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Copyright ©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastrointest Endosc. Aug 16, 2017; 9(8): 346-358
Published online Aug 16, 2017. doi: 10.4253/wjge.v9.i8.346
Terahertz endoscopic imaging for colorectal cancer detection: Current status and future perspectives
Pallavi Doradla, Cecil Joseph, Robert H Giles
Pallavi Doradla, Wellman Center for Photomedicine, Harvard Medical School, Boston, MA 02114, United States
Pallavi Doradla, Cecil Joseph, Robert H Giles, Biomedical Terahertz Technology center, Department of Physics, University of Massachusetts Lowell, Lowell, MA 01854, United States
Author contributions: Doradla P performed the research work, analyzed the collected data, conducted the literature review, and wrote the manuscript; Joseph C contributed to the review of the literature and revised the draft; Giles RH supervised the review.
Conflict-of-interest statement: Authors declare no conflicts of interests for this article.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Pallavi Doradla, PhD, Wellman Center for Photomedicine, Harvard Medical School, 55 Fruit Street, Boston, MA 02114, United States. pdoradla@mgh.harvard.edu
Telephone: +1-617-7263417 Fax: +1-617-6439208
Received: December 31, 2016
Peer-review started: January 5, 2017
First decision: February 21, 2017
Revised: June 8, 2017
Accepted: July 14, 2017
Article in press: July 15, 2017
Published online: August 16, 2017
Processing time: 222 Days and 19.5 Hours
Abstract

Terahertz (THz) imaging is progressing as a robust platform for myriad applications in the field of security, health, and material science. The THz regime, which comprises wavelengths spanning from microns to millimeters, is non-ionizing and has very low photon energy: Making it inherently safe for biological imaging. Colorectal cancer is one of the most common causes of death in the world, while the conventional screening and standard of care yet relies exclusively on the physician’s experience. Researchers have been working on the development of a flexible THz endoscope, as a potential tool to aid in colorectal cancer screening. This involves building a single-channel THz endoscope, and profiling the THz response from colorectal tissue, and demonstrating endogenous contrast levels between normal and diseased tissue when imaging in reflection modality. The current level of contrast provided by the prototype THz endoscopic system represents a significant step towards clinical endoscopic application of THz technology for in-vivo colorectal cancer screening. The aim of this paper is to provide a short review of the recent advances in THz endoscopic technology and cancer imaging. In particular, the potential of single-channel THz endoscopic imaging for colonic cancer screening will be highlighted.

Keywords: Endoscopy; Terahertz imaging; Colonoscopy; Colon; Cancer detection; Flexible waveguides; Metal-coated; Polarization-sensitive; Polarization; Cross-pol

Core tip: Terahertz (THz) imaging is progressing as a robust platform for a myriad of applications in the field of medicine. The non-ionizing THz radiation associated with safe energy levels has the potential to achieve high-resolution images of an organ or tissue, effectively combining both macroscopic and microscopic information. THz reflection imaging provides an intrinsic contrast between normal and diseased tissues, in real-time. This review describes the design, development, and practical implication of flexible THz endoscopic system, while simultaneously obtaining an overview of the existing technology. In addition to the state-of-art THz endoscopy, the feasibility study of a single-channel THz endoscopic system for colorectal cancer screening will be highlighted.