CHICAGO – Researchers in Germany have identified bone disease in the fossilized jaw of a Tyrannosaurus rex using a CT-based nondestructive imaging approach, according to a study presented today at the annual meeting of the Radiological Society of North America (RSNA). The imaging method could have significant applications in paleontology, the researchers said, as an alternative to fossil evaluation methods that involve destroying samples.
A familiar subject of popular culture today, the T. rex was a huge carnivorous dinosaur that roamed what is now the western United States millions of years ago. In 2010, a commercial paleontologist working in Carter County, Montana discovered one of the most complete T. rex skeletons ever found. The fossilized skeleton dates back approximately 68 million years to the Late Cretaceous period. It was sold to an investment banker, who dubbed it “Tristan Otto” before lending it to the Museum für Naturkunde Berlin in Germany. It is one of only two original T. rex skeletons in Europe.
Charlie Hamm, MD, a radiologist at Charité University Hospital in Berlin, and his colleagues recently had the opportunity to investigate a portion of Tristan Otto’s lower left jaw. While previous fossil studies have relied primarily on invasive sampling and analysis, Dr. Hamm and his colleagues used a noninvasive approach with a clinical CT scanner and a technique called dual-energy computed tomography (DECT). DECT displays X-rays at two different energy levels to provide information about tissue composition and disease processes not possible with single-energy CT.
“We hypothesize that DECT could potentially enable non-invasive quantitative element-based decomposition of material and thus help paleontologists characterize unique fossils,” said Dr Hamm.
The CT technique allowed the researchers to overcome the difficulties of scanning a large part of Tristan Otto’s lower jaw called the left dentary. The high density of the part was particularly challenging, as the quality of CT images is known to suffer from artifacts, or misrepresentations of tissue structures, when viewing very dense objects.
“We needed to adjust the current and voltage of the CT scanner tube to minimize artifacts and improve image quality,” said Dr. Hamm.
On visual inspection and computed tomography, the left dentary showed thickening and a mass on its surface that extended to the root of one of the teeth. DECT detected a significant accumulation of the element fluorine in the mass, a finding associated with areas of decreased bone density. The accumulation of mass and fluoride supported the diagnosis of osteomyelitis tumefacta, an infection of the bone.
“While this is a proof-of-concept study, noninvasive DECT imaging that provides structural and molecular information about unique fossil objects has the potential to address an unmet need in paleontology, avoiding defragmentation or destruction,” said Dr. Hamm. .
“The DECT approach shows promise in other paleontological applications, such as age determination and differentiation of real bone from replicas,” added Oliver Hampe, Ph.D., senior scientist and vertebrate paleontologist at the Museum für Naturkunde Berlin. “The experimental design, including the use of a clinical computed tomography scanner, will allow for a wide variety of applications.”
Dr. Hamm and colleagues also collaborated with paleontologists at Chicago’s Field Museum and colleagues at the Richard and Loan Hill Department of Biomedical Engineering at the University of Illinois at Chicago to perform a CT analysis of the world-famous T. rex “Sue.” which is in the museum.
“With each project, our collaborative network grew and evolved into a truly multidisciplinary group of experts in geology, mineralogy, paleontology, and radiology, emphasizing the potential and relevance of the results to different scientific fields,” said Dr. Hamm.
Additional coauthors are Patrick Asbach, MD, Torsten Diekhoff, MD, and Lynn Savic, MD.
Note: Copies of RSNA 2021 press releases and electronic images will be available online at RSNA.org/press21.
RSNA is an association of radiologists, radiation oncologists, medical physicists and allied scientists who promote excellence in patient care and health care delivery through education, research and technological innovation. The Society is headquartered in Oak Brook, Illinois. (RSNA.org)
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