Winship Cancer Institute of Emory University 1 article published in JoVE Medicine Segmentation and Linear Measurement for Body Composition Analysis using Slice-O-Matic and Horos Sean Steele1, Fangyi Lin1, Thien-Linh Le1, Alexandra Medline1, Michelle Higgins1, Alex Sandberg1, Sean Evans1, Gordon Hong2, Milton A. Williams3, Mehmet A. Bilen4, Sarah Psutka5, Kenneth Ogan1, Viraj A. Master1 1Department of Urology, Emory University School of Medicine, 2Northeast Ohio Medical University, 3Department of Urology, University of Alabama at Birmingham, 4Department of Medical Oncology, Winship Cancer Institute of Emory University, 5Department of Urology, University of Washington Segmentation and linear measurements quantify skeletal muscle mass and adipose tissues using Computed Tomography and/or Magnetic Resonance Imaging images. Here, we outline the use of Slice-O-Matic software and Horos image viewer for rapid and accurate analysis of body composition. These methods can provide important information for prognosis and risk stratification.