This paper presents the results of the proof of concept of the project MiWEndo that aims to improve the endoscopy outcomes for the early detection and prevention of colorectal cancer using microwave imaging. The project was supported by the Indústria del Coneixement Llavor and Producte programs from Generalitat de Catalunya, Caixaimpulse from La Caixa and Desarrollo Tecnológico en Salud from Instituto de Salud Carlos III. The paper by Physense and SIMBIOsys research groups at BCN MedTech, in collaboration with CommSensLab (UPC) and Hospital Clinic de Barcelona, is published in Medical Physics.
Colorectal cancer is highly preventable by detecting and removing polyps, which are the precursors. Currently, the most accurate test is colonoscopy, but still misses 22% of polyps due to visualization limitations. In this paper we preliminary assess the potential of microwave imaging and dielectric properties (e.g. complex permittivity) as a complementary method for detecting polyps and cancer tissue in the colon. The dielectric properties of biological tissues have been used in a wide variety of applications, including safety assessment of wireless technologies and design of medical diagnostic or therapeutic techniques (microwave imaging, hyperthermia and ablation). The main purpose of this work is to measure the complex permittivity of different types of colon polyps, cancer and normal mucosa in ex vivo human samples to study if the dielectric properties are appropriate for classification purposes.
The complex permittivity of freshly excised healthy colon tissue, cancer and histological samples of different types of polyps from 23 patients was characterized using an open-ended coaxial probe between 0.5 and 20 GHz. The obtained measurements were classified into five tissue groups before applying a data reduction step with a frequency dispersive single-pole Debye model.
We demonstrated that the complex permittivity progressively increases as the tissue degenerates from normal to cancer. When comparing to the gold-standard histological tissue analysis, the sensitivity and specificity of the proposed method is the following: 100% and 95% for cancer diagnosis; 91% and 62% for adenomas with high grade dysplasia; 100% and 61% for adenomas with low grade dysplasia; and 100% and 74% for hyperplastic polyps, respectively. It opens the door to the development of a microwave endoscopic device to complement the outcomes of colonoscopy with functional tissue information.
Reference work: Guardiola M, Buitrago S, Fernández-Esparrach G, O'Callaghan JM, Romeu J, Cuatrecasas M, Córdova H, González Ballester MÁ, Camara O (2018), “Dielectric properties of colon polyps, cancer and normal mucosa: ex vivo measurements from 0.5 to 20 GHz” Med Phys.