MTL Annual Research Report 2013

An Ingestible Pill for Ultrasound Imaging of Small Intestine

The small intestine is one of the most difficult organs to image because of its length and narrow winding path. For this reason accurate diagnosis and monitoring of small bowel disease such as Crohn’s disease (CD) through various imaging modalities have been an important focus of both clinical and research effort. Among these are computed tomography (CT), magnetic resonance imaging (MRI), and transabdominal ultrasound (TUS)^[1]. Also, recently wireless capsule endoscopy (WCE) technology has been developed to substitute for conventional endoscopy (Figure 1)^[2], which generally cannot be used for the small bowel. CT and MRI provide good imaging capability, but repetitive exposure to radiation make them less preferable. WCE can detect bleeding and lesions, but it is less effective in detecting inflammation of the bowel, which is a key symptom of Crohn’s disease. TUS is a good candidate since it can detect inflammation without the use of ionizing radiation, but it still faces challenges due to the requirement for deep scan depth as well as blocked view by various other organs.

This project aims to develop an ingestible pill that can be used for ultrasound imaging of the small bowel, essentially combining the benefits of WCE and TUS. Patients can simply swallow the pill, which will travel through the gastrointestinal (GI) tract via peristalsis while ultrasound imaging the surrounding wall. The image data will be wirelessly transmitted to an outside base station before the pill gets excreted naturally. The overall system consists of ultrasound transducers and electronics; a radio, control circuits, power management circuits, and a battery. The main challenges are in the integration of all components, especially the ultrasound transducers and the battery, into a very small package (around 1 cm in diameter and 3 cm in length) and power management including achieving low system power while also providing the high voltages required for ultrasound transducers. A prototype pill has been designed, which is planned to be used for initial imaging of tissues (Figure 2).

1. K. Nylund, S. Ødegaard, T. Hausken, G. Folvik, G. A. Lied, I. Viola, H. Hauser, and O. H. Gilja, “Sonography of the small intestine,” World Journal of Gastroenterology, vol. 15, no. 11, pp. 1319-1330, Mar. 2009. [↩]
2. J. R. Beveridge and E. M. Riseman, “How easy is matching 2D line models using local search?” IEEE Transactions on Pattern Analysis and Machine Intelligence, vol. 19, pp. 564-579, June 1997. [↩]