Agents for Seeing
Contrast agents, which allow us to see inside living tissue, are not only crucial to imaging techniques, but also to extending the life of laboratory animals.
Michael Jiang ’12 and Alyssa Henning ’11 were undergraduate researchers in the lab of Jonathan Butcher, Biomedical Engineering, tackling the world’s most common birth defect—the congenital heart defect (CHD). A congenital heart defect is any abnormality in the structure of the heart or heart vessels that arises during embryonic heart development. These abnormalities may be caused by genetic mutations or by environmental factors, such as prenatal infections, illnesses, or drugs. CHD affects approximately 9 of 1,000 births and is the leading birth defect–related cause of infant mortality.
Jiang and Henning wanted to contribute to developing preventive measures and possibly treatments for human CHD by studying the hearts of embryonic chicks, which are quite similar to human hearts. By inducing heart defects in chicks during their development, researchers can better understand how defects form in humans and how they may be prevented.
Jiang and Henning used x-ray microtomography (microCT) imaging to observe the chick at different stages and construct a movie of its development in real time. MicroCT works like a human CT scan: x-rays create cross-sections of an object, which are then built into a 3-D virtual image. “Micro” refers to the high-resolution, micrometerscaled pixels of the resulting images, as well as the smaller physical size of the machine itself. This winning combination makes microCT a better and more cost-efficient alternative to traditional CT imaging for producing detailed images of smaller specimens.
Unfortunately, microCT on its own cannot effectively image soft tissue—contrast agents must be injected into the specimen to highlight soft tissue structures, such as the heart.
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