title: Structured Illumination Microscopy and a Quantitative Image Analysis for the Detection of Positive Margins in a Pre-Clinical Genetically Engineered Mouse Model of Sarcoma.
abstract: Intraoperative assessment of surgical margins is critical to ensuring residual tumor does not remain in a patient. Previously, we developed a fluorescence structured illumination microscope (SIM) system with a single-shot field of view (FOV) of 2.1 × 1.6 mm (3.4 mm2) and sub-cellular resolution (4.4 μm). The goal of this study was to test the utility of this technology for the detection of residual disease in a genetically engineered mouse model of sarcoma. Primary soft tissue sarcomas were generated in the hindlimb and after the tumor was surgically removed, the relevant margin was stained with acridine orange (AO), a vital stain that brightly stains cell nuclei and fibrous tissues. The tissues were imaged with the SIM system with the primary goal of visualizing fluorescent features from tumor nuclei. Given the heterogeneity of the background tissue (presence of adipose tissue and muscle), an algorithm known as maximally stable extremal regions (MSER) was optimized and applied to the images to specifically segment nuclear features. A logistic regression model was used to classify a tissue site as positive or negative by calculating area fraction and shape of the segmented features that were present and the resulting receiver operator curve (ROC) was generated by varying the probability threshold. Based on the ROC curves, the model was able to classify tumor and normal tissue with 77% sensitivity and 81% specificity (Youden's index). For an unbiased measure of the model performance, it was applied to a separate validation dataset that resulted in 73% sensitivity and 80% specificity. When this approach was applied to representative whole margins, for a tumor probability threshold of 50%, only 1.2% of all regions from the negative margin exceeded this threshold, while over 14.8% of all regions from the positive margin exceeded this threshold.
authors.affiliation: Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States of America.
authors.forename: Henry L
authors.initials: HL
authors.lastname: Fu
authors.affiliation: Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States of America.
authors.forename: Jenna L
authors.initials: JL
authors.lastname: Mueller
authors.affiliation: Department of Pharmacology & Cancer Biology, Duke University School of Medicine, Durham, North Carolina, United States of America.
authors.forename: Melodi J
authors.initials: MJ
authors.lastname: Whitley
authors.affiliation: Department of Pathology, Duke University School of Medicine, Durham, North Carolina, United States of America.
authors.forename: Diana M
authors.initials: DM
authors.lastname: Cardona
authors.affiliation: Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin, United States of America.
authors.forename: Rebecca M
authors.initials: RM
authors.lastname: Willett
authors.affiliation: Department of Pharmacology & Cancer Biology, Duke University School of Medicine, Durham, North Carolina, United States of America.|Department of Radiation Oncology, Duke University School of Medicine, Durham, North Carolina, United States of America.
authors.forename: David G
authors.initials: DG
authors.lastname: Kirsch
authors.affiliation: Department of Biomedical Engineering, Tulane University, New Orleans, Louisiana, United States of America.
authors.forename: J Quincy
authors.initials: JQ
authors.lastname: Brown
authors.affiliation: Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States of America.
authors.forename: Nimmi
authors.initials: N
authors.lastname: Ramanujam
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005818:Genetic Engineering; D051379:Mice; D008856:Microscopy, Fluorescence / Q000379:methods*; D012509:Sarcoma / Q000235:genetics / Q000473:pathology*