Differences in regions of interest to identify deeply invasive colorectal cancers: Computer-aided diagnosis vs expert endoscopists

Yuki Nakajima; Daiki Nemoto; Zhe Guo; Peng Boyuan; Zhang Ruiyao; Shinichi Katsuki; Takahito Takezawa; Ryo Maemoto; Keisuke Kawasaki; Ken Inoue; Takashi Akutagawa; Hirohito Tanaka; Koichiro Sato; Teppei Omori; Yoshikazu Hayashi; Yasuyuki Miyakura; Takayuki Matsumoto; Naohisa Yoshida; Motohiro Esaki; Toshio Uraoka; Hiroyuki Kato; Yuji Inoue; Hironori Yamamoto; Xin Zhu; Kazutomo Togashi

doi:10.1055/a-2401-6611

Differences in regions of interest to identify deeply invasive colorectal cancers: Computer-aided diagnosis vs expert endoscopists

Endosc Int Open. 2024 Nov 7;12(11):E1260-E1266. doi: 10.1055/a-2401-6611. eCollection 2024 Nov.

Authors

Yuki Nakajima¹, Daiki Nemoto², Zhe Guo³, Peng Boyuan³, Zhang Ruiyao³, Shinichi Katsuki⁴, Takahito Takezawa⁵, Ryo Maemoto⁶, Keisuke Kawasaki⁷, Ken Inoue⁸, Takashi Akutagawa⁹, Hirohito Tanaka¹⁰, Koichiro Sato¹¹, Teppei Omori¹², Yoshikazu Hayashi⁵, Yasuyuki Miyakura⁶, Takayuki Matsumoto⁷, Naohisa Yoshida⁸, Motohiro Esaki⁹, Toshio Uraoka¹⁰, Hiroyuki Kato¹¹, Yuji Inoue¹², Hironori Yamamoto⁵, Xin Zhu³, Kazutomo Togashi²

Affiliations

¹ Department of Gastroenterology, Aizu Medical Center, Fukushima Medical University, Aizuwakamatsu, Japan.
² Department of Coloproctology, Aizu Medical Center, Fukushima Medical University, Aizuwakamatsu, Japan.
³ Biomedical Information Engineering Lab, The University of Aizu, Aizuwakamatsu, Japan.
⁴ Department of Gastroenterology, Otaru Ekisaikai Hospital, Otaru, Japan.
⁵ Department of Medicine, Division of Gastroenterology, Jichi Medical University, Shimotsuke, Japan.
⁶ Department of Surgery, Saitama Medical Center, Jichi Medical University, Saitama, Japan.
⁷ Department of Gastroenterology, Iwate Medical University, Morioka, Japan.
⁸ Department of Molecular Gastroenterology and Hepatology, Kyoto Prefectural University of Medicine, Kyoto, Japan.
⁹ Division of Gastroenterology, Department of Internal Medicine, Faculty of Medicine, Saga University, Saga, Japan.
¹⁰ Department of Gastroenterology and Hepatology, Gunma University Graduate School of Medicine, Maebashi, Japan.
¹¹ Department of Clinical Laboratory and Endoscopy, Tokyo Women's Medical University Medical Center East, Tokyo, Japan.
¹² Institute of Gastroenterology, Tokyo Women's Medical University, Tokyo, Japan.

Abstract

Background and study aims Diagnostic performance of a computer-aided diagnosis (CAD) system for deep submucosally invasive (T1b) colorectal cancer was excellent, but the "regions of interest" (ROI) within images are not obvious. Class activation mapping (CAM) enables identification of the ROI that CAD utilizes for diagnosis. The purpose of this study was a quantitative investigation of the difference between CAD and endoscopists. Patients and methods Endoscopic images collected for validation of a previous study were used, including histologically proven T1b colorectal cancers (n = 82; morphology: flat 36, polypoid 46; median maximum diameter 20 mm, interquartile range 15-25 mm; histological subtype: papillary 5, well 51, moderate 24, poor 2; location: proximal colon 26, distal colon 27, rectum 29). Application of CAM was limited to one white light endoscopic image (per lesion) to demonstrate findings of T1b cancers. The CAM images were generated from the weights of the previously fine-tuned ResNet50. Two expert endoscopists depicted the ROI in identical images. Concordance of the ROI was rated by intersection over union (IoU) analysis. Results Pixel counts of ROIs were significantly lower using 165K[x103] [108K-227K] than by endoscopists (300K [208K-440K]; P < 0.0001) and median [interquartile] of the IoU was 0.198 [0.024-0.349]. IoU was significantly higher in correctly identified lesions (n = 54, 0.213 [0.116-0.364]) than incorrect ones (n=28, 0.070 [0.000-0.2750, P = 0.033). Concusions IoU was larger in correctly diagnosed T1b colorectal cancers. Optimal annotation of the ROI may be the key to improving diagnostic sensitivity of CAD for T1b colorectal cancers.

Keywords: Colorectal cancer; Diagnosis and imaging (inc chromoendoscopy, NBI, iSCAN, FICE, CLE...); Endoscopy Lower GI Tract.

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