3D High Speed Imaging Tech To Screen Cancer
This is a 3-D OCT volumetric data set from an excised human colon specimen. (A) En face view showing regular organization of normal colon. (B and C) Cross-sectional views along two different directions showing sub-surface features. Two cross-sections are shown as examples, however multiple cross-sectional views can be extracted from the 3-D OCT data. Scale bar: 500um. MIT/Science Daily

The Massachusetts Institute of Technology (MIT) has extended the use of 3D imaging technology to screen oesophageal and colon cancer. The new imaging system is based on Optical coherence tomography (OCT) and has the advantage of detecting underlying microscopic pre-cancerous tissues.

According to the American Cancer Society, oesophageal and colon cancer are diagnosed in more than 1.5 million people worldwide each year.

What Is New?

OCT is similar to medical ultrasound imaging; only that OCT uses light instead of sound waves to detect pre-cancerous tissues that lie below the surface. OCT utilizes light waves of higher resolution to see images in the body in real time and can capture data equivalent to 980 frames or 480, 000 axial scans, which is 10 times faster than existing devices. The system can also measure microscopic features lesser than eight millionth of a meter in size.

OCT pioneer James G. Fujimoto of MIT and his colleagues presented a report, published by the Optical Society in its journal, Biomedical Optics Express, on oesophageal endoscopy using OCT. They noted that with high speeds and super fine resolution, the system would enable 3-D microscopic imaging of pre-cancerous changes in the oesophagus or colon and in the guidance of endoscopic therapies.

Fujimoto, lead author of the paper said, "Ultra high speed imaging is important because it enables the acquisition of large three dimensional volumetric data sets with micron-scale resolution."

"This new system represents a significant advance in real-time, 3-D endoscopic OCT imaging in that it offers the highest volumetric imaging speed in an endoscopic setting, while maintaining a small probe size and a low, safe drive voltage," says Xingde Li, associate professor at the Whitaker Biomedical Engineering Institute and Department of Biomedical Engineering at Johns Hopkins University, who is not affiliated with the research team.

OCT And It's Potential Applications?

The MIT researchers have teamed up with clinicians at the VA Boston Healthcare System and Harvard Medical School to examine endoscopic OCT as a method for guiding excisional biopsy.

Fujimoto explains, "Excisional biopsy is one of the gold standards for the diagnosis of cancer, but is a sampling procedure. If the biopsy is taken in a normal region of tissue and misses the cancer, the biopsy result is negative although the patient still has cancer."

The Procedure:

For endoscopic OCT, miniature probes with diameters of a few millimeters are needed, which can scan optical beams in two dimensions to generate high-resolution 3-D data sets. While scanning the beam in one transverse direction generates image in a cross-sectional plane; scanning the beam in two directions generates a stack of cross-sectional images or 3-D (volumetric) image.

The optical catheter developed by MIT researchers and their collaborators utilizes a piezoelectric transducer, a miniature device that bends in response to electrical current, allowing a laser-light emitting optical fibre to be rapidly scanned over the area to be imaged.

The Future Of OCT In Endoscopy

Fujimoto notes, "Before it can be deployed with the standard endoscopes now used, has only been used in animal models and in samples of human colons that had been removed during surgical procedures; further development and testing of the technology is needed before it can be tested in human patients."

He added, "The ultimate clinical utility of new devices must be established by large clinical studies, which assess the ability of the technology to improve diagnoses or therapy," he says. "This is a much more complex and lengthy task than the initial development of the technology itself."

Nevertheless, OCT has found good scope and is now commonly used in ophthalmology to generate images of the retina, enabling diagnosis and monitoring conditions; such as glaucoma. It also shows promising applications in cardiology, where the method is used to examine plaques in blood vessels that trigger heart attacks.