Application of radial ray based segmentation to cervical lymph nodes in CT images

Deep Reinforcement Learning for Weakly-Supervised Lymph Node Segmentation in CT Images

Accurate and automated lymph node segmentation is pivotal for quantitatively accessing disease progression and potential therapeutics. The complex variation of lymph node morphology and the difficulty of acquiring voxel-wise manual annotations make lymph node segmentation a challenging task. Since the Response Evaluation Criteria in Solid Tumors (RECIST) annotation, which indicates the location, length, and width of a lymph node, is commonly available in hospital data archives, we advocate to use RECIST annotations as the supervision, and thus formulate this segmentation task into a weakly-supervised learning problem. In this paper, we propose a deep reinforcement learning-based lymph node segmentation (DRL-LNS) model. Based on RECIST annotations, we segment RECIST-slices in an unsupervised way to produce pseudo ground truths, which are then used to train U-Net as a segmentation network. Next, we train a DRL model, in which the segmentation network interacts with the policy network to optimize the lymph node bounding boxes and segmentation results simultaneously. The proposed DRL-LNS model was evaluated against three widely used image segmentation networks on a public thoracoabdominal Computed Tomography (CT) dataset that contains 984 3D lymph nodes, and achieves the mean Dice similarity coefficient (DSC) of 77.17% and the mean Intersection over Union (IoU) of 64.78% in the four-fold cross-validation. Our results suggest that the DRL-based bounding box prediction strategy outperforms the label propagation strategy and the proposed DRL-LNS model is able to achieve the state-of-the-art performance on this weakly-supervised lymph node segmentation task.

3D Neuron Microscopy Image Segmentation via the Ray-Shooting Model and a DC-BLSTM Network

The morphology reconstruction (tracing) of neurons in 3D microscopy images is important to neuroscience research. However, this task remains very challenging because of the low signal-to-noise ratio (SNR) and the discontinued segments of neurite patterns in the images. In this paper, we present a neuronal structure segmentation method based on the ray-shooting model and the Long Short-Term Memory (LSTM)-based network to enhance the weak-signal neuronal structures and remove background noise in 3D neuron microscopy images. Specifically, the ray-shooting model is used to extract the intensity distribution features within a local region of the image. And we design a neural network based on the dual channel bidirectional LSTM (DC-BLSTM) to detect the foreground voxels according to the voxel-intensity features and boundary-response features extracted by multiple ray-shooting models that are generated in the whole image. This way, we transform the 3D image segmentation task into multiple 1D ray/sequence segmentation tasks, which makes it much easier to label the training samples than many existing Convolutional Neural Network (CNN) based 3D neuron image segmentation methods. In the experiments, we evaluate the performance of our method on the challenging 3D neuron images from two datasets, the BigNeuron dataset and the Whole Mouse Brain Sub-image (WMBS) dataset. Compared with the neuron tracing results on the segmented images produced by other state-of-the-art neuron segmentation methods, our method improves the distance scores by about 32% and 27% in the BigNeuron dataset, and about 38% and 27% in the WMBS dataset.

PETMiner-A Visual Analysis Tool for Petrophysical Properties of Core Sample Data

The aim of the PETMiner software is to reduce the time and monetary cost of analysing petrophysical data that is obtained from reservoir sample cores. Analysis of these data requires tacit knowledge to fill 'gaps' so that predictions can be made for incomplete data. Through discussions with 30 industry and academic specialists, we identified three analysis use cases that exemplified the limitations of current petrophysics analysis tools. We used those use cases to develop nine core requirements for PETMiner, which is innovative because of its ability to display detailed images of the samples as data points, directly plot multiple sample properties and derived measures for comparison, and substantially reduce interaction cost. An 11-month evaluation demonstrated benefits across all three use cases by allowing a consultant to: (1) generate more accurate reservoir flow models, (2) discover a previously unknown relationship between one easy-to-measure property and another that is costly, and (3) make a 100-fold reduction in the time required to produce plots for a report.

Visualization System Requirements for Data Processing Pipeline Design and Optimization

The rising quantity and complexity of data creates a need to design and optimize data processing pipelines-the set of data processing steps, parameters and algorithms that perform operations on the data. Visualization can support this process but, although there are many examples of systems for visual parameter analysis, there remains a need to systematically assess users' requirements and match those requirements to exemplar visualization methods. This article presents a new characterization of the requirements for pipeline design and optimization. This characterization is based on both a review of the literature and first-hand assessment of eight application case studies. We also match these requirements with exemplar functionality provided by existing visualization tools. Thus, we provide end-users and visualization developers with a way of identifying functionality that addresses data processing problems in an application. We also identify seven future challenges for visualization research that are not met by the capabilities of today's systems.

Visual parameter optimisation for biomedical image processing

Background

Biomedical image processing methods require users to optimise input parameters to ensure high-quality output. This presents two challenges. First, it is difficult to optimise multiple input parameters for multiple input images. Second, it is difficult to achieve an understanding of underlying algorithms, in particular, relationships between input and output.

Results

We present a visualisation method that transforms users' ability to understand algorithm behaviour by integrating input and output, and by supporting exploration of their relationships. We discuss its application to a colour deconvolution technique for stained histology images and show how it enabled a domain expert to identify suitable parameter values for the deconvolution of two types of images, and metrics to quantify deconvolution performance. It also enabled a breakthrough in understanding by invalidating an underlying assumption about the algorithm.

Conclusions

The visualisation method presented here provides analysis capability for multiple inputs and outputs in biomedical image processing that is not supported by previous analysis software. The analysis supported by our method is not feasible with conventional trial-and-error approaches.