Publications by authors named "Ashley M Laughney"

22 Publications

  • Page 1 of 1

High-resolution mouse subventricular zone stem-cell niche transcriptome reveals features of lineage, anatomy, and aging.

Proc Natl Acad Sci U S A 2020 12 23;117(49):31448-31458. Epub 2020 Nov 23.

Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065;

Adult neural stem cells (NSC) serve as a reservoir for brain plasticity and origin for certain gliomas. Lineage tracing and genomic approaches have portrayed complex underlying heterogeneity within the major anatomical location for NSC, the subventricular zone (SVZ). To gain a comprehensive profile of NSC heterogeneity, we utilized a well-validated stem/progenitor-specific reporter transgene in concert with single-cell RNA sequencing to achieve unbiased analysis of SVZ cells from infancy to advanced age. The magnitude and high specificity of the resulting transcriptional datasets allow precise identification of the varied cell types embedded in the SVZ including specialized parenchymal cells (neurons, glia, microglia) and noncentral nervous system cells (endothelial, immune). Initial mining of the data delineates four quiescent NSC and three progenitor-cell subpopulations formed in a linear progression. Further evidence indicates that distinct stem and progenitor populations reside in different regions of the SVZ. As stem/progenitor populations progress from neonatal to advanced age, they acquire a deficiency in transition from quiescence to proliferation. Further data mining identifies stage-specific biological processes, transcription factor networks, and cell-surface markers for investigation of cellular identities, lineage relationships, and key regulatory pathways in adult NSC maintenance and neurogenesis.
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http://dx.doi.org/10.1073/pnas.2014389117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7733854PMC
December 2020

L1CAM defines the regenerative origin of metastasis-initiating cells in colorectal cancer.

Nat Cancer 2020 Jan 13;1(1):28-45. Epub 2020 Jan 13.

Cancer Biology and Genetics Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA.

Metastasis-initiating cells with stem-like properties drive cancer lethality, yet their origins and relationship to primary-tumor-initiating stem cells are not known. We show that L1CAM cells in human colorectal cancer (CRC) have metastasis-initiating capacity, and we define their relationship to tissue regeneration. L1CAM is not expressed in the homeostatic intestinal epithelium, but is induced and required for epithelial regeneration following colitis and in CRC organoid growth. By using human tissues and mouse models, we show that L1CAM is dispensable for adenoma initiation but required for orthotopic carcinoma propagation, liver metastatic colonization and chemoresistance. L1CAM cells partially overlap with LGR5 stem-like cells in human CRC organoids. Disruption of intercellular epithelial contacts causes E-cadherin-REST transcriptional derepression of L1CAM, switching chemoresistant CRC progenitors from an L1CAM to an L1CAM state. Thus, L1CAM dependency emerges in regenerative intestinal cells when epithelial integrity is lost, a phenotype of wound healing deployed in metastasis-initiating cells.
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http://dx.doi.org/10.1038/s43018-019-0006-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7351134PMC
January 2020

Regenerative lineages and immune-mediated pruning in lung cancer metastasis.

Nat Med 2020 02 10;26(2):259-269. Epub 2020 Feb 10.

Cancer Biology and Genetics Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA.

Developmental processes underlying normal tissue regeneration have been implicated in cancer, but the degree of their enactment during tumor progression and under the selective pressures of immune surveillance, remain unknown. Here we show that human primary lung adenocarcinomas are characterized by the emergence of regenerative cell types, typically seen in response to lung injury, and by striking infidelity among transcription factors specifying most alveolar and bronchial epithelial lineages. In contrast, metastases are enriched for key endoderm and lung-specifying transcription factors, SOX2 and SOX9, and recapitulate more primitive transcriptional programs spanning stem-like to regenerative pulmonary epithelial progenitor states. This developmental continuum mirrors the progressive stages of spontaneous outbreak from metastatic dormancy in a mouse model and exhibits SOX9-dependent resistance to natural killer cells. Loss of developmental stage-specific constraint in macrometastases triggered by natural killer cell depletion suggests a dynamic interplay between developmental plasticity and immune-mediated pruning during metastasis.
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http://dx.doi.org/10.1038/s41591-019-0750-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7021003PMC
February 2020

Adult Human Glioblastomas Harbor Radial Glia-like Cells.

Stem Cell Reports 2020 02 30;14(2):338-350. Epub 2020 Jan 30.

Department of Neurosurgery, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA. Electronic address:

Radial glia (RG) cells are the first neural stem cells to appear during embryonic development. Adult human glioblastomas harbor a subpopulation of RG-like cells with typical RG morphology and markers. The cells exhibit the classic and unique mitotic behavior of normal RG in a cell-autonomous manner. Single-cell RNA sequencing analyses of glioblastoma cells reveal transcriptionally dynamic clusters of RG-like cells that share the profiles of normal human fetal radial glia and that reside in quiescent and cycling states. Functional assays show a role for interleukin in triggering exit from dormancy into active cycling, suggesting a role for inflammation in tumor progression. These data are consistent with the possibility of persistence of RG into adulthood and their involvement in tumor initiation or maintenance. They also provide a putative cellular basis for the persistence of normal developmental programs in adult tumors.
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http://dx.doi.org/10.1016/j.stemcr.2020.01.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7014025PMC
February 2020

Urothelial organoids originating from Cd49f mouse stem cells display Notch-dependent differentiation capacity.

Nat Commun 2019 09 27;10(1):4407. Epub 2019 Sep 27.

Epithelial Carcinogenesis Group, Spanish National Cancer Research Centre-CNIO, Madrid, Spain.

Understanding urothelial stem cell biology and differentiation has been limited by the lack of methods for their unlimited propagation. Here, we establish mouse urothelial organoids that can be maintained uninterruptedly for >1 year. Organoid growth is dependent on EGF and Wnt activators. High CD49f/ITGA6 expression features a subpopulation of organoid-forming cells expressing basal markers. Upon differentiation, multilayered organoids undergo reduced proliferation, decreased cell layer number, urothelial program activation, and acquisition of barrier function. Pharmacological modulation of PPARγ and EGFR promotes differentiation. RNA sequencing highlighted genesets enriched in proliferative organoids (i.e. ribosome) and transcriptional networks involved in differentiation, including expression of Wnt ligands and Notch components. Single-cell RNA sequencing (scRNA-Seq) analysis of the organoids revealed five clusters with distinct gene expression profiles. Together, with the use of γ-secretase inhibitors and scRNA-Seq, confirms that Notch signaling is required for differentiation. Urothelial organoids provide a powerful tool to study cell regeneration and differentiation.
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http://dx.doi.org/10.1038/s41467-019-12307-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6764959PMC
September 2019

A Markov chain for numerical chromosomal instability in clonally expanding populations.

PLoS Comput Biol 2018 09 11;14(9):e1006447. Epub 2018 Sep 11.

Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America.

Cancer cells frequently undergo chromosome missegregation events during mitosis, whereby the copies of a given chromosome are not distributed evenly among the two daughter cells, thus creating cells with heterogeneous karyotypes. A stochastic model tracing cellular karyotypes derived from clonal populations over hundreds of generations was recently developed and experimentally validated, and it was capable of predicting favorable karyotypes frequently observed in cancer. Here, we construct and study a Markov chain that precisely describes karyotypic evolution during clonally expanding cancer cell populations. The Markov chain allows us to directly predict the distribution of karyotypes and the expected size of the tumor after many cell divisions without resorting to computationally expensive simulations. We determine the limiting karyotype distribution of an evolving tumor population, and quantify its dependency on several key parameters including the initial karyotype of the founder cell, the rate of whole chromosome missegregation, and chromosome-specific cell viability. Using this model, we confirm the existence of an optimal rate of chromosome missegregation probabilities that maximizes karyotypic heterogeneity, while minimizing the occurrence of nullisomy. Interestingly, karyotypic heterogeneity is significantly more dependent on chromosome missegregation probabilities rather than the number of cell divisions, so that maximal heterogeneity can be reached rapidly (within a few hundred generations of cell division) at chromosome missegregation rates commonly observed in cancer cell lines. Conversely, at low missegregation rates, heterogeneity is constrained even after thousands of cell division events. This leads us to conclude that chromosome copy number heterogeneity is primarily constrained by chromosome missegregation rates and the risk for nullisomy and less so by the age of the tumor. This model enables direct integration of karyotype information into existing models of tumor evolution based on somatic mutations.
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http://dx.doi.org/10.1371/journal.pcbi.1006447DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6150543PMC
September 2018

Chromosomal instability drives metastasis through a cytosolic DNA response.

Nature 2018 01 17;553(7689):467-472. Epub 2018 Jan 17.

Sandra and Edward Meyer Cancer Center, Weill Cornell Medicine, New York, New York 10065, USA.

Chromosomal instability is a hallmark of cancer that results from ongoing errors in chromosome segregation during mitosis. Although chromosomal instability is a major driver of tumour evolution, its role in metastasis has not been established. Here we show that chromosomal instability promotes metastasis by sustaining a tumour cell-autonomous response to cytosolic DNA. Errors in chromosome segregation create a preponderance of micronuclei whose rupture spills genomic DNA into the cytosol. This leads to the activation of the cGAS-STING (cyclic GMP-AMP synthase-stimulator of interferon genes) cytosolic DNA-sensing pathway and downstream noncanonical NF-κB signalling. Genetic suppression of chromosomal instability markedly delays metastasis even in highly aneuploid tumour models, whereas continuous chromosome segregation errors promote cellular invasion and metastasis in a STING-dependent manner. By subverting lethal epithelial responses to cytosolic DNA, chromosomally unstable tumour cells co-opt chronic activation of innate immune pathways to spread to distant organs.
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http://dx.doi.org/10.1038/nature25432DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5785464PMC
January 2018

Predicting therapeutic nanomedicine efficacy using a companion magnetic resonance imaging nanoparticle.

Sci Transl Med 2015 Nov;7(314):314ra183

Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA. Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA. Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA.

Therapeutic nanoparticles (TNPs) have shown heterogeneous responses in human clinical trials, raising questions of whether imaging should be used to identify patients with a higher likelihood of NP accumulation and thus therapeutic response. Despite extensive debate about the enhanced permeability and retention (EPR) effect in tumors, it is increasingly clear that EPR is extremely variable; yet, little experimental data exist to predict the clinical utility of EPR and its influence on TNP efficacy. We hypothesized that a 30-nm magnetic NP (MNP) in clinical use could predict colocalization of TNPs by magnetic resonance imaging (MRI). To this end, we performed single-cell resolution imaging of fluorescently labeled MNPs and TNPs and studied their intratumoral distribution in mice. MNPs circulated in the tumor microvasculature and demonstrated sustained uptake into cells of the tumor microenvironment within minutes. MNPs could predictably demonstrate areas of colocalization for a model TNP, poly(d,l-lactic-co-glycolic acid)-b-polyethylene glycol (PLGA-PEG), within the tumor microenvironment with >85% accuracy and circulating within the microvasculature with >95% accuracy, despite their markedly different sizes and compositions. Computational analysis of NP transport enabled predictive modeling of TNP distribution based on imaging data and identified key parameters governing intratumoral NP accumulation and macrophage uptake. Finally, MRI accurately predicted initial treatment response and drug accumulation in a preclinical efficacy study using a paclitaxel-encapsulated NP in tumor-bearing mice. These approaches yield valuable insight into the in vivo kinetics of NP distribution and suggest that clinically relevant imaging modalities and agents can be used to select patients with high EPR for treatment with TNPs.
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http://dx.doi.org/10.1126/scitranslmed.aac6522DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5462466PMC
November 2015

Dynamics of Tumor Heterogeneity Derived from Clonal Karyotypic Evolution.

Cell Rep 2015 Aug 23;12(5):809-20. Epub 2015 Jul 23.

Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA. Electronic address:

Numerical chromosomal instability is a ubiquitous feature of human neoplasms. Due to experimental limitations, fundamental characteristics of karyotypic changes in cancer are poorly understood. Using an experimentally inspired stochastic model, based on the potency and chromosomal distribution of oncogenes and tumor suppressor genes, we show that cancer cells have evolved to exist within a narrow range of chromosome missegregation rates that optimizes phenotypic heterogeneity and clonal survival. Departure from this range reduces clonal fitness and limits subclonal diversity. Mapping of the aneuploid fitness landscape reveals a highly favorable, commonly observed, near-triploid state onto which evolving diploid- and tetraploid-derived populations spontaneously converge, albeit at a much lower fitness cost for the latter. Finally, by analyzing 1,368 chromosomal translocation events in five human cancers, we find that karyotypic evolution also shapes chromosomal translocation patterns by selecting for more oncogenic derivative chromosomes. Thus, chromosomal instability can generate the heterogeneity required for Darwinian tumor evolution.
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http://dx.doi.org/10.1016/j.celrep.2015.06.065DOI Listing
August 2015

Numerical chromosomal instability mediates susceptibility to radiation treatment.

Nat Commun 2015 Jan 21;6:5990. Epub 2015 Jan 21.

1] Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755, USA [2] Norris-Cotton Cancer Center, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire 03756, USA.

The exquisite sensitivity of mitotic cancer cells to ionizing radiation (IR) underlies an important rationale for the widely used fractionated radiation therapy. However, the mechanism for this cell cycle-dependent vulnerability is unknown. Here we show that treatment with IR leads to mitotic chromosome segregation errors in vivo and long-lasting aneuploidy in tumour-derived cell lines. These mitotic errors generate an abundance of micronuclei that predispose chromosomes to subsequent catastrophic pulverization thereby independently amplifying radiation-induced genome damage. Experimentally suppressing whole-chromosome missegregation reduces downstream chromosomal defects and significantly increases the viability of irradiated mitotic cells. Further, orthotopically transplanted human glioblastoma tumours in which chromosome missegregation rates have been reduced are rendered markedly more resistant to IR, exhibiting diminished markers of cell death in response to treatment. This work identifies a novel mitotic pathway for radiation-induced genome damage, which occurs outside of the primary nucleus and augments chromosomal breaks. This relationship between radiation treatment and whole-chromosome missegregation can be exploited to modulate therapeutic response in a clinically relevant manner.
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http://dx.doi.org/10.1038/ncomms6990DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4516720PMC
January 2015

Single-cell pharmacokinetic imaging reveals a therapeutic strategy to overcome drug resistance to the microtubule inhibitor eribulin.

Sci Transl Med 2014 Nov;6(261):261ra152

Center for Systems Biology, Massachusetts General Hospital, 185 Cambridge Street, CPZN 5206, Boston, MA 02114, USA. Department of Systems Biology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA.

Eribulin mesylate was developed as a potent microtubule-targeting cytotoxic agent to treat taxane-resistant cancers, but recent clinical trials have shown that it eventually fails in many patient subpopulations for unclear reasons. To investigate its resistance mechanisms, we developed a fluorescent analog of eribulin with pharmacokinetic (PK) properties and cytotoxic activity across a human cell line panel that are sufficiently similar to the parent drug to study its cellular PK and tissue distribution. Using intravital imaging and automated tracking of cellular dynamics, we found that resistance to eribulin and the fluorescent analog depended directly on the multidrug resistance protein 1 (MDR1). Intravital imaging allowed for real-time analysis of in vivo PK in tumors that were engineered to be spatially heterogeneous for taxane resistance, whereby an MDR1-mApple fusion protein distinguished resistant cells fluorescently. In vivo, MDR1-mediated drug efflux and the three-dimensional tumor vascular architecture were discovered to be critical determinants of drug accumulation in tumor cells. We furthermore show that standard intravenous administration of a third-generation MDR1 inhibitor, HM30181, failed to rescue drug accumulation; however, the same MDR1 inhibitor encapsulated within a nanoparticle delivery system reversed the multidrug-resistant phenotype and potentiated the eribulin effect in vitro and in vivo in mice. Our work demonstrates that in vivo assessment of cellular PK of an anticancer drug is a powerful strategy for elucidating mechanisms of drug resistance in heterogeneous tumors and evaluating strategies to overcome this resistance.
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http://dx.doi.org/10.1126/scitranslmed.3009318DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4330962PMC
November 2014

In vivo imaging of multidrug resistance using a third generation MDR1 inhibitor.

Bioconjug Chem 2014 Jun 14;25(6):1137-42. Epub 2014 May 14.

Center for Systems Biology, Massachusetts General Hospital , 185 Cambridge Street, CPZN 5206, Boston, Massachusetts 02114, United States.

Cellular up-regulation of multidrug resistance protein 1 (MDR1) is a common cause for resistance to chemotherapy; development of third generation MDR1 inhibitors-several of which contain a common 6,7-dimethoxy-2-phenethyl-1,2,3,4-tetrahydroisoquinoline substructure-is underway. Efficacy of these agents has been difficult to ascertain, partly due to a lack of pharmacokinetic reporters for quantifying inhibitor localization and transport dynamics. Some of the recent third generation inhibitors have a pendant heterocycle, for example, a chromone moiety, which we hypothesized could be converted to a fluorophore. Following synthesis and teasing of a small set of analogues, we identified one lead compound that can be used as a cellular imaging agent that exhibits structural similarity and behavior akin to the latest generation of MDR1 inhibitors.
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http://dx.doi.org/10.1021/bc500154cDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4098115PMC
June 2014

A photoactivatable drug-caged fluorophore conjugate allows direct quantification of intracellular drug transport.

Chem Commun (Camb) 2013 Dec;49(94):11050-11052

Center for Systems Biology, Massachusetts General Hospital/Harvard Medical School, 185 Cambridge St., Boston, MA 02114 (USA).

We report here a method that utilizes a photoactivatable drug-caged fluorophore conjugate to quantify intracellular drug trafficking processes at single cell resolution. Photoactivation is performed in labeled cellular compartments to visualize intracellular drug exchange under physiological conditions, without the need for washing, facilitating its translation into in vivo cancer models.
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http://dx.doi.org/10.1039/c3cc46089dDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3856557PMC
December 2013

Spectral discrimination of breast pathologies in situ using spatial frequency domain imaging.

Breast Cancer Res 2013 ;15(4):R61

Introduction: Nationally, 25% to 50% of patients undergoing lumpectomy for local management of breast cancer require a secondary excision because of the persistence of residual tumor. Intraoperative assessment of specimen margins by frozen-section analysis is not widely adopted in breast-conserving surgery. Here, a new approach to wide-field optical imaging of breast pathology in situ was tested to determine whether the system could accurately discriminate cancer from benign tissues before routine pathological processing.

Methods: Spatial frequency domain imaging (SFDI) was used to quantify near-infrared (NIR) optical parameters at the surface of 47 lumpectomy tissue specimens. Spatial frequency and wavelength-dependent reflectance spectra were parameterized with matched simulations of light transport. Spectral images were co-registered to histopathology in adjacent, stained sections of the tissue, cut in the geometry imaged in situ. A supervised classifier and feature-selection algorithm were implemented to automate discrimination of breast pathologies and to rank the contribution of each parameter to a diagnosis.

Results: Spectral parameters distinguished all pathology subtypes with 82% accuracy and benign (fibrocystic disease, fibroadenoma) from malignant (DCIS, invasive cancer, and partially treated invasive cancer after neoadjuvant chemotherapy) pathologies with 88% accuracy, high specificity (93%), and reasonable sensitivity (79%). Although spectral absorption and scattering features were essential components of the discriminant classifier, scattering exhibited lower variance and contributed most to tissue-type separation. The scattering slope was sensitive to stromal and epithelial distributions measured with quantitative immunohistochemistry.

Conclusions: SFDI is a new quantitative imaging technique that renders a specific tissue-type diagnosis. Its combination of planar sampling and frequency-dependent depth sensing is clinically pragmatic and appropriate for breast surgical-margin assessment. This study is the first to apply SFDI to pathology discrimination in surgical breast tissues. It represents an important step toward imaging surgical specimens immediately ex vivo to reduce the high rate of secondary excisions associated with breast lumpectomy procedures.
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http://dx.doi.org/10.1186/bcr3455DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3979079PMC
December 2014

Direct identification of breast cancer pathologies using blind separation of label-free localized reflectance measurements.

Biomed Opt Express 2013 Jul 12;4(7):1104-18. Epub 2013 Jun 12.

Photonics Engineering Group, Dep. TEISA, University of Cantabria, Plaza de la Ciencia sn, 39005 Santander, Spain.

Breast tumors are blindly identified using Principal (PCA) and Independent Component Analysis (ICA) of localized reflectance measurements. No assumption of a particular theoretical model for the reflectance needs to be made, while the resulting features are proven to have discriminative power of breast pathologies. Normal, benign and malignant breast tissue types in lumpectomy specimens were imaged ex vivo and a surgeon-guided calibration of the system is proposed to overcome the limitations of the blind analysis. A simple, fast and linear classifier has been proposed where no training information is required for the diagnosis. A set of 29 breast tissue specimens have been diagnosed with a sensitivity of 96% and specificity of 95% when discriminating benign from malignant pathologies. The proposed hybrid combination PCA-ICA enhanced diagnostic discrimination, providing tumor probability maps, and intermediate PCA parameters reflected tissue optical properties.
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http://dx.doi.org/10.1364/BOE.4.001104DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3704092PMC
July 2013

System analysis of spatial frequency domain imaging for quantitative mapping of surgically resected breast tissues.

J Biomed Opt 2013 Mar;18(3):036012

Dartmouth College, Thayer School of Engineering, Hanover, New Hampshire 03755, USA.

The feasibility of spatial frequency domain imaging (SFDI) for breast surgical margin assessment was evaluated in tissue-simulating phantoms and in fully intact lumpectomy specimens at the time of surgery. Phantom data was evaluated according to contrast-detail resolution, quantitative accuracy and model-data goodness of fit, where optical parameters were estimated by minimizing the residual sum of squares between the measured modulation amplitude and its solutions, modeled according to diffusion and scaled-Monte Carlo simulations. In contrast-detail phantoms, a 1.25-mm-diameter surface inclusion was detectable for scattering contrast >28%; a fraction of this scattering contrast (7%) was detectable for a 10 mm surface inclusion and at least 33% scattering contrast was detected up to 1.5 mm below the phantom surface, a probing depth relevant to breast surgical margin assessment. Recovered hemoglobin concentrations were insensitive to changes in scattering, except for overestimation at visible wavelengths for total hemoglobin concentrations <15  μM. The scattering amplitude increased linearly with scattering concentration, but the scattering slope depended on both the particle size and number density. Goodness of fit was comparable for the diffusion and scaled-Monte Carlo models of transport in spatially modulated, near-infrared reflectance acquired from 47 lumpectomy tissues, but recovered absorption parameters varied more linearly with expected hemoglobin concentration in liquid phantoms for the scaled-Monte Carlo forward model. SFDI could potentially reduce the high secondary excision rate associated with breast conserving surgery; its clinical translation further requires reduced image reconstruction time and smart inking strategies.
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http://dx.doi.org/10.1117/1.JBO.18.3.036012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3605471PMC
March 2013

Scanning in situ spectroscopy platform for imaging surgical breast tissue specimens.

Opt Express 2013 Jan;21(2):2185-94

Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, New Hampshire 03755, USA.

A non-contact localized spectroscopic imaging platform has been developed and optimized to scan 1 x 1 cm² square regions of surgically resected breast tissue specimens with ~150-micron resolution. A color corrected, image-space telecentric scanning design maintained a consistent sampling geometry and uniform spot size across the entire imaging field. Theoretical modeling in ZEMAX allowed estimation of the spot size, which is equal at both the center and extreme positions of the field with ~5% variation across the designed waveband, indicating excellent color correction. The spot sizes at the center and an extreme field position were also measured experimentally using the standard knife-edge technique and were found to be within ~8% of the theoretical predictions. Highly localized sampling offered inherent insensitivity to variations in background absorption allowing direct imaging of local scattering parameters, which was validated using a matrix of varying concentrations of Intralipid and blood in phantoms. Four representative, pathologically distinct lumpectomy tissue specimens were imaged, capturing natural variations in tissue scattering response within a given pathology. Variations as high as 60% were observed in the average reflectance and relative scattering power images, which must be taken into account for robust classification performance. Despite this variation, the preliminary data indicates discernible scatter power contrast between the benign vs malignant groups, but reliable discrimination of pathologies within these groups would require investigation into additional contrast mechanisms.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3601741PMC
http://dx.doi.org/10.1364/OE.21.002185DOI Listing
January 2013

Scatter spectroscopic imaging distinguishes between breast pathologies in tissues relevant to surgical margin assessment.

Clin Cancer Res 2012 Nov 20;18(22):6315-25. Epub 2012 Aug 20.

Thayer School of Engineering, Dartmouth College Hanover, Lebanon, New Hampshire, USA.

Purpose: A new approach to spectroscopic imaging was developed to detect and discriminate microscopic pathologies in resected breast tissues; diagnostic performance of the prototype system was tested in 27 tissues procured during breast conservative surgery.

Experimental Design: A custom-built, scanning in situ spectroscopy platform sampled broadband reflectance from a 150-μm-diameter spot over a 1 × 1 cm(2) field using a dark field geometry and telecentric lens; the system was designed to balance sensitivity to cellular morphology and imaging the inherent diversity within tissue subtypes. Nearly 300,000 broadband spectra were parameterized using light scattering models and spatially dependent spectral signatures were interpreted using a cooccurrence matrix representation of image texture.

Results: Local scattering changes distinguished benign from malignant pathologies with 94% accuracy, 93% sensitivity, 95% specificity, and 93% positive and 95% negative predictive values using a threshold-based classifier. Texture and shape features were important to optimally discriminate benign from malignant tissues, including pixel-to-pixel correlation, contrast and homogeneity, and the shape features of fractal dimension and Euler number. Analysis of the region-based diagnostic performance showed that spectroscopic image features from 1 × 1 mm(2) areas were diagnostically discriminant and enabled quantification of within-class tissue heterogeneities.

Conclusions: Localized scatter-imaging signatures detected by the scanning spectroscopy platform readily distinguished benign from malignant pathologies in surgical tissues and showed new spectral-spatial signatures of clinical breast pathologies.
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http://dx.doi.org/10.1158/1078-0432.CCR-12-0136DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3500421PMC
November 2012

Dark-field scanning in situ spectroscopy platform for broadband imaging of resected tissue.

Opt Lett 2011 May;36(10):1911-3

Thayer School of Engineering, 8000 Cummings Hall, Dartmouth College, Hanover, New Hampshire 03755, USA.

A dark-field geometry spectral imaging system is presented to raster scan thick tissue samples in situ in 1.5 cm square sections, recovering full spectra from each 100 μm diameter pixel. This spot size provides adequate resolution for wide field scanning, while also facilitating scatter imaging without requiring sophisticated light-tissue transport modeling. The system is demonstrated showing accurate estimation of localized scatter parameters and the potential to recover absorption-based contrast from broadband reflectance data measured from 480 nm up to 750 nm in tissue phantoms. Results obtained from xenograft pancreas tumors show the ability to quantitatively image changes in localized scatter response in this fast-imaging geometry. The polychromatic raster scan design allows the rapid scanning necessary for use in surgical/clinical applications where timely decisions are required about tissue pathology.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3538824PMC
http://dx.doi.org/10.1364/OL.36.001911DOI Listing
May 2011

Automated classification of breast pathology using local measures of broadband reflectance.

J Biomed Opt 2010 Nov-Dec;15(6):066019

Dartmouth College, Thayer School of Engineering, Hanover, NH 03755, USA.

We demonstrate that morphological features pertinent to a tissue's pathology may be ascertained from localized measures of broadband reflectance, with a mesoscopic resolution (100-μm lateral spot size) that permits scanning of an entire margin for residual disease. The technical aspects and optimization of a k-nearest neighbor classifier for automated diagnosis of pathologies are presented, and its efficacy is validated in 29 breast tissue specimens. When discriminating between benign and malignant pathologies, a sensitivity and specificity of 91 and 77% was achieved. Furthermore, detailed subtissue-type analysis was performed to consider how diverse pathologies influence scattering response and overall classification efficacy. The increased sensitivity of this technique may render it useful to guide the surgeon or pathologist where to sample pathology for microscopic assessment.
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http://dx.doi.org/10.1117/1.3516594DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3032233PMC
May 2011

Measurement of pressure-displacement kinetics of hemoglobin in normal breast tissue with near-infrared spectral imaging.

Appl Opt 2009 Apr;48(10):D130-6

Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755, USA.

Applying localized external displacement to the breast surface can change the interstitial fluid pressure such that regional transient microvascular changes occur in oxygenation and vascular volume. Imaging these dynamic responses over time, while different pressures are applied, could provide selective temporal contrast for cancer relative to the surrounding normal breast. In order to investigate this possibility in normal breast tissue, a near-infrared spectral tomography system was developed that can simultaneously acquire data at three wavelengths with a 15 s time resolution per scan. The system was tested first with heterogeneous blood phantoms. Changes in regional blood concentrations were found to be linearly related to recovered mean hemoglobin concentration (Hb(T)) values (R(2)=0.9). In a series of volunteer breast imaging exams, data from 17 asymptomatic subjects were acquired under increasing and decreasing breast compression. Calculations show that a 10 mm displacement applied to the breast results in surface pressures in the range of 0-55 kPa depending on breast density. The recovered human data indicate that Hb(T) was reduced under compression and the normalized change was significantly correlated to the applied pressure with a p value of 0.005. The maximum Hb(T) decreases in breast tissue were associated with body mass index (BMI), which is a surrogate indicator of breast density. No statistically valid correlations were found between the applied pressure and the changes in tissue oxygen saturation (S(t)O(2)) or water percentage (H(2)O) across the range of BMI values studied.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2804884PMC
http://dx.doi.org/10.1364/ao.48.00d130DOI Listing
April 2009