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Papers by Mohammed Rahman

Research paper thumbnail of Global approaches to cancer prevention

Research paper thumbnail of High resolution, molecular-specific, reflectance imaging in optically dense tissue phantoms with structured-illumination

Research paper thumbnail of Low-cost, multimodal, portable screening system for early detection of oral cancer

Journal of Biomedical Optics, 2008

Research paper thumbnail of Evaluation of a low-cost, portable imaging system for early detection of oral cancer

Head & Neck Oncology, 2010

Background There is an important global need to improve early detection of oral cancer. Recent re... more 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 classi...

Research paper thumbnail of Fluorescent nanocrystals for use in early cervical cancer detection

Gynecologic Oncology, 2005

Research paper thumbnail of Imaging performance of a miniature integrated microendoscope

Journal of Biomedical Optics, 2008

An integrated miniature multi-modal microscope ͑4M de-vice͒ for microendoscopy was built and test... more An integrated miniature multi-modal microscope ͑4M de-vice͒ 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.

Research paper thumbnail of Optical imaging of cervical pre-cancers with structured illumination: An integrated approach

Gynecologic Oncology, 2005

Objective. Structured illumination microscopy is an inexpensive alternative to confocal microscop... more 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 normal 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.

Research paper thumbnail of Optical imaging of cervical pre-cancers with structured illumination: An integrated approach

Gynecologic Oncology, 2005

Objective. Structured illumination microscopy is an inexpensive alternative to confocal microscop... more 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 normal 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.

Research paper thumbnail of Multi-modal miniature microscope: 4M Device for bio-imaging applications���an overview of the system

The multi-modal miniature microscope (4M) device to image morphology and cytochemistry in vivo is... more 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 ...

Research paper thumbnail of Global approaches to cancer prevention

Research paper thumbnail of High resolution, molecular-specific, reflectance imaging in optically dense tissue phantoms with structured-illumination

Research paper thumbnail of Low-cost, multimodal, portable screening system for early detection of oral cancer

Journal of Biomedical Optics, 2008

Research paper thumbnail of Evaluation of a low-cost, portable imaging system for early detection of oral cancer

Head & Neck Oncology, 2010

Background There is an important global need to improve early detection of oral cancer. Recent re... more 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 classi...

Research paper thumbnail of Fluorescent nanocrystals for use in early cervical cancer detection

Gynecologic Oncology, 2005

Research paper thumbnail of Imaging performance of a miniature integrated microendoscope

Journal of Biomedical Optics, 2008

An integrated miniature multi-modal microscope ͑4M de-vice͒ for microendoscopy was built and test... more An integrated miniature multi-modal microscope ͑4M de-vice͒ 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.

Research paper thumbnail of Optical imaging of cervical pre-cancers with structured illumination: An integrated approach

Gynecologic Oncology, 2005

Objective. Structured illumination microscopy is an inexpensive alternative to confocal microscop... more 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 normal 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.

Research paper thumbnail of Optical imaging of cervical pre-cancers with structured illumination: An integrated approach

Gynecologic Oncology, 2005

Objective. Structured illumination microscopy is an inexpensive alternative to confocal microscop... more 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 normal 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.

Research paper thumbnail of Multi-modal miniature microscope: 4M Device for bio-imaging applications���an overview of the system

The multi-modal miniature microscope (4M) device to image morphology and cytochemistry in vivo is... more 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 ...