Improving Image Correlation and Differentiation of 3D Endoluminal Lesions in the Air Spaces Using a Novel Target Gray Level Mapping Technique: A Preliminary Study of Its Application to Computed Tomographic Colonography and Comparison with Traditional Surface Rendering Method

Lih-Shyang Chen; Ta-Wen Hsu; Shao-Jer Chen; Shu-Han Chang; Chih-Wen Lin; Yu-Ruei Chen; Chin-Chiang Hsieh; Shu-Chen Han; Ku-Yaw Chang; Chun-Ju Hou

doi:10.1007/s40846-020-00565-0

Improving Image Correlation and Differentiation of 3D Endoluminal Lesions in the Air Spaces Using a Novel Target Gray Level Mapping Technique: A Preliminary Study of Its Application to Computed Tomographic Colonography and Comparison with Traditional Surface Rendering Method

J Med Biol Eng. 2020;40(6):868-879. doi: 10.1007/s40846-020-00565-0. Epub 2020 Sep 26.

Authors

Lih-Shyang Chen¹, Ta-Wen Hsu^{2

3}, Shao-Jer Chen^{3

4

5}, Shu-Han Chang¹, Chih-Wen Lin^{3

4}, Yu-Ruei Chen^{3

4}, Chin-Chiang Hsieh⁶, Shu-Chen Han⁷, Ku-Yaw Chang⁸, Chun-Ju Hou⁹

Affiliations

¹ Department of Electric Engineering, National Cheng Kung University, Tainan, Taiwan, ROC.
² Department of General Surgery, Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chiayi, Taiwan, ROC.
³ School of Medicine, Tzu Chi University, Hualien, Taiwan, ROC.
⁴ Department of Medical Imaging, Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chiayi, Taiwan, ROC.
⁵ Department of Medical Imaging, Buddhist Dalin Tzu Chi General Hospital, No. 2, Min-Sheng Road, Dalin Town, Chiayi, 622 Taiwan, ROC.
⁶ Department of Radiology, Tainan Hospital, Ministry of Health and Welfare, Tainan, Taiwan, ROC.
⁷ Department of Radiology, Tainan Municipal Hospital, Tainan, Taiwan, ROC.
⁸ Department of Computer Science and Information Engineering, Da-Yeh University, Changhua, Taiwan, ROC.
⁹ Department of Electrical Engineering, Southern Taiwan University of Science and Technology, Tainan, Taiwan, ROC.

Abstract

Purpose: To improve the three dimensional (3D) and two dimensional (2D) image correlation and differentiation of 3D endoluminal lesions in the traditional surface rendering (SR) computed tomographic endoscopy (CTE), a target gray level mapping (TGM) technique is developed and applied to computed tomographic colonography (CTC) in this study.

Methods: A study of sixty-two various endoluminal lesions from thirty patients (13 males, 17 females; age range 31-90 years) was approved by our institutional review board and evaluated retrospectively. The endoluminal lesions were segmented using gray level threshold. The marching cubes algorithm was used to detect isosurfaces in the segmented volumetric data sets. TGM allows users to interactively apply grey level mapping (GM) to region of interest (ROI) in the 3D CTC. Radiologists conducted the clinical evaluation and the resulting data were analyzed.

Results: TGM and GM are significantly superior to SR in terms of surface texture, 3D shape, the confidence of 3D to 2D, 2D to 3D image correlation, and clinical classification of endoluminal lesions (P < 0.01). The specificity and diagnostic accuracy of GM and TGM methods are significantly better than those of SR (P < 0.01). Moreover, TGM performs better than GM (specificity: 75.0-85.7% vs. 53.6-64.3%; accuracy: 88.7-93.5% vs. 77.4-83.9%). TGM is a preferable display mode for further localization and differentiation of a lesion in CTC navigation.

Conclusions: Compared with only the spatial shape information in traditional SR of CTC images, the 3D shapes and gray level information of endoluminal lesions can be provided by TGM simultaneously. 3D to 2D image correlations are also increased and facilitated at the same time. TGM is less affected by adjacent colon surfaces than GM. TGM serves as a better way to improve the image correlation and differentiation of endoluminal lesions.

Keywords: CT colonography; Colonic neoplasms; Computer-assisted; Image processing; Imaging; Three-dimensional; Tomography; X-ray computed.