An Information Theoretic Approach For Feature Selection And Segmentation In Posterior Fossa Tumors

Posterior Fossa (PF) is a type of brain tumor located in or near brain stem and cerebellum. About 55% - 70 % pediatric brain tumors arise in the posterior fossa, compared with only 15% - 20% of adult tumors. For segmenting PF tumors we should have features to study the characteristics of tumors. In literature, different types of texture features such as Fractal Dimension (FD) and Multifractional Brownian Motion (mBm) have been exploited for measuring randomness associated with brain and tumor tissues structures, and the varying appearance of tissues in magnetic resonance images (MRI). For selecting best features techniques such as neural network and boosting methods have been exploited. However, neural network cannot descirbe about the properties of texture features. We explore methods such as information theroetic methods which can perform feature selection based on properties of texture features. The primary contribution of this dissertation is investigating efficacy of different image features such as intensity, fractal texture, and level - set shape in segmentation of PF tumor for pediatric patients. We explore effectiveness of using four different feature selection and three different segmentation techniques respectively to discriminate tumor regions from normal tissue in multimodal brain MRI. Our research suggest that Kullback - Leibler Divergence (KLD) measure for feature ranking and selection and Expectation Maximization (EM) algorithm for feature fusion and tumor segmentation offer the best performance for the patient data in this study. To improve segmentation accuracy, we need to consider abnormalities such as cyst, edema and necrosis which surround tumors. In this work, we exploit features which describe properties of cyst and technique which can be used to segment it. To achieve this goal, we extend the two class KLD techniques to multiclass feature selection techniques, so that we can effectively select features for tumor, cyst and non tumor tissues. We compute segemntation accuracy by computing number of pixels segemented to total number of pixels for the best features. For automated process we integrate the inhomoheneity correction, feature selection using KLD and segmentation in an integrated EM framework. To validate results we have used similarity coefficients for computing the robustness of segmented tumor and cyst

Texture analysis of multimodal magnetic resonance images in support of diagnostic classification of childhood brain tumours

Primary brain tumours are recognised as the most common form of solid tumours in children, with pilocytic astrocytoma, medulloblastoma and ependymoma being found most frequently. Despite their high mortality rate, early detection can be facilitated through the use of Magnetic Resonance Imaging (MRI), which is the preferred scanning technique for paediatric patients. MRI offers a variety of imaging sequences through structural and functional imaging, as well as providing complementary tissue information. However visual examination of MR images provides limited ability to characterise distinct histological types of brain tumours. In order to improve diagnostic classification, we explore the use of a computer-aided system based on texture analysis (TA) methods. TA has been applied on conventional MRI but has been less commonly studied on diffusion MRI of brain-related pathology. Furthermore, the combination of textural features derived from both imaging approaches has not yet been widely studied. In this thesis, the aim of the research is to investigate TA based on multi-centre multimodal MRI, in order to provide more comprehensive information and develop an automated processing framework for the classification of childhood brain tumours

Characterization of alar ligament on 3.0T MRI: a cross-sectional study in IIUM Medical Centre, Kuantan

INTRODUCTION: The main purpose of the study is to compare the normal anatomy of alar ligament on MRI between male and female. The specific objectives are to assess the prevalence of alar ligament visualized on MRI, to describe its characteristics in term of its course, shape and signal homogeneity and to find differences in alar ligament signal intensity between male and female. This study also aims to determine the association between the heights of respondents with alar ligament signal intensity and dimensions. MATERIALS & METHODS: 50 healthy volunteers were studied on 3.0T MR scanner Siemens Magnetom Spectra using 2-mm proton density, T2 and fat-suppression sequences. Alar ligament is depicted in 3 planes and the visualization and variability of the ligament courses, shapes and signal intensity characteristics were determined. The alar ligament dimensions were also measured. RESULTS: Alar ligament was best depicted in coronal plane, followed by sagittal and axial planes. The orientations were laterally ascending in most of the subjects (60%), predominantly oval in shaped (54%) and 67% showed inhomogenous signal. No significant difference of alar ligament signal intensity between male and female respondents. No significant association was found between the heights of the respondents with alar ligament signal intensity and dimensions. CONCLUSION: Employing a 3.0T MR scanner, the alar ligament is best portrayed on coronal plane, followed by sagittal and axial planes. However, tremendous variability of alar ligament as depicted in our data shows that caution needs to be exercised when evaluating alar ligament, especially during circumstances of injury

Case series of breast fillers and how things may go wrong: radiology point of view

INTRODUCTION: Breast augmentation is a procedure opted by women to overcome sagging breast due to breastfeeding or aging as well as small breast size. Recent years have shown the emergence of a variety of injectable materials on market as breast fillers. These injectable breast fillers have swiftly gained popularity among women, considering the minimal invasiveness of the procedure, nullifying the need for terrifying surgery. Little do they know that the procedure may pose detrimental complications, while visualization of breast parenchyma infiltrated by these fillers is also deemed substandard; posing diagnostic challenges. We present a case series of three patients with prior history of hyaluronic acid and collagen breast injections. REPORT: The first patient is a 37-year-old lady who presented to casualty with worsening shortness of breath, non-productive cough, central chest pain; associated with fever and chills for 2-weeks duration. The second patient is a 34-year-old lady who complained of cough, fever and haemoptysis; associated with shortness of breath for 1-week duration. CT in these cases revealed non thrombotic wedge-shaped peripheral air-space densities. The third patient is a 37‐year‐old female with right breast pain, swelling and redness for 2- weeks duration. Previous collagen breast injection performed 1 year ago had impeded sonographic visualization of the breast parenchyma. MRI breasts showed multiple non- enhancing round and oval shaped lesions exhibiting fat intensity. CONCLUSION: Radiologists should be familiar with the potential risks and hazards as well as limitations of imaging posed by breast fillers such that MRI is required as problem-solving tool

Clinical Management and Evolving Novel Therapeutic Strategies for Patients with Brain Tumors

A dramatic increase in knowledge regarding the molecular biology of brain tumors has been established over the past few years, and this has lead to the development of novel therapeutic strategies for these patients. In this book a review of the options available for the clinical management of patients with these tumors are outlined. In addition advances in radiology both for pre-operative diagnostic purposes along with surgical planning are described. Furthermore a review of newer developments in chemotherapy along with the evolving field of photodynamic therapy both for intra-operative management and subsequent therapy is provided. A discussion of certain surgical management issues along with tumor induced epilepsy is included. Finally a discussion of the management of certain unique problems including brain metastases, brainstem glioma, central nervous system lymphoma along with issues involving patients with a brain tumor and pregnancy is provided

Effect of Mandibular Displacement on Condylar Cartilage Remodelling In Sprague Dawley Rats: A Micro-Structural Analysis

Three dimensional (3D) imaging of cartilage has always been difficult due to the inherent intermediary density between soft tissue and hard tissue in X-rays images, particularly in Micro Computer Tomography (MicroCT). Recent advances in imaging techniques have allowed for the enhancement of cartilage visualization for MicroCT use. Aim: The objective of this study was to provide a new insight in understanding changes in condylar cartilage, determined qualitatively and quantitatively, with normal growth and after the placement of an appliance over a 4 week period. Materials and Methods: Seventy Sprague Dawley rats (five weeks old) were divided into either a control group or an experimental group in which bite ramps were placed on the lower incisors at Day 0. Animals were sacrificed at Days 0, 7, 21 and 28. Right hemisections were then taken and stained with gadolinium chloride for six days before being scanned via a MicroCT unit. Condylar cartilage was digitally extracted from the scans and volumetric measurements were carried out and assessed quantitatively. Three dimensional images of the condyles were also assessed qualitatively for morphological changes between appliances and over the experimental duration. An intra-individual method error study was also carried out. Results Conformational changes were noted in the shape of the condyle between appliance groups and over the treatment duration. Qualitative assessment of the condyles demonstrated a reduction in size over time in all groups with a change in shape of the condylar heads. Anterior displacement of the mandible resulted in significant remodeling and distinctive shape changes that differ from both control and posterior displacement groups. Quantitative analysis demonstrated differences between control and appliance groups in regards to Total volume of the whole condylar head, Total cartilage volume, Total volume of the posterior hemisection of the condylar head and Posterior cartilage volume. The Method error study demonstrated the high reproducibility of results with a coefficient of variation of 5-13%. Discussion This study demonstrated a new method for analysing changes in the condylar head following orthopaedic intervention. Assessment of these changes in the condylar head can now be depicted via a three dimensional, non-destructive method. Hence, growth changes of the condylar head can now be evaluated in its totality compared to traditional methods of assessing cartilage changes sectionally via histological slices. Therefore, this provides a new avenue for improving our understanding in the changes that occur in the condylar head with growth and after intervention. It may also promote further investigations into the effects of systemic drugs on normal growth and manipulation of this important site of growth

Effect of Mandibular Displacement on Condylar Cartilage Remodelling In Sprague Dawley Rats: A Micro-Structural Analysis

Three dimensional (3D) imaging of cartilage has always been difficult due to the inherent intermediary density between soft tissue and hard tissue in X-rays images, particularly in Micro Computer Tomography (MicroCT). Recent advances in imaging techniques have allowed for the enhancement of cartilage visualization for MicroCT use. Aim: The objective of this study was to provide a new insight in understanding changes in condylar cartilage, determined qualitatively and quantitatively, with normal growth and after the placement of an appliance over a 4 week period. Materials and Methods: Seventy Sprague Dawley rats (five weeks old) were divided into either a control group or an experimental group in which bite ramps were placed on the lower incisors at Day 0. Animals were sacrificed at Days 0, 7, 21 and 28. Right hemisections were then taken and stained with gadolinium chloride for six days before being scanned via a MicroCT unit. Condylar cartilage was digitally extracted from the scans and volumetric measurements were carried out and assessed quantitatively. Three dimensional images of the condyles were also assessed qualitatively for morphological changes between appliances and over the experimental duration. An intra-individual method error study was also carried out. Results Conformational changes were noted in the shape of the condyle between appliance groups and over the treatment duration. Qualitative assessment of the condyles demonstrated a reduction in size over time in all groups with a change in shape of the condylar heads. Anterior displacement of the mandible resulted in significant remodeling and distinctive shape changes that differ from both control and posterior displacement groups. Quantitative analysis demonstrated differences between control and appliance groups in regards to Total volume of the whole condylar head, Total cartilage volume, Total volume of the posterior hemisection of the condylar head and Posterior cartilage volume. The Method error study demonstrated the high reproducibility of results with a coefficient of variation of 5-13%. Discussion This study demonstrated a new method for analysing changes in the condylar head following orthopaedic intervention. Assessment of these changes in the condylar head can now be depicted via a three dimensional, non-destructive method. Hence, growth changes of the condylar head can now be evaluated in its totality compared to traditional methods of assessing cartilage changes sectionally via histological slices. Therefore, this provides a new avenue for improving our understanding in the changes that occur in the condylar head with growth and after intervention. It may also promote further investigations into the effects of systemic drugs on normal growth and manipulation of this important site of growth

Endoscopy

Endoscopy is a fast moving field, and new techniques are continuously emerging. In recent decades, endoscopy has evolved and branched out from a diagnostic modality to enhanced video and computer assisting imaging with impressive interventional capabilities. The modern endoscopy has seen advances not only in types of endoscopes available, but also in types of interventions amenable to the endoscopic approach. To date, there are a lot more developments that are being trialed. Modern endoscopic equipment provides physicians with the benefit of many technical advances. Endoscopy is an effective and safe procedure even in special populations including pediatric patients and renal transplant patients. It serves as the tool for diagnosis and therapeutic interventions of many organs including gastrointestinal tract, head and neck, urinary tract and others

Advanced Computational Methods for Oncological Image Analysis

[Cancer is the second most common cause of death worldwide and encompasses highly variable clinical and biological scenarios. Some of the current clinical challenges are (i) early diagnosis of the disease and (ii) precision medicine, which allows for treatments targeted to specific clinical cases. The ultimate goal is to optimize the clinical workflow by combining accurate diagnosis with the most suitable therapies. Toward this, large-scale machine learning research can define associations among clinical, imaging, and multi-omics studies, making it possible to provide reliable diagnostic and prognostic biomarkers for precision oncology. Such reliable computer-assisted methods (i.e., artificial intelligence) together with clinicians’ unique knowledge can be used to properly handle typical issues in evaluation/quantification procedures (i.e., operator dependence and time-consuming tasks). These technical advances can significantly improve result repeatability in disease diagnosis and guide toward appropriate cancer care. Indeed, the need to apply machine learning and computational intelligence techniques has steadily increased to effectively perform image processing operations—such as segmentation, co-registration, classification, and dimensionality reduction—and multi-omics data integration.