A Survey on Various Brain MR Image Segmentation Techniques

Prior to medical image analysis, segmentation is an essential step in the preprocessing process. Partitioning an image into distinct regions based on characteristics like texture, color, and intensity is its primary goal. Numerous applications include tumor and coronary border recognition, surgical planning, tumor volume measurement, blood cell classification and heart image extraction from cardiac cine angiograms are all made possible by this technique. Many segmentation methods have been proposed recently for medical images. Thresholding, region-based, edge-based, clustering-based and fuzzy based methods are the most important segmentation processes in medical image analysis. A variety of image segmentation methods have been developed by researchers for efficient analysis. An overview of widely used image segmentation methods, along with their benefits and drawbacks, is provided in this paper

Image Segmentation Techniques: A Survey

Segmenting an image utilizing diverse strategies is the primary technique of Image Processing. The technique is broadly utilized in clinical image handling, face acknowledgment, walker location, and so on. Various objects in an image can be recognized using image segmentation methods. Researchers have come up with various image segmentation methods for effective analysis. This paper presents a survey and sums up the designs process of essential image segmentation methods broadly utilized with their advantages and weaknesses

Image Segmentation Techniques: A Survey

Segmenting an image utilizing diverse strategies is the primary technique of Image Processing. The technique is broadly utilized in clinical image handling, face acknowledgment, walker location, and so on. Various objects in an image can be recognized using image segmentation methods. Researchers have come up with various image segmentation methods for effective analysis. This paper presents a survey and sums up the designs process of essential image segmentation methods broadly utilized with their advantages and weaknesses

Automated detection of brain abnormalities in neonatal hypoxia ischemic injury from MR images.

We compared the efficacy of three automated brain injury detection methods, namely symmetry-integrated region growing (SIRG), hierarchical region splitting (HRS) and modified watershed segmentation (MWS) in human and animal magnetic resonance imaging (MRI) datasets for the detection of hypoxic ischemic injuries (HIIs). Diffusion weighted imaging (DWI, 1.5T) data from neonatal arterial ischemic stroke (AIS) patients, as well as T2-weighted imaging (T2WI, 11.7T, 4.7T) at seven different time-points (1, 4, 7, 10, 17, 24 and 31 days post HII) in rat-pup model of hypoxic ischemic injury were used to assess the temporal efficacy of our computational approaches. Sensitivity, specificity, and similarity were used as performance metrics based on manual ('gold standard') injury detection to quantify comparisons. When compared to the manual gold standard, automated injury location results from SIRG performed the best in 62% of the data, while 29% for HRS and 9% for MWS. Injury severity detection revealed that SIRG performed the best in 67% cases while 33% for HRS. Prior information is required by HRS and MWS, but not by SIRG. However, SIRG is sensitive to parameter-tuning, while HRS and MWS are not. Among these methods, SIRG performs the best in detecting lesion volumes; HRS is the most robust, while MWS lags behind in both respects

Computerized Analysis of Magnetic Resonance Images to Study Cerebral Anatomy in Developing Neonates

The study of cerebral anatomy in developing neonates is of great importance for the understanding of brain development during the early period of life. This dissertation therefore focuses on three challenges in the modelling of cerebral anatomy in neonates during brain development. The methods that have been developed all use Magnetic Resonance Images (MRI) as source data. To facilitate study of vascular development in the neonatal period, a set of image analysis algorithms are developed to automatically extract and model cerebral vessel trees. The whole process consists of cerebral vessel tracking from automatically placed seed points, vessel tree generation, and vasculature registration and matching. These algorithms have been tested on clinical Time-of- Flight (TOF) MR angiographic datasets. To facilitate study of the neonatal cortex a complete cerebral cortex segmentation and reconstruction pipeline has been developed. Segmentation of the neonatal cortex is not effectively done by existing algorithms designed for the adult brain because the contrast between grey and white matter is reversed. This causes pixels containing tissue mixtures to be incorrectly labelled by conventional methods. The neonatal cortical segmentation method that has been developed is based on a novel expectation-maximization (EM) method with explicit correction for mislabelled partial volume voxels. Based on the resulting cortical segmentation, an implicit surface evolution technique is adopted for the reconstruction of the cortex in neonates. The performance of the method is investigated by performing a detailed landmark study. To facilitate study of cortical development, a cortical surface registration algorithm for aligning the cortical surface is developed. The method first inflates extracted cortical surfaces and then performs a non-rigid surface registration using free-form deformations (FFDs) to remove residual alignment. Validation experiments using data labelled by an expert observer demonstrate that the method can capture local changes and follow the growth of specific sulcus

Airway analysis of prematurely born babies based on X-ray CT and MRI scans

Předkládaná Diplomová práce se zabývá analýzou a tvorbou modelů dýchacích cest předčasně narozených dětí. Nejprve je položen teoretický základ v oblasti vývoje dýchacího ústrojí a tvorby modelů dýchacích cest. Poté jsou představeny využité zobrazovací modality a popsány metody pro práci s obrazovými daty. Praktická část práce se zabývá vytvořením modelů dýchacích cest tří novorozenců. Všechny tyto modely jsou vytvořeny na základě klinických CT a MRI dat novorozenců narozených ve 30. týdnu gestačního věku. U těchto vytvořených modelů jsou dále analyzovány vybrané parametry související s anatomickou strukturou dýchacích cest. Na základě analýzy těchto parametrů byl následně navrhnut reprezentativní model, odpovídající dýchacím cestám novorozence daného gestačního věku.The proposed Master’s thesis deals with the analysis and creation of airway models of premature babies. Firstly, the theoretical basis is discussed in the field of development of the respiratory system and the creation of airway models. Then the used imaging modalities are introduced, and methods for working with image data are described. The practical part of the thesis deals with the creation of airway models of three newborns. All of these models are based on clinical CT and MRI data of neonates born at 30 weeks of gestational age. In these created models, selected parameters related to the anatomical structure of the airways are further analysed. Based on the analysis of these parameters, a representative model corresponding to the airways of a newborn of a given gestational age was subsequently proposed.

White matter volume assessment in premature infants on MRI at term - computer aided volume analysis

The objective of this study is the development of an automatic segmentation framework for measuring volume changes in the white matter tissue from premature infant MRI data. The early stage of the brain development presents several major computational challenges such as structure and shape variations between patients. Furthermore, a high water content is present in the brain tissue, that leads to inconsistencies and overlapping intensity values across different brain structures. Another problem lies in low-frequency multiplicative intensity variations, which arises from an inhomogeneous magnetic field during the MRI acquisition. Finally, the segmentation is influenced by the partial volume effects which describe voxels that are generated by more than one tissue type. To overcome these challenges, this study is divided into three parts with the intention to locally segment the white matter tissue without the guidance of an atlas. Firstly, a novel brain extraction method is proposed with the aim to remove all non-brain tissue. The data quality can be improved by noise reduction using an anisotropic diffusion filter and intensity variations adjustments throughout the volume. In order to minimise the influence of missing contours and overlapping intensity values between brain and nonbrain tissue, a brain mask is created and applied during the extraction of the brain tissue. Secondly, the low-frequency intensity inhomogeneities are addressed by calculating the bias field which can be separated and corrected using low pass filtering. Finally, the segmentation process is performed by combining probabilistic clustering with classification algorithms. In order to achieve the final segmentation, the algorithm starts with a pre-segmentation procedure which was applied to reduce the intensity inhomogeneities within the white matter tissue. The key element in the segmentation process is the classification of diffused and missing contours as well as the partial volume voxels by performing a voxel reclassification scheme. The white matter segmentation framework was tested using the Dice Similarity Metric, and the numerical evaluation demonstrated precise segmentation results

Methodology for extensive evaluation of semiautomatic and interactive segmentation algorithms using simulated Interaction models

Performance of semiautomatic and interactive segmentation(SIS) algorithms are usually evaluated by employing a small number of human operators to segment the images. The human operators typically provide the approximate location of objects of interest and their boundaries in an interactive phase, which is followed by an automatic phase where the segmentation is performed under the constraints of the operator-provided guidance. The segmentation results produced from this small set of interactions do not represent the true capability and potential of the algorithm being evaluated. For example, due to inter-operator variability, human operators may make choices that may provide either overestimated or underestimated results. As well, their choices may not be realistic when compared to how the algorithm is used in the field, since interaction may be influenced by operator fatigue and lapses in judgement. Other drawbacks to using human operators to assess SIS algorithms, include: human error, the lack of available expert users, and the expense. A methodology for evaluating segmentation performance is proposed here which uses simulated Interaction models to programmatically generate large numbers of interactions to ensure the presence of interactions throughout the object region. These interactions are used to segment the objects of interest and the resulting segmentations are then analysed using statistical methods. The large number of interactions generated by simulated interaction models capture the variabilities existing in the set of user interactions by considering each and every pixel inside the entire region of the object as a potential location for an interaction to be placed with equal probability. Due to the practical limitation imposed by the enormous amount of computation for the enormous number of possible interactions, uniform sampling of interactions at regular intervals is used to generate the subset of all possible interactions which still can represent the diverse pattern of the entire set of interactions. Categorization of interactions into different groups, based on the position of the interaction inside the object region and texture properties of the image region where the interaction is located, provides the opportunity for fine-grained algorithm performance analysis based on these two criteria. Application of statistical hypothesis testing make the analysis more accurate, scientific and reliable in comparison to conventional evaluation of semiautomatic segmentation algorithms. The proposed methodology has been demonstrated by two case studies through implementation of seven different algorithms using three different types of interaction modes making a total of nine segmentation applications to assess the efficacy of the methodology. Application of this methodology has revealed in-depth, fine details about the performance of the segmentation algorithms which currently existing methods could not achieve due to the absence of a large, unbiased set of interactions. Practical application of the methodology for a number of algorithms and diverse interaction modes have shown its feasibility and generality for it to be established as an appropriate methodology. Development of this methodology to be used as a potential application for automatic evaluation of the performance of SIS algorithms looks very promising for users of image segmentation