PROJECT DNTS/France 01/7/ 09.05.2017 “Polarized light histolology of tumours (POLHIS)”

Funded by BSF-MES

   

Partners:

Institute of Electronics, Bulgarian Academy of Sciences

LPICM Laboratoire de Physique des Interfaces et Couches Minces, CNRS, Ecole polytechnique

   

   

Scientific team

Bulgarian scientific team :

Ekaterina Borisova, Assoc. Prof., PhD – team coordinator,
Institute of Electronics, BAS

Petranka Troyanova, Prof., PhD, MD
University hospital “Tsaritsa Yoanna-ISUL”

Tsanislava Genova-Hristova
PhD student at Institute of Electronics, BAS

Aleksandra Zhelyazkova
MS, Physicist, Institute of Electronics, BAS

Liliya Angelova,
MS, Biologist, Institute of Electronics, BAS

Yana Andreeva
BS, Physicist, Institute of Electronics, BAS

 

French scientific team:

Tatiana Novikova, PhDteam coordinator

Razvigor Ossikovski, PhD, HDR

Enric Garcia-Caurel, PhD

Sang Hyuk Yoo
PhD student

 

PROJECT SUMMARY:

Early detection of cancer plays an important role in global cancer control initiatives as it significantly increases the survival rate and improves quality of life of the patients. Currently, the “gold standard” and most widely used method for reliable cancer diagnosis is an excisional biopsy. However, the conclusive diagnosis by histological analysis for some types of cancer may not be achieved in as much as 25-35% of cases [1].
The polarized light imaging has already been proven to increase the image contrast and detect the subtle differences between healthy epithelial tissue and early precancerous changes of epithelium, that would remain invisible using conventional methods of diagnostics. Recent experiments with colon [2] and cervical specimens [3] showed that both degree of polarization of backscattered probing light beam and its retardance are particularly sensitive to pathological alterations of tissue. This experimental evidence requires the fundamental studies of interlinked physical mechanisms (scattering, anisotropy, absorption) that explain the tissue response to polarized light.

In the current project we are going to (i) undertake detailed experimental and theoretical studies of polarized light interaction with healthy and cancerous human tissue, (ii) to define and explore the set of optical markers with increased sensitivity to cancer which can be used for biomedical diagnostics (so called “optical biopsy” of tissue).

Polarimetric Mueller microscopes developed by the French partner and operating either in transmission or reflection mode in the visible wavelength range [4,5] will be used for the measurements of fixed stained and unstained histological slides of human tissue of different thickness (5Вµm, 10Вµm, 15Вµm). These samples containing both healthy and cancerous zones of skin and colon tissue will be provided by the Bulgarian partner, as a part of current cooperation agreement between IE-BAS and University Hospital “Queen Jiovanna-ISUL” in Sofia for a development of optical biopsy systems for early diagnostics of malignant tumours (Approval of Ethical Committee #286/24.07.2012).

We plan to study the different types of polar decomposition for the interpretation of experimental Mueller matrix images of tissue. Apart from depolarization and scalar retardance of tissue obtained with conventional Lu-Chipman decomposition of Mueller matrices [6], we will explore the extended set of optical markers (both linear and circular depolarization, dichroism and birefringence) which will be obtained within the framework of differential Mueller matrix formalism developed by Prof R. Ossikovski, LPICM, Ecole polytechnique [7]. The preliminary studies of tissue phantoms with controlled scattering properties have already confirmed the validity of this approach for the isotropic scattering optical media [8].

In general, human tissue is optically anisotropic due to the presence of collagen fibers. It is known that development of cancer starts from subtle alterations in biological tissue morphology and triggers the re-arrangement of the extra-cellular collagen matrix. Hence, we expect the linear and circular birefringence of the sample to be very sensitive to the very first stage of malignant transformation of tissue. The studies of dependence of the values of these optical markers on sample thickness will pave the way to optical staging of tumor, i.e. the estimation of depth of cancer proliferation from Mueller matrix measurements.

Thus, an overall goal of the project is to investigate the potential increase in sensitivity of Mueller polarimetry for non-invasive tissue diagnosis (optical biopsy) by using new optical markers defined within the framework of phenomenological theory of the fluctuating medium.

Our project will be a new collaboration between French and Bulgarian teams which both possess the complimentary set of skills.
French partner has a world-known expertise in the field of theory of polarimetry and design and construction of new polarimetric instruments. The biomedical applications of Mueller polarimetry were among the core activities of French team during the last decade.

Bulgarian team explores many different aspects of biophotonics including development of optical biopsy systems, skin cancer diagnostics using autofluorescence (AF) and diffuse-reflectance spectroscopy (DRS) techniques, photodiagnosis of gastrointestinal tumours, using exogenous fluorescent markers, as well as synchronous fluorescence spectroscopy (SFS) and excitation-emission matrices (EEMs) detection of tumour tissues samples in vivo and ex vivo. Polarimetric investigations of the tissues endogenous fluorophores emission are carried out as well in the last few years.

The selection and preparation of necessary histological slides of human tissue (type of tissue, cancerous and healthy, with variable thickness of the slides, different staining agents, etc.) will be performed by the Bulgarian partner team. Polarization-sensitive fluorescence measurements will be also carried out by BG group to evaluate the effect of extracellular collagen cell matrix disintegration due to tumour growth.

References

 

1. K. Nouri, Skin Cancer, The McGraw-Hill Companies Inc. (2008).
2. T. Novikova et al “The origins of polarimetric image contrast between healthy and cancerous human colon tissue”, Appl. Phys. Lett. 102, 241103 (4pp) (2013).
3. J. Rehbinder et al “Ex vivo Mueller polarimetric imaging of the uterine cervix: a first statistical evaluation”, J. Biomed. Opt. 21(7), 071113 (2016).
4. T. Novikova et al “Polarimetric imaging for cancer diagnosis and staging”, Optics and Photonics News, 26, (October 2012).
5. S. Bancelin et al “Determination of collagen fiber orientation in histological slides using Mueller microscopy and validation by second harmonic generation imaging”, Opt. Express, 22(19) 22561 (2014).
6. S.-Y. Lu and R. A. Chipman, “Interpretation of Mueller matrices based on polar decomposition,” J. Opt. Soc. Am. A 13(5), 1106 (1996).
7. R. Ossikovski, Differential matrix formalism for depolarizing anisotropic media, Opt. Lett. 36, 2330 (2011).
8. N. Agarwal et al “Spatial evolution of depolarization in homogeneous turbid media within the differential Mueller matrix formalism”, Opt. Lett, 40(23) 5634 (2015).

 

EXPECTED RESULTS:

Reducing stress during initial diagnosis, shortening of analysis time, high diagnostic accuracy to be achieved by application of polarizing and spectral analysis of tissue neoplasia will undoubtedly benefit patients, to whom subsequently will be applied diagnostic methods developed.
Application of new non-invasive diagnostic methods working contactless and in real-time, characterized with high diagnostic accuracy, are of significant benefit to patients, which leads to significant social impact of the developments, envisaged in the plan of the present cooperative project.

It is expected to achieve the following results:

1. There will be obtained new scientific knowledge about the polarization characteristics of the skin and gastrointestinal (GI) tissues in normal and in the malignant condition;
2. it will be achieved improvement of knowledge and technical skills in the field of optical polarization spectroscopy and the resulting two-dimensional tissue neoplasia imaging of the skin and GIT;
3. Algorithms will be developed for 1-D and 2-D polarization spectral analysis for diagnosis of tumors of the skin and GIT with high sensitivity and specificity;
4. In Bulgarian partner organization would be developed system for polarization-sensitive fluorescence spectroscopy and diffuse-reflectance polarization spectroscopy of tissue neoplasia;
5. New, original experimental results would be achieved about the polarization properties of tumors and the correlation would be evaluated between the types of pathologies and received optical data with the ability to develop diagnostic and prognostic clinical algorithms;
6. The scientific results will be published in specialized international journals and reported at conferences necessary for their popularization, and will contribute to the overall advancement of young scientists, involved in the project team;

Research carried out, prepared and presented lectures by experienced researchers from the project team, implementation of short-term research visits to the partner laboratories will be an important prerequisite for the development of new knowledge and skills in the young scientists and graduate students in the field of biophotonics.