Feasibility and Safety of Ultrasound Capsule Endoscopy for Esophagus Examination：a Pilot Study

Wireless capsule endoscopy has opened a new era by enabling remote diagnostic assessment of the gastrointestinal tract in a painless procedure. However, most commercially available devices only utilise optical imaging to examine the GI wall surface. Using this sensing modality, pathology within the GI wall cannot be detected. Micro-ultrasound (mUS) using high-frequency (>20 MHz) ultrasound can provide a means of transmural or cross-sectional image of the GI tract. Depth of imaging is approximately 10 mm with a resolution of between 40-120 μm that is sufficient to differentiate between subsurface histologic layers of the various regions of the GI tract. Ultrasound capsule endoscopy (USCE) uses a capsule equipped with mUS transducers that are capable of imaging below the GI wall surface, offering thereby a complementary sensing technique to optical imaging capsule endoscopy. In this work, a USCE device integrated with a 40 MHz ultrasonic transducer was developed to capture a full 360˚ image of the lumen. Previous animal studies of two anaesthetised Landrace pigs have demonstrated the effectiveness of the device. The reconstructed images demonstrate clear layer differentiation of the lumen wall. The tissue thicknesses measured from the B-scan images show good agreement with ex vivo images from the literature. The aim of this pilot study is to assess the feasibility and safety of the clinical application of ultrasound capsule endoscopy in esophageal examination compared with conventional endoscopic ultrasound examination.