. 2020 Jan 15;12(1):54–65. doi: 10.4251/wjgo.v12.i1.54
©The Author(s) 2019. Published by Baishideng Publishing Group Inc. All rights reserved.
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.
Figure 4.
Representative images of PPA in each group. A: PPA group; B: Sham group.