Imaging plays a vital role in successful facial transplantations.
Some accidents leave survivors with a visual reminder of their trauma, which can range from a scar to severe facial deformities.
Now, thanks to a team of interdisciplinary physician specialists, an innovative procedure gives hope to individuals who have suffered serious injuries to the face. The development of total facial transplantations have drastically improved the quality of life of patients with extreme facial damage. But this procedure would not be possible without the participation of radiologists who perform and interpret CT and functional MRI (fMRI), as well an interventional procedures, to map a patient's blood vessels and monitor postsurgical complications.
Restoring Form and Function
Eighteen patients have received facial transplants since 2005.1 The majority of these procedures are considered partial transplants, in which physicians restore portions of the face or correct less severe deformities. For many years, full facial transplantation was deemed impossible, largely because of the complexity of the tissue perfusion and the surgery based on the blood supply, as well as the implications about medical ethics and patient welfare. However, a multidisciplinary team at Brigham and Women's Hospital (BWH) in Boston has now completed three successful full face transplants.
According to Srinivasan Mukundan Jr., M.D., Ph.D., section head of neuroradiology at BWH and associate professor of radiology at Harvard Medical School in Boston, the facial transplant concept is in large part the brainchild of the team's Principal Investigator Bohdan Pomohac, M.D., director of plastic surgery transplantation at BWH, medical director of the BWH Burn Center, assistant professor at Harvard Medical School, and the lead author of a recent New England Journal of Medicine article about three full facial transplantations.1
Mukundan elaborates, "Pomohac had a dream of being able to offer restorative surgery as opposed to reconstructive. Ideally, he sought to not just patch up injuries but to return patients to full form and function."
Frank J. Rybicki, M.D., Ph.D., FAHA, director of the Applied Imaging Science Lab at BWH and associate professor of radiology at Harvard Medical School, defines function as "one's ability to eat normally, breathe through the nose, move eyelids, have facial expressions, and feel sensations in the face, among other things. Full transplants are done on patients whose injuries have destroyed the functionality of all facial features. It restores both form and function." Adds Mukundan, "You are putting a new face onto a body that's been damaged, but the face should animated and human as well."
"Then, there's form," Rybicki continues, "which is essentially aesthetics." Patients are often too self-conscious to go out in public prior to transplant. "This procedure is made to give life back to people," he says. To read one transplant patient's story at BWH, visit http://bit.ly/BWHFaceTransplant.
Mapping Blood Vessels and Nerves
But how does radiology assist in full facial transplantation? Rybicki says that the surgery is largely vascular, which is where imaging plays a vital role. He elaborates, "What you need to do is take tissue from a cadaver and have it perfused by a patient's own blood supply." After that, with maintained perfusion, the surgery proceeds with the bones, soft tissues, nerves, and sewing on the skin. But, as Rybicki stresses, "You can't do anything until you connect the blood vessels; the whole procedure hinges on that."
Imaging is the tool that maps a patient's blood vessels — a time-consuming process. Ideally, you'd want a perfect map of the donor's vascular attributes as well, but New England Organ Bank regulations currently prohibit information sharing. This makes providing an accurate map of the recipient even more critical.
This process of mapping is further complicated by the fact that the facial blood vessels of a patient who has experienced extraordinary trauma and injury are likely atypical. Frequently, these individuals were injured long ago and have thus had several conventional reconstructive surgeries, which entail placing a skin graft from a patient's thigh on his or her face, says Rybicki. "The anatomical changes from surgeries are significant," he explains. To map the patients' blood vessels, investigators from the Applied Imaging Science Lab have helped create and implement the "Soga Protocol," which involves a dynamic volume CT angiogram and is named for its developer Shigeyoshi Soga, M.D.2 "This 320-detector row CT protocol is proven in the peer-review literature to make very unique maps of the external carotid systems that guide surgery," says Rybicki.3,4
In addition to CT, imagers under the leadership of Mukundan and colleague Alexandra Golby, M.D., neurosurgeon at BWH and associate professor at Harvard Medical School, also use fMRI to provide a baseline assessment of the patient and to track the nerve rewiring following surgery. This has been integral to transplant success.
Mukundan and Golby also perform fMRI scans at postoperative intervals to gauge if reconnected nerves function properly. "Typically, a patient is placed in a scanner, and you have her or him perform some paradigm — maybe winking an eye or puckering lips," says Mukundan. "The radiologist and neurosurgeon then compare the fMRI results when the tasks were performed to the fMRI scans when the patient lay still." These studies are also compared to baseline MRIs. The goal is to confirm whether the nerve connections made during transplant repaired the associated motor and sensory skills.
Along with the use of CT and MRI, image-guided interventional procedures are also crucial to monitoring transplantation patients after surgery. "After transplantation of cells, tissues, or organs from a donor to a genetically non-identical recipient, the recipient needs to be immunosuppressed," explains Thomas C. Lee, M.D., staff neuroradiologist at BWH and Dana Farber Cancer Institute in Boston. "Such transplantation exposes patients to increased complications. There is a heightened need for early intervention to identify whether any potential infections need to be addressed."
As an interventional neuroradiologist, Lee will sometimes perform standardized head and neck CT scans to identify problems and determine whether additional procedures are necessary. Other times, he will simply use ultrasound- or CT-guided imaging to diagnose or treat post-transplant processes such as abscesses or enlarged lymph nodes. Infected fluid or pus can be extracted to determine what type of bacteria is present. "That way, the clinical team can tailor the antibiotics to combat the specific bacteria," Lee adds.
Because patients are prone to inflammation and fluid collection, this process is a key step in the success of the overall procedure. "There's an increasing utilization of minimally invasive procedures," explains Lee. "When there is a complication that can be addressed with a minimally invasive image-guided procedure, referring physicians and patients appreciate it."
Far Reaching Implications
Although many of the technologies and procedures used in these transplants have been used often, when applied together, they form a genuinely rare example of how radiology aids one of the newest, and possibly most impressive, surgeries in existence. And, because of its promise to restore key senses, the surgery is becoming more popular. "A large number of individuals ask about partial or full facial transplantation surgeries each month," says Rybicki. "However, screening from the Pomohac team is extensive, and only a few undergo imaging to determine if they meet the strict anatomic, metabolic, immunologic, and psycho-social criteria for this procedure." As a result, Rybicki explains, "[Facial transplantation] is a growing field. The main limitation now is experience, specifically the number of surgeons with the technical expertise, and the number of radiologists who can implement these protocols, complete the extensive image post-processing, and interpret the images necessary to the transplant."
One thing is certain: the team at BWH will continue to advocate for the benefits of full facial transplantations because of its transformational possibilities related to form and function. "You see unbelievable things that happen with each patient," says Rybicki.
1. Pomahac B, et al. “Three Patients With Full Facial Transplantation.” New England Journal of Medicine 2011 [Epub ahead of print]. Accessed Jan. 25, 2012.
2. Soga S, et al. “Surgical Planning for Composite Tissue Allotransplantation of the Face Using 320- Detector Row Computed Tomography.” Journal of Computed Assisted Tomography 2010;34:766–9.
3. Soga S, et al. “Preoperative Vascular Mapping for Facial Allotransplantation: Four-Dimensional Computer Tomographic Angiography versus Magnetic Resonance Angiography. Plastic and Reconstructive Surgery 2011;128:883–91.
4. Soga S, Wake N, et al. “Noninvasive Vascular Images for Face Transplant Surgical Planning.” ePlasty 2011;11:519–29.
By Alyssa Martino