Phantom Validation of Polyp Automatic Detection using Microwave Endoscopy for Colorectal Cancer Prevention and Early Detection

Abstract

A system to integrate microwave imaging with optical colonoscopy is presented. The overarching goal is to improve the prevention, diagnosis and understanding of one of the main health and economic burdens of an increasingly ageing population that is colorectal cancer. Our system can address the two main challenges of colonoscopy – improve the detection of precancerous lesions called polyps and classify them according to their malignancy – and moves forward a major trend of the field that is automating medical explorations. To do so, a complete imaging system able to emit an alarm when a polyp is detected is designed, manufactured and validated with a realistic colon phantom composed by tissue-mimicking oil-gelatin materials reproducing the anatomy and dielectric properties of a human colon with a polyp. The acquisition is done by a miniaturized ring-shaped switched array of 16 antennas attachable at the tip of a conventional colonoscope. It has been conceived to satisfy endoscopy size restrictions, patient safety and intercompatibility with the current clinical practice. A Modified Monofocusing imaging method preceded by a previous frame average subtraction as calibration technique shows perfect detection of a 10-mm polyp (100% sensitivity and specificity) in the two analyzed trajectories. Results of realistic phantom demonstrate the feasibility of the system in future preclinical trials.

Preliminary phantom-based dynamic calibration techniques assessment for microwave colonoscopy systems

“…The container is filled with an oil-gelatin-based material that mimics the dielectric properties of healthy colon mucosa based on a recipe developed for breast phantoms [9]. The polyp is a 10 mm sphere made of a similar material but with the dielectric properties of an adenocarcinoma [7] [10].…”

“…To be able to reproduce a realistic colonoscopy exploration [11] inside the phantom, we have built a 3D positioning system [10] composed of an L-shaped metallic structure on top of a plastic base that supports a plastic bar equipped with a ruler to move the accessory along the z-direction. The phantom is placed on mobile supports to be carried in the XY plane.…”

New Diagnostics Methods for Colorectal Cancer Early-Detection

“…Once the initial hypothesis had been validated, a device consisting of a set of miniaturized antennas was built as an accessory device to be mounted at the tip of the colonoscope. Up to know, it has been tested in preclinical studies using phantoms and ex-vivo tissue showing very promising results [10,11]. Soon this technical innovation will be tested on patients.…”