Visualization Of Penile Lengthening Surgery

BackgroundPenile lengthening surgery is the common surgical intervention for patient with shortpenis. Although various penile lengthening procedures have been described, the satisfactionrate is not very well. There are two kinds of the reasons: one situation in which despite theincrease in penile length, patients are dissatisfied with the outcome of the surgery, becausethey often have unrealistic expectations. Another situation is surgical procedureunsuccessful. Success is depended on whether the surgeons have a better anatomicknowledge and surgical skill. In view of the situation described above, it is important todevelop an effective patient tutorial for correct information about the surgical procedure,and a source for resident education about anatomic knowledge and surgical skill.The use of computer modeling and animation is beneficial to plastic surgery. Theanimation of surgery can be used for advanced doctor-patient communication. As busysurgeons may provide insufficient or perhaps overly technical information, while virtualsurgical animation can provide comprehensible information about the surgery. In addition,animation of surgery can also be used for resident education. Transparency can be used inanimations to display underlying anatomy that is rarely visible during an operation but iscritical to the understanding of the procedure itself.For penile lengthening procedures, there are complicated anatomic structures,abundant of blood vessel and nerves relating to the penile lengthening surgery. In traditionalmedical education, the common resources used by surgeons in preparation for surgery arethe form of text description, two-dimensional pictures and cadavers. However, the textdescription seems very abstract, and the two-dimensional pictures cannot give anillustration of the relevant anatomical relationships. Fresh cadavers are difficult to come by,increasingly expensive and non-reusable. The viewing system of three-dimensional virtualorgan model offers many distinct advantages over text description, two-dimensionalpictures and human cadavers. Based on the virtual models which providing a three-dimensional representation of anatomic structure, and virtual viewing and interactiontechnology, it can make the users immersed in a virtual environment. As a result, complexanatomical concepts can be more readily comprehended in dynamic three-dimensionalvirtual space. So, it is important to develop a viewing system of virtual penile anatomicstructure for surgeon.The quality of the animation or virtual roaming system is dependent on the fidelity ofthe digital model, as the digital models are the working materials on which these methodsare constructed. Previously, a three-dimensional digital model of the penis with its adjacentwas constructed using Chinese Visible Human data base as references by our research team.However, this preliminary model had many defects:1) the appearance was unnatural;2)absent of many anatomical structures;3) the model was reconstructed using data fromcadavers but not patient. In this study, we evaluate the feasibility of creatingpatient-specific virtual3D model of penis and its adjacent structures based on magneticresonance images. The model was used to create digital animation of penile lengtheningsurgery, including ordered steps of the procedure. A viewing system of virtual penileanatomic structure was developed, which may serve as a resource for resident educationoutside the operating room.Methods1. MR images were obtained using a3.0Tesla MRI system. The participant wasimaged using an axial sectioning plane by T1and T2weighted imaging with varying slicethickness (1-mm,3-mm,5-mm). The effects of different imaging parameters on the MRimages were compared. With the surface rendering construction, the3D virtual model wasestablished by Amira software.2.(1) Three-dimensional polygonal surface model constructed by Amira was importedinto the Maya software for processing. First, the preliminary model was smoothed andsimplified in Maya. After smoothing and simplifying processing, models of the anatomicalstructures absent in the preliminary model, such as the penile fundiform ligament, nerves,blood vessels, and other significant structures, were constructed in Maya after a literaturereview. Finally, textures were added to all tissue surfaces to maximize the fidelity of themodel.(2) The refined model was used to create digital animation of penile lengtheningsurgery, including ordered steps of the procedure, using Maya software. 3. Based on the refined model, a viewing system of virtual penile anatomic structurewas developed. The function of the viewing system was defined by JavaScript programs.Results1. The anatomical details imaging is better in T2-weighted fast spin-echo images with3mm slice thickness. A preliminary three-dimensional polygonal surface model of thepenis with its adjacent structures was constructed by Amira5using MR images asreferences. The suspensory ligament stretches between the pubic symphysis and the corporacavernosa. The penile roots attach to inferior ramus of pubis.2.(1) The refined model contained a decreased number of polygons, high-fidelitytextural surfaces, and all major anatomical structures relevant to penile lengthening surgery.(2) Based on the model, a three-dimensional digital animation was developed to illustratepenile lengthening surgery. All major surgical steps were observed, including skin incision,exposure, transversal incision of the fundiform ligament, partial division and release of thesuspensory ligament. Transparency was used in the animations to display underlyinganatomy that is rarely visible during an operation but is critical to the understanding of theprocedure itself.3. The virtual penile model in the viewing system contained high-fidelity texturalsurfaces and illustrated anatomical relationships. As a result, complex anatomical conceptscan be more comprehended. In the viewing system, the virtual model can be1) enlarged orreduced;2) moved in parallel;3) rotated at any degree;4) transparent/reappearance;5)displayed the name of selected anatomic structure. In addition, as an executable program(.exe format), this viewing system can independently run on a personal computer withWindows operating system.Conclusion1. The optimizing magnetic resonance imaging parameters (T2-weighted fastspin-echo images with3mm slice thickness) was determined, for the purpose ofreconstruction the three-dimensional model of penis with its adjacent structure. The virtualmodel offer unique insights into the complex penile anatomy and illustrate anatomicalrelationships.2. Three-dimensional reconstruction model can be processed to correct many defectsby using Maya software. The refined model contains a decreased number of polygons, high-fidelity textural surfaces, and all major anatomical structures. The animation of penilelengthening surgery can be used to teach surgical residents and provide patients with morecomprehensible information about the surgery to facilitate doctor-patient communication.3. A viewing system of virtual penile anatomic structures was developed. This systemcan display the complex anatomy and anatomic relationship of penis with its adjacentstructure. This system is interactive and can be used as a digital platform to learn the penileanatomy.