Ultrasound Capsule Endoscopy With a Mechanically Scanning Micro-ultrasound: A Porcine Study

Abstract

Wireless capsule endoscopy has been used for the clinical examination of the gastrointestinal (GI) tract for two decades. 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 40À120 mm 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 »30 MHz ultrasonic transducer was developed to capture a full 360˚image of the lumen. The performance of the device was initially evaluated using a wire phantom, indicating an axial resolution of 69.0 mm and lateral resolution of 262.5 mm. Later, in vivo imaging performance was characterised in the oesophagus and small intestine of anaesthetized pigs. 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 high-resolution ultrasound images in the in vivo porcine model achieved with this device is an encouraging preliminary step in the translation of these devices toward future clinical use.

The Clinical Application of Remimazolam Benzenesulfonate Combined with Esketamine Intravenous Anesthesia in Endoscopic Retrograde Cholangiopancreatography

“…Median filtering is an effective nonlinear filtering technique for image protection [ 19 ]. During the window sliding process, window width cannot be obtained at the edge.…”

Smart pills for gastrointestinal diagnostics and therapy

“…The miniaturisation of this technology to fit within a capsule has been a goal of several groups. Though this technology is still in its infancy, several smart pills capable of ultrasound imaging have been reported based on different technological approaches [14,15,20,21], which are summarised in Table 2. The Khuri-Yakub group at Stanford University, USA, are attempting to produce an ultrasound imaging capsule incorporating a multi-element ring array to generate a 360 o image of the intestinal wall [20].…”

“…Subsequent ultrasound imaging capsules developed by Qiu [21] and Lee [23] achieved radial imaging of the wall of the small intestine through mechanical rotation of 30 MHz and 10 MHz transducers, respectively. The resolution of the Qiu capsule, which utilised the same frequency as the Sonopill transducer, was measured using a wire phantom to have a -6 dB axial and lateral spatial resolution of 69 and 262.5 μm, respectively [21]. The Lee capsule was measured to have a -6 dB axial and lateral spatial resolution of 300 and 680 μm, respectively [23].…”

Capsule Endoscopy: Pitfalls and Approaches to Overcome

“…Ultrasound capsule endoscopy (USCE) is still in its infancy, but several research teams are developing it [38][39][40]. Qiu et al investigated a mechanical method using a single-element transducer powered by a vibration motor that enables radial imaging of the bowel wall (Figure 8) [41]. The frequency of the transducer plays an important role in USCE, affecting penetration depth and image resolution.…”