomogeneity are two major causes of artifacts in electronic cleansing (EC) for non-cathartic CT colonography (CTC). Our purpose was to develop a novel method of EC for non-cathartic dual-energy CTC (DECTC) using a subvoxel multi-spectral material classifier and a regional material decomposition method for differentiation of residual fecal materials from colonic soft-tissue structures. In this study, an anthropomorphic colon phantom, which was filled with a mixture of aqueous fiber (psyllium), ground foodstuff (cereal), and non-ionic iodinated agent (Omnipaque iohexol, GE Healthcare, Milwaukee, WI), was scanned by a dual-energy CT scanner (SOMATON, Siemens) with two photon energies: 80 kVp and 140 kVp. The DE-CTC images were subjected to a dual-energy EC (DE-EC) scheme, in which a multi-spectral material classifier was used to compute the fraction of each material within one voxel by an expectation-maximization (EM) algorithm. This was followed by a regional material segmentation method for identifying of homogeneous sub-regions (tiles) as fecal materials from other tissue types. The results were compared with the structural-analysis cleansing (SA-EC) method based upon the CTC images of native phantom without fillings. The mean cleansing ratio of the DE-EC scheme was 96.57±1.21% compared to 76.3±5.56% of the SA-EC scheme. The soft-tissue preservation ratio of the DE-EC scheme was 97.05%±0.64% compared to 99.25±0.77% of the SA-EC scheme.
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Wenli Cai, Bob Liu, and Hiroyuki Yoshida "Dual-energy electronic cleansing for non-cathartic CT colonography: a phantom study", Proc. SPIE 7624, Medical Imaging 2010: Computer-Aided Diagnosis, 76240C (9 March 2010);

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