Electronic cleansing in computed tomography colonography using AT layer identification with integration of gradient directional second derivative and material fraction model

Krisorn Chunhapongpipat,Rajalida Lipikorn,Sirod Sirisup,Ratinan Boonklurb,Bundit Chaopathomkul

doi:10.1186/s12880-017-0224-6

Krisorn Chunhapongpipat, Rajalida Lipikorn + Show 3 more

Open Access

https://doi.org/10.1186/s12880-017-0224-6

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Abstract

BackgroundIn computed tomography colonography images, electronic cleansing (EC) is applied to remove opacified residual materials, called fecal-tagging materials (FTM), using positive-contrast tagging agents and laxative to facilitate polyp detection.MethodsThe proposed EC, ECprop, integrates the gradient directional second derivative into material fraction model to preserve submerged soft tissue (ST) under FTM. Three-material fraction model is used to remove FTM and artifacts at air-tagging (AT) layers and T-junctions where air, ST, and FTM material meet simultaneously. Moreover, the proposed AT layer identification is used to distinguish AT layers from air-tissue-tagging (ATT) layers in order to preserve ATT layers during cleansing. The clinical evaluation on 467 3-Dimensional band view images was conducted by the abdominal radiologist using four grading levels of cleansing quality with five causes of low quality EC. The amount of the remaining artifacts at T-junctions was approximated from the results of ECprop. The results from ECprop were compared with the results from syngo.via Client 3.0 Software, ECsyngo, and the fast three-material modeling, ECprev, using the preference of the radiologist. Two-tailed paired Wilcoxon signed rank test is used to indicate statistical significance.ResultsThe average grade on cleansing quality is 2.89 out of 4. The artifacts at T-junctions from 86.94% of the test images can be removed, whereas artifacts at T-junctions from only 13.06% of the test images cannot be removed. For 13.06% of the test images, the results from ECprop are more preferable to the results from ECsyngo (p<0.008). For all the test images, the results from ECprop are more preferable to the results from ECprev (p<0.001). Finally, the visual assessment shows that ECprop can preserve ATT layers, submerged polyps and folds while ECprev can preserve only submerged folds but fails to preserve ATT layers.ConclusionFrom our implementation, ECprop can improve the performance of the existing EC, such that it can preserve ST, especially ATT layers and remove the artifacts at T-junctions which have never been proposed by any other methods before.

Highlights

In computed tomography colonography images, electronic cleansing (EC) is applied to remove opacified residual materials, called fecal-tagging materials (FTM), using positive-contrast tagging agents and laxative to facilitate polyp detection
Five cases of computed tomography colonography (CTC) data were randomly selected from Walter Reed Army Medical Center (WRAMC) which could be downloaded from the National Institutes of Health that provides a Computed tomography (CT) colonography database with complete associated colonoscopy findings and ten cases of CTC data were randomly selected from King Chulalongkorn Memorial Hospital as the test data
18.20% of the test images are graded as excellent while Table 4 indicates that the most common cause of low quality cleansing is the artifacts at T-junctions which is as high as 69.81%

Summary

Introduction

In computed tomography colonography images, electronic cleansing (EC) is applied to remove opacified residual materials, called fecal-tagging materials (FTM), using positive-contrast tagging agents and laxative to facilitate polyp detection. Virtual colonoscopy (VC) or computed tomography colonography (CTC) is one of the most acceptable techniques for non-invasive screening of colon cancer [1,2,3,4,5]. To enhance the ability of polyp detection while performing 3D fly-through in virtual colonoscopy, electronic cleansing (EC) [13,14,15,16,17,18,19,20,21] is used to remove the residual colonic materials in CTC data. CTC data with both cathartic and oral contrast are still practical in many health care institutes, such as in Japan [26], UW Health in USA [27], University of California, San Francisco, in USA [28], Bumrungrad International Hospital, Bangkok, in Thailand [29], King Chulalongkorn Memorial hospital, Bangkok, in Thailand, etc

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