H&E-like histology of unstained fresh and formalin fixed breast tissue with Photo Acoustic Remote Sensing (PARS) microscopy.

e12590 Background: Approximately 30% of breast cancer patients undergoing breast-conserving surgery (BCS) require re-excision(s) to obtain clear margins, causing delays in adjuvant treatment, poor aesthetic results, and increased infection rates, costs, and patient anxiety. Frozen section pathology assessment (FSA) reduces re-excision rates from 27% to 6%, but FSA extends operative times and has a false negative rate of 17%. Photo-Acoustic Remote Sensing (PARS) is a new laser-based light microscope that permits non-contact cellular resolution imaging of unstained tissues. Methods: We used an ultraviolet reflection-mode PARS microscope to study i) formalin-fixed, paraffin embedded (FFPE) breast tissue blocks, ii) unstained thin sections of FFPE invasive ductal carcinoma and ductal carcinoma in situ, iii) formalin fixed bulk surgical specimens of benign and malignant human breast tissue, and iv) benign and malignant fresh rodent mammary tissue without fixation, processing, or staining. Fresh tissues were imaged after a range of warm ischemic times and across a range of cold ischemic times in neutral phosphate buffered saline at 4°C. For each condition, an ultraviolet laser was used to excite DNA and other cellular components in these samples, and signals were captured using a continuous-wave detection laser. The PARS signal was false-colored to closely replicate traditional hematoxylin and eosin staining. Results: In all fixed tissues, PARS virtual histology images were of diagnostic quality, permitted margin assessment, and analogous to transmission light microscopy of standard hematoxylin and eosin-stained FFPE slides, achieved without tissue sectioning or tissue staining. Furthermore, PARS microscopy also provided cellular level virtual histology images in fresh breast tissue with warm and cold ischemic times ranging from twenty minutes to two hours; these images have no available clinical comparators as non-contact cellular level imaging of unprocessed fresh tissue has not previously been reported. In aggregate, we demonstrate the feasibility of PARS to provide diagnostic and margin assessment images across a range of tissues including formalin fixed and freshly resected, unstained, unprocessed breast tissue. Conclusions: PARS is a new microscope technology addressing the practical needs of intraoperative margin assessment during BCS: i) no requirement for tissue staining, ii) rapid acquisition of hematoxylin and eosin-like images without the requirement for tissue freezing, embedding, or sectioning, iii) diagnostic quality cellular resolution, and iv) assessment of resected bulk tissue margins. In principle, this technology may also permit label-free non-contact intraoperative margin assessment of the surgical cavity. These data support the clinical development and evaluation of PARS microscopic intraoperative assessment of BCS margins.

Mapping 3D structure of a Sargassum forest with high-resolution sounding data obtained by multibeam echosounder

Sargassum forests play an important role in coastal waters as habitats for marine organisms, including commercial species. However, human activities have negatively affected their distribution causing a worldwide decline of Sargassum forests. Mapping and monitoring the distribution and biomass of these habitats using acoustic remote sensing techniques is key for their conservation. Nonetheless, most researches based on acoustic remote sensing methods focus on estimations of macrophyte area and its canopy height, and less researches reporting 3D visualization of these habitats. This study demonstrates the use of high-resolution multibeam echosounder (MBES) bathymetric data to visualize the 3D structure of Sargassum forests. Comparing acoustic data and underwater camera photos collected in field surveys, we identified Sargassum individuals as vertical clusters of contiguous sounding points with a base close to the sea bottom in the sounding data of the MBES. Using this criterion, we could distinguish Sargassum echoes, visualize the 3D structure of Sargassum forests and estimate the number of Sargassum individuals in the survey area. Using the relation between thallus length and dry weight of sampled Sargassum plants, standing stock and biomass could be estimated assuming the thallus length was the height of Sargassum plants identified with the MBES.

Acoustic remote sensing monitoring of morphological and sedimentological seabed evolution of small and medium-scale French estuaries

<p>Estuarine benthic habitat quality health is integrated within the framework of the EU Water Directive and Marine Strategy Framework Directive. The long-term monitoring of small and medium-scale estuarine benthic habitat is based on recurrent observation of several factors, mainly bathymetry and seabed nature. Numerous studies have already addressed the performance and limitations of acoustic remote sensing and mapping techniques. However, most of these studies are limited to the marine and coastal domains and do not include the estuarine domain. Estuaries are considered as transitional domains, with various seabed morphologies (from rocky reefs to hydraulic dunes with anthropic modification overlap) and subtle granulometric variations of the seabed nature.</p><p>The objectives of our study are to explore the mapping performance of several acoustic remote sensing techniques and to determine which physical factors are the most representative of morphological and sedimentological characteristics of subtidal estuarine environment and of its evolution. The exploration of these cartographic variables has been performed for three small and medium-scale French estuaries: the Orne estuary, the Baie de Somme and the Belon estuary. These estuaries have been chosen to cover different morphological and sedimentological estuarine contexts.</p><p>Firstly, we evaluate the capacity of the main variables derived from bathymetry (slope, curvature, ruggedness) to map seabed morphology. We extend the variable exploration to the “Terrain Variable” GIS category and BTM (Benthic Terrain Modeler Toolbox) as well. Secondly, we explore the capacity of several cartographic variables, extracted from bathymetric, seabed acoustic backscatter and acoustic ground discrimination system (i.e. RoxAnn©), to map seabed sediment characteristics and variations. The seabed nature mapping is validated with ground truthing data, namely grab samples and seabed video profiles. Moreover, quantitative (D90, roughness, sorting) and qualitive information (apparent roughness of the seabed, benthic habitat) are extracted from the grab samples and seabed video profiles, respectively. The capacity of these variables to produce seabed nature maps is also explored.</p><p>Mapping results on the three areas are compared, in terms of mapping precision and reproducibility, and transposed into recommendations for small and medium-scale estuaries monitoring. The next step of the AUPASED project is he exploration of image analysis and machine learning classifications and their comparison to manual morphological and sedimentological maps produced.</p><p>The AUPASED project is funded by the AFB (French Agency for Biodiversity) as part of a convention between the AFB and the CNRS (UMR 6143, M2C).</p>