Terahertz refractive index-based morphological dilation for breast carcinoma delineation

Quentin Cassar,Thomas Zimmer,Philipp Hillger,Ullrich Pfeiffer,Patrick Mounaix,Thomas Bücher,Samuel Caravera,Jean-Paul Guillet,Gaëtan Macgrogan

doi:10.1038/s41598-021-85853-8

Abstract

This paper reports investigations led on the combination of the refractive index and morphological dilation to enhance performances towards breast tumour margin delineation during conserving surgeries. The refractive index map of invasive ductal and lobular carcinomas were constructed from an inverse electromagnetic problem. Morphological dilation combined with refractive index thresholding was conducted to classify the tissue regions as malignant or benign. A histology routine was conducted to evaluate the performances of various dilation geometries associated with different thresholds. It was found that the combination of a wide structuring element and high refractive index was improving the correctness of tissue classification in comparison to other configurations or without dilation. The method reports a sensitivity of around 80% and a specificity of 82% for the best case. These results indicate that combining the fundamental optical properties of tissues denoted by their refractive index with morphological dilation may open routes to define supporting procedures during breast-conserving surgeries.

Highlights

This paper reports investigations led on the combination of the refractive index and morphological dilation to enhance performances towards breast tumour margin delineation during conserving surgeries
Operating dilation from regions exhibiting a higher refractive index should allow bypassing class-overlapping limitations. Such a process is referred to as terahertz refractive index-based morphological dilation and operates as follows: (1) the refractive index map of a freshly excised breast tissue is extracted through a specific objective function minimization; (2) a refractive index threshold is defined such that pixels exhibiting a refractive index higher than the threshold are classified as malignant while others are classified as benign; (3) morphological dilation is used to spread the malignant zones to the neighborhood
The classifiers are employed to evaluate their effectiveness on three freshly excised breast tissues. Two of these samples were diagnosed as invasive ductal carcinoma (IDC) and one was identified as an invasive lobular carcinoma (ILC)

Summary

Introduction

This paper reports investigations led on the combination of the refractive index and morphological dilation to enhance performances towards breast tumour margin delineation during conserving surgeries. The method is based on the extraction of the terahertz refractive index map of freshly excised samples followed by morphological dilation.

Results

Conclusion