Frauke Wilm, Michaela Benz, Volker Bruns, Serop Baghdadlian, Jakob Dexl, David Hartmann, Petr Kuritcyn, Martin Weidenfeller, Thomas Wittenberg, Susanne Merkel, Arndt Hartmann, Markus Eckstein, Carol Immanuel Geppert
Purpose: Automatic outlining of different tissue types in digitized histological specimen provides a basis for follow-up analyses and can potentially guide subsequent medical decisions. The immense size of whole-slide-images (WSIs), however, poses a challenge in terms of computation time. In this regard, the analysis of nonoverlapping patches outperforms pixelwise segmentation approaches but still leaves room for optimization. Furthermore, the division into patches, regardless of the biological structures they contain, is a drawback due to the loss of local dependencies.
Approach: We propose to subdivide the WSI into coherent regions prior to classification by grouping visually similar adjacent pixels into superpixels. Afterward, only a random subset of patches per superpixel is classified and patch labels are combined into a superpixel label. We propose a metric for identifying superpixels with an uncertain classification and evaluate two medical applications, namely tumor area and invasive margin estimation and tumor composition analysis.
Results: The algorithm has been developed on 159 hand-annotated WSIs of colon resections and its performance is compared with an analysis without prior segmentation. The algorithm shows an average speed-up of 41% and an increase in accuracy from 93.8% to 95.7%. By assigning a rejection label to uncertain superpixels, we further increase the accuracy by 0.4%. While tumor area estimation shows high concordance to the annotated area, the analysis of tumor composition highlights limitations of our approach.
Conclusion: By combining superpixel segmentation and patch classification, we designed a fast and accurate framework for whole-slide cartography that is AI-model agnostic and provides the basis for various medical endpoints.
The analysis and interpretation of histopathological samples and images is an important discipline in the diagnosis of
various diseases, especially cancer. An important factor in prognosis and treatment with the aim of a precision medicine
is the determination of so-called cancer stem cells (CSC) which are known for their resistance to chemotherapeutic
treatment and involvement in tumor recurrence. Using immunohistochemistry with CSC markers like CD13, CD133 and
others is one way to identify CSC. In our work we aim at identifying CSC presence on ubiquitous Hematoxilyn and Eosin
(HE) staining as an inexpensive tool for routine histopathology based on their distinct morphological features.
We present initial results of a new method based on color deconvolution (CD) and convolutional neural networks
(CNN). This method performs favorably (accuracy 0.936) in comparison with a state-of-the-art method based on 1DSIFT
and eigen-analysis feature sets evaluated on the same image database. We also show that accuracy of the CNN is
improved by the CD pre-processing.
Malaria is one of the world’s most common and serious tropical diseases, caused by parasites of the genus plasmodia that
are transmitted by Anopheles mosquitoes. Various parts of Asia and Latin America are affected but highest malaria
incidence is found in Sub-Saharan Africa. Standard diagnosis of malaria comprises microscopic detection of parasites in
stained thick and thin blood films. As the process of slide reading under the microscope is an error-prone and tedious
issue we are developing computer-assisted microscopy systems to support detection and diagnosis of malaria.
In this paper we focus on a deep learning (DL) approach for the detection of plasmodia and the evaluation of the
proposed approach in comparison with two reference approaches. The proposed classification schemes have been
evaluated with more than 180,000 automatically detected and manually classified plasmodia candidate objects from so-called
thick smears. Automated solutions for the morphological analysis of malaria blood films could apply such a
classifier to detect plasmodia in the highly complex image data of thick smears and thereby shortening the examination
time. With such a system diagnosis of malaria infections should become a less tedious, more reliable and reproducible
and thus a more objective process. Better quality assurance, improved documentation and global data availability are
additional benefits.
The morphological differentiation of bone marrow is fundamental for the diagnosis of leukemia. Currently, the counting and classification of the different types of bone marrow cells is done manually under the use of bright field microscopy. This is a time-consuming, subjective, tedious and error-prone process. Furthermore, repeated examinations of a slide may yield intra- and inter-observer variances. For that reason a computer assisted diagnosis system for bone marrow differentiation is pursued. In this work we focus (a) on a new method for the separation of nucleus and plasma parts and (b) on a knowledge-based hierarchical tree classifier for the differentiation of bone marrow cells in 16 different classes. Classification trees are easily interpretable and understandable and provide a classification together with an explanation. Using classification trees, expert knowledge (i.e. knowledge about similar classes and cell lines in the tree model of hematopoiesis) is integrated in the structure of the tree. The proposed segmentation method is evaluated with more than 10,000 manually segmented cells. For the evaluation of the proposed hierarchical classifier more than 140,000 automatically segmented bone marrow cells are used. Future automated solutions for the morphological analysis of bone marrow smears could potentially apply such an approach for the pre-classification of bone marrow cells and thereby shortening the examination time.
Oğuzhan Oğuz, Cem Emre Akbaş, Maen Mallah, Kasım Taşdemir, Ece Akhan Güzelcan, Christian Muenzenmayer, Thomas Wittenberg, Ayşegül Üner, A. Cetin, Rengül Çetin Atalay
In this article, algorithms for cancer stem cell (CSC) detection in liver cancer tissue images are developed. Conventionally, a pathologist examines of cancer cell morphologies under microscope. Computer aided diagnosis systems (CAD) aims to help pathologists in this tedious and repetitive work. The first algorithm locates CSCs in CD13 stained liver tissue images. The method has also an online learning algorithm to improve the accuracy of detection. The second family of algorithms classify the cancer tissues stained with H and E which is clinically routine and cost effective than immunohistochemistry (IHC) procedure. The algorithms utilize 1D-SIFT and Eigen-analysis based feature sets as descriptors. Normal and cancerous tissues can be classified with 92.1% accuracy in H and E stained images. Classification accuracy of low and high-grade cancerous tissue images is 70.4%. Therefore, this study paves the way for diagnosing the cancerous tissue and grading the level of it using H and E stained microscopic tissue images.
The morphological analysis of bone marrow smears is fundamental for the diagnosis of leukemia. Currently, the counting and classification of the different types of bone marrow cells is done manually with the use of bright field microscope. This is a time consuming, partly subjective and tedious process. Furthermore, repeated examinations of a slide yield intra- and inter-observer variances. For this reason an automation of morphological bone marrow analysis is pursued. This analysis comprises several steps: image acquisition and smear detection, cell localization and segmentation, feature extraction and cell classification. The automated classification of bone marrow cells is depending on the automated cell segmentation and the choice of adequate features extracted from different parts of the cell. In this work we focus on the evaluation of support vector machines (SVMs) and random forests (RFs) for the differentiation of bone marrow cells in 16 different classes, including immature and abnormal cell classes. Data sets of different segmentation quality are used to test the two approaches. Automated solutions for the morphological analysis for bone marrow smears could use such a classifier to pre-classify bone marrow cells and thereby shortening the examination duration.
KEYWORDS: Panoramic photography, Bladder, Video, Cystoscopy, Electroluminescent displays, Endoscopes, Distortion, In vivo imaging, Visualization, Surgery
Inspection of the urinary bladder with an endoscope (cystoscope) is the usual procedure for early detection of bladder cancer. The very limited field of view provided by the endoscope makes it challenging to ensure, that the interior bladder wall has been examined completely. Panorama imaging techniques can be used to assist the surgeon and provide a larger view field. Different approaches have been proposed, but generating a panorama image of the entire bladder from real patient data is still a challenging research topic. We propose a graph-based and hierarchical approach to assess this problem to first generate several local panorama images, followed by a global textured three-dimensional reconstruction of the organ. In this contribution, we address details of the first level of the approach including a graph-based algorithm to deal with the challenging condition of in-vivo data. This graph strategy gives rise to a robust relocalization strategy in case of tracking failure, an effective keyframe
selection process as well as the concept of building locally optimized sub-maps, which lay the ground for a global optimization process. Our results show the successful application of the method to four in-vivo data sets.
Computer-assisted diagnosis (CADx) for the interactive characterization of mammographic masses as benign or malignant has a high potential to help radiologists during the critical process of diagnostic decision making. By default, the characterization of mammographic masses is performed by extracting features from a region of interest (ROI) depicting the mass. To investigate the influence of a so-called bilateral filter based emph{flat texture} (FT) preprocessing step on the classification performance, textural as well as frequency-based features are calculated in the ROI, in the core of the mass and in the mass margin for preprocessed and unprocessed images. Furthermore. the influence of the parameterization of the bilateral filter on the classification performance is investigated. Additionally, as reference Median and Gaussian filters have been used to compute the FT image and the resulting classification performances of the feature extractors are compared to those obtained with the bilateral filters. Classification is done using a k-NN classifier. The classification performance was evaluated using the area Az under the receiver operating characteristic (ROC) curve. A publicly available mammography database was used as reference image data set. The results show that the proposed FT preprocessing step has a positive influence on the texture-based feature extractors while most of the frequency-based feature extractors perform better on the unprocessed images. For some of the features the original Az could be improved up to 10%. The comparison of the bilateral filter approach with the Median and Gaussian filter approaches showed the superiority of the bilateral filter.
Computer-assisted diagnosis (CADx) for the characterization of mammographic masses as benign or malignant has a very high potential to help radiologists during the critical process of diagnostic decision making.
By default, the characterization of mammographic masses is performed by extracting features from a region of interest (ROI) depicting the mass.
To investigate the influence of the region on the classification performance, textural, morphological, frequency- as well as moment-based features are calculated in subregions of the ROI, which has been delineated manually by an expert.
The investigated subregions are
(a) the semi-automatically segmented area which includes only the core of the mass,
(b) the outer border region of the mass, and
(c) the combination of the outer and the inner border region, referred to as mass margin.
To extract the border region and the margin of a mass an extended version of the rubber band straightening transform (RBST) was developed. Furthermore, the effectiveness of the features extracted from the RBST transformed border region and mass margin is compared to the effectiveness of the same features extracted from the untransformed regions.
After the feature extraction process a preferably optimal feature subset is selected for each feature extractor. Classification is done using a k-NN classifier.
The classification performance was evaluated using the area Az under the receiver operating characteristic curve.
A publicly available mammography database was used as data set. Results showed that the manually drawn ROI lead to superior classification performances for the morphological feature extractors and that the transformed outer border region and the mass margin are not suitable for moment-based features but yield to promising results for textural and frequency-based features.
Beyond that the mass margin, which combines the inner and the outer border region, leads to better classification performances compared to the outer border region for its own.
Virtual microscopy has the potential to partially replace traditional microscopy. For virtualization, the slide is scanned once by a fully automatized robotic microscope and saved digitally. Typically, such a scan results in several hundreds to thousands of fields of view. Since robotic stages have positioning errors, these fields of view have to be registered locally and globally in an additional step. In this work we propose a new global mosaicking method for the creation of virtual slides based on sub-pixel exact phase correlation for local alignment in combination with Prim's minimum spanning tree algorithm for global alignment. Our algorithm allows for a robust reproduction of the original slide even in the presence of views with little to no information content. This makes it especially suitable for the mosaicking of cervical smears. These smears often exhibit large empty areas, which do not contain enough information for common stitching approaches.
KEYWORDS: Computer aided diagnosis and therapy, Breast cancer, Picture Archiving and Communication System, Mammography, Magnetic resonance imaging, Telecommunications, Medical imaging, Ultrasonography, Breast, Digital breast tomosynthesis
While screening mammography is accepted as the most adequate technique for the early detection of breast cancer, its low positive predictive value leads to many breast biopsies performed on benign lesions. Therefore, we have previously developed a knowledge-based system for computer-aided diagnosis (CADx) of mammographic lesions. It supports the radiologist in the discrimination of benign and malignant lesions. So far, our approach operates on the lesion level and employs the paradigm of content-based image retrieval (CBIR). Similar lesions with known diagnosis are retrieved automatically from a library of references. However, radiologists base their diagnostic decisions on additional resources, such as related mammographic projections, other modalities (e.g. ultrasound, MRI), and clinical data. Nonetheless, most CADx systems disregard the relation between the craniocaudal (CC) and mediolateral-oblique (MLO) views of conventional mammography. Therefore, we extend our approach to the full case level: (i) Multi-frame features are developed that jointly describe a lesion in different views of mammography. Taking into account the geometric relation between different images, these features can also be extracted from multi-modal data; (ii) the CADx system architecture is extended appropriately; (iii) the CADx system is integrated into the radiology information system (RIS) and the picture archiving and communication system (PACS). Here, the framework for image retrieval in medical applications (IRMA) is used to support access to the patient's health care record. Of particular interest is the application of the proposed CADx system to digital breast tomosynthesis (DBT), which has the potential to succeed digital mammography as the standard technique for breast cancer screening. The proposed system is a natural extension of CADx approaches that integrate only two modalities. However, we are still collecting a large enough database of breast lesions with images from multiple modalities to evaluate the benefits of the proposed approach on.
KEYWORDS: Esophagus, Cancer, Computer aided diagnosis and therapy, Medical imaging, Current controlled current source, Therapeutics, Standards development, Biopsy, Visible radiation
Cancer of the esophagus has the worst prediction of all known cancers in Germany. The early detection of suspicious changes in the esophagus allows therapies that can prevent the cancer. Barrett's esophagus is a premalignant change of the esophagus that is a strong indication for cancer. Therefore there is a big interest to detect Barrett's esophagus as early as possible. The standard examination is done with a videoscope where the physician checks the esophagus for suspicious regions. Once a suspicious region is found, the physician takes a biopsy of that region to get a histological result of it. Besides the traditional white light for the illumination there is a new technology: the so called narrow-band Imaging (NBI). This technology uses a smaller spectrum of the visible light to highlight the scene captured by the videoscope. Medical studies indicate that the use of NBI instead of white light can increase the rate of correct diagnoses of a physician. In the future, Computer-Assisted Diagnosis (CAD) which is well known in the area of mammography might be used to support the physician in the diagnosis of different lesions in the esophagus. A knowledge-based system which uses a database is a possible solution for this task. For our work we have collected NBI images containing 326 Regions of Interest (ROI) of three typical classes: epithelium, cardia mucosa and Barrett's esophagus. We then used standard texture analysis features like those proposed by Haralick, Chen, Gabor and Unser to extract features from every ROI. The performance of the classification was evaluated with a classifier using the leaving-one-out sampling. The best result that was achieved is an accuracy of 92% for all classes and an accuracy of 76% for Barrett's esophagus. These results show that the NBI technology can provide a good diagnosis support when used in a CAD system.
An alternative solution for surface inspection is being presented. It is based on a concerted combination of an adapted stripe-illumination principle together with an image processing approach specialized on the analysis of the obtained stripe images. This approach is capable of detecting, segmenting, and classifying nondefective surfaces, as well as three- and two-dimensional defective surfaces from perturbations in the stripe illumination. In contrast to alternative procedures, no calibration of illumination or camera is necessary. The principle of the proposed method using a concrete industrial application for the inspection of cylindrical metallic surfaces under structured lighting is explained. Furthermore, based on several examples involving different surface types, we demonstrate the broad range of applications for the proposed algorithm.
In optical nondestructive testing, a novel solution is presented for fault detection based on the interpretation of fringe images. These images can be acquired using different optical methods, such as structured lighting or interferometry. We propose a set of eight special features adapted to the problem of surface inspection using structured illumination. These characteristics are combined with six further features specially developed for the classification of faults using interferometric images. We apply two kinds of decision rules: the Bayesian and the nearest neighbor classifiers. The proposed features are evaluated using a noisy and a noise-free image data set. All patterns were obtained by means of structured lighting. Concerning the noisy data set, we obtain better classification rates when all the 14 features are used in combination with a one-nearest-neighbor classifier. In case of a noise-free data set, we show that similar classification rates are obtained when the 14 features or only the 8 specific features are involved. The methods described are designed to address a broad range of optical nondestructive applications involving the interpretation and classification of fringe patterns.
The exact segmentation of nucleus and plasma of a white blood cell (leukocyte) is the basis for the creation of an
automatic, image based differential white blood cell count(WBC). In this contribution we present an approach
for the according segmentation of leukocytes. For a valid classification of the different cell classes, a precise
segmentation is essential. Especially concerning immature cells, which can be distinguished from their mature
counterparts only by small differences in some features, a segmentation of nucleus and plasma has to be as precise
as possible, to extract those differences. Also the problems with adjacent erythrocyte cells and the usage of a LED
illumination are considered. The presented approach can be separated into several steps. After preprocessing by
a Kuwahara-filter, the cell is localized by a simple thresholding operation, afterwards a fast-marching method for
the localization of a rough cell boundary is defined. To retrieve the cell area a shortest-path-algorithm is applied
next. The cell boundary found by the fast-marching approach is finally enhanced by a post-processing step. The
concluding segmentation of the cell nucleus is done by a threshold operation. An evaluation of the presented
method was done on a representative sample set of 80 images recorded with LED illumination and a 63-fold
magnification dry objective. The automatically segmented cell images are compared to a manual segmentation
of the same dataset using the Dice-coefficient as well as Hausdorff-distance. The results show that our approach
is able to handle the different cell classes and that it improves the segmentation quality significantly.
A digital high-speed camera system for the endoscopic examination of the larynx delivers recording speeds of up to 10,000 frames/s. Recordings of up to 1 s duration can be stored and used for further evaluation. Maximum resolution is 128 multiplied by 128 pixel. The acoustic and electroglottographic signals are recorded simultaneously. An image processing program especially developed for this purpose renders time-way-waveforms (high-speed glottograms) of several locations on the vocal cords. From the graphs all of the known objective parameters of the voice can be derived. Results of examinations in normal subjects and patients are presented.
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