Imaging of human brain tumor tissue by near-infrared laser coherence tomography

Abstract

IntroductionIntraoperative detection of residual tumor remains an important challenge in surgery to treat gliomas. New developments in optical techniques offer non-invasive high-resolution imaging that may integrate well into the workflow of neurosurgical operations. Using an intracranial glioma model, we have recently shown that time domain optical coherence tomography (OCT) allows discrimination of normal brain, diffusely invaded brain tissue, and solid tumor. OCT imaging allowed acquisition of 2D and 3D data arrays for multiplanar analysis of the tumor to brain interface. In this study we have analyzed biopsy specimens of human brain tumors and we present the first feasibility study of intraoperative OCT and post-image acquisition processing for non-invasive imaging of the brain and brain tumor.MethodsWe used a Sirius 713 Tomograph with a superluminescence diode emitting light at a near infrared central wavelength of 1,310 nm and a coherence length of 15 µm. The light is passed through an optical mono mode fiber to a modified OCT adapter containing a lens system with a working distance of 10 cm and an integrated pilot laser. Navigation-registered tumor biopsies were imaged ex vivo and the intraoperative site of optical tissue analysis was registered by marker acquisition using a neuronavigation system.ResultsOptical coherence tomography non-contact measurements of brain and brain tumor tissue produced B-scan images of 4 mm in width and 1.5–2.0 mm in depth at an axial and lateral optical resolution of 15 µm. OCT imaging demonstrated a different microstructure and characteristic signal attenuation profiles of tumor versus normal brain. Post-image acquisition processing and automated detection of the tissue to air interface was used to realign A-scans to compensate for image distortions caused by pulse- and respiration-induced movements of the target volume. Realigned images allowed monitoring of intensity changes within the scan line and facilitated selection of areas for the averaging of A-scans and the calculation of attenuation coefficients for specific regions of interest.ConclusionThis feasibility study has demonstrated that OCT analysis of the tissue microstructure and light attenuation characteristics discriminate normal brain, areas of tumor infiltrated brain, solid tumor, and necrosis. The working distance of the OCT adapter and the A-scan acquisition rate conceptually allows integration of the OCT applicator into the optical path of the operating microscopes. This would allow a continuous analysis of the resection plain, providing optical tomography, thereby adding a third dimension to the microscopic view and information on the light attenuation characteristics of the tissue.

Multiphoton Tomography and Cross-Polarization Optical Coherence Tomography for Diagnosing Brain Gliomas: Pilot Study

“…According to the reference sources, the resolution + between perifocal zone and glioblastoma, p<0.0000003; v between glioblastoma and pilocytic astrocytoma, p<0.000001 capacity of OCT is sufficient to determine the area of tumor infiltration where there are specific changes in the scattering properties compared with healthy brain tissue [28]. Our results showed that visually the signal from glial tumors in the OcT images in co-polarization looks heterogeneous in comparison with the homogeneous signal of the brain tissue from the perifocal zone, and this correlates with the data from other studies [17].…”

“…The spatial resolution of OcT (unlike MPT) cannot provide subcellular visualization and differentiation between benign and malignant brain tumors. Qualitative evaluation of images and the differentiation criteria in this case are based on the intensity and heterogeneity of the OcT signal, and the rate of its attenuation [17,28].…”

Optical coherence tomography for precision brain imaging, neurosurgical guidance and minimally invasive theranostics

“…Bizheva et al reported the first studies on ex vivo human tissues (65). Böhringer et al reported imaging of human brain tumor specimens using TD-OCT and SD-OCT system to identify tumor and normal tissue using optical characteristics (66)(67)(68). Due to the intrinsic optical property of brain tissue, near-infrared OCT has a deeper viewing field/range than visible light used in the OCT system (42,67-69).…”

‘Go with the flow ’: A review of methods and advancements in blood flow imaging

“…psoriasis [318]; assessment of arteriosclerotic plaques [319,320]; and determining burn extent and tissue viability by defining tissue barrier layers characteristic of scarring (wound healing and graft flow) [321][322][323]. However, in truth, OCT has ubiquitous applications, having emerged in a variety of clinical fields: ophthalmology [324][325][326], intravascular imaging in cardiology [327,328], oncology [329,330], gastroenterology [331][332][333], general dermatology [334][335][336], dentistry [337,338], and gynaecology [339,340], to name a few. Functional extensions of OCT have emerged: polarisation-sensitive systems used, for example, in the diagnosis of neoplastic 6 processes; differential phase-sensitive methods for use in photorefractive surgery; full-field advancement of the conventional single-point OCT detection technique; and endoscopic OCT.…”