Minimally Invasive Spine surgery (MISS) was developed to treat disorders of the spine with less disruption to the muscles. Surgeons use CT images to monitor the volume of muscles after operation in order to evaluate the progress of patient recovery. The first step in the task is to segment the muscle regions from other tissues/organs in CT images. However, manual segmentation of muscle regions is not only inaccurate, but also time consuming. In this work, Gray Space Map (GSM) is used in fuzzy c-means clustering algorithm to segment muscle regions in CT images. GSM com- bines both spatial and intensity information of pixels. Experiments show that the proposed GSM- based fuzzy c-means clustering muscle CT image segmentation yields very good results.
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 Tsutsumimoto, T., Shimogata, M., Ohta, H. and Misawa, H. (2009) Mini-Open versus Conventional Open Posterior Lumbar Interbody Fusion for the Treatment of Lumbar De-generative Spondylolisthesis: Comparison of Paraspinal Muscle Damage and Slip Reduction. Spine, 34, 1923-1928. http://dx.doi.org/10.1097/BRS.0b013e3181a9d28e
 Langheinrich, A.C., Kampschulte, M., Cr??mann, C., Moritz, R., Rau, W.S., Bohle, R.M. and Ritman, E.L. (2009) Role of Computed Tomography Voxel Size in Detection and Discrimination of Calcium and Iron Deposits in Atheros-clerotic Human Coronary Artery Specimens. Journal of Computer Assisted Tomography, 33, 517-522.