Amira (software)

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Amira
Amira Screenshot with Honeybee Brain visualization.png
Developer(s) Zuse Institute Berlin
FEI Visualization Sciences Group
Initial release October 1999; 17 years ago (1999-10)
Stable release
6.1.1 / May 1, 2016; 15 months ago (2016-05-01)
Operating system Windows XP SP3, Windows Vista, Windows 7
OS X 10.5, OS X 10.6, OS X 10.7
RHEL 5.5
Platform IA-32, x64
Available in English
Type 3D data visualization and processing
License Trialware
Website amira.com

Amira (pronounce: Ah-meer-ah) is a software platform for 3D and 4D data visualization, processing, and analysis. It is being actively developed by FEI Visualization Sciences Group, Bordeaux, France in collaboration with the Zuse Institute Berlin (ZIB), Germany and commercially distributed by FEI.

Overview[edit]

Amira[1] is an extendable software system for scientific visualization, data analysis, and presentation of 3D and 4D data. It is being used by several thousand researchers and engineers in academia and industry around the world. Its flexible user interface and modular architecture make it a universal tool for processing and analysis of data from various modalities; e.g. micro-CT,[2] PET,[3] Ultrasound.[4] Its ever-expanding functionality has made it a versatile data analysis and visualization solution, applicable to and being used in many fields, such as microscopy in biology[5] and materials science,[6] molecular biology,[7] quantum physics,[8] astrophysics,[9] computational fluid dynamics (CFD),[10] finite element modeling (FEM),[11] non-destructive testing (NDT),[12] and many more. One of the key features, besides data visualization, is Amira’s set of tools for image segmentation[13] and geometry reconstruction.[14] This allows the user to mark (or segment) structures and regions of interest in 3D image volumes using automatic, semi-automatic, and manual tools. The segmentation can then be used for a variety of subsequent tasks, such as volumetric analysis,[4] density analysis,[15] shape analysis,[16] or the generation of 3D computer models for visualization,[17] numerical simulations,[18] or rapid prototyping[19] or 3D printing, to name a few. Other key Amira features are multi-planar and volume visualization, image registration,[20] filament tracing,[21] cell separation and analysis,[16] tetrahedral mesh generation,[22] fiber-tracking from diffusion tensor imaging (DTI) data,[23] skeletonization,[24] spatial graph analysis, and stereoscopic rendering[25] of 3D data over multiple displays including CAVEs (Cave automatic virtual environments).[26] As a commercial product Amira requires the purchase of a license or an academic subscription. A time-limited, but full-featured evaluation version is available for download free of charge.

History[edit]

1994–1998: Research software[edit]

Amira’s roots go back to 1994 and the Department for Scientific Visualization, headed by Hans-Christian Hege at the Zuse Institute Berlin (ZIB). The ZIB is a research institute for mathematics and informatics. The Scientific Visualization department’s mission is to help solve computationally and scientifically challenging tasks in medicine, biology, and engineering. For this purpose, it develops algorithms and software for 2D, 3D, and 4D data visualization and visually supported exploration and analysis. At that time, the young visualization group at the ZIB had experience with the extendable, data flow-oriented visualization environments apE,[27] IRIS Explorer,[28] and Advanced Visualization Studio (AVS), but was not satisfied with these products’ interactivity, flexibility, and ease-of-use for non-computer scientists.

Therefore, in a subproject[29] within a medically oriented, multi-disciplinary collaborative research center[30] the development of a new software system was started in early 1994. The initial development was performed by Detlev Stalling, who later became the chief software architect. The software system was called “HyperPlan”, highlighting its initial target application  – a planning system for hyperthermia cancer treatment. The system was being developed on Silicon Graphics (SGI) computers, which at the time were the standard workstations used for high-end graphics computing. Software development was based on libraries such as OpenGL, SGI Open Inventor, and the graphical user interface libraries X11, Motif (software), and ViewKit. In 1998, X11/Motif/Viewkit were replaced by the Qt toolkit.

The HyperPlan framework served as the base for more and more projects at the ZIB and was used by a growing number of researchers in collaborating institutions. The projects included applications in neurobiology, confocal microscopy, flow visualization, molecule visualization and analysis and computational astrophysics.

1998–today: Commercially supported product[edit]

The growing number of users of the system started to exceed the capacities that ZIB could spare for software distribution and support, as ZIB’s primary mission was algorithmic research. Therefore, the spin-off company Indeed, – Visual Concepts GmbH was founded by Hans-Christian Hege, Detlev Stalling, and Malte Westerhoff with the vision of making the extensive capabilities of the software available to researchers in industry and academia worldwide and to provide the product support and robustness needed in today’s fast-paced and competitive world.

In Feb 1998 the HyperPlan software was given the new, less application-specific name “Amira”. This name is not an acronym but was chosen for being pronounceable in different languages, starting with an ‘A’, and having an appropriate connotation: the Latin verb “admirare” (to admire), meaning “to look at” and “to wonder at”, describes a typical situation in data visualization.

A major re-design of the software was undertaken by Detlev Stalling and Malte Westerhoff in order to make it a commercially supportable product and to make it available on non-SGI computers as well. In March 1999, the first version of the commercial Amira was shown at the CeBIT tradeshow in Hannover, Germany on SGI IRIX and Hewlett-Packard UniX (HP-UX). Versions for Linux and Microsoft Windows followed within the following twelve months. Later Mac OS X support was added. Indeed, – Visual Concepts selected the Bordeaux, France and San Diego, United States based company TGS, Inc. as the worldwide distributor for Amira and completed five major releases (up to version 3.1) in the subsequent four years.

In 2003 both Indeed, as well as TGS were acquired by Massachusetts-based Mercury Computer Systems, Inc. (NASDAQ:MRCY) and became part of Mercury’s newly formed life sciences business unit, later branded Visage Imaging. In 2009, Mercury Computer Systems, Inc. spun off Visage Imaging again and sold it to Melbourne, Australia based Promedicus Ltd (ASX:PME), a leading provider of radiology information systems and medical IT solutions. During this time, Amira continued to be developed in Berlin, Germany and in close collaboration with the ZIB, still headed by the original creators of Amira. TGS, located in Bordeaux, France was sold by Mercury Computer systems to a French investor and renamed to Visualization Sciences Group (VSG). VSG continued the work on a complementary product named Avizo, based on the same source code but customized for material sciences.

In August 2012, FEI, to that date the largest OEM reseller of Amira, purchased VSG and the Amira business from Promedicus. In August 2013, Visualization Sciences Group (VSG) became a business unit of FEI. Amira and Avizo are still being marketed as two different products; Amira for life sciences and Avizo for materials science, but the development efforts are now joined once again. As in the beginning, the Amira roadmap continues to be driven by the interesting and challenging scientific questions that Amira users around the world are trying to answer, often at the leading edge in their fields.

Amira options[edit]

Microscopy option[edit]

  • Specific readers for microscopy data
  • Image deconvolution
  • Exploration of 3D imagery obtained from virtually any microscope
  • Extraction and editing of filament networks from microscopy images

DICOM reader[edit]

  • Import of clinical and preclinical data in DICOM format

Mesh option[edit]

  • Generation of 3D finite element (FE) meshes from segmented image data
  • Support for many state-of-the-art FE solver formats
  • High-quality visualization of simulation mesh-based results, using scalar, vector, and tensor field display modules

Skeletonization option[edit]

  • Reconstruction and analysis of neural and vascular networks
  • Visualization of skeletonized networks
  • Length and diameter quantification of network segments
  • Ordering of segments in a tree graph
  • Skeletonization of very large image stacks

Molecular option[edit]

  • Advanced tools for the visualization of molecule models
  • Hardware-accelerated volume rendering
  • Powerful molecule editor
  • Specific tools for complex molecular visualization

Developer option[edit]

  • Creation of new custom components for visualizing or data processing
  • Implementation of new file readers or writers
  • C++ programming language
  • Development wizard for getting started quickly

Neuro option[edit]

  • Medical image analysis for DTI and brain perfusion
  • Fiber tracking supporting several stream-line based algorithms
  • Fiber separation into fiber bundles based on user defined source and destination regions
  • Computation of tensor fields, diffusion weighted maps
  • Eigenvalue decomposition of tensor fields
  • Computation of mean transit time, cerebral blood flow, and cerebral blood volume

VR option[edit]

  • Visualization of data on large tiled displays or in immersive Virtual Reality (VR) environments
  • Support of 3D navigation devices
  • Fast multi-threaded and distributed rendering

Very large data option[edit]

  • Support for visualization of image data exceeding the available main memory, using efficient out-of-core data management
  • Extensions of many standard modules, such as orthogonal and oblique slicing, volume rendering, and isosurface rendering, to work on out-of-core data

Application areas[edit]

References[edit]

  1. ^ Stalling, D.; Westerhoff, M.; Hege, H.-C. (2005). C.D. Hansen and C.R. Johnson, ed. "Amira: A Highly Interactive System for Visual Data Analysis". The Visualization Handbook. Elsevier: 749–767. CiteSeerX 10.1.1.129.6785Freely accessible. 
  2. ^ Adam, R.; Smith, A.R.; Sieren, J.C.; Eggleston, T.; McLennan, G. (2010). "Characterization Of The Airways And Lungs For The FABP/CFTR-Knockout Mouse Using Micro-Computed Tomography And Large Image Microscope Array" (PDF). American Journal of Respiratory and Critical Care Medicine. Am Thoracic Soc. 181: A6264. doi:10.1164/ajrccm-conference.2010.181.1_meetingabstracts.a6264. 
  3. ^ Awasthi, V.; Holter, J.; Thorp, K.; Anderson, S.; Epstein, R. (2010). "F-18-fluorothymidine-PET evaluation of bone marrow transplant in a rat model". Nuclear Medicine Communications. 31 (2): 152–158. doi:10.1097/mnm.0b013e3283339f92. 
  4. ^ a b Ayers, G.D.; McKinley, E.T.; Zhao, P.; Fritz, J.M.; Metry, R.E.; Deal, B.C.; Adlerz, K.M.; Coffey, R.J.; Manning, H.C. (2010). "Volume of Preclinical Xenograft Tumors Is More Accurately Assessed by Ultrasound Imaging Than Manual Caliper Measurements". Journal of Ultrasound in Medicine. Am inst Ultrasound Med. 29 (6): 891. 
  5. ^ Dlasková, A.; Spacek, T.; Santorová, J.; Plecitá-Hlavatá, L.; Berková, Z.; Saudek, F.; Lessard, M.; Bewersdorf, J.; Jezek, P. (2010). "4Pi microscopy reveals an impaired three-dimensional mitochondrial network of pancreatic islet beta-cells, an experimental model of type-2 diabetes.". Biochimica et Biophysica Acta (BBA) - Bioenergetics. Elsevier. 1797: 1327–1341. doi:10.1016/j.bbabio.2010.02.003. 
  6. ^ Clark, N.D.L.; Daly., C. (2010). "Using confocal laser scanning microscopy to image trichome inclusions in amber" (PDF). Journal of Paleontological Techniques. 8. 
  7. ^ Amstalden van Hove, E.R.; Blackwell, T.R.; Klinkert, I.; Eijkel, G.B.; Heeren, R.; Glunde, K. (2010). "Multimodal Mass Spectrometric Imaging of Small Molecules Reveals Distinct Spatio-Molecular Signatures in Differentially Metastatic Breast Tumor Models". Cancer Research. AACR. 70 (22): 9012–9021. PMID 21045154. doi:10.1158/0008-5472.can-10-0360. 
  8. ^ Sherman, D.M. (2010). "Metal complexation and ion association in hydrothermal fluids: insights from quantum chemistry and molecular dynamics.". Geofluids. John Wiley & Sons. 10 (1–2): 41–57. doi:10.1002/9781444394900.ch4. 
  9. ^ O'Neill, S.M.; Jones, T.W. (2010). "Three-Dimensional Simulations of Bi-Directed Magnetohydrodynamic Jets Interacting with Cluster Environments.". The Astrophysical Journal. IOP Publishing. 710 (1): 180–196. Bibcode:2010ApJ...710..180O. arXiv:1001.1747Freely accessible. doi:10.1088/0004-637x/710/1/180. 
  10. ^ Baharoglu, M.I.; Schirmer, C.M.; Hoit, D.A.; Gao, B.L.; Malek, A.M. (2010). "Aneurysm Inflow-Angle as a Discriminant for Rupture in Sidewall Cerebral Aneurysms". Morphometric and Computational Fluid Dynamic Analysis. Stroke, Am Heart Assoc. 
  11. ^ Bardyn,, T.; Gédet, P.; Hallermann, W.; Büchler., P. (2010). "Prediction of dental implant torque with a fast and automatic finite element analysis: a pilot study.". Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology. Elsevier. 109: 594–603. doi:10.1016/j.tripleo.2009.11.010. 
  12. ^ Shearing, P.R.; Gelb, J.; Yi, J.; Lee, W.K.; Drakopolous, M.; Brandon, N.P. (2010). "Analysis of Triple Phase Contact in Ni-YSZ Microstructures Using Non-destructive X-ray Tomography with Synchrotron Radiation". Electrochemistry Communications. Elsevier. 12: 1021–1024. doi:10.1016/j.elecom.2010.05.014. 
  13. ^ Jährling, N.; Becker, K.; Schönbauer, C.; Schnorrer, F.; Dodt, H.U. (2010). "Three-dimensional reconstruction and segmentation of intact Drosophila by ultramicroscopy". Frontiers in Systems Neuroscience. Frontiers Research Foundation. 4: 1. PMC 2831709Freely accessible. PMID 20204156. doi:10.3389/neuro.06.001.2010. 
  14. ^ Zheng, G. (2010). "Statistical shape model-based reconstruction of a scaled, patient-specific surface model of the pelvis from a single standard AP x-ray radiograph.". Medical Physics. 37: 1424. Bibcode:2010MedPh..37.1424Z. doi:10.1118/1.3327453. 
  15. ^ Rodriguez-Soto, A.E.; Fritscher, K.D.; Schuler, B.; Issever, A.S.; Roth, T.; Kamelger, F.; Kammerlander, C.; Blauth, M.; Schubert, R.; Link, T.M. (2010). "Texture Analysis, Bone Mineral Density, and Cortical Thickness of the Proximal Femur: Fracture Risk Prediction.". Journal of Computer Assisted Tomography. 34 (6): 949–957. doi:10.1097/rct.0b013e3181ec05e4. 
  16. ^ a b Leischner, U.; Schierloh, A.; Zieglgänsberger, W.; Dodt, H.U. (2010). "Formalin-Induced Fluorescence Reveals Cell Shape and Morphology in Biological Tissue Samples". Public Library of Science. 5 (4): e10391. Bibcode:2010PLoSO...510391L. PMC 2861007Freely accessible. PMID 20436930. doi:10.1371/journal.pone.0010391. 
  17. ^ Felts, R.L.; Narayan, K.; Estes, J.D.; Shi, D.; Trubey, C.M.; Fu, J.; Hartnell, L.M.; Ruthel, G.T.; Schneider, D.K.; Nagashima, K. (2010). "3D visualization of HIV transfer at the virological synapse between dendritic cells and T cells.". Proceedings of the National Academy of Sciences of the United States of America. National Acad Sciences. 107 (30): 13336–13341. Bibcode:2010PNAS..10713336F. PMC 2922156Freely accessible. PMID 20624966. doi:10.1073/pnas.1003040107. 
  18. ^ Taylor, D.J.; Doorly, D.J.; Schroter, R.C. (2010). "Inflow boundary profile prescription for numerical simulation of nasal airflow.". Journal of the Royal Society Interface. The Royal Society. 7 (44): 515–527. doi:10.1098/rsif.2009.0306. 
  19. ^ Lucas, B.C.; Bogovic, J.A.; Carass, A.; Bazin, P.L.; Prince, J.L.; Pham, D.L.; Landman, B.A. (2010). "The Java Image Science Toolkit (JIST) for Rapid Prototyping and Publishing of Neuroimaging Software" (PDF). Neuroinformatics. Springer. 8 (1): 5–17. doi:10.1007/s12021-009-9061-2. 
  20. ^ Dasgupta, S.; Feleppa, E.; Ramachandran, S.; Ketterling, J.; Kalisz, A.; Haker, S.; Tempany, C.; Porter, C.; Lacrampe, M.; Isacson, C. (2007). "8A-4 Spatial Co-Registration of Magnetic Resonance and Ultrasound Images of the Prostate as a Basis for Multi-Modality Tissue-Type Imaging": 641–643. 
  21. ^ Oberlaender, M.; Bruno, R.M.; Sakmann, B.; Broser, P.J. (2007). "Transmitted light brightfield mosaic microscopy for three-dimensional tracing of single neuron morphology.". Journal of Biomedical Optics. 12: 064029. Bibcode:2007JBO....12f4029O. doi:10.1117/1.2815693. 
  22. ^ Lamecker, H.; Mansi, T.; Relan, J.; Billet, F.; Sermesant, M.; Ayache, N.; Delingette., H. (2009). "Adaptive Tetrahedral Meshing for Personalized Cardiac Simulations.". Citeseer. 
  23. ^ Boretius, S.; Michaelis, T.; Tammer, R.; Ashery-Padan, R.; Frahm, J.; Stoykova, A. (2009). "In vivo MRI of altered brain anatomy and fiber connectivity in adult pax6 deficient mice.". Cerebral Cortex. Oxford University Press. 19 (12): 2838–2847. PMID 19329571. doi:10.1093/cercor/bhp057. 
  24. ^ Kohjiya, S.; Katoh, A.; Suda, T.; Shimanuki, J.; Ikeda, Y. (2006). "Visualisation of carbon black networks in rubbery matrix by skeletonisation of 3D-TEM image.". Polymer. Elsevier. 47 (10): 3298–3301. doi:10.1016/j.polymer.2006.03.008. 
  25. ^ Clements, R.J.; Mintz, E.M.; Blank, J.L. (2009). "High resolution stereoscopic volume visualization of the mouse arginine vasopressin system.". Journal of neuroscience methods. Elsevier. 187: 41–45. doi:10.1016/j.jneumeth.2009.12.011. 
  26. ^ Ohno, N.; Kageyama., A. (2009). "Region-of-interest visualization by CAVE VR system with automatic control of level-of-detail.". Computer Physics Communications. Elsevier. 181: 720–725. Bibcode:2010CoPhC.181..720O. doi:10.1016/j.cpc.2009.12.002. 
  27. ^ Dyer, D.S. (1990). "A dataflow toolkit for visualization.". Computer Graphics and Applications. IEEE. 10: 60–69. doi:10.1109/38.56300. 
  28. ^ Foulser, D. (1995). "IRIS Explorer: A framework for investigation.". Computer Graphics. ACM SIGGRAPH. 29: 13–16. doi:10.1145/204362.204365. 
  29. ^ "DFG Project: Algorithmen zur Planung und Kontrolle von Hyperthermiebehandlungen". DFG Deutsche Forschungsgemeinschaft. Retrieved 28 January 2015. 
  30. ^ "DFG Project SFB 273: Hyperthermia: Methodics and Clinics". DFG Deutsche Forschungsgemeinschaft. Retrieved 28 January 2015. 
  31. ^ a b c de Boer, B.A.; Soufan, A.T.; Hagoort, J.; Mohun, T.J.; van den Hoff, M.J.B; Hasman, A.; Voorbraak, F.P.J.M.; Moorman, A.F.M.; Ruijter, J.M. (2011). "The interactive presentation of 3D information obtained from reconstructed datasets and 3D placement of single histological sections with the 3D portable document format.". Development. 138 (1): 159–167. PMC 2998169Freely accessible. PMID 21138978. doi:10.1242/dev.051086. 
  32. ^ Specht, M.; Lebrun, R.; Zollikofer, C.P.E. (2007). "Visualizing shape transformation between chimpanzee and human braincases." (PDF). The Visual Computer: International Journal of Computer Graphics archive. 23 (9): 743–751. doi:10.1007/s00371-007-0156-1. 
  33. ^ a b c Gaemers, I.C.; Stallen, J.M.; Kunne, C.; Wallner, C.; van Werven, J.; Nederveen, A.; Lamers, W.H. (2011). "Lipotoxicity and steatohepatitis in an overfed mouse model for non-alcoholic fatty liver disease.". Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease. Elsevier. 1812: 447–458. doi:10.1016/j.bbadis.2011.01.003. 
  34. ^ a b Kudryashev, M; Cyrklaff, M.; Alex, B.; Lemgruber, L.; Baumeister, W.; Wallich, R.; Frischknecht, F. (2011). "Evidence of direct cell-cell fusion in Borrelia by cryogenic electron tomography.". Cellular Microbiology. Wiley Online Library. 13: 731–741. doi:10.1111/j.1462-5822.2011.01571.x. 
  35. ^ Meisslitzer-Ruppitsch, C.; Röhrl, C.; Ranftler, C.; Neumüller, J.; Vetterlein, M.; Ellinger, A.; Pavelka, M. (2011). "The ceramide-enriched trans-Golgi compartments reorganize together with other parts of the Golgi apparatus in response to ATP-depletion.". Histochemistry and Cell Biology. Springer. 135 (2): 159–171. doi:10.1007/s00418-010-0773-z. 
  36. ^ Bevan, R.L.T.; Sazonov, I.; Saksono, P.H.; Nithiarasu, P.; van Loon, R.; Luckraz, H.; Ashral, S. (2011). "Patient-specific blood flow simulation through an aneurysmal thoracic aorta with a folded proximal neck.". Numerical Methods in Biomedical Engineering. Wiley. 27 (8): 1167–1184. doi:10.1002/cnm.1425. 
  37. ^ Bujotzek, A.; Shan, M.; Haag, R.; Weber, M. (2011). "Towards a rational spacer design for bivalent inhibition of estrogen receptor". Journal of Computer-Aided Molecular Design. 25 (3): 253–262. Bibcode:2011JCAMD..25..253B. doi:10.1007/s10822-011-9417-1. 
  38. ^ a b Cai, W.; Lee, E.Y.; Vij, A.; Mahmood, S.A.; Yoshida, H. (2011). "MDCT for Computerized Volumetry of Pneumothoraces in Pediatric Patients.". Academic Radiology. Elsevier. 
  39. ^ a b Irving, S.; Moore, D.R.; Liberman, M.C.; Sumner, C.J. (2011). "Olivocochlear Efferent Control in Sound Localization and Experience-Dependent Learning.". Journal of Neuroscience. Soc Neuroscience. 31 (7): 2493–2501. PMC 3292219Freely accessible. PMID 21325517. doi:10.1523/jneurosci.2679-10.2011. 
  40. ^ a b Obenaus, A.; Hayes, P. (2011). "Drill hole defects: induction, imaging, and analysis in the rodent.". Methods in molecular biology. Springer. 690: 301–314. doi:10.1007/978-1-60761-962-8_20. 
  41. ^ Ertürk, A.; Mauch, C.P.; Hellal, F.; Förstner, F.; Keck, T.; Becker, K.; Jährling, N.; Steffens, H.; Richter, M.; Hübener, M.; Kramer, E.; Kirchhoff, F.; Dodt; Bradke, F. (2011). "Three-dimensional imaging of the unsectioned adult spinal cord to assess axon regeneration and glial responses after injury.". Nature Medicine. 18: 166–171. PMID 22198277. doi:10.1038/nm.2600. 
  42. ^ Carlson, K.J.; Wrangham, R.W.; Muller, M.N.; Sumner, D.R.; Morbeck, M.E.; Nishida, T.; Yamanaka, A.; Boesch, C. (2011). "Comparisons of Limb Structural Properties in Free-ranging Chimpanzees from Kibale, Gombe, Mahale, and Tai Communities.". Primate Locomotion. Springer: 155–182. doi:10.1007/978-1-4419-1420-0_9. 
  43. ^ Hartwig, T.; Streitparth, F.; Gro, C.; Müller, M.; Perka, C.; Putzier, M.; Strube, P. (2011). "Digital 3-Dimensional Analysis of the Paravertebral Lumbar Muscles After Circumferential Single-level Fusion.". Journal of Spinal Disorders & Techniques. 
  44. ^ Lee, J.; Eddington, D.K.; Nadol, J.B. (2011). "The Histopathology of Revision Cochlear Implantation.". Audiology and Neurotology. 16 (5): 336–346. doi:10.1159/000322307. 
  45. ^ Han, M.; Kim, C.; Mozer, P.; Schafer, F.; Badaan, S.; Vigaru, B.; Tseng, K.; Petrisor, D.; Trock, B.; Stoianovici, D. (2011). "Tandem-robot Assisted Laparoscopic Radical Prostatectomy to Improve the Neurovascular Bundle Visualization: A Feasibility Study." (PDF). Urology. 77 (2): 502–6. PMC 3051397Freely accessible. PMID 21067797. doi:10.1016/j.urology.2010.06.064. 

External links[edit]