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Page 12 of 21 Tsuboi et al. Mini-invasive Surg 2024;8:26 https://dx.doi.org/10.20517/2574-1225.2023.94

Despite the potential benefits, several challenges remain in the clinical application of AI for CE: (1)
determining the timing of AI support - before, during, or after physician reading through real-time
assistance or double-checking; (2) addressing the wide variety of small-bowel lesions; and (3) managing the
decrease in the number of images of interest with AI assistance. Currently, the timing of AI assistance for
CE remains to be determined. Real-time AI-assistance systems are already available for CS and EGD.
Additionally, the small-bowel presents a diverse range of lesions, which are often challenging even for
expert physicians. The development of AI systems with high sensitivity may increase the number of images
selected for physician review, potentially prolonging the reading time. It is essential to develop an AI system
that integrates various small-bowel lesions for prospective validation in the future.

MCCE
Conventional CE is not suitable for observing the stomach, which has a wide lumen, as the capsule is moved
by physiological peristalsis and automatically captures images. To address this limitation, MCCE was
[148]
described by Carpi et al. in 2006 . In 2010, Rey et al. reported the first study utilizing MCCE to observe
[149]
the human stomach . The MCCE uses magnetic force to control the position of the capsule, offering a less
invasive and mentally burdensome alternative to the conventional EGD. A list of currently available MCCE
devices is presented in Supplementary Table 2. Recent reports on the MCCE [150-153] demonstrate a diagnostic
consistency of 86.8% to 96.2% with conventional EGD, a high complete examination rate of gastric
anatomical landmarks ranging from 85% to 97%, and improved tolerability . In addition, MCCE can
[154]
detect both gastric and small-bowel bleeding. MCCE is a novel modality that significantly differs from
conventional CE, directly influencing the quality of examination. To ensure competent performance and
interpretation of MCCE findings, medical staff must undergo standardized training at professional
institutions and acquire necessary qualifications.

Amid the spread of COVID-19, concerns regarding droplet exposure during conventional EGD have risen.
The MCCE offers a convenient alternative, as patients simply swallow the capsule, minimizing the risk of
droplet exposure to CE operators. This feature has garnered attention as a valuable option during the
COVID-19 pandemic. Remote-controlled MCCE, which completely avoids patient-examiner contact,
proves particularly useful in upper gastrointestinal endoscopic practice during these challenging times .
[155]
Zhu et al. developed a remote-control MCCE system and reported comparable completion rates, safety, and
diagnostic performance to conventional MCCE . Adequate training is crucial for effective interpretation
[156]
of MCCE results. In this context, the usefulness of AI using images has been reported [157,158] . The availability
of AI for MCCE in the near future could further expand the utilization of this modality.

Novel CE
In recent years, various novel types of CE, such as ultrasound CE and sampling CE, have been developed to
enhance the diagnosis and monitoring of gastrointestinal conditions, offering improved features compared
to traditional capsule endoscopes.

Endoscopic ultrasonography (EUS), which combines ultrasound and endoscopic technologies, provides
high-resolution, real-time imaging of the gastrointestinal wall layers and surrounding extramural structures.
However, EUS is an invasive procedure that carries potential risks, including perforation and bleeding. To
address these concerns, several groups have proposed the concept of capsule endoscopy using ultrasound
(USCE) and have explored its feasibility for subsurface imaging of the gastrointestinal tract [159-164] . However,
these reports have primarily focused on laboratory or animal studies. Qiu et al. developed a novel USCE for
[165]
esophageal lesions and reported its use and safety in humans . They concluded that their novel USCE is
comfortable for patients, easy to operate, and cost-effective, with the potential for widespread clinical
application.