Imaging and quantification of prostate cancer-associated bone by polarization-sensitive optical coherence tomography

Prostate cancer frequently metastasizes to bone, leading to a spectrum of osteosclerotic and osteolytic lesions that cause debilitating symptoms. Accurate differentiation of bone tissue or lesion types can provide opportunity for local pathologic investigation, which is critical for understanding the bone metastasis and remains challenging. Current imaging methods lack the ability to directly differentiate tissues based on collagen organization and may induce invasive effect on bone tissues. We introduce Polarization-Sensitive Optical Coherence Tomography (PS-OCT) to investigate normal, osteosclerotic, and osteolytic bone tissues. High-resolution PS-OCT imaging reveals collagen fiber arrangement, enabling nuanced distinction of degree of collagen alignment among different bone tissue types or regions. We present a novel feature named degree of ordered organization (DOO), derived from the multiple contrasts of PS-OCT that can quantitatively evaluate bone samples from different pathologic groups, including control,osteoblastic and osteolytic tissues. The capacity of PS-OCT to differentiate trabecular/lamellar and irregular (woven bone) regions within the same specimen is tested and validated on ex-vivo samples extracted from 13 subjects. Our study is the first time that PS-OCT is applied to metastatic bone disease with the aim of enhancing the understanding of bone-related pathologies, and potentially impacting clinical practice. This work demonstrates that PS-OCT can provide useful insight into bone microstructures, and thus it has potential applications across diverse bone disorders.