Medical imaging is one of the most powerful tools for gaining information about internal organs and tissues. Nowadays medical imaging has become highly indispensable for all kinds of disease diagnosis and treatment. It is a challenging task to develop sophisticated image analysis methods in order to improve the accuracy of diagnosis. The objectives of this book is to elaborate the following research work. 1) Develop Computer Aided Diagnostic (CAD) scheme to detect Lung Emphysema in chest Computed Tomography (CT) images.2) Develop a CAD scheme to detect Brain tumor in Magnetic Resonance (MR) Brain Images using Active Contour Models. 3) Develop a CAD scheme for MR Brain Image based on Markov Random Field (MRF) to detect Brain cancer.