Using an augmented reality (AR) headset to view CT angiography (CTA) images allowed researchers from the U.K. to improve the accuracy and speed of reconstructive surgery in the leg for a series of cases detailed in an article published online on 31 January in European Radiology Experimental.
The team of surgeons and radiologists from Imperial College London modified CTA scans of the lower limb through various computer software. By wearing an augmented reality gadget, they were able to visualize medical images directly on the patient’s leg and, what’s more, manipulate this virtual anatomy with hand gestures during surgery (Eur Radiol Exp, 31 January 2018).
Incorporating augmented reality in the operating room facilitated the identification, dissection, and attachment of blood vessels during leg surgery and ultimately reduced surgical time and morbidity, according to the authors.
“There are a number of areas we would like to explore, and further improvements are needed, but the small case series has shown that for reconstructive surgery, this [augmented reality technique] seems to be a valuable tool in the operating theater,” lead author Dr. Philip Pratt noted in a statement from the university.
Traumatic injuries involving tissue damage or open wounds often require reconstructive surgery, for which flaps of tissue — including skin and blood vessels — are extracted from an unaffected area and integrated into the wounded area for proper healing and closure.
Presently, the gold standard for connecting the blood vessels of undamaged tissue to vessels around an injury relies on handheld ultrasound scanning to identify the location of the vessels as blood flows through them. Ultrasound scans can help surgeons estimate the location of blood vessels near the wound that they can eventually attach to the “new” tissue. But ultrasound is limited in its visualization of the vasculature and is also restricted to preoperative use for this application.
Aiming to resolve this issue, Pratt and colleagues combined the image quality of CT to the potential intraoperative application of augmented reality in a new approach to reconstructive flap surgery.
They began by acquiring contrast-enhanced CTA scans of patients in need of reconstructive surgery in the lower extremity. Scans of each patient then went through several rounds of image processing: segmentation into skin, bone, muscle, fat, and vascular models (Vitrea 6.7, Vital Images); refinement via an open-source software known as ITK-SNAP 3.6; and smoothing with the open-source software MeshLab 1.3.3.
The group then input the edited images into a custom-developed application written within a program (Unity 2017.1, Unity Technologies) that is compatible with an augmented reality device (HoloLens, Microsoft). After launching the application, they only needed to put on the HoloLens augmented reality headset to be able to see holographic overlays of the patients’ internal anatomy directly on their legs.
Image Credit: Dr. Philip Pratt