Lessons from the Past

Although she died when the Roman Empire ruled her native land, a five-year-old Egyptian child named Sherit is nevertheless pushing the envelope in high-tech medicine.

Oct 24, 2005
Bennett Daviss
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Image courtesy of Silicon Graphics, Inc. NASA/Stanford Biocomputational Center

Although she died when the Roman Empire ruled her native land, a five-year-old Egyptian child named Sherit is nevertheless pushing the envelope in high-tech medicine.

In August, Sherit, or "little one" in her ancient language, became the first mummy to be digitally unwrapped by a new computed tomography (CT) technology developed by Siemens. The newest version of Siemens' AXIOM Artis dTA C-arm scanning system captured about 35 times as much X-ray data as typical scanning systems like the one the Egyptian Museum in Cairo used in 2002 to tour the body of King Tutankhamun.

That original scan took 1,700 "slices" of data through the royal remains, each about 750 microns thick. In contrast, Siemens' new system took 30,000 slices in 200-micron-thick sections and yielded 92 GB of visual data. All that information simplified the job of constructing three-dimensional images, one of which is shown above.

The system scans at 30 frames per second, quadrupling the previous pace of 7.5. While existing detectors are sensitive enough to absorb data at that pace, other parts of scanning systems rarely are. Siemens revamped the Axiom's pre- and post-processing hardware to handle the increased load and created more capable reconstruction software called "DynaCT" to turn the sudden wealth of X-ray images into detailed 3D information.

In another first, the data was configured using Silicon Graphics' Prism visualization software coupled to Volume Graphics' radiant ray-tracing program – the same technique movie animators use to cast virtual light on a digital image to create reflections, shadows, and contrasts. (SGI, of Mountain View, Calif., organized the Sherit project.)

The tiny body had lain in the collection of the Rosicrucian Egyptian Museum in San Jose, Calif., since 1930. "We had no plans of ever opening this sarcophagus," says museum director Julie Scott. Breaking into the brittle shroud of linen and plaster "would have completely destroyed the covering and probably caused immediate damage to the mummy itself."

But without disturbing a thread, dentist Paul Brown, a visiting researcher at the Stanford-NASA Biocomputational Center, could see Sherit's adult teeth poised to emerge. He expects Sherit to become a case study for dental students. "I've worked with high-resolution 3D visualizations for years," he says. "By far, this is the best visualization of a child's skull I've seen." Stephen Schendel, director of the craniofacial surgery program at Stanford University Medical School, where the CT scans were done, cast a model of the girl's skull and crafted on it a clay likeness of her face.

"We estimate that we have 10 years of research to do on the data from the scan," Scott says, hoping that Sherit's story will reveal details about life and health in ancient Egypt as well as about the mummification process itself.

The technology could mean even more to those still living. Stanford radiologist Garry Gold, part of the Sherit project team, believes the new system will enable clinicians to create more detailed three-dimensional images while the patient is on the table. The technology will not only make it possible to do complicated interventions more easily and precisely, he predicts, but also may reduce patient trauma, treatment time, and hospital stays.

In addition, Gold says he expects surgeons to use the new equipment for image-guided interventions such as placing stents or targeting tumors. "It may also be useful for rapid imaging of a patient who has undergone skeletal trauma, such as an auto accident victim," he says. Hospitals already have begun to install the new $1.85-million dTA system or upgrade their present dBA, dFA, and dTA equipment.

But patients from the past won't be forgotten. "There are thousands of mummies all over the world that have on their chest plates all their information – their names, their professions, their family lineage," notes Afshad Mistri, manager of advanced visualization technologies at SGI. "With this breakthrough, we will be able to peer under those bandages and be able to give a name, a title, even a face to all of these people who lost their identities so long ago."