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Dr. Daisuke Kobayashi had been treating children’s sick hearts for years, and had all of the Detroit Medical Center’s sophisticated imaging technology at his disposal. But he still couldn’t get a clear enough picture of teenager Ariana Smith’s aorta to figure out the best way to treat her.

A walnut-sized aneurysm blocked his view of what he suspected was a congenital narrowing of Smith’s aorta, the body’s biggest vessel. Both the aneurysm and the aorta needed treatment to prevent chronic or catastrophic consequences.

Kobayashi wasn’t sure if he should treat Smith — who turns 18 in October — with a minimally invasive repair, or prescribe traditional open-heart surgery by another doctor. Taking safety, effectiveness, and invasiveness into account, he recalled a lecture given by Materialise, a global company with North American headquarters in Plymouth. Todd Pietila, the company’s business development manager,��had shown Children’s Hospital doctors how 3-D printed models could help them.

Kobayashi and Pietila’s discussion eventually led to the firm printing a 3-D model of part of Smith’s heart and aorta. The model gave Kobayashi and his team the tool they needed to help the Taylor teen. They even used the model to test run a procedure they planned to use.

Their strategy required careful pre-procedure conversations.

“In these complex cases, we discuss a lot,” Kobayashi says. “We were not completely sure that the stent would align, and if it doesn’t align and fit well, she needs surgery. And if we didn’t plan well, there could be complications.”

Their planning paid off. During three hours in the catheterization lab in March, doctors used a balloon catheter to stretch the narrowing. They also inserted two stents in Smith’s aorta that block blood flow to the aneurysm, making it harmless.

The procedure went smoothly.

Smith is among a growing number of people to benefit directly from 3-D printing. Doctors are increasingly using imaging scans of a patient’s body, along with software that translates that data, to construct, layer by layer, replicas such as the teen’s heart model.

“We’re always met with some level of skepticism,” says Pietila, who’s talked to doctors in every major hospital in southeast Michigan about 3-D printing. “People look at it and say, ‘Right, but I’m not sure how I can use it.’ When they saw Ariana’s case, it became clear.”

He adds that the patient-specific models his company makes also give patients a peek inside their body in a way that’s easy for them to grasp.

“I think it gives them a sense of involvement in their care,” he says.

Jacqueline Foster, Smith’s mother, says she looked at the heart model the day after the catheterization. “I thought it was really cool that I was holding it and could see the actual size of the aneurysm,” Foster says, adding that her daughter is doing “great.”

Smith graduated from high school in May, and she is looking for a job and at colleges for a possible nursing degree. She returns for a repeat heart catheterization in September, in part to check on her aneurysm.

The technique of 3-D printing has many uses in health care. Some, including invisible braces, in-ear hearing aids, and custom foot orthotics, are already widespread.

Less commonly, doctors at the University of Michigan use 3-D-print splints for babies with underdeveloped tracheas, giving their bodies time to develop a functioning airway as the splint slowly dissolves.

Today about 15 percent of people who have a knee replacement benefit from a 3-D printed surgical guide, helping their surgeon determine where best to cut bone and drill holes. It’s a big step up from the traditional approach: using a ruler and the patient’s X-ray to plan surgery.

The technology is also helping the medical devices industry. Manufacturers can use 3-D printing to generate prototypes of their design that allow much speedier testing and refinements.

The brave-new-world technology is even being used with stem cells and growth factors to bio-print human tissue for drug testing and other uses, with the eventual goal of printing replacement organs or body parts.

Its use in surgical and treatment planning may become more widespread when 3-D printing gets the insurance code that doctors need for billing. For now, physicians pay for models out of their fee or with some other strategy, which may include a discount from Materialise, says Managing Director Bryan Crutchfield.

“It’s allowing doctors to really visualize what the problem is and what is the best way to solve it,” because now they know what they are getting into, he says.