Background There is an important global need to improve early detection of oral cancer. Recent reports suggest that optical imaging technologies can aid in the identification of neoplastic lesions in the oral cavity; however, there is little data evaluating the use of optical imaging modalities in resource limited settings where oral cancer impacts patients disproportionately. In this article, we evaluate a simple, low-cost optical imaging system that is designed for early detection of oral cancer in resource limited settings. We report results of a clinical study conducted at Tata Memorial Hospital (TMH) in Mumbai, India using this system as a tool to improve detection of oral cancer and its precursors. Methods Reflectance images with white light illumination and fluorescence images with 455 nm excitation were obtained from 261 sites in the oral cavity from 76 patients and 90 sites in the oral cavity from 33 normal volunteers. Quantitative image features were used to develop classification algorithms to identify neoplastic tissue, using clinical diagnosis of expert observers as the gold standard. Results Using the ratio of red to green autofluorescence, the algorithm identified tissues judged clinically to be cancer or clinically suspicious for neoplasia with a sensitivity of 90% and a specificity of 87%. Conclusions Results suggest that the performance of this simple, objective low-cost system has potential to improve oral screening efforts, especially in low-resource settings.

An integrated miniature multi-modal microscope (4M device) for microendoscopy was built and tested. Imaging performance is evaluated and imaging results are presented for both fluorescence and reflectance samples. Images of biological samples show successful imaging of both thin layers of fixed cells prepared on a slide as well as thick samples of excised fixed porcine epithelial tissue, thus demonstrating the potential for in vivo use.

The multi-modal miniature microscope (4M) device to image morphology and cytochemistry in vivo is a microscope on a chip including optical, micro-mechanical, and electronic components. This paper describes all major system components: optical system, custom high speed CMOS detector and comb drive actuator. The hybrid sol-gel lenses, their fabrication and assembling technology, optical system parameters, and various operation modes (fluorescence, reflectance, structured illumination) are also discussed. A particularly interesting method is a structured illumination technique that delivers confocal-imaging capabilities and may be used for optical sectioning. For reconstruction of the sectioned layer a sine approximation algorithm is applied. Structured illumination is produced with LIGA fabricated actuator scanning in resonance. The spatial resolution of the system is 1 μm, and was magnified by 4x matching the CMOS pixel size of 4 μm (a lateral magnification is 4:1), and the extent of field of the system is 250μm. An overview of the 4M device is combined with the presentation of imaging results for epithelial cell phantoms with optical properties characteristic of normal and cancerous tissue labeled with nanoparticles.

Objective. Structured illumination microscopy is an inexpensive alternative to confocal microscopy that allows optical sectioning at a sub-cellular resolution. However, its application in imaging biological tissue has been limited by inadequate contrast present in them especially in reflectance imaging. Novel, optically active contrast agents like gold nanoparticles and quantum dots targeted against biomarkers of cancer can be integrated with structured illumination to image both the morphological and biochemical changes associated with epithelial pre-cancers.Methods. We modified the optical path of a widefield microscope to implement structured illumination both in reflectance and fluorescence modes. For imaging, we used 25-nm-diameter gold nanoparticles and CdSe quantum dots for reflectance and fluorescence imaging, respectively, to label three-dimensional tissue constructs of SiHa cervical cancer cells. Contrast agents were targeted against the epidermal growth factor receptor (EGFR) using an anti-EGFR monoclonal antibody. Agents targeted with a non-specific IgG antibody served as a control to monitor non-specific labeling.Results. Our result shows that optically sectioned images taken with structured illumination are very comparable to those obtained using confocal microscopy. Moreover, images of three-dimensional cultures stained with the anti-EGFR agents show significantly more image intensity than those stained with the IgG targeted control.Conclusion. Our findings suggest that the combination of novel optical contrast agents and structured illumination can differentiate neoplastic cells which overexpress EGFR from non-nal cells in intact tissue. Combining structured illumination microscopy with novel contrast agents can potentially provide a powerful and inexpensive tool to aid in the detection of cervical pre-cancers. (C) 2005 Elsevier Inc. All rights reserved.

We present an integrated approach to optical imaging of oral and cervical pre-cancer in reflectance and fluorescence mode using structured illumination and optically active molecular specific novel contrast agents.

The multi-modal miniature microscope (4M) device for early cancer detection is based on micro-optical table (MOT) platform which accommodates on a chip: optical, micro-mechanical, and electronic components. The MOT is a zeroalignment optical-system concept developed for a wide variety of opto-mechanical instruments. In practical terms this concept translates into assembly errors that are smaller than the tolerances on the performance of the optical system. This paper discusses all major system elements: optical system, custom high speed CMOS detector and comb drive actuator. It also points to mutual relations between different technologies. The hybrid sol-gel lenses, their fabrication and assembling techniques, optical system parameters, and various operation modes are also discussed. A particularly interesting mode is a structured illumination technique that delivers confocal-imaging capabilities and may be used for optical sectioning. Structured illumination is produced with LIGA fabricated actuator scanning in resonance and reconstructed using sine approximation algorithm.

This paper presents the multi-modal miniature microscope (4M) device for pre-cancer detection.Recent progress has affected all major system components including optics, micro-mechanics, and electronics.Results of imaging thick tissue phantoms using epi-illumination mode and structured illumination mode are presented and discussed.

We present an integrated approach to optical imaging of oral and cervical pre-cancer using structured illumination by combining sine approximation image reconstruction algorithm and optically active molecular specific novel contrast agents.

A miniature microscope objective is fabricated and assembled using refractive microoptics patterned directly in hybrid sol-gel glass. Imaging performance is assessed and design considerations for future improvements including tilted elements for stray-light reduction are discussed.

Structured-illumination microscopy delivers confocal-imaging capabilities and may be used for optical sectioning in bio-imaging applications. However, previous structured-illumination implementations are not capable of imaging molecular changes within highly scattering, biological samples in reflectance mode. Here, we present two advances which enable successful structured illumination reflectance microscopy to image molecular changes in epithelial tissue phantoms. First, we present the sine approximation algorithm to improve the ability to reconstruct the in-focus plane when the out-of-focus light is much greater in magnitude. We characterize the dependencies of this algorithm on phase step error, random noise and backscattered out-of-focus contributions. Second, we utilize a molecular-specific reflectance contrast agent based on gold nanoparticles to label disease-related biomarkers and increase the signal and signal-to-noise ratio (SNR) in structured illumination microscopy of biological tissue. Imaging results for multi-layer epithelial cell phantoms with optical properties characteristic of normal and cancerous tissue labeled with nanoparticles targeted against the epidermal growth factor receptor (EGFR) are presented. Structured illumination images reconstructed with the sine approximation algorithm compare favorably to those obtained with a standard confocal microscope; this new technique can be implemented in simple and small imaging platforms for future clinical studies.