Basic Study
Copyright ©The Author(s) 2018. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Aug 21, 2018; 24(31): 3531-3537
Published online Aug 21, 2018. doi: 10.3748/wjg.v24.i31.3531
Stomach wall structure and vessels imaging by acoustic resolution photoacoustic microscopy
Cheng Wang, Yu-Fei Lu, Chun-Miao Cai, Hua-Zhong Xiang, Gang Zheng
Cheng Wang, Yu-Fei Lu, Hua-Zhong Xiang, Gang Zheng, Institute of Biomedical Optics and Optometry, School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
Chun-Miao Cai, Department of Pathology, Shanghai Tenth People’s Hospital Affiliated to Tongji University, Shanghai 200093, China
Author contributions: Wang C designed and performed the research; Wang C and Lu YF wrote the paper; Cai CM harvested experimental samples and provided the pathology images; Wang C, Lu YF, Xiang HZ, and Gang Z performed the photoacoustic imaging experiment and processed the experiment data.
Supported by the National Nature Science Foundation of China, No. 61378060.
Institutional review board statement: This study was approved by the Laboratory Animal Ethics Committee of Shanghai Tenth People’s Hospital. The design is reasonable and in line with the animal requirement. The ethics committee agreed to carry out a formal experiment.
Conflict-of-interest statement: To the best of our knowledge, no conflict of interest exists.
Data sharing statement: No additional data are available.
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: Cheng Wang, PhD, Associate Professor, Institute of Biomedical Optics and Optometry, School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, No. 516 Jungong Road, Shanghai 200093, China. c.wang@usst.edu.cn
Telephone: +86-21-55271165 Fax: +86-21-55271200
Received: April 12, 2018
Peer-review started: April 13, 2018
First decision: May 17, 2018
Revised: May 26, 2018
Accepted: June 27, 2018
Article in press: June 27, 2018
Published online: August 21, 2018
Processing time: 127 Days and 3.9 Hours
Abstract
AIM

To image stomach wall blood vessels and tissue, layer-by-layer.

METHODS

We built up the acoustic resolution photoacoustic microscopy (AR-PAM) system for imaging layered tissues, such as the stomach wall. A tunable dye laser system was coupled to a fiber bundle. The fibers of the bundle were placed in nine directions with an incident angle of 45° around a high-frequency ultrasound transducer attached to the acoustic lens. This structure formed a dark field on the tissue surface under the acoustic lens and the nine light beams from the fibers to be combined near the focal point of the acoustic lens. The sample piece was cut from a part of the porcine stomach into a petri dish. In order to realize photoacoustic depth imaging of tumor, we designed a tumor model based on indocyanine green (ICG) dye. The ICG solution (concentration of 129 μM/mL) was mixed into molten gel, and then a gel mixture of ICG (concentration of 12.9 μM/mL) was injected into the stomach submucosa. The injection quantity was controlled by 0.1 mL to make a small tumor model.

RESULTS

An acoustic resolution photoacoustic microscopy based on fiber illumination was established and an axial resolution of 25 μm and a lateral resolution of 50 μm in its focal zone range of 500 μm has been accomplished. We tuned the laser wavelength to 600 nm. The photoacoustic probe was driven to do B-scan imaging in tissue thickness of 200 μm. The photoacoustic micro-image of mucosa and submucosa of the tissue have been obtained and compared with a pathological photograph of the tissue stained by hematoxylin-eosin staining. We have observed more detailed internal structure of the tissue. We also utilized this photoacoustic microscopy to image blood vessels inside the submucosa. High contrast imaging of the submucosa tumor model was obtained using ICG dye.

CONCLUSION

This AR-PAM is able to image layer-by-layer construction and some blood vessels under mucosa in the stomach wall without any contrast agents.

Keywords: Photoacoustic imaging; Stomach; Layered tissue; Acoustic resolution; Fiber

Core tip: In order to image layered tissue and blood vessels, acoustic resolution photoacoustic microscopy based on fiber illumination was established and an axial resolution of 25 μm and a lateral resolution of 50 μm in its focal zone range of 500 μm was accomplished. Layer-by-layer imaging of the stomach tissue and stomach mucosa blood vessels were obtained. High contrast imaging of the submucosa tumor model was obtained using ICG dye.