Liver resection is becoming more common as a treatment for liver cancer and disease; a Washington University physician co-founded a new FDA-approved image-planning and operation-guidance software for this procedure. This technology generates a 3-D image from CT and MRI scans and accurately calculates the planned volume of liver to be removed and the volume that will be left in place. It provides a useful aid for surgeons planning what are often complicated liver surgeries.
The technology, called Pathfinder, consists of an optical tracking system, tracked surgical instruments and the image-guided surgery software that provides 3-D visualization of anatomic structures and real-time tracking of therapeutic delivery tools. William Chapman, MD, professor of surgery and chief of the Division of General Surgery, as well as chief of the Section of Transplant Surgery at Washington University, is one of the founders of Pathfinder and began developing the technology 14 years ago.
“For tumor removal or living donor transplantation, it’s important to know the margin of working liver left behind,” says Chapman. “The liver is made up of eight individual segments, each with its own blood supply and bile duct drainage. One of the challenges of liver surgery is that there are few surface markings that define the location of major vessels within the substance of the liver or boundaries of the liver segments.”
During surgery, Pathfinder uses infrared emitters to track operative instruments within a 1/10 millimeter in a standard operating room. “When planning, I can see where I want to make the resection,” says Chapman. “But once I start the surgery, I can now correlate my pre-operative images with the real-time surgical location. While working, I can register my position and track where I am inside the liver while making the resection.”
Pathfinder’s capability to calculate the volume of liver removed and remaining is key, says Chapman. “When removing a tumor, it’s important to know what part of the liver is still functional and how much of the tumor can be left without risk for reoccurrence in the patient. The pre-operative planning gives physicians assurance that the remnant liver is functional and adequate for the patient.”
Chapman says that ultrasound, CT scanning and other imaging still is used. “This is just another way to provide reassurance to surgeons as well as save time and provide a more streamlined way of surgical planning.”