Granular Cell Tumor Imaging Using Optical Coherence Tomography

Background: Granular cell tumor (GCT) is a relatively uncommon tumor that may affect the skin. The tumor can develop anywhere on the body, although it is predominately seen in oral cavities and in the head and neck regions. Here, we present the results of optical coherence tomography (OCT) imaging of a large GCT located on the abdomen of a patient. We also present an analytical method to differentiate between healthy tissue and GCT tissues. Materials and methods: A multibeam, Fourier domain, swept source OCT was used for imaging. The OCT had a central wavelength of 1305 ± 15 nm and lateral and axial resolutions of 7.5 and 10 µm, respectively. Qualitative and quantitative analyses of the tumor and healthy skin are reported. Results: Abrupt changes in architectures of the dermal and epidermal layers in the GCT lesion were observed. These architectural changes were not observed in healthy skin. Discussion: To quantitatively differentiate healthy skin from tumor regions, an optical attenuation coefficient analysis based on single-scattering formulation was performed. The methodology introduced here could have the capability to delineate boundaries of a tumor prior to surgical excision

A practical guide to photoacoustic tomography in the life sciences

The life sciences can benefit greatly from imaging technologies that connect microscopic discoveries with macroscopic observations. One technology uniquely positioned to provide such benefits is photoacoustic tomography (PAT), a sensitive modality for imaging optical absorption contrast over a range of spatial scales at high speed. In PAT, endogenous contrast reveals a tissue's anatomical, functional, metabolic, and histologic properties, and exogenous contrast provides molecular and cellular specificity. The spatial scale of PAT covers organelles, cells, tissues, organs, and small animals. Consequently, PAT is complementary to other imaging modalities in contrast mechanism, penetration, spatial resolution, and temporal resolution. We review the fundamentals of PAT and provide practical guidelines for matching PAT systems with research needs. We also summarize the most promising biomedical applications of PAT, discuss related challenges, and envision PAT's potential to lead to further breakthroughs

Further study on iterative control loop for aberration correction in imaging systems with single mode fibre aperture

An iterative control system was designed for compensation of wavefront aberration utilizing a micromachined deformable mirror through simulated annealing algorithm. 37 elements within a deformable mirror are controlled individually in a closed-loop to maximize the output optical intensity collected in a single mode aperture. In this paper, the design of the control system is explained comprehensively. The effect of the parameters involved on the achievable accuracy, computational load and speed of the algorithm are investigated. The shape of the mirror's surface throughout the runtime of the algorithm is also monitored and analyzed

Optical coherence tomography imaging of melanoma skin cancer

No consensus guidelines exist on the use of optical coherence tomography (OCT) for diagnosis of cutaneous melanoma. The objectives of this review are to provide a descriptive review of the literature on characteristics of cutaneous melanomas seen on high-definition OCT (HD-OCT), speckle variance OCT (SV-OCT), and conventional OCT and to compare their diagnostic ability with that of histopathology. A review of PubMed and Google Scholar identified all available literature on OCT in melanoma skin cancer that included all in vivo and ex vivo studies on human or human tissues and excluded all studies on non-human subjects or animal studies. Two hundred nine abstracts were considered for evaluation, 31 abstracts were selected for manuscript review, and 14 abstracts were included that met all criteria. Diagnoses of MIS and MM using HD-OCT and SV-OCT were consistently reported to correlate with histopathology. However, accuracy of diagnosis using conventional OCT varied. Most authors agreed that it was difficult to differentiate MM from benign nevi using conventional OCT. HD-OCT, SV-OCT, and conventional OCT show promise for visualizing cutaneous melanoma. The use of OCT in diagnosis of melanoma is rarely reported in the literature. There is a need to increase and standardize reporting of OCT for diagnosis of cutaneous melanoma

Mitigation of Speckle Noise in Optical Coherence Tomograms

Optical Coherence Tomography (OCT) is a promising high-resolution imaging technique that works based on low coherent interferometry. However, like other low coherent imaging modalities, OCT suffers from an artifact called, speckle. Speckle reduces the detectability of diagnostically relevant features in the tissue. Retinal optical coherence tomograms are of a great importance in detecting and diagnosing eye diseases. Different hardware or software based techniques are devised in literatures to mitigate speckle noise. The ultimate aim of any software-based despeckling technique is to suppress the noise part of speckle while preserves the information carrying portion of that. In this chapter, we reviewed the most prominent speckle reduction methods for OCT images to date and then present a novel and intelligent speckle reduction algorithm to reduce speckle in OCT images of retina, based on an ensemble framework of Multi-Layer Perceptron (MLP) neural networks