Polarimetry-based method to extract geometry-independent metrics of tissue anisotropy

Abstract

Recently, we have used polarimetry as a method for assessing the linear retardance of infarcted myocardium. While linear retardance reflects tissue anisotropy, experimental geometry has a confounding effect due to dependence of the linear retardance on the orientation of the sample with respect to the probing beam. Here, polarimetry imaging of an 8mm diameter birefringent polystyrene sphere of known anisotropy axis was used to test a dual-projection method by which the anisotropy axis and its true magnitude can be reconstructed, thus eliminating the confounding effect of anisotropy axis orientation. Feasibility is demonstrated in ex-vivo tissue imaging.

Review of the emerging role of optical polarimetry in characterization of pathological myocardium

“…13 In addition, the orientation of cardiomyocytes in cardiac muscle has previously been explored accurately with optical polarimetry. 15,22 Collectively, these studies illustrate that the optical polarimetry holds much promise for the characterization of myocardial pathologies, including sketching of myofiber organization. In this context, herein, the status of optical polarimetry to visualize, identify, and quantify myocardial pathologies and speculate on its future clinical translation has been summarized.…”

Polarized light imaging in biomedicine: emerging Mueller matrix methodologies for bulk tissue assessment

“…The Mueller matrix, thus, analyzed via various decomposition methods can then yield various optical effects, including the tissue's linear retardance (proportional to linear birefringence/tissue anisotropy), circular retardance (proportional to circular birefringence/chiral molecule content), and depolarization. [17][18][19][20][21][22] Depolarization abnormalities, arising from changes in tissue scattering and absorption properties (transport albedo), are related to alterations in the stroma (e.g., collagen remodeling) and cellular compartment disorders (e.g., nuclear enlargement). [23][24][25][26][27] Given the fundamental and clinical importance of these and related changes, Mueller matrix polarimetry yielding depolarization and retardance has been used in a variety of (mostly preclinical) studies.…”

Optical assessment of tissue anisotropy in <italic>ex vivo</italic> distended rat bladders

“…37 Here we keep the measurement angle ϕ fixed at 25 deg reflection mode, and report differences in apparent tissue birefringence from different bladder regions and under different distension pressures. However, we have developed methods to derive the true Δn that require additional angular projections, 37 and these will be applied to the bladder distension studies in future publications.…”