Premium
Dielectric properties of colon polyps, cancer, and normal mucosa: Ex vivo measurements from 0.5 to 20 GHz
Author(s) -
Guardiola Marta,
Buitrago Santiago,
FernándezEsparrach Glòria,
O'Callaghan Joan M.,
Romeu Jordi,
Cuatrecasas Miriam,
Córdova Henry,
González Ballester Miguel Ángel,
Camara Oscar
Publication year - 2018
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1002/mp.13016
Subject(s) - colorectal cancer , ex vivo , permittivity , cancer , colonoscopy , materials science , dielectric , biomedical engineering , in vivo , medicine , pathology , biology , optoelectronics , microbiology and biotechnology
Purpose 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. Methods 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 GH z. The obtained measurements were classified into five tissue groups before applying a data reduction step with a frequency dispersive single‐pole Debye model. The classification was finally compared with pathological analysis of tissue samples, which is the gold standard. Results 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. In addition, complex permittivity measurements were independent of the lesion shape and size, which is also an interesting property comparing to current colonoscopy techniques. Conclusions The contrast in complex permittivities between normal and abnormal colon tissues presented here for the first time demonstrate the potential of these measurements for tissue classification. It also opens the door to the development of a microwave endoscopic device to complement the outcomes of colonoscopy with functional tissue information.