Complete Mueller polarimetry: do we need it for biological tissues diagnosis?

The advent of polarization-sensitive cameras opens the avenue for real-time in-vivo polarimetric diagnostic imaging of biological tissues in clinical settings, but this approach allows measuring only the first three rows of 4×4 Mueller matrix. In order to extract diagnostically relevant images of tissue linear retardance, azimuth of the optical axis and depolarization from the partial Mueller matrix we have formulated a theoretical framework for the decomposition of 3×4 Mueller matrices and tested its validity on both simulated data for optical phantoms and experimental data collected from thick sections of formalin-fixed human brain measured in reflection. The polarimetric maps calculated with our algorithm and Lu-Chipman polar decomposition of the complete Mueller matrices demonstrate compelling correlation and preserve diagnostic image contrast.