Non-invasive laparoscopic detection of small tumors of the digestive tract using inductive sensors of proximity

Abstract

The precise location of gastric and colorectal tumors is of paramount importance for the oncological surgeon as it dictates the limits of resection and the extent of lymphadenectomy. However, this task proves sometimes to be very challenging, especially in the laparoscopic setting when the tumors are small, have a soft texture, and do not invade the serosa. In this view, our research team has developed a new instrument adapted to minimally-invasive surgery, and manipulated solely by the operating surgeon which has the potential to locate precisely tumors of the digestive tract. It consists of an inductive proximity sensor and an electronic block encapsulated into an autoclavable stainless-steel cage that works in tandem with an endoscopic hemostatic clip whose structure was modified to increase detectability. By scanning the serosal side of the colon or stomach, the instrument is capable to accurately pinpoint the location of the clip placed previously during diagnostic endoscopy on the normal bowel mucosa, adjacent to the tumor. In the current in-vivo experiments performed on large animals, the modified clips were transported without difficulties to the point of interest and attached to the mucosa of the bowel. Using a laparoscopic approach, the detection rate of this system reached 65% when the sensor scanned the bowel at a speed of 0.3 cm/s, and applying slight pressure on the serosa. This value increased to 95% when the sensor was guided directly on the point of clip attachment. The detection rate dropped sharply when the scanning speed exceeded 1 cm/s and when the sensor-clip distance exceeded the cut-off value of 3 mm. In conclusion, the proposed detection system demonstrated its potential to offer a swift and convenient solution for the digestive laparoscopic surgeons, however its detection range still needs to be improved to render it useful for the clinical setting.

Figure 1

Principle of tumor detection by the complex formed from the sensing laparoscopic instrument and the endoscopically attached metallic tags—tumor markers.

Figure 2

The modular laparoscopic detection instrument composed from a proximal handle that hosts the electronic block covered by a lid to preserve an sterile environment on the surface (corner left), the titanium alloy at the junction between the case and the rod (middle left), the inductive sensor present at the distal tip of the instrument, encapsulated in a watertight junction (middle right). Overview of the whole instrument (right).

Figure 3

System for endoscopic deployment of modified clip at the point of interest into the gastrointestinal tract.

Figure 4

(A) Laparoscopic surgical access to the peritoneal cavity; (B) trans-oral insertion of the clip and deployment into the duodenum.

Figure 5

Combined laparoscopic and endoscopic approach to identify the position of the clip with zoom on instruments scanning clip position.