Integrated 3D Imaging Facilitates Human Face Transplantation

By incorporating traditional medical imaging with some of the same three-dimensional (3D) modeling techniques used in movies, researchers are providing new hope to victims of devastating facial injuries.

Findings of a new study on human face transplantation, led by Darren M. Smith, MD, plastic surgery resident from the University of Pittsburgh Medical Center (UPMC; PA, USA), were presented November 28, 2011, at the annual meeting of the Radiological Society of North America (RSNA) held in Chicago (IL, USA).

Serious injuries or defects of the face are incredibly challenging, if not impossible, to satisfactorily reconstruct by traditional surgical techniques. In face transplantation, facial tissue from a donor is transferred to reconstruct the defect, restore fundamental life-sustaining functions--such as breathing, chewing, and speaking--and most importantly, reestablish a normal human appearance.

“This surgery is for patients with devastating injuries to the face, who have lost their ability to smell, eat and engage socially and have no other conventional treatment options,” said Vijay S. Gorantla, MD, PhD, administrative medical director of the Reconstructive Transplantation Program at UPMC.

Distinctly defining and understanding the complex tissue deficits and defects that go along with devastating facial injuries like electric burns, blast wounds, and accidental trauma are critical for both technical effectiveness and objective analysis of the return of function after face transplantation.

Medical imaging plays a major role in the entire spectrum of face transplantation, ranging from patient selection, donor and recipient surgical planning, and postoperative assessment of returning motor and sensory function. Face transplantation is a long, complex procedure that involves reconstruction of multiple tissues--such as skin, muscle, blood vessels, nerves, and bone--by a team of surgeons.

Currently, to prepare for facial transplantation, plaster or plastic models are first created based on 3D computed tomography (CT) or angiographic images or reconstruction. Following this, mock cadaveric dissections are performed to allow surgeons to prepare for the donor and recipient surgeries. Magnetic resonance imaging (MRI) and other imaging exams may also be used to provide supplemental information.

By combining data from multiple imaging exams and creating a sophisticated 3-D computer model, the researchers for this study were better able to assess the facial structure and contours, the underlying bone, muscles, nerves, and vessels, as well as the extent of damage.

Using advanced computer modeling software, Drs. Smith and Gorantla, along with Joseph Losee, MD, integrated information from 3D CT, CT angiography, MRI and high-definition tractography to create a 3D model of the patient’s head and neck anatomy. The same kind of modeling technology is frequently used in movies to animate computer-generated characters with detailed 3D human features and realistic expressions.

“We have integrated data from multiple imaging sources into a single 3D representation that allows for real-time user interaction and modification,” Dr. Smith said. “In assessing eligibility for this procedure, it is critical to understand whether the patient has enough blood vessels and bone structure to support new facial tissue. This 3D modeling helps us customize the procedure to the patient’s individual anatomy so that the donor tissue will fit like a puzzle piece onto the patient’s face.”

Utilizing computer modeling, the team also overlaid the patient model with a polygon mesh of a generic human face and then personalized it to the recipient facial anatomy. Dr. Smith noted that the ability to manipulate this 3D facial wrapper over the residual face model allows the entire surgical team to participate in planning exactly where bone, blood vessel, and nerves will be cut and connected, as well as to assess the outcomes of reconstructive transplantation, including nerve regeneration within the transplanted facial tissue.

“The goal of face transplantation is not just structural,” Dr. Gorantla said. “It is about restoring function, so that patients are once again able to chew their food, smile and regain the most important aspect of a normal face--to look human."

Related Links:
University of Pittsburgh Medical Center
Video: Creating 3-D Models to Prepare for Face Transplants