Advanced Imaging


Advanced Imaging Magazine

Updated: July 8th, 2008 05:26 PM CDT

Biomedical Imaging Put to Work

Imaging Is the Interface to Vew the Human Machine
Biomedical Image
A biomedical image should help diagnose, monitor, guide and describe a patient's condition.
'We are biological machines, and imaging provides a way to see how these machines work.' -Roderic Pettigrew

By Mike May

Modern biomedical images are often attention grabbers. They can appear as art when various fluorescent markers create a pattern of color inside cells. Scientists today, however, demand more than pretty pictures. Images must work. A biomedical image should diagnose a disease, describe a biochemical pathway, monitor the impact of a treatment, or guide a procedure.

Roderic Pettigrew, director of the National Institute of Biomedical Imaging and Bioengineering (Bethesda, MD), says that imaging has value on several levels. Perhaps the most obvious value is the ability to diagnose a disease without invading the body. "There is a tremendous shift in the whole healthcare paradigm," Pettigrew says, "from hunting down disease and treating it to forecasting disease and preventing it."

To predict the future, imaging must surpass simple observation. Biomedical scientists now use imaging to understand structure and function and how the two interact. "We are biological machines," says Pettigrew, "and imaging provides a way to see how these machines work."

From the Heart

David Piwnica-Worms, director of the Molecular Imaging Center at Washington University School of Medicine (St. Louis), does imaging research on molecular functions. His work uses Tc-99m-Sestamibi (Cardiolite), a radioactive compound from Bristol-Myers Squibb (New York) that is used to image blood flow in the heart. This fat-loving compound diffuses across cell membranes and accumulates in the mitochondria in heart cells. At the whole-tissue level, the retained radiopharmaceutical generates a snapshot of blood flow to different regions of the heart.

Cancer cells also have lots of mitochondria, and Cardiolite, an imaging agent, gets in them, too. In some cancer cells, though, a membrane transporter known as P-glycoprotein pumps chemotherapy agents out of the cell. In cells with this protein, entire families of chemotherapy agents fail. P-glycoprotein also recognizes Cardiolite, and pumps it out of the cancerous cell. With Cardiolite, Piwnica-Worms can noninvasively examine cancer cells in patients using gamma cameras and see if they resist chemotherapy by way of the P-glycoprotein. "This shows if a certain cancer is multi-drug resistant," says Piwnica-Worms. "If it is, then a different agent is needed to fight it."

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