JIP_V1_N3_A1 R. Neela R. Kalaimagal Journal on Image Processing 2349-6827 1 3 1 10 MRI Segmentation, Automatic Segmentation, Intensity Based and Model Based Segmentation of various structures is a crucial step in the diagnosis and treatment of various diseases. Various imaging techniques such as X-ray, CT, (Computer Tomography), DTI (Diffusion Tensor Image), MRI (Magnetic Resonance Imaging), FMRI (Functional Magnetic Resource Imaging), PET (Positron Emission Tomography), SPECT (Single Photon Emission Computed Tomography), etc. are used in the treatment of diseases. Selection of the segmentation method depends on the modality used and the structures to be segmented. Accurate segmentation of various structures and computation of volume of tissues are required in the treatment of various diseases. In this paper, the authors present an overview of various segmentation techniques used in MRI analysis and their pros and cons. Also, the performance measures of some methods are evaluated. July - September 2014 Copyright © 2014 i-manager publications. All rights reserved. i-manager Publications http://www.imanagerpublications.com/Article.aspx?ArticleId=2958