RSNA: Surgeons leverage 3D printing in separation of conjoined twins

CHICAGO — In a medical first, CT imaging and 3D printing technology have been used to help plan the surgical separation of conjoined twins.

About one of every 200,000 live births results in conjoined twins and survival rates are low. Separating them through surgery is extremely difficult because they often share organs and blood vessels.

Knatalye Hope and Adeline Faith Mata, conjoined twins from Lubbock, Texas, were born on April 11, 2014, connected from the chest all the way down to the pelvis. "This case was unique in the extent of fusion," said the study's lead author, Rajesh Krishnamurthy, MD, chief of radiology research and cardiac imaging at Texas Children's Hospital. Krishnamurthy presented the case during the RSNA annual meeting. "It was one of the most complex separations ever for conjoined twins."

To prepare for the separation surgery, Krishnamurthy and colleagues performed volumetric CT imaging with a 320-detector scanner, administering intravenous contrast separately to both twins to enhance views of vital structures and help plan how to separate them to ensure survival of both children. They used target mode prospective EKG gating to freeze the motion of the hearts on the images and get a more detailed view of the cardiovascular anatomy, while keeping the radiation exposure low.

"The CT scans showed that the babies' hearts were in the same cavity but were not fused," Krishnamurthy said. "Also, we detected a plane of separation of the liver that the surgeons would be able to use."

The team translated the CT imaging results into a color-coded physical 3D model with skeletal structures and supports made in hard plastic resin, and organs built from a rubber-like material. The livers were printed as separate pieces of the transparent resin, with major blood vessels depicted in white for better visibility. The models were designed so they could be assembled together or separated during the surgical planning process.

On February 17, the 10-month-old sisters underwent surgical separation by a team of more than 26 clinicians, including 12 surgeons, six anesthesiologists and eight surgical nurses. The official separation took place approximately 18 hours into the 26-hour surgery.

There were no major discrepancies between the models and the twins' actual anatomy. "The surgeons found the landmarks for the liver, hearts and pelvic organs just as we had described," Krishnamurthy said. "The concordance was almost perfect."

Krishnamurthy expects the combination of volumetric CT, 3D modeling, and 3D printing to become a standard part of preparation for surgical separation of conjoined twins, although barriers remain to its adoption. 3D printing technology has advanced notably and costs are declining. However, he cited a lack of reimbursement for these services.