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Ramanujam, Nimmi

Overview:

Since coming to Duke University in 2005, Prof. Ramanujam has established the Tissue Optical Spectroscopy laboratory. Prof. Ramanujam's group is innovating on optical strategies to peer into the biological landscape of thick tissues. Technologies being developed in her lab leverage principles of optical spectroscopy, optical sectioning microscopy, and molecular imaging. Her research group is developing and applying these optically based tools for three problems in cancer: cancer screening in resource-limited settings, intra-operative margin assessment to detect residual disease during cancer surgery, and visualizing tumor hypoxia and metabolism in the context of cancer therapy and drug discovery. Prof. Ramanujam is leading a multi-disciplinary effort to translate these technologies to clinical applications in the breast, and cervix. In addition to her academic efforts, Prof. Ramanujam has spun out a company, Zenalux, to commercialize several of the technologies developed in her lab.  


In October of 2013, Dr. Nimmi Ramanujam founded the Global Women’s Health Technologies Center. The http://gwht.pratt.duke.edu/">Global Women’s Health Technologies Center reflects a partnership between the Pratt School of Engineering and the https://globalhealth.duke.edu/">Duke Global Health Institute and is led by Center Director http://www.bme.duke.edu/faculty/nirmala-ramanujam">Nimmi Ramanujam, professor of biomedical engineering and global health. The center’s mission is to increase research, training and education in women’s diseases, with a focus on breast cancer, cervical cancer, and maternal-fetal health; and to increase retention of women and underrepresented minorities in Science, Technology, Engineering, and Mathematics (STEM) educational disciplines locally and globally.


Prof. Ramanujam has received several awards for her work in cancer research and technology development for women's health. She received the TR100 Young Innovator Award from MIT in 2003, a $2.5M DOD Era of Hope Scholar award in 2004, the Global Indus Technovator award from MIT in 2005 and a $3M Era of Hope Research Scholar award in 2009 and an NIH BRP grant in 2011. In 2011, she received the Stansell Family Distinguished Research Award from the Pratt School of Engineering at Duke University. Dr. Ramanujam is a fellow of OSA, SPIE and AIMBE.  


She is member of the NIH BMIT-A study section and chair elect of the DOD’s breast cancer research program (BCRP) integration panel (IP) that sets the vision of the BCRP program and plans the dissemination of over $100 M of funds for breast cancer research annually. She is co-editor  of the Handbook of Biomedical Optics (publisher Taylor and Francis).  


Dr. Ramanujam earned her Ph.D. in Biomedical Engineering from the University of Texas, Austin in 1995 and then trained as an NIH postdoctoral fellow at the University of Pennsylvania from 1996-2000. Prior to her tenure at Duke, she was an assistant professor in the Dept. Biomedical Engineering at the University of Wisconsin, Madison from 2000-2005.

Positions:

Robert W. Carr, Jr., Professor of Biomedical Engineering

Biomedical Engineering
Pratt School of Engineering

Professor of Biomedical Engineering

Biomedical Engineering
Pratt School of Engineering

Research Professor of Global Health

Duke Global Health Institute
Institutes and Provost's Academic Units

Professor of Pharmacology and Cancer Biology

Pharmacology & Cancer Biology
School of Medicine

Affiliate of the Duke Initiative for Science & Society

Duke Science & Society
Institutes and Provost's Academic Units

Member of the Duke Cancer Institute

Duke Cancer Institute
School of Medicine

Education:

B.S. 1989

B.S. — University of Texas at Austin

M.S. 1992

M.S. — University of Texas at Austin

Ph.D. 1995

Ph.D. — University of Texas at Austin

News:

Grants:

Translational Research in Surgical Oncology

Administered By
Surgery, Surgical Sciences
AwardedBy
National Institutes of Health
Role
Mentor
Start Date
January 01, 2002
End Date
August 31, 2021

Culturally appropriate screening and diagnosis of cervical cancer in East Africa

Administered By
Biomedical Engineering
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
August 01, 2015
End Date
July 31, 2020

Training in Medical Imaging

Administered By
Biomedical Engineering
AwardedBy
National Institutes of Health
Role
Mentor
Start Date
July 15, 2003
End Date
August 31, 2019

A Viable Solution for a See and Treat Paradigm for Cervical Pre-cancer in Africa

Administered By
Biomedical Engineering
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
July 01, 2015
End Date
June 30, 2018

Enhanced Design Experiences for Duke BME Students

Administered By
Pratt School of Engineering
AwardedBy
National Institutes of Health
Role
Co Investigator
Start Date
April 01, 2011
End Date
March 31, 2017

A Novel Optical Spectral Imaging System for Rapid Imaging of Breast Tumor Margins

Administered By
Biomedical Engineering
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
April 01, 2011
End Date
March 31, 2017

Targeted Chemoprevention of Breast Cancer: From the Bench to Clinical Testing

Administered By
Medicine, Medical Oncology
AwardedBy
National Institutes of Health
Role
Co Investigator
Start Date
April 12, 2012
End Date
September 30, 2015

Harnessing the power of light to see and treat breast cancer

Administered By
Biomedical Engineering
AwardedBy
United States Army Medical Research and Materiel Command
Role
Principal Investigator
Start Date
September 18, 2009
End Date
September 17, 2015

Smart Optical Sensor for Detection of Cervical Cancer In the Developing World

Administered By
Biomedical Engineering
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
July 01, 2011
End Date
June 30, 2015

Automated Micromanufacturing for Optical Sensing and Computational Imaging, Metamaterials, and Quantum Computing

Administered By
Electrical and Computer Engineering
AwardedBy
Air Force Office of Scientific Research
Role
Co-Principal Investigator
Start Date
September 30, 2012
End Date
September 29, 2014

A Fluorescence Histology System for In Vivo Breast Tumor Margin Assessment

Administered By
Biomedical Engineering
AwardedBy
National Institutes of Health
Role
Collaborator
Start Date
March 01, 2011
End Date
February 28, 2013

Can Optical Spectroscopy Predict Early Treatment Response in Solid Tumors

Administered By
Biomedical Engineering
AwardedBy
National Institutes of Health
Role
Mentor
Start Date
May 07, 2010
End Date
September 07, 2012

A Smart Fiber Optic Sensor for in Vivo Tissue Optical Spectroscopy

Administered By
Biomedical Engineering
AwardedBy
National Institutes of Health
Role
Collaborator
Start Date
August 01, 2010
End Date
July 26, 2012

Investigation of Anti-Angiogenic Mechanisms Using Novel Imaging Techniques

Administered By
Biomedical Engineering
AwardedBy
US Army Medical Research and Materiel Command
Role
Mentor
Start Date
February 01, 2009
End Date
February 29, 2012

Diagnosis of Breast Cancer using Optical Spectroscopy

Administered By
Biomedical Engineering
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
September 01, 2005
End Date
March 31, 2010

Near Infrared Spectroscopy for Improving Breast Core Needle Biopsy

Administered By
Biomedical Engineering
AwardedBy
United States Army Medical Research and Materiel Command
Role
Principal Investigator
Start Date
February 10, 2006
End Date
November 30, 2009

Multi-Label Molecular FLIM of Breast Cancer

Administered By
Biomedical Engineering
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
September 01, 2006
End Date
August 31, 2009

Fiber Probe Design for Epithelial Precancer Detection

Administered By
Biomedical Engineering
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
July 01, 2006
End Date
June 30, 2009

Optical Spectroscopy and Multiphoton Imaging for the Diagnosis and Characterization Hyperplasias in the Mouse Mammary

Administered By
Biomedical Engineering
AwardedBy
United States Army Medical Research and Materiel Command
Role
Principal Investigator
Start Date
October 01, 2005
End Date
September 30, 2007

Diffuse Optical Spectroscopy Guided Breast Needle Biopsy

Administered By
Biomedical Engineering
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
July 01, 2005
End Date
August 31, 2007
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Awards:

Fellow. International Society for Optics and Photonics.

Type
National
Awarded By
International Society for Optics and Photonics
Date
January 01, 2013

Fellows. American Institute for Medical and Biological Engineering.

Type
National
Awarded By
American Institute for Medical and Biological Engineering
Date
January 01, 2012

Fellows. Optical Society of America.

Type
National
Awarded By
Optical Society of America
Date
January 01, 2010

Publications:

Oxygen and Perfusion Kinetics in Response to Fractionated Radiation Therapy in FaDu Head and Neck Cancer Xenografts Are Related to Treatment Outcome.

To test whether oxygenation kinetics correlate with the likelihood for local tumor control after fractionated radiation therapy.We used diffuse reflectance spectroscopy to noninvasively measure tumor vascular oxygenation and total hemoglobin concentration associated with radiation therapy of 5 daily fractions (7.5, 9, or 13.5 Gy/d) in FaDu xenografts. Spectroscopy measurements were obtained immediately before each daily radiation fraction and during the week after radiation therapy. Oxygen saturation and total hemoglobin concentration were computed using an inverse Monte Carlo model.First, oxygenation kinetics during and after radiation therapy, but before tumor volumes changed, were associated with local tumor control. Locally controlled tumors exhibited significantly faster increases in oxygenation after radiation therapy (days 12-15) compared with tumors that recurred locally. Second, within the group of tumors that recurred, faster increases in oxygenation during radiation therapy (day 3-5 interval) were correlated with earlier recurrence times. An area of 0.74 under the receiver operating characteristic curve was achieved when classifying the local control tumors from all irradiated tumors using the oxygen kinetics with a logistic regression model. Third, the rate of increase in oxygenation was radiation dose dependent. Radiation doses ≤9.5 Gy/d did not initiate an increase in oxygenation, whereas 13.5 Gy/d triggered significant increases in oxygenation during and after radiation therapy.Additional confirmation is required in other tumor models, but these results suggest that monitoring tumor oxygenation kinetics could aid in the prediction of local tumor control after radiation therapy.

Authors
Hu, F; Vishwanath, K; Salama, JK; Erkanli, A; Peterson, B; Oleson, JR; Lee, WT; Brizel, DM; Ramanujam, N; Dewhirst, MW
MLA Citation
Hu, F, Vishwanath, K, Salama, JK, Erkanli, A, Peterson, B, Oleson, JR, Lee, WT, Brizel, DM, Ramanujam, N, and Dewhirst, MW. "Oxygen and Perfusion Kinetics in Response to Fractionated Radiation Therapy in FaDu Head and Neck Cancer Xenografts Are Related to Treatment Outcome." International journal of radiation oncology, biology, physics 96.2 (October 2016): 462-469.
PMID
27598811
Source
epmc
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
96
Issue
2
Publish Date
2016
Start Page
462
End Page
469
DOI
10.1016/j.ijrobp.2016.06.007

Dark field optical imaging reveals vascular changes in an inducible hamster cheek pouch model during carcinogenesis.

In this study, we propose a low-cost cross-polarized dark field microscopy system for in vivo vascular imaging to detect head and neck cancer. A simple-to-use Gabor-filter-based image processing technique was developed to objectively and automatically quantify several important vascular features, including tortuosity, length, diameter and area fraction, from vascular images. Simulations were performed to evaluate the accuracies of vessel segmentation and feature extraction for our algorithm. Sensitivity and specificity for vessel segmentation of the Gabor masks both remained above 80% at all contrast levels when compared to gold-standard masks. Errors for vascular feature extraction were under 5%. Moreover, vascular contrast and vessel diameter were identified to be the two primary factors which affected the segmentation accuracies. After our algorithm was validated, we monitored the blood vessels in an inducible hamster cheek pouch carcinogen model over 17 weeks and quantified vascular features during carcinogenesis. A significant increase in vascular tortuosity and a significant decrease in vessel length were observed during carcinogenesis.

Authors
Hu, F; Morhard, R; Murphy, HA; Zhu, C; Ramanujam, N
MLA Citation
Hu, F, Morhard, R, Murphy, HA, Zhu, C, and Ramanujam, N. "Dark field optical imaging reveals vascular changes in an inducible hamster cheek pouch model during carcinogenesis." Biomedical optics express 7.9 (September 2016): 3247-3261.
PMID
27699096
Source
epmc
Published In
Biomedical Optics Express
Volume
7
Issue
9
Publish Date
2016
Start Page
3247
End Page
3261
DOI
10.1364/boe.7.003247

Correlation of breast tissue histology and optical signatures to improve margin assessment techniques.

Authors
Kennedy, S; Caldwell, M; Bydlon, T; Mulvey, C; Mueller, J; Wilke, L; Barry, W; Ramanujam, N; Geradts, J
MLA Citation
Kennedy, S, Caldwell, M, Bydlon, T, Mulvey, C, Mueller, J, Wilke, L, Barry, W, Ramanujam, N, and Geradts, J. "Correlation of breast tissue histology and optical signatures to improve margin assessment techniques." Journal of biomedical optics 21.6 (June 2016): 66014-.
PMID
27327487
Source
epmc
Published In
Journal of Biomedical Optics
Volume
21
Issue
6
Publish Date
2016
Start Page
66014
DOI
10.1117/1.jbo.21.6.066014

Label-free vascular imaging in a spontaneous hamster cheek pouch carcinogen model for pre-cancer detection (Conference Presentation)

Authors
Hu, F; Morhard, R; Liu, H; Murphy, H; Farsiu, S; Ramanujam, N
MLA Citation
Hu, F, Morhard, R, Liu, H, Murphy, H, Farsiu, S, and Ramanujam, N. "Label-free vascular imaging in a spontaneous hamster cheek pouch carcinogen model for pre-cancer detection (Conference Presentation)." 2016.
Source
wos-lite
Published In
Proceedings of SPIE - The International Society for Optical Engineering
Volume
9703
Publish Date
2016
DOI
10.1117/12.2213782

A quantitative microscopic approach to predict local recurrence based on in vivo intraoperative imaging of sarcoma tumor margins.

The goal of resection of soft tissue sarcomas located in the extremity is to preserve limb function while completely excising the tumor with a margin of normal tissue. With surgery alone, one-third of patients with soft tissue sarcoma of the extremity will have local recurrence due to microscopic residual disease in the tumor bed. Currently, a limited number of intraoperative pathology-based techniques are used to assess margin status; however, few have been widely adopted due to sampling error and time constraints. To aid in intraoperative diagnosis, we developed a quantitative optical microscopy toolbox, which includes acriflavine staining, fluorescence microscopy, and analytic techniques called sparse component analysis and circle transform to yield quantitative diagnosis of tumor margins. A series of variables were quantified from images of resected primary sarcomas and used to optimize a multivariate model. The sensitivity and specificity for differentiating positive from negative ex vivo resected tumor margins was 82 and 75%. The utility of this approach was tested by imaging the in vivo tumor cavities from 34 mice after resection of a sarcoma with local recurrence as a bench mark. When applied prospectively to images from the tumor cavity, the sensitivity and specificity for differentiating local recurrence was 78 and 82%. For comparison, if pathology was used to predict local recurrence in this data set, it would achieve a sensitivity of 29% and a specificity of 71%. These results indicate a robust approach for detecting microscopic residual disease, which is an effective predictor of local recurrence.

Authors
Mueller, JL; Fu, HL; Mito, JK; Whitley, MJ; Chitalia, R; Erkanli, A; Dodd, L; Cardona, DM; Geradts, J; Willett, RM; Kirsch, DG; Ramanujam, N
MLA Citation
Mueller, JL, Fu, HL, Mito, JK, Whitley, MJ, Chitalia, R, Erkanli, A, Dodd, L, Cardona, DM, Geradts, J, Willett, RM, Kirsch, DG, and Ramanujam, N. "A quantitative microscopic approach to predict local recurrence based on in vivo intraoperative imaging of sarcoma tumor margins." International journal of cancer 137.10 (November 2015): 2403-2412.
PMID
25994353
Source
epmc
Published In
International Journal of Cancer
Volume
137
Issue
10
Publish Date
2015
Start Page
2403
End Page
2412
DOI
10.1002/ijc.29611

Micro-anatomical quantitative optical imaging: toward automated assessment of breast tissues.

Pathologists currently diagnose breast lesions through histologic assessment, which requires fixation and tissue preparation. The diagnostic criteria used to classify breast lesions are qualitative and subjective, and inter-observer discordance has been shown to be a significant challenge in the diagnosis of selected breast lesions, particularly for borderline proliferative lesions. Thus, there is an opportunity to develop tools to rapidly visualize and quantitatively interpret breast tissue morphology for a variety of clinical applications.Toward this end, we acquired images of freshly excised breast tissue specimens from a total of 34 patients using confocal fluorescence microscopy and proflavine as a topical stain. We developed computerized algorithms to segment and quantify nuclear and ductal parameters that characterize breast architectural features. A total of 33 parameters were evaluated and used as input to develop a decision tree model to classify benign and malignant breast tissue. Benign features were classified in tissue specimens acquired from 30 patients and malignant features were classified in specimens from 22 patients.The decision tree model that achieved the highest accuracy for distinguishing between benign and malignant breast features used the following parameters: standard deviation of inter-nuclear distance and number of duct lumens. The model achieved 81 % sensitivity and 93 % specificity, corresponding to an area under the curve of 0.93 and an overall accuracy of 90 %. The model classified IDC and DCIS with 92 % and 96 % accuracy, respectively. The cross-validated model achieved 75 % sensitivity and 93 % specificity and an overall accuracy of 88 %.These results suggest that proflavine staining and confocal fluorescence microscopy combined with image analysis strategies to segment morphological features could potentially be used to quantitatively diagnose freshly obtained breast tissue at the point of care without the need for tissue preparation.

Authors
Dobbs, JL; Mueller, JL; Krishnamurthy, S; Shin, D; Kuerer, H; Yang, W; Ramanujam, N; Richards-Kortum, R
MLA Citation
Dobbs, JL, Mueller, JL, Krishnamurthy, S, Shin, D, Kuerer, H, Yang, W, Ramanujam, N, and Richards-Kortum, R. "Micro-anatomical quantitative optical imaging: toward automated assessment of breast tissues." Breast cancer research : BCR 17 (August 20, 2015): 105-.
PMID
26290094
Source
epmc
Published In
Breast Cancer Research
Volume
17
Publish Date
2015
Start Page
105
DOI
10.1186/s13058-015-0617-9

Light for Life: International Year of Light 2015.

Authors
Leitgeb, RA; Andersen, PE; Popp, J; Ramanujam, N; Svanberg, K
MLA Citation
Leitgeb, RA, Andersen, PE, Popp, J, Ramanujam, N, and Svanberg, K. "Light for Life: International Year of Light 2015." Journal of biomedical optics 20.6 (June 2015): 061101-.
PMID
26057030
Source
epmc
Published In
Journal of Biomedical Optics
Volume
20
Issue
6
Publish Date
2015
Start Page
061101
DOI
10.1117/1.jbo.20.6.061101

Non-invasive, simultaneous quantification of vascular oxygenation and glucose uptake in tissue.

We report the development of non-invasive, fiber-based diffuse optical spectroscopy for simultaneously quantifying vascular oxygenation (SO2) and glucose uptake in solid tumors in vivo. Glucose uptake was measured using a fluorescent glucose analog, 2-[N-(7-nitrobenz-2-oxa-1,3-diaxol-4-yl)amino]-2-deoxyglucose (2-NBDG). Quantification of label-free SO2 and 2-NBDG-fluorescence-based glucose uptake 60 minutes after administration of the tracer (2-NBDG60) was performed using computational models of light-tissue interaction. This study was carried out on normal tissue and 4T1 and 4T07 murine mammary tumor xenografts in vivo. Injection of 2-NBDG did not cause a significant change in optical measurements of SO2, demonstrating its suitability as a functional reporter of tumor glucose uptake. Correction of measured 2-NBDG-fluorescence for the effects of absorption and scattering significantly improved contrast between tumor and normal tissue. The 4T1 and 4T07 tumors showed significantly decreased SO2, and 4T1 tumors demonstrated increased 2-NBDG60 compared with normal tissue (60 minutes after the administration of 2-NBDG when perfusion-mediated effects have cleared). 2-NBDG-fluorescence was found to be highly sensitive to food deprivation-induced reduction in blood glucose levels, demonstrating that this endpoint is indeed sensitive to glycolytic demand. 2-NBDG60 was also found to be linearly related to dose, underscoring the importance of calibrating for dose when comparing across animals or experiments. 4T1 tumors demonstrated an inverse relationship between 2-NBDG60 and SO2 that was consistent with the Pasteur effect, particularly when exposed to hypoxic gas breathing. Our results illustrate the potential of optical spectroscopy to provide valuable information about the metabolic status of tumors, with important implications for cancer prognosis.

Authors
Rajaram, N; Reesor, AF; Mulvey, CS; Frees, AE; Ramanujam, N
MLA Citation
Rajaram, N, Reesor, AF, Mulvey, CS, Frees, AE, and Ramanujam, N. "Non-invasive, simultaneous quantification of vascular oxygenation and glucose uptake in tissue." PloS one 10.1 (January 30, 2015): e0117132-.
PMID
25635865
Source
epmc
Published In
PloS one
Volume
10
Issue
1
Publish Date
2015
Start Page
e0117132
DOI
10.1371/journal.pone.0117132

Chromophore based analyses of steady-state diffuse reflectance spectroscopy: Current status and perspectives for clinical adoption

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Diffuse reflectance spectroscopy is a rapidly growing technology in the biophotonics community where it has shown promise in its ability to classify different tissues. In the steady-state domain a wide spectrum of clinical applications is supported with this technology ranging from diagnostic to guided interventions. Diffuse reflectance spectra provide a wealth of information about tissue composition; however, extracting biologically relevant information from the spectra in terms of chromophores may be more useful to gain acceptance into the clinical community. The chromophores that absorb light in the visible and near infrared wavelengths can provide information about tissue composition. The key characteristics of these chromophores and their relevance in different organs and clinical applications is the focus of this review, along with translating their use to the clinic. Diffuse reflectance spectroscopy has shown promise in classifying different tissues for a variety of clinical applications. The spectra provide a wealth of information about tissue composition; however, extracting biologically relevant information, in terms of light absorbing chromophores, may be more useful to gain acceptance into the clinical community. This review focuses on these chromophores, their relevance in different organs and clinical applications, and translating their use to the clinic.

Authors
Bydlon, TM; Nachabé, R; Ramanujam, N; Sterenborg, HJCM; Hendriks, BHW
MLA Citation
Bydlon, TM, Nachabé, R, Ramanujam, N, Sterenborg, HJCM, and Hendriks, BHW. "Chromophore based analyses of steady-state diffuse reflectance spectroscopy: Current status and perspectives for clinical adoption." Journal of Biophotonics 8.1-2 (January 1, 2015): 9-24.
Source
scopus
Published In
Journal of biophotonics
Volume
8
Issue
1-2
Publish Date
2015
Start Page
9
End Page
24
DOI
10.1002/jbio.201300198

Chromophore based analyses of steady-state diffuse reflectance spectroscopy: current status and perspectives for clinical adoption.

Diffuse reflectance spectroscopy is a rapidly growing technology in the biophotonics community where it has shown promise in its ability to classify different tissues. In the steady-state domain a wide spectrum of clinical applications is supported with this technology ranging from diagnostic to guided interventions. Diffuse reflectance spectra provide a wealth of information about tissue composition; however, extracting biologically relevant information from the spectra in terms of chromophores may be more useful to gain acceptance into the clinical community. The chromophores that absorb light in the visible and near infrared wavelengths can provide information about tissue composition. The key characteristics of these chromophores and their relevance in different organs and clinical applications is the focus of this review, along with translating their use to the clinic.

Authors
Bydlon, TM; Nachabé, R; Ramanujam, N; Sterenborg, HJCM; Hendriks, BHW
MLA Citation
Bydlon, TM, Nachabé, R, Ramanujam, N, Sterenborg, HJCM, and Hendriks, BHW. "Chromophore based analyses of steady-state diffuse reflectance spectroscopy: current status and perspectives for clinical adoption." Journal of biophotonics 8.1-2 (January 2015): 9-24.
PMID
24760790
Source
epmc
Published In
Journal of biophotonics
Volume
8
Issue
1-2
Publish Date
2015
Start Page
9
End Page
24
DOI
10.1002/jbio.201300198

A Quantitative Diffuse Reflectance Imaging (QDRI) System for Comprehensive Surveillance of the Morphological Landscape in Breast Tumor Margins.

In an ongoing effort to address the clear clinical unmet needs surrounding breast conserving surgery (BCS), our group has developed a next-generation multiplexed optical-fiber-based tool to assess breast tumor margin status during initial surgeries. Specifically detailed in this work is the performance and clinical validation of a research-grade intra-operative tool for margin assessment based on diffuse optical spectroscopy. Previous work published by our group has illustrated the proof-of-concept generations of this device; here we incorporate a highly optimized quantitative diffuse reflectance imaging (QDRI) system utilizing a wide-field (imaging area = 17 cm(2)) 49-channel multiplexed fiber optic probe, a custom raster-scanning imaging platform, a custom dual-channel white LED source, and an astronomy grade imaging CCD and spectrograph. The system signal to noise ratio (SNR) was found to be greater than 40 dB for all channels. Optical property estimation error was found to be less than 10%, on average, over a wide range of absorption (μa = 0-8.9 cm(-1)) and scattering (μs' = 7.0-9.7 cm(-1)) coefficients. Very low inter-channel and CCD crosstalk was observed (2% max) when used on turbid media (including breast tissue). A raster-scanning mechanism was developed to achieve sub-pixel resolution and was found to be optimally performed at an upsample factor of 8, affording 0.75 mm spatially resolved diffuse reflectance images (λ = 450-600 nm) of an entire margin (area = 17 cm(2)) in 13.8 minutes (1.23 cm(2)/min). Moreover, controlled pressure application at the probe-tissue interface afforded by the imaging platform reduces repeated scan variability, providing <1% variation across repeated scans of clinical specimens. We demonstrate the clinical utility of this device through a pilot 20-patient study of high-resolution optical parameter maps of the ratio of the β-carotene concentration to the reduced scattering coefficient. An empirical cumulative distribution function (eCDF) analysis is used to reduce optical property maps to quantitative distributions representing the morphological landscape of breast tumor margins. The optimizations presented in this work provide an avenue to rapidly survey large tissue areas on intra-operative time scales with improved sensitivity to regions of focal disease that may otherwise be overlooked.

Authors
Nichols, BS; Schindler, CE; Brown, JQ; Wilke, LG; Mulvey, CS; Krieger, MS; Gallagher, J; Geradts, J; Greenup, RA; Von Windheim, JA; Ramanujam, N
MLA Citation
Nichols, BS, Schindler, CE, Brown, JQ, Wilke, LG, Mulvey, CS, Krieger, MS, Gallagher, J, Geradts, J, Greenup, RA, Von Windheim, JA, and Ramanujam, N. "A Quantitative Diffuse Reflectance Imaging (QDRI) System for Comprehensive Surveillance of the Morphological Landscape in Breast Tumor Margins." PloS one 10.6 (January 2015): e0127525-.
PMID
26076123
Source
epmc
Published In
PloS one
Volume
10
Issue
6
Publish Date
2015
Start Page
e0127525
DOI
10.1371/journal.pone.0127525

Design of a Novel Low Cost Point of Care Tampon (POCkeT) Colposcope for Use in Resource Limited Settings.

Current guidelines by WHO for cervical cancer screening in low- and middle-income countries involves visual inspection with acetic acid (VIA) of the cervix, followed by treatment during the same visit or a subsequent visit with cryotherapy if a suspicious lesion is found. Implementation of these guidelines is hampered by a lack of: trained health workers, reliable technology, and access to screening facilities. A low cost ultra-portable Point of Care Tampon based digital colposcope (POCkeT Colposcope) for use at the community level setting, which has the unique form factor of a tampon, can be inserted into the vagina to capture images of the cervix, which are on par with that of a state of the art colposcope, at a fraction of the cost. A repository of images to be compiled that can be used to empower front line workers to become more effective through virtual dynamic training. By task shifting to the community setting, this technology could potentially provide significantly greater cervical screening access to where the most vulnerable women live. The POCkeT Colposcope's concentric LED ring provides comparable white and green field illumination at a fraction of the electrical power required in commercial colposcopes. Evaluation with standard optical imaging targets to assess the POCkeT Colposcope against the state of the art digital colposcope and other VIAM technologies.Our POCkeT Colposcope has comparable resolving power, color reproduction accuracy, minimal lens distortion, and illumination when compared to commercially available colposcopes. In vitro and pilot in vivo imaging results are promising with our POCkeT Colposcope capturing comparable quality images to commercial systems.The POCkeT Colposcope is capable of capturing images suitable for cervical lesion analysis. Our portable low cost system could potentially increase access to cervical cancer screening in limited resource settings through task shifting to community health workers.

Authors
Lam, CT; Krieger, MS; Gallagher, JE; Asma, B; Muasher, LC; Schmitt, JW; Ramanujam, N
MLA Citation
Lam, CT, Krieger, MS, Gallagher, JE, Asma, B, Muasher, LC, Schmitt, JW, and Ramanujam, N. "Design of a Novel Low Cost Point of Care Tampon (POCkeT) Colposcope for Use in Resource Limited Settings." PloS one 10.9 (January 2015): e0135869-.
Website
http://hdl.handle.net/10161/10961
PMID
26332673
Source
epmc
Published In
PloS one
Volume
10
Issue
9
Publish Date
2015
Start Page
e0135869
DOI
10.1371/journal.pone.0135869

Assessment of the sensitivity and specificity of tissue-specific-based and anatomical-based optical biomarkers for rapid detection of human head and neck squamous cell carcinoma.

We propose the use of morphological optical biomarkers for rapid detection of human head and neck squamous cell carcinoma (HNSCC) by leveraging the underlying tissue characteristics in aerodigestive tracts.Diffuse reflectance spectra were obtained from malignant and contra-lateral normal tissues of 57 patients undergoing panendoscopy and biopsy. Oxygen saturation, total hemoglobin concentration, and the reduced scattering coefficient were extracted. Differences in malignant and normal tissues were examined based on two different groupings: anatomical site and morphological tissue type.Measurements were acquired from 252 sites, of which 51 were pathologically classified as SCC. Optical biomarkers exhibited statistical differences between malignant and normal samples. Contrast was enhanced when parsing tissues by morphological classification rather than anatomical subtype for unpaired comparisons. Corresponding linear discriminant models using multiple optical biomarkers showed improved predictive ability when accounting for morphological classification, particularly in node-positive lesions. The false-positive rate was retrospectively found to decrease by 34.2% in morphologically- vs. anatomically-derived predictive models. In glottic tissue, the surgeon exhibited a false-positive rate of 45.7% while the device showed a lower false-positive rate of 12.4%. Additionally, comparisons of optical parameters were made to further understand the physiology of tumor staging and potential causes of high surgeon false-positive rates. Optical spectroscopy is a user-friendly, non-invasive tool capable of providing quantitative information to discriminate malignant from normal head and neck tissues. Predictive models demonstrated promising results for real-time diagnostics. Furthermore, the strategy described appears to be well suited to reduce the clinical false-positive rate.

Authors
Hu, F; Vishwanath, K; Wolfgang Beumer, H; Puscas, L; Afshari, HR; Esclamado, RM; Scher, R; Fisher, S; Lo, J; Mulvey, C; Ramanujam, N; Lee, WT
MLA Citation
Hu, F, Vishwanath, K, Wolfgang Beumer, H, Puscas, L, Afshari, HR, Esclamado, RM, Scher, R, Fisher, S, Lo, J, Mulvey, C, Ramanujam, N, and Lee, WT. "Assessment of the sensitivity and specificity of tissue-specific-based and anatomical-based optical biomarkers for rapid detection of human head and neck squamous cell carcinoma." Oral oncology 50.9 (September 2014): 848-856.
PMID
25037162
Source
epmc
Published In
Oral Oncology
Volume
50
Issue
9
Publish Date
2014
Start Page
848
End Page
856
DOI
10.1016/j.oraloncology.2014.06.015

Measuring tumor cycling hypoxia and angiogenesis using a side-firing fiber optic probe.

Hypoxia and angiogenesis can significantly influence the efficacy of cancer therapy and the behavior of surviving tumor cells. There is a growing demand for technologies to measure tumor hypoxia and angiogenesis temporally in vivo to enable advances in drug development and optimization. This paper reports the use of frequency-domain photon migration with a side-firing probe to quantify tumor oxygenation and hemoglobin concentrations in nude rats bearing human head/neck tumors administered with carbogen gas, cycling hypoxic gas or just room air. Significant increase (with carbogen gas breathing) or decrease (with hypoxic gas breathing) in tumor oxygenation was observed. The trend in tumor oxygenation during forced cycling hypoxia (CH) followed that of the blood oxygenation measured with a pulse oximeter. Natural CH was also observed in rats under room air. The studies demonstrated the potential of the technology for longitudinal monitoring of tumor CH during tumor growth or in response to therapy.

Authors
Yu, B; Shah, A; Wang, B; Rajaram, N; Wang, Q; Ramanujam, N; Palmer, GM; Dewhirst, MW
MLA Citation
Yu, B, Shah, A, Wang, B, Rajaram, N, Wang, Q, Ramanujam, N, Palmer, GM, and Dewhirst, MW. "Measuring tumor cycling hypoxia and angiogenesis using a side-firing fiber optic probe." J Biophotonics 7.7 (July 2014): 552-564.
PMID
23242854
Source
pubmed
Published In
Journal of biophotonics
Volume
7
Issue
7
Publish Date
2014
Start Page
552
End Page
564
DOI
10.1002/jbio.201200187

Optical monitoring of glucose demand and vascular delivery in a preclinical murine model

Targeted therapies such as PI3K inhibition can affect tumor vasculature, and hence delivery of imaging agents like FDG, while independently modifying intrinsic glucose demand. Therefore, it is important to identify whether perceived changes in glucose uptake are caused by vascular or true metabolic changes. This study sought to develop an optical strategy for quantifying tissue glucose uptake free of cross-talk from tracer delivery effects. Glucose uptake kinetics were measured using a fluorescent D-glucose derivative 2-(N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)Amino)-2-deoxy-Dglucose (2-NBDG), and 2-(N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)Amino)-2-deoxy-L-glucose (2-NBDLG) was used as a control to report on non-specific uptake. Vascular oxygenation (SO2) was calculated from wavelength-dependent hemoglobin absorption. We have previously shown that the rate of 2-NBDG delivery in vivo profoundly affects perceived demand. In this study, we investigated the potential of the ratio of 2-NBDG uptake to the rate of delivery (2-NBDG60/R D) to report on 2-NBDG demand in vivo free from confounding delivery effects. In normal murine tissue, we show that 2-NBDG60/RD can distinguish specific uptake from non-specific cell membrane binding, whereas fluorescence intensity alone cannot. The ratio 2-NBDG 60/RD also correlates with blood glucose more strongly than 2-NBDG60 does in normal murine tissue. Additionally, 2-NBDG 60/RD can distinguish normal murine tissue from a murine metastatic tumor across a range of SO2 values. The results presented here indicate that the ratio of 2-NBDG uptake to the rate of 2-NBDG delivery (2- NBDG60/RD) is superior to 2-NBDG intensity alone for quantifying changes in glucose demand. © 2014 SPIE.

Authors
Frees, A; Rajaram, N; McCachren, S; Vaz, A; Dewhirst, M; Ramanujam, N
MLA Citation
Frees, A, Rajaram, N, McCachren, S, Vaz, A, Dewhirst, M, and Ramanujam, N. "Optical monitoring of glucose demand and vascular delivery in a preclinical murine model." January 1, 2014.
Source
scopus
Published In
Proceedings of SPIE
Volume
8947
Publish Date
2014
DOI
10.1117/12.2040950

Assessment of the sensitivity and specificity of tissue-specific-based and anatomical-based optical biomarkers for rapid detection of human head and neck squamous cell carcinoma

Objectives We propose the use of morphological optical biomarkers for rapid detection of human head and neck squamous cell carcinoma (HNSCC) by leveraging the underlying tissue characteristics in aerodigestive tracts. Materials and Methods Diffuse reflectance spectra were obtained from malignant and contra-lateral normal tissues of 57 patients undergoing panendoscopy and biopsy. Oxygen saturation, total hemoglobin concentration, and the reduced scattering coefficient were extracted. Differences in malignant and normal tissues were examined based on two different groupings: anatomical site and morphological tissue type. Results and Conclusions Measurements were acquired from 252 sites, of which 51 were pathologically classified as SCC. Optical biomarkers exhibited statistical differences between malignant and normal samples. Contrast was enhanced when parsing tissues by morphological classification rather than anatomical subtype for unpaired comparisons. Corresponding linear discriminant models using multiple optical biomarkers showed improved predictive ability when accounting for morphological classification, particularly in node-positive lesions. The false-positive rate was retrospectively found to decrease by 34.2% in morphologically- vs. anatomically-derived predictive models. In glottic tissue, the surgeon exhibited a false-positive rate of 45.7% while the device showed a lower false-positive rate of 12.4%. Additionally, comparisons of optical parameters were made to further understand the physiology of tumor staging and potential causes of high surgeon false-positive rates. Optical spectroscopy is a user-friendly, non-invasive tool capable of providing quantitative information to discriminate malignant from normal head and neck tissues. Predictive models demonstrated promising results for real-time diagnostics. Furthermore, the strategy described appears to be well suited to reduce the clinical false-positive rate. © 2014 Elsevier Ltd. All rights reserved.

Authors
Hu, F; Vishwanath, K; Wolfgang Beumer, H; Puscas, L; Afshari, HR; Esclamado, RM; Scher, R; Fisher, S; Lo, J; Mulvey, C; Ramanujam, N; Lee, WT
MLA Citation
Hu, F, Vishwanath, K, Wolfgang Beumer, H, Puscas, L, Afshari, HR, Esclamado, RM, Scher, R, Fisher, S, Lo, J, Mulvey, C, Ramanujam, N, and Lee, WT. "Assessment of the sensitivity and specificity of tissue-specific-based and anatomical-based optical biomarkers for rapid detection of human head and neck squamous cell carcinoma." Oral Oncology 50.9 (January 1, 2014): 848-856.
Source
scopus
Published In
Oral Oncology
Volume
50
Issue
9
Publish Date
2014
Start Page
848
End Page
856
DOI
10.1016/j.oraloncology.2014.06.015

Delivery-corrected imaging of fluorescently-labeled glucose reveals distinct metabolic phenotypes in murine breast cancer.

When monitoring response to cancer therapy, it is important to differentiate changes in glucose tracer uptake caused by altered delivery versus a true metabolic shift. Here, we propose an optical imaging method to quantify glucose uptake and correct for in vivo delivery effects. Glucose uptake was measured using a fluorescent D-glucose derivative 2-(N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)Amino)-2-deoxy-D-glucose (2-NBDG) in mice implanted with dorsal skin flap window chambers. Additionally, vascular oxygenation (SO2) was calculated using only endogenous hemoglobin contrast. Results showed that the delivery factor proposed for correction, "RD", reported on red blood cell velocity and injected 2-NBDG dose. Delivery-corrected 2-NBDG uptake (2-NBDG60/RD) inversely correlated with blood glucose in normal tissue, indicating sensitivity to glucose demand. We further applied our method in metastatic 4T1 and nonmetastatic 4T07 murine mammary adenocarcinomas. The ratio 2-NBDG60/RD was increased in 4T1 tumors relative to 4T07 tumors yet average SO2 was comparable, suggesting a shift toward a "Warburgian" (aerobic glycolysis) metabolism in the metastatic 4T1 line. In heterogeneous regions of both 4T1 and 4T07, 2-NBDG60/RD increased slightly but significantly as vascular oxygenation decreased, indicative of the Pasteur effect in both tumors. These data demonstrate the utility of delivery-corrected 2-NBDG and vascular oxygenation imaging for differentiating metabolic phenotypes in vivo.

Authors
Frees, AE; Rajaram, N; McCachren, SS; Fontanella, AN; Dewhirst, MW; Ramanujam, N
MLA Citation
Frees, AE, Rajaram, N, McCachren, SS, Fontanella, AN, Dewhirst, MW, and Ramanujam, N. "Delivery-corrected imaging of fluorescently-labeled glucose reveals distinct metabolic phenotypes in murine breast cancer." PloS one 9.12 (January 2014): e115529-.
PMID
25526261
Source
epmc
Published In
PloS one
Volume
9
Issue
12
Publish Date
2014
Start Page
e115529
DOI
10.1371/journal.pone.0115529

Optimization of illumination frequency and preclinical validation of a wide-field structured illumination microscope designed for imaging in situ tumor margins

We present a widefield structured illumination microscope for imaging surgical tumor margins in situ. The impact of frequency and turbidity on optical section thickness and SNR was characterized to determine the optimal imaging frequency. © OSA 2013.

Authors
Fu, HL; Mueller, JL; Javid, M; Kirsch, DG; Ramanujam, N; Brown, JQ
MLA Citation
Fu, HL, Mueller, JL, Javid, M, Kirsch, DG, Ramanujam, N, and Brown, JQ. "Optimization of illumination frequency and preclinical validation of a wide-field structured illumination microscope designed for imaging in situ tumor margins." CLEO: Applications and Technology, CLEO_AT 2013 (November 19, 2013).
Source
scopus
Published In
CLEO: Applications and Technology, CLEO_AT 2013
Publish Date
2013

Delivery Rate Affects Uptake of a Fluorescent Glucose Analog in Murine Metastatic Breast Cancer

We demonstrate an optical strategy using intravital microscopy of dorsal skin flap window chamber models to image glucose uptake and vascular oxygenation in vivo. Glucose uptake was imaged using a fluorescent glucose analog, 2-[N-(7-nitrobenz-2-oxa-1,3-diaxol-4-yl)amino]-2-deoxyglucose (2-NBDG). SO2 was imaged using the differential absorption properties of oxygenated [HbO2] and deoxygenated hemoglobin [dHb]. This study was carried out on two sibling murine mammary adenocarcinoma lines, 4T1 and 4T07. 2-NBDG uptake in the 4T1 tumors was lowest when rates of delivery and clearance were lowest, indicating perfusion-limited uptake in poorly oxygenated tumor regions. For increasing rates of delivery that were still lower than the glucose consumption rate (as measured in vitro), both 2-NBDG uptake and the clearance rate from the tumor increased. When the rate of delivery of 2-NBDG exceeded the glucose consumption rate, 2-NBDG uptake decreased with any further increase in rate of delivery, but the clearance rate continued to increase. This inflection point was not observed in the 4T07 tumors due to an absence of low delivery rates close to the glucose consumption rate. In the 4T07 tumors, 2-NBDG uptake increased with increasing rates of delivery at low rates of clearance. Our results demonstrate that 2-NBDG uptake in tumors is influenced by the rates of delivery and clearance of the tracer. The rates of delivery and clearance are, in turn, dependent on vascular oxygenation of the tumors. Knowledge of the kinetics of tracer uptake as well as vascular oxygenation is essential to make an informed assessment of glucose demand of a tumor. © 2013 Rajaram et al.

Authors
Rajaram, N; Frees, AE; Fontanella, AN; Zhong, J; Hansen, K; Dewhirst, MW; Ramanujam, N
MLA Citation
Rajaram, N, Frees, AE, Fontanella, AN, Zhong, J, Hansen, K, Dewhirst, MW, and Ramanujam, N. "Delivery Rate Affects Uptake of a Fluorescent Glucose Analog in Murine Metastatic Breast Cancer." PLoS ONE 8.10 (October 18, 2013).
PMID
24204635
Source
scopus
Published In
PloS one
Volume
8
Issue
10
Publish Date
2013
DOI
10.1371/journal.pone.0076524

Optical and radioiodinated tethered Hsp90 inhibitors reveal selective internalization of ectopic Hsp90 in malignant breast tumor cells.

Inhibitors of heat-shock protein 90 (Hsp90) have demonstrated an unusual selectivity for tumor cells despite its ubiquitous expression. This phenomenon has remained unexplained, but could be influenced by ectopically expressed Hsp90 in tumors. In this work, we synthesized Hsp90 inhibitors that can carry optical or radioiodinated probes via a polyethyleneglycol tether. We show that these tethered inhibitors selectively recognize cells expressing ectopic Hsp90 and become internalized. The internalization process is blocked by Hsp90 antibodies, suggesting that active cycling of the protein occurs at the plasma membrane. In mice, we observed exquisite accumulation of the fluor-tethered versions within breast tumors at very sensitive levels. Cell-based assays with the radiolabeled version showed picomolar detection in cells that express ectopic Hsp90. Our findings show that fluor-tethered or radiolabeled inhibitors that target ectopic Hsp90 can be used to detect breast cancer malignancies through noninvasive imaging.

Authors
Barrott, JJ; Hughes, PF; Osada, T; Yang, X-Y; Hartman, ZC; Loiselle, DR; Spector, NL; Neckers, L; Rajaram, N; Hu, F; Ramanujam, N; Vaidyanathan, G; Zalutsky, MR; Lyerly, HK; Haystead, TA
MLA Citation
Barrott, JJ, Hughes, PF, Osada, T, Yang, X-Y, Hartman, ZC, Loiselle, DR, Spector, NL, Neckers, L, Rajaram, N, Hu, F, Ramanujam, N, Vaidyanathan, G, Zalutsky, MR, Lyerly, HK, and Haystead, TA. "Optical and radioiodinated tethered Hsp90 inhibitors reveal selective internalization of ectopic Hsp90 in malignant breast tumor cells." Chem Biol 20.9 (September 19, 2013): 1187-1197.
PMID
24035283
Source
pubmed
Published In
Chemistry and Biology
Volume
20
Issue
9
Publish Date
2013
Start Page
1187
End Page
1197
DOI
10.1016/j.chembiol.2013.08.004

Radiation induces aerobic glycolysis through reactive oxygen species.

BACKGROUND AND PURPOSE: Although radiation induced reoxygenation has been thought to increase radiosensitivity, we have shown that its associated oxidative stress can have radioprotective effects, including stabilization of the transcription factor hypoxia inducible factor 1 (HIF-1). HIF-1 is known to regulate many of the glycolytic enzymes, thereby promoting aerobic glycolysis, which is known to promote treatment resistance. Thus, we hypothesized that reoxygenation after radiation would increase glycolysis. We previously showed that blockade of oxidative stress using a superoxide dismutase (SOD) mimic during reoxygenation can downregulate HIF-1 activity. Here we tested whether concurrent use of this drug with radiotherapy would reduce the switch to a glycolytic phenotype. MATERIALS AND METHODS: 40 mice with skin fold window chambers implanted with 4T1 mammary carcinomas were randomized into (1) no treatment, (2) radiation alone, (3) SOD mimic alone, and (4) SOD mimic with concurrent radiation. All mice were imaged on the ninth day following tumor implantation (30 h following radiation treatment) following injection of a fluorescent glucose analog, 2-[N-(7-nitrobenz-2-oxa-1,3-diaxol-4-yl)amino]-2-deoxyglucose (2-NBDG). Hemoglobin saturation was measured by using hyperspectral imaging to quantify oxygenation state. RESULTS: Mice treated with radiation showed significantly higher 2-NBDG fluorescence compared to controls (p=0.007). Hemoglobin saturation analysis demonstrated reoxygenation following radiation, coinciding with the observed increase in glycolysis. The concurrent use of the SOD mimic with radiation demonstrated a significant reduction in 2-NBDG fluorescence compared to effects seen after radiation alone, while having no effect on reoxygenation. CONCLUSIONS: Radiation induces an increase in tumor glucose demand approximately 30 h following therapy during reoxygenation. The use of an SOD mimic can prevent the increase in aerobic glycolysis when used concurrently with radiation, without preventing reoxygenation.

Authors
Zhong, J; Rajaram, N; Brizel, DM; Frees, AE; Ramanujam, N; Batinic-Haberle, I; Dewhirst, MW
MLA Citation
Zhong, J, Rajaram, N, Brizel, DM, Frees, AE, Ramanujam, N, Batinic-Haberle, I, and Dewhirst, MW. "Radiation induces aerobic glycolysis through reactive oxygen species." Radiother Oncol 106.3 (March 2013): 390-396.
PMID
23541363
Source
pubmed
Published In
Radiotherapy and Oncology
Volume
106
Issue
3
Publish Date
2013
Start Page
390
End Page
396
DOI
10.1016/j.radonc.2013.02.013

Optimization of illumination frequency and preclinical validation of a wide-field structured illumination microscope designed for imaging in situ tumor margins

We present a widefield structured illumination microscope for imaging surgical tumor margins in situ. The impact of frequency and turbidity on optical section thickness and SNR was characterized to determine the optimal imaging frequency. © 2013 The Optical Society.

Authors
Fu, HL; Mueller, JL; Javid, M; Kirsch, DG; Ramanujam, N; Brown, JQ
MLA Citation
Fu, HL, Mueller, JL, Javid, M, Kirsch, DG, Ramanujam, N, and Brown, JQ. "Optimization of illumination frequency and preclinical validation of a wide-field structured illumination microscope designed for imaging in situ tumor margins." 2013 Conference on Lasers and Electro-Optics, CLEO 2013 (January 1, 2013).
Source
scopus
Published In
2013 Conference on Lasers and Electro-Optics, CLEO 2013
Publish Date
2013

Rapid determination of oxygen saturation and vascularity for cancer detection.

A rapid heuristic ratiometric analysis for estimating tissue hemoglobin concentration and oxygen saturation from measured tissue diffuse reflectance spectra is presented. The analysis was validated in tissue-mimicking phantoms and applied to clinical measurements in head and neck, cervical and breast tissues. The analysis works in two steps. First, a linear equation that translates the ratio of the diffuse reflectance at 584 nm and 545 nm to estimate the tissue hemoglobin concentration using a Monte Carlo-based lookup table was developed. This equation is independent of tissue scattering and oxygen saturation. Second, the oxygen saturation was estimated using non-linear logistic equations that translate the ratio of the diffuse reflectance spectra at 539 nm to 545 nm into the tissue oxygen saturation. Correlations coefficients of 0.89 (0.86), 0.77 (0.71) and 0.69 (0.43) were obtained for the tissue hemoglobin concentration (oxygen saturation) values extracted using the full spectral Monte Carlo and the ratiometric analysis, for clinical measurements in head and neck, breast and cervical tissues, respectively. The ratiometric analysis was more than 4000 times faster than the inverse Monte Carlo analysis for estimating tissue hemoglobin concentration and oxygen saturation in simulated phantom experiments. In addition, the discriminatory power of the two analyses was similar. These results show the potential of such empirical tools to rapidly estimate tissue hemoglobin in real-time spectral imaging applications.

Authors
Hu, F; Vishwanath, K; Lo, J; Erkanli, A; Mulvey, C; Lee, WT; Ramanujam, N
MLA Citation
Hu, F, Vishwanath, K, Lo, J, Erkanli, A, Mulvey, C, Lee, WT, and Ramanujam, N. "Rapid determination of oxygen saturation and vascularity for cancer detection. (Published online)" PLoS One 8.12 (2013): e82977-.
PMID
24358243
Source
pubmed
Published In
PloS one
Volume
8
Issue
12
Publish Date
2013
Start Page
e82977
DOI
10.1371/journal.pone.0082977

Wavelength optimization for quantitative spectral imaging of breast tumor margins.

A wavelength selection method that combines an inverse Monte Carlo model of reflectance and a genetic algorithm for global optimization was developed for the application of spectral imaging of breast tumor margins. The selection of wavelengths impacts system design in cost, size, and accuracy of tissue quantitation. The minimum number of wavelengths required for the accurate quantitation of tissue optical properties is 8, with diminishing gains for additional wavelengths. The resulting wavelength choices for the specific probe geometry used for the breast tumor margin spectral imaging application were tested in an independent pathology-confirmed ex vivo breast tissue data set and in tissue-mimicking phantoms. In breast tissue, the optical endpoints (hemoglobin, β-carotene, and scattering) that provide the contrast between normal and malignant tissue specimens are extracted with the optimized 8-wavelength set with <9% error compared to the full spectrum (450-600 nm). A multi-absorber liquid phantom study was also performed to show the improved extraction accuracy with optimization and without optimization. This technique for selecting wavelengths can be used for designing spectral imaging systems for other clinical applications.

Authors
Lo, JY; Brown, JQ; Dhar, S; Yu, B; Palmer, GM; Jokerst, NM; Ramanujam, N
MLA Citation
Lo, JY, Brown, JQ, Dhar, S, Yu, B, Palmer, GM, Jokerst, NM, and Ramanujam, N. "Wavelength optimization for quantitative spectral imaging of breast tumor margins. (Published online)" PLoS One 8.4 (2013): e61767-.
PMID
23613927
Source
pubmed
Published In
PloS one
Volume
8
Issue
4
Publish Date
2013
Start Page
e61767
DOI
10.1371/journal.pone.0061767

Experimental radiotherapy Radiation induces aerobic glycolysis through reactive oxygen species

Background and purpose Although radiation induced reoxygenation has been thought to increase radiosensitivity, we have shown that its associated oxidative stress can have radioprotective effects, including stabilization of the transcription factor hypoxia inducible factor 1 (HIF-1). HIF-1 is known to regulate many of the glycolytic enzymes, thereby promoting aerobic glycolysis, which is known to promote treatment resistance. Thus, we hypothesized that reoxygenation after radiation would increase glycolysis. We previously showed that blockade of oxidative stress using a superoxide dismutase (SOD) mimic during reoxygenation can downregulate HIF-1 activity. Here we tested whether concurrent use of this drug with radiotherapy would reduce the switch to a glycolytic phenotype. Materials and methods 40 mice with skin fold window chambers implanted with 4T1 mammary carcinomas were randomized into (1) no treatment, (2) radiation alone, (3) SOD mimic alone, and (4) SOD mimic with concurrent radiation. All mice were imaged on the ninth day following tumor implantation (30 h following radiation treatment) following injection of a fluorescent glucose analog, 2-[N-(7-nitrobenz-2-oxa-1,3-diaxol-4-yl)amino]-2- deoxyglucose (2-NBDG). Hemoglobin saturation was measured by using hyperspectral imaging to quantify oxygenation state. Results Mice treated with radiation showed significantly higher 2-NBDG fluorescence compared to controls (p = 0.007). Hemoglobin saturation analysis demonstrated reoxygenation following radiation, coinciding with the observed increase in glycolysis. The concurrent use of the SOD mimic with radiation demonstrated a significant reduction in 2-NBDG fluorescence compared to effects seen after radiation alone, while having no effect on reoxygenation. Conclusions Radiation induces an increase in tumor glucose demand approximately 30 h following therapy during reoxygenation. The use of an SOD mimic can prevent the increase in aerobic glycolysis when used concurrently with radiation, without preventing reoxygenation. © 2013 Elsevier Ireland Ltd. All rights reserved.

Authors
Zhong, J; Rajaram, N; Brizel, DM; Frees, AE; Ramanujam, N; Batinic-Haberle, I; Dewhirst, MW
MLA Citation
Zhong, J, Rajaram, N, Brizel, DM, Frees, AE, Ramanujam, N, Batinic-Haberle, I, and Dewhirst, MW. "Experimental radiotherapy Radiation induces aerobic glycolysis through reactive oxygen species." Radiotherapy and Oncology 106.3 (2013): 390-396.
Source
scival
Published In
Radiotherapy & Oncology
Volume
106
Issue
3
Publish Date
2013
Start Page
390
End Page
396
DOI
10.1016/j.radonc.2013.02.013

Monitoring of cycling hypoxia and angiogenesis in FaDu head and neck tumors using a side-firing sensor

Many studies have found that hypoxia, particularly cycling hypoxia (CH), can lead to enhanced tumor metastasis and resistance to radiation and chemotherapy. It was also reported that tumor total hemoglobin content (THb), which is directly related to tumor angiogenesis, can have significant impact on tumor's response to radiation and neoadjuvant chemotherapy. There is a growing demand for technologies to measure tumor hypoxia and angiogenesis temporally in vivo. In this paper, a side-firing fiber optic sensor based on a multi-wavelength frequency-domain near infrared spectroscopy (FD-NIRS) instrument was used to quantify tumor oxygenation and hemoglobin concentrations in nude rats bearing human FaDu head and neck (H & N) tumors during normoxia and forced hyperoxia and cyclic hypoxia. Significant increase (with carbogen gas inhalation) or decrease (with reduced O2 supply) in tumor oxygenation was observed. The studies demonstrated the feasibility of the technology for longitudinal monitoring of H and N tumor's response to therapy. © 2013 Copyright SPIE.

Authors
Yu, B; Shah, A; Wang, B; Rajaram, N; Wang, Q; Ramanujam, N; Palmer, GM; Dewhirst, MW
MLA Citation
Yu, B, Shah, A, Wang, B, Rajaram, N, Wang, Q, Ramanujam, N, Palmer, GM, and Dewhirst, MW. "Monitoring of cycling hypoxia and angiogenesis in FaDu head and neck tumors using a side-firing sensor." Progress in Biomedical Optics and Imaging - Proceedings of SPIE 8578 (2013).
Source
scival
Published In
Proceedings of SPIE
Volume
8578
Publish Date
2013
DOI
10.1117/12.2002837

Quantitative segmentation of fluorescence microscopy images of heterogeneous tissue: Approach for tuning algorithm parameters

The combination of fluorescent contrast agents with microscopy is a powerful technique to obtain real time images of tissue histology without the need for fixing, sectioning, and staining. The potential of this technology lies in the identification of robust methods for image segmentation and quantitation, particularly in heterogeneous tissues. Our solution is to apply sparse decomposition (SD) to monochrome images of fluorescently-stained microanatomy to segment and quantify distinct tissue types. The clinical utility of our approach is demonstrated by imaging excised margins in a cohort of mice after surgical resection of a sarcoma. Representative images of excised margins were used to optimize the formulation of SD and tune parameters associated with the algorithm. Our results demonstrate that SD is a robust solution that can advance vital fluorescence microscopy as a clinically significant technology. © 2013 Copyright SPIE.

Authors
Mueller, JL; Harmany, ZT; Mito, JK; Kennedy, SA; Kim, Y; Dodd, L; Geradts, J; Kirsch, DG; Willett, RM; Brown, JQ; Ramanujam, N
MLA Citation
Mueller, JL, Harmany, ZT, Mito, JK, Kennedy, SA, Kim, Y, Dodd, L, Geradts, J, Kirsch, DG, Willett, RM, Brown, JQ, and Ramanujam, N. "Quantitative segmentation of fluorescence microscopy images of heterogeneous tissue: Approach for tuning algorithm parameters." Progress in Biomedical Optics and Imaging - Proceedings of SPIE 8587 (2013).
Source
scival
Published In
Proceedings of SPIE
Volume
8587
Publish Date
2013
DOI
10.1117/12.2006429

Quantitative Segmentation of Fluorescence Microscopy Images of Heterogeneous Tissue: Application to the Detection of Residual Disease in Tumor Margins.

PURPOSE: To develop a robust tool for quantitative in situ pathology that allows visualization of heterogeneous tissue morphology and segmentation and quantification of image features. MATERIALS AND METHODS: TISSUE EXCISED FROM A GENETICALLY ENGINEERED MOUSE MODEL OF SARCOMA WAS IMAGED USING A SUBCELLULAR RESOLUTION MICROENDOSCOPE AFTER TOPICAL APPLICATION OF A FLUORESCENT ANATOMICAL CONTRAST AGENT: acriflavine. An algorithm based on sparse component analysis (SCA) and the circle transform (CT) was developed for image segmentation and quantification of distinct tissue types. The accuracy of our approach was quantified through simulations of tumor and muscle images. Specifically, tumor, muscle, and tumor+muscle tissue images were simulated because these tissue types were most commonly observed in sarcoma margins. Simulations were based on tissue characteristics observed in pathology slides. The potential clinical utility of our approach was evaluated by imaging excised margins and the tumor bed in a cohort of mice after surgical resection of sarcoma. RESULTS: Simulation experiments revealed that SCA+CT achieved the lowest errors for larger nuclear sizes and for higher contrast ratios (nuclei intensity/background intensity). For imaging of tumor margins, SCA+CT effectively isolated nuclei from tumor, muscle, adipose, and tumor+muscle tissue types. Differences in density were correctly identified with SCA+CT in a cohort of ex vivo and in vivo images, thus illustrating the diagnostic potential of our approach. CONCLUSION: The combination of a subcellular-resolution microendoscope, acriflavine staining, and SCA+CT can be used to accurately isolate nuclei and quantify their density in anatomical images of heterogeneous tissue.

Authors
Mueller, JL; Harmany, ZT; Mito, JK; Kennedy, SA; Kim, Y; Dodd, L; Geradts, J; Kirsch, DG; Willett, RM; Brown, JQ; Ramanujam, N
MLA Citation
Mueller, JL, Harmany, ZT, Mito, JK, Kennedy, SA, Kim, Y, Dodd, L, Geradts, J, Kirsch, DG, Willett, RM, Brown, JQ, and Ramanujam, N. "Quantitative Segmentation of Fluorescence Microscopy Images of Heterogeneous Tissue: Application to the Detection of Residual Disease in Tumor Margins. (Published online)" PLoS One 8.6 (2013): e66198-.
PMID
23824589
Source
pubmed
Published In
PloS one
Volume
8
Issue
6
Publish Date
2013
Start Page
e66198
DOI
10.1371/journal.pone.0066198

Optical spectral surveillance of breast tissue landscapes for detection of residual disease in breast tumor margins.

We demonstrate a strategy to "sense" the micro-morphology of a breast tumor margin over a wide field of view by creating quantitative hyperspectral maps of the tissue optical properties (absorption and scattering), where each voxel can be deconstructed to provide information on the underlying histology. Information about the underlying tissue histology is encoded in the quantitative spectral information (in the visible wavelength range), and residual carcinoma is detected as a shift in the histological landscape to one with less fat and higher glandular content. To demonstrate this strategy, fully intact, fresh lumpectomy specimens (n = 88) from 70 patients were imaged intra-operatively. The ability of spectral imaging to sense changes in histology over large imaging areas was determined using inter-patient mammographic breast density (MBD) variation in cancer-free tissues as a model system. We discovered that increased MBD was associated with higher baseline β-carotene concentrations (p = 0.066) and higher scattering coefficients (p = 0.007) as measured by spectral imaging, and a trend toward decreased adipocyte size and increased adipocyte density as measured by histological examination in BMI-matched patients. The ability of spectral imaging to detect cancer intra-operatively was demonstrated when MBD-specific breast characteristics were considered. Specifically, the ratio of β-carotene concentration to the light scattering coefficient can report on the relative amount of fat to glandular density at the tissue surface to determine positive margin status, when baseline differences in these parameters between patients with low and high MBD are taken into account by the appropriate selection of threshold values. When MBD was included as a variable a priori, the device was estimated to have a sensitivity of 74% and a specificity of 86% in detecting close or positive margins, regardless of tumor type. Superior performance was demonstrated in high MBD tissue, a population that typically has a higher percentage of involved margins.

Authors
Brown, JQ; Bydlon, TM; Kennedy, SA; Caldwell, ML; Gallagher, JE; Junker, M; Wilke, LG; Barry, WT; Geradts, J; Ramanujam, N
MLA Citation
Brown, JQ, Bydlon, TM, Kennedy, SA, Caldwell, ML, Gallagher, JE, Junker, M, Wilke, LG, Barry, WT, Geradts, J, and Ramanujam, N. "Optical spectral surveillance of breast tissue landscapes for detection of residual disease in breast tumor margins. (Published online)" PLoS One 8.7 (2013): e69906-.
PMID
23922850
Source
pubmed
Published In
PloS one
Volume
8
Issue
7
Publish Date
2013
Start Page
e69906
DOI
10.1371/journal.pone.0069906

Optimization of a widefield structured illumination microscope for non-destructive assessment and quantification of nuclear features in tumor margins of a primary mouse model of sarcoma.

Cancer is associated with specific cellular morphological changes, such as increased nuclear size and crowding from rapidly proliferating cells. In situ tissue imaging using fluorescent stains may be useful for intraoperative detection of residual cancer in surgical tumor margins. We developed a widefield fluorescence structured illumination microscope (SIM) system with a single-shot FOV of 2.1 × 1.6 mm (3.4 mm(2)) and sub-cellular resolution (4.4 µm). The objectives of this work were to measure the relationship between illumination pattern frequency and optical sectioning strength and signal-to-noise ratio in turbid (i.e. thick) samples for selection of the optimum frequency, and to determine feasibility for detecting residual cancer on tumor resection margins, using a genetically engineered primary mouse model of sarcoma. The SIM system was tested in tissue mimicking solid phantoms with various scattering levels to determine impact of both turbidity and illumination frequency on two SIM metrics, optical section thickness and modulation depth. To demonstrate preclinical feasibility, ex vivo 50 µm frozen sections and fresh intact thick tissue samples excised from a primary mouse model of sarcoma were stained with acridine orange, which stains cell nuclei, skeletal muscle, and collagenous stroma. The cell nuclei were segmented using a high-pass filter algorithm, which allowed quantification of nuclear density. The results showed that the optimal illumination frequency was 31.7 µm(-1) used in conjunction with a 4 × 0.1 NA objective (v=0.165). This yielded an optical section thickness of 128 µm and an 8.9 × contrast enhancement over uniform illumination. We successfully demonstrated the ability to resolve cell nuclei in situ achieved via SIM, which allowed segmentation of nuclei from heterogeneous tissues in the presence of considerable background fluorescence. Specifically, we demonstrate that optical sectioning of fresh intact thick tissues performed equivalently in regards to nuclear density quantification, to physical frozen sectioning and standard microscopy.

Authors
Fu, HL; Mueller, JL; Javid, MP; Mito, JK; Kirsch, DG; Ramanujam, N; Brown, JQ
MLA Citation
Fu, HL, Mueller, JL, Javid, MP, Mito, JK, Kirsch, DG, Ramanujam, N, and Brown, JQ. "Optimization of a widefield structured illumination microscope for non-destructive assessment and quantification of nuclear features in tumor margins of a primary mouse model of sarcoma. (Published online)" PLoS One 8.7 (2013): e68868-.
PMID
23894357
Source
pubmed
Published In
PloS one
Volume
8
Issue
7
Publish Date
2013
Start Page
e68868
DOI
10.1371/journal.pone.0068868

Imaging human stratified squamous epithelia using nonlinear optical microscopy

Authors
Gill, EM; Ivarie, CA; Eliceiri, KW; Ramanujam, N; White, JG; Allen-Hoffmann, BL
MLA Citation
Gill, EM, Ivarie, CA, Eliceiri, KW, Ramanujam, N, White, JG, and Allen-Hoffmann, BL. "Imaging human stratified squamous epithelia using nonlinear optical microscopy." JOURNAL OF INVESTIGATIVE DERMATOLOGY 126 (April 2006): 64-64.
Source
wos-lite
Published In
Journal of Investigative Dermatology
Volume
126
Publish Date
2006
Start Page
64
End Page
64

Physiologic, metabolic, and structural alterations in breast cancer: Assessment via optical technologies

Optical spectroscopy was used to assess structural and functional changes which occur in breast tissue for the optical diagnosis of cancer in humans in vivo, and characterization of mammary tumor biology in animal models. © 2006 Optical Society of America.

Authors
Ramanujam, N; Quincy Brown, J
MLA Citation
Ramanujam, N, and Quincy Brown, J. "Physiologic, metabolic, and structural alterations in breast cancer: Assessment via optical technologies." Optics InfoBase Conference Papers (January 1, 2006).
Source
scopus
Published In
Optics InfoBase Conference Papers
Publish Date
2006

Physiologic, metabolic, and structural alterations in breast cancer: Assessment via optical technologies

Optical spectroscopy was used to assess structural and functional changes which occur in breast tissue for the optical diagnosis of cancer in humans in vivo, and characterization of mammary tumor biology in animal models. © 2006 Optical Society of America.

Authors
Ramanujam, N; Brown, JQ
MLA Citation
Ramanujam, N, and Brown, JQ. "Physiologic, metabolic, and structural alterations in breast cancer: Assessment via optical technologies." Optics InfoBase Conference Papers (January 1, 2006).
Source
scopus
Published In
Optics InfoBase Conference Papers
Publish Date
2006

Physiologic, metabolic, and structural alterations in breast cancer: Assessment via optical technologies

Optical spectroscopy was used to assess structural and functional changes which occur in breast tissue for the optical diagnosis of cancer in humans in vivo, and characterization of mammary tumor biology in animal models. © 2006 Optical Society of America.

Authors
Ramanujam, N; Quincy Brown, J
MLA Citation
Ramanujam, N, and Quincy Brown, J. "Physiologic, metabolic, and structural alterations in breast cancer: Assessment via optical technologies." Optics InfoBase Conference Papers (January 1, 2006).
Source
scopus
Published In
Optics InfoBase Conference Papers
Publish Date
2006

Use of a multiseparation fiber optic probe for the optical diagnosis of breast cancer

We explore the effects of the illumination and collection geometry on optical spectroscopic diagnosis of breast cancer. Fluorescence and diffuse reflectance spectroscopy in the UV-visible spectral range are made with a multiseparation probe at three illuminationcollection separations of 735, 980, and 1225 μm, respectively, from 13 malignant and 34 nonmalignant breast tissues. Statistical analysis is carried out on two types of data inputs: (1) the fluorescence and diffuse reflectance spectra recorded at each of the three illuminationcollection separations and (2) the integrated fluorescence (at each excitation wavelength) or diffuse reflectance over the entire spectrum at all three illumination-collection separations. The results show that using the integrated fluorescence intensities recorded at a single excitation wavelength at all three illumination-collection separations can discriminate malignant from nonmalignant breast tissues with similar classification accuracy to that using spectral data measured at several excitation wavelengths with a single illumination-collection separation. These findings have significant implications with respect to the design of an optical system for breast cancer diagnosis. Examining the intensity attenuation at a single wavelength rather than spectral intensities at multiple wavelengths can significantly reduce the measurement and data processing time in a clinical setting as well as the cost and complexity of the optical system. © 2005 Society of Photo-Optical Instrumentation Engineers.

Authors
Zhu, C; Palmer, GM; Breslin, TM; Xu, F; Ramanujam, N
MLA Citation
Zhu, C, Palmer, GM, Breslin, TM, Xu, F, and Ramanujam, N. "Use of a multiseparation fiber optic probe for the optical diagnosis of breast cancer." Journal of Biomedical Optics 10.2 (March 1, 2005).
Source
scopus
Published In
Journal of Biomedical Optics
Volume
10
Issue
2
Publish Date
2005
DOI
10.1117/1.1897398

Antepartum, transabdominal near infrared spectroscopy: Feasibility of measuring photon migration through the fetal head in utero

Objective: We report the feasibility of measuring photon migration through the fetal head in utero using antepartum, transabdominal, near infrared (NIR) spectroscopy. Methods: We developed a continuous wave (CW) spectrometer that incorporates a halogen light source, silicon photodetectors, and a differential processing circuit for antepartum, transabdominal, NIR spectroscopy. By placement of the light source and photodetector on the midline of the maternal abdomen above the fetal head at a separation (~10 cm) large enough for the light to propagate through maternal and fetal tissues via multiple scattering events before being detected at the surface and the use of filtered illumination and detection at wavelengths (760 nm, 850 nm), which coincide with the absorption bands of oxygenated and deoxygenated hemoglobin in the NIR window, we performed studies to evaluate whether antepartum, transabdominal NIR spectroscopy can measure photon migration through the fetal head in utero. Results: The results demonstrate that the CW spectrometer we developed can be employed to make NIR measurements from the maternal abdomen at a 10 cm source-detector separation, with an excellent signal-to-noise ratio. Furthermore, a variety of antepartum, transabdominal NIR measurements that we performed on patients undergoing a routine nonstress test demonstrate the feasibility of measuring photon migration through the fetal head in utero. Conclusions: Preliminary assessment of transabdominal NIR spectroscopy suggests that this technique can enable photon migration through the fetal head in utero. This is an important step towards the development of this technique for measuring and quantifying fetal cerebral blood oxygenation in utero.

Authors
Ramanujam, N; Long, H; Rode, M; Forouzan, I; Morgan, M; Chance, B
MLA Citation
Ramanujam, N, Long, H, Rode, M, Forouzan, I, Morgan, M, and Chance, B. "Antepartum, transabdominal near infrared spectroscopy: Feasibility of measuring photon migration through the fetal head in utero." Journal of Maternal-Fetal Medicine 8.6 (November 22, 1999): 275-288.
Source
scopus
Published In
Journal of Maternal-Fetal Medicine
Volume
8
Issue
6
Publish Date
1999
Start Page
275
End Page
288
DOI
10.1002/(SICI)1520-6661(199911/12)8:6<275::AID-MFM8>3.0.CO;2-X

Introduction

Authors
Becker, RC; Ansell, J
MLA Citation
Becker, RC, and Ansell, J. "Introduction." Journal of Thrombosis and Thrombolysis 7.2 (1999): 89--.
Source
scival
Published In
Journal of Thrombosis and Thrombolysis
Volume
7
Issue
2
Publish Date
1999
Start Page
89-
DOI
10.1023/A:1008863532453

Spectroscopic diagnosis of cervical intraepithelial neoplasia (CIN) in vivo using laser-induced fluorescence spectra at multiple excitation wavelengths

Background and Objective: The diagnostic contribution of cervical tissue fluorescence spectra acquired in vivo at 380 and 460 nm excitation were analyzed using a general multivariate statistical algorithm. Materials and Methods: The primary steps of the algorithm are to: (1) preprocess data to reduce interpatient and intrapatient variation of tissue spectra from the same diagnostic category, without a priori information, (2) dimensionally reduce the preprocessed spectral data using Principal Component Analysis, and (3) develop a probability based classification scheme based on logistic discrimination using the diagnostically useful principal components. The algorithm was tested on cervical tissue spectra acquired from 165 sites at 380 nm excitation and from 147 sites at 460 nm excitation. A retrospective and propsective estimate of the algorithm's performance was determined. Results: At 460 nm excitation, (1) SILs can be differentiated from normal squamous tissues with an average sensitivity and specificity of 91% ± 1.3 and 75.5% ± 1, respectively; furthermore, (2) high grade SILs can be differentiated from low grade SILs with an average sensitivity and specificity of 80% ± 4 and 76% ± 5, respectively. In addition, using tissue spectra at 380 nm excitation, SILs can be differentiated from normal columnar epithelia and inflammation with an average sensitivity and specificity of 77% ± 1 and 72% ± 9, respectively. Conclusions: Fluorescence spectra at multiple excitation wavelengths are essential for the detection and differential diagnosis of SILs at colposcopy.

Authors
Ramanujam, N; Mitchell, MF; Mahadevan, A; Thomsen, S; Malpica, A; Wright, T; Atkinson, N; Richards Kortum, R
MLA Citation
Ramanujam, N, Mitchell, MF, Mahadevan, A, Thomsen, S, Malpica, A, Wright, T, Atkinson, N, and Richards Kortum, R. "Spectroscopic diagnosis of cervical intraepithelial neoplasia (CIN) in vivo using laser-induced fluorescence spectra at multiple excitation wavelengths." Lasers in Surgery and Medicine 19.1 (September 11, 1996): 63-74.
Source
scopus
Published In
Lasers in Surgery and Medicine
Volume
19
Issue
1
Publish Date
1996
Start Page
63
End Page
74
DOI
10.1002/(SICI)1096-9101(1996)19:1<63::AID-LSM8>3.0.CO;2-O

Development of a multivariate statistical algorithm to analyze human cervical tissue fluorescence spectra acquired in vivo

Background and Objective: A general multivariate statistical algorithm has been developed to analyze the diagnostic content of cervical tissue fluorescence spectra acquired in vivo. Materials and Methods: The primary steps of the algorithm are to: (1) preprocess the data to reduce inter- patient and intra-patient variation of tissue spectra within a diagnostic category, without a priori information, (2) dimensionally reduce the preprocessed fluorescence emission spectrum with minimal information loss and use it to select the minimum number of the original emission variables of the fluorescence spectrum required to achieve classification with negligible decrease in predictive ability, and (3) assign a posterior probability to the diagnosis of each sample, so that samples with relative uncertain diagnosis can be reevaluated by a clinician. The algorithm was tested retrospectively and prospectively on cervical tissue spectra acquired from 476 sites from 92 patients at 337 nm excitation. Results: The algorithm based on the entire fluorescence spectrum differentiates squamous intraepithelial lesions (SILs) from normal squamous epithelia and inflammation with an average sensitivity and specificity of 88%±1.4 and 70%±1, respectively. The average sensitivity and specificity of the identical algorithm based on intensity selected at only two emission wavelengths is 88%±1.4 and 71%±1.4, respectively. Conclusion: The multivariate statistical algorithm based on both types of spectral inputs at 337 nm excitation has a similar sensitivity and significantly improved specificity relative to colposcopy in expert hands.

Authors
Ramanujam, N; Mitchell, MF; Mahadevan, A; Thomsen, S; Malpica, A; Wright, T; Atkinson, N; Richards-Kortum, R
MLA Citation
Ramanujam, N, Mitchell, MF, Mahadevan, A, Thomsen, S, Malpica, A, Wright, T, Atkinson, N, and Richards-Kortum, R. "Development of a multivariate statistical algorithm to analyze human cervical tissue fluorescence spectra acquired in vivo." Lasers in Surgery and Medicine 19.1 (September 11, 1996): 46-62.
Source
scopus
Published In
Lasers in Surgery and Medicine
Volume
19
Issue
1
Publish Date
1996
Start Page
46
End Page
62
DOI
10.1002/(SICI)1096-9101(1996)19:1<46::AID-LSM7>3.0.CO;2-Q

Statistical techniques for diagnosing CIN using fluorescence spectroscopy: SVD and CART

Authors
Atkinson, EN; Mitchell, MF; Ramanujam, N; Richards-Kortum, R
MLA Citation
Atkinson, EN, Mitchell, MF, Ramanujam, N, and Richards-Kortum, R. "Statistical techniques for diagnosing CIN using fluorescence spectroscopy: SVD and CART." Journal of Cellular Biochemistry 59.S23 (1995): 125-130.
Source
crossref
Published In
Journal of Cellular Biochemistry
Volume
59
Issue
S23
Publish Date
1995
Start Page
125
End Page
130
DOI
10.1002/jcb.240590916
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