128 - 3-D Printing for Vessel Location in Anterolateral Thigh (ALT) Grafts During Phalloplasty Procedures

Poster Board Number: 128
There are separate poster presentation times for odd and even posters.
Odd poster #s – first hour
Even poster #s – second hour

Abstract Body : The goal of this study was to create a patient specific 3D printed model from segmented computed tomography (CT) scans, which could accurately represent the relevant vasculature necessary for anterolateral thigh (ALT) graft phalloplasty procedures. If an accurate method is produced, it could then be tested in the future on its ability to improve phalloplasty procedures by potentially reducing surgery times and complications.
Phalloplasty procedures are performed to alter or construct a phallus in cases of external genital repair/augmentation and gender affirming surgeries. In the case of gender affirmation care, these procedures are one of many used to combat feelings of stress and anxiety related to gender dysphoria in which one’s perceived gender identity does not match one’s physical appearance. One phalloplasty procedural method utilizes an ALT pedicle graft in which the vasculature supplying the harvested area is not severed, but rather the graft is transplanted to the mons pubis area with the supplying vasculature remaining intact. The most commonly sought-after vessels in this graft harvesting method derive from the descending branch of the lateral circumflex femoral artery, which can typically be found traveling within the intermuscular septum between the rectus femoris and vastus lateralis.
Current procedures attempt to locate the relevant vasculature with surface level landmarks to find a midpoint between the anterior superior iliac spine and the superolateral border of the patella, paired with 2D patient CT scans. Relying on superficial landmarks as well as 2D CT images to guide surgery in a three-dimensional space can lead to obstacles in the planning and execution of ALT graft harvesting as surgeons must execute a 2D plan on a 3D structure. Recent studies have shown that the use of three-dimensional anatomical models allow for an improvement in spatial recognition and visualization of vasculature during surgical procedures, additional studies have recorded reduction in surgical times and complications with the use of 3D models for surgical planning and anatomical reference.
Our method involved segmenting deidentified phalloplasty patient contrasted CT scans in 3D Slicer (2022) and exporting the created models as Standard Tessellation Language files. The segmentations consist of the relevant bones (pelvis, femur, and patella), musculature of the anterior compartment of the thigh, and vasculature deriving from profunda femoris artery. The musculature is then overlaid with a 1x1x1cm grid for better use when determining vessel location in the thigh using Autodesk Monolith (2016), a voxel-based modeling environment. The created models with grids were printed using a multi-color polyjet printer and brought to the surgical team for evaluation.
The 3D printed models will be compared to the 2D CT images they were segmented from, as well as photos of the in-situ vasculature taken during phalloplasty operations. Additionally, the created model will be brought into the operating room for direct comparison and potential use for surgical planning.
With the use of 3D printed models for presurgical planning showing a reduction in harvest time and complications, this method holds promise that it could be viable for use in other grafts such as the latissimus dorsi and radial forearm flap. Surgeons would benefit from a 3D guide of the respective bones, vessels, and soft tissue, and patients could benefit from a better-informed surgical approach.