# Comparison of Bone Segmentation Software over Different Anatomical Parts
###### Abstract  
Three-dimensional bone shape reconstruction is a fundamental step for any subject-specific musculo-skeletal model. Typically, medical images are processed to reconstruct bone surfaces via slice-by-slice contour identification. Freeware software packages are available, but commercial ones must be used for the necessary certification in clinics. The commercial software packages also imply expensive hardware and demanding training, but offer valuable tools. The aim of the present work is to report the performance of five commercial software packages (Mimics(r), Amira(tm), D2P(tm), Simpleware(tm), and Segment 3D Print(tm)), particularly the time to import and to create the modelidentification [19; 20; 21; 22]. Image segmentation is a long and critical process, which implies manual, automatic, or semi-automatic tracking of the silhouette contours of the bony structures, and, therefore, requires anatomical knowledge, computer skills, and awareness of the scopes [15; 23; 24]. Many dedicated software packages are offered on the market, from freeware tools with basic functions [25; 26; 27], running more likely on fairly performing computers, to expensive software packages with more effective segmentation algorithms and features [26; 28; 29], likely running on powerful computers. The optimal image segmentation software should support the user in carefully defining the bone models, and eventually providing a file to be exported in standard stereo-lithography (STL) format, with a suitable number of triangles, a uniform mesh, and a minimum overall size. The reconstruction of 3D bone models requires extensive work; a good compromise should be found for each application, between the automation of the segmentation process and the quality of the final results [25; 30; 31; 32].  
The current commercial software packages for image segmentation claim high performance and valuable technical tools, but require robust hardware, demanding training, and careful maintenance, and thus these result in expensive licenses. Hence, cheap and easy-to-use software tools [33] are still pursued and utilized. The performance of a number of freeware software programs was previously analyzed and compared while processing fifteen different human bones from five different anatomical areas; a number of valuable features and fair quality of the reconstructed bone models were found [25]. However, large differences in the number of triangles of the output meshes and in the file size were found, with the triangles per megabyte (MByte) ratio ranging from around 4 to 20 thousand [25]. Distance map analysis amongst outputs from these different free software packages revealed that root-mean-square deviations ranged from 0.13 to 2.21 mm when averaged over the five anatomical areas [25].  
However, the major concern of these freeware software packages is the lack of certification as medical diagnostic devices, i.e., the official recognition to be used as appropriate preoperative software for implant design and surgical planning in the standard clinical practice [34]. Hence, the aim of the present work is to report on the performance of five commercial image segmentation packages. For a possible reasonable comparison, also the same exact CT scans of bony parts that we previously examined with freeware software packages [25] were used. From the presented original combination of these two analyses, advantages and disadvantages of commercial and freeware software packages for bone segmentation from CT scans can be established.