Phase distribution analysis of tissues based on the off-axis digital holographic hybrid reconstruction algorithm.

Sujuan Huang,Liang Dong,Yunyi Lin,Haige Chen

doi:10.1364/boe.9.000001

Abstract

Off-axis digital holography (DH) has great potential in histopathology for its high efficiency and precision. Phase distribution, usually extracted by the angular spectrum (AS) algorithm from a digital hologram, reflects important structural information of biological tissues. However, the complex structure of tissues introduces spectrum aliasing of the hologram, making the AS algorithm hard to realize and accurate phase analysis difficult to conduct. Here, we present a hybrid reconstruction algorithm, combining Fresnel reconstruction in spatial domain with the AS algorithm in frequency domain, to solve aliasing by spatial filtering. Through simulation, we demonstrate the feasibility and superiority of the hybrid algorithm and verified the precision (10-3 rad) of the hybrid algorithm with spectrum aliasing. We extract phase distributions from normal urothelial and bladder cancer tissues by the hybrid algorithm and make quantitative analysis through histogram and standard deviation. The result shows the hybrid algorithm in off-axis DH has great advantage for the high-precision phase extraction of tissues and supplies significant information for cancer diagnosis.

Highlights

The gold standard of cancer diagnosis is mainly based on manual investigation of hematoxylin and eosin (H&E) stained tissue slides and mainly relies on the experience of pathologists [1,2], making it subject to investigator bias and resulting in low throughput.Recently, some studies showed there was structural discrepancy between normal and cancer tissues
We demonstrate the feasibility and superiority of hybrid algorithm and verify that the precision of hybrid algorithm with spectrum aliasing is 10−3 rad, which is equal to the precision of angular spectrum (AS) algorithm without spectrum aliasing
3.3 Hybrid reconstruction algorithm According to the idea said above, we propose a hybrid algorithm, combining Fresnel amplitude reconstruction in spatial domain with AS algorithm in frequency domain, to solve the spectrum aliasing of digital hologram and improve the precision of biological tissues phase extraction in off-axis digital holography (DH)

Summary

Introduction

The gold standard of cancer diagnosis is mainly based on manual investigation of hematoxylin and eosin (H&E) stained tissue slides and mainly relies on the experience of pathologists [1,2], making it subject to investigator bias and resulting in low throughput. The Fresnel algorithm is usually used to reconstruct object image, while the AS algorithm, an analytical solution of wave equation, has higher precision for phase extraction and are widely-used algorithm in biological analysis. To extract high-precision phase distribution of biological tissues, we present a hybrid algorithm to solve spectrum aliasing in off-axis digital hologram. We extract high-precision phase distributions from normal urothelial and bladder cancer tissues and make quantitative analysis through phase histogram and standard deviation. Through adjusting BS2, we get appropriate incident angle θ between the object and reference wave, which interfere on the CCD sensor interface and generate the off-axis digital hologram, saved in the computer for further processing. The zero-order diffraction part contains intensity information of object and reference wave This part is nothing to do with phase extraction and is the main noise of digital hologram. RR*O contains useful object information we need, and RRO* is the conjugation of object image

Off-axis DH reconstruction algorithm

Simulation

Phase extraction without spectrum aliasing

Conclusion