3D OCT shows promise for cancer screening
Researchers at the Massachusetts Institute of Technology (MIT) in Cambridge, Mass., have developed an imaging system that enables high-speed, 3D imaging of microscopic precancerous changes in the esophagus or colon. The optical coherence tomography (OCT) offers a way to see below the surface with 3D microscopic detail.
The endoscopic OCT imaging system reported by James G. Fujimoto, PhD, professor of electrical engineering and computer science at MIT, and colleagues captured data at a rate of 980 frames (equivalent to 480,000 axial scans) per second while imaging microscopic features less than 8 millionths of a meter in size.
"Ultrahigh-speed imaging is important because it enables the acquisition of large 3D volumetric data sets with micron-scale resolution," Fujimoto said in a statement.
In OCT imaging, microscopic-scale structural and pathological features are examined by directing a beam of light on a tissue and measuring the magnitude and echo time-delay of backscattered light. Because the amount of light that can be recaptured and analyzed decreases quickly with depth in tissue due to scattering, the technique can generally only be used to visualize sub-surface features to a depth of 1 to 2 mm.
"However, these depths are comparable to those sampled by pinch biopsies and unlike biopsy, information is available in real time," Fujimoto said. By using miniature fiber optic scanning catheters or probes, either on their own or in combination with standard endoscopes, colonoscopes or laparoscopes, OCT can be performed inside the body.
In collaboration with clinicians at the VA Boston Healthcare System and Harvard Medical School in Boston, the team is investigating endoscopic OCT as a method for guiding excisional biopsy to reduce false negative rates and improve diagnostic sensitivity.
"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," noted Fujimoto.
Endoscopic OCT requires miniature optical catheters or probes a few millimeters in diameter that can scan an optical beam in two dimensions to generate high-resolution 3D datasets.
"This device development is one of the major technical challenges in endoscopic OCT because probes must be small enough so that they can be introduced into the body, but still be able to scan an optical beam at high speeds," Fujimoto said.
The optical catheter developed by the MIT researchers and their collaborators uses a piezoelectric transducer, a miniature device that bends in response to electrical current, allowing a laser-light emitting optical fiber to be rapidly scanned over the area to be imaged.
So far, the device, which must be further reduced in size before it can be deployed with standard endoscopes, has only been used in animal models and in samples of human colons that had been removed during surgical procedures.
The endoscopic OCT imaging system reported by James G. Fujimoto, PhD, professor of electrical engineering and computer science at MIT, and colleagues captured data at a rate of 980 frames (equivalent to 480,000 axial scans) per second while imaging microscopic features less than 8 millionths of a meter in size.
"Ultrahigh-speed imaging is important because it enables the acquisition of large 3D volumetric data sets with micron-scale resolution," Fujimoto said in a statement.
In OCT imaging, microscopic-scale structural and pathological features are examined by directing a beam of light on a tissue and measuring the magnitude and echo time-delay of backscattered light. Because the amount of light that can be recaptured and analyzed decreases quickly with depth in tissue due to scattering, the technique can generally only be used to visualize sub-surface features to a depth of 1 to 2 mm.
"However, these depths are comparable to those sampled by pinch biopsies and unlike biopsy, information is available in real time," Fujimoto said. By using miniature fiber optic scanning catheters or probes, either on their own or in combination with standard endoscopes, colonoscopes or laparoscopes, OCT can be performed inside the body.
In collaboration with clinicians at the VA Boston Healthcare System and Harvard Medical School in Boston, the team is investigating endoscopic OCT as a method for guiding excisional biopsy to reduce false negative rates and improve diagnostic sensitivity.
"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," noted Fujimoto.
Endoscopic OCT requires miniature optical catheters or probes a few millimeters in diameter that can scan an optical beam in two dimensions to generate high-resolution 3D datasets.
"This device development is one of the major technical challenges in endoscopic OCT because probes must be small enough so that they can be introduced into the body, but still be able to scan an optical beam at high speeds," Fujimoto said.
The optical catheter developed by the MIT researchers and their collaborators uses a piezoelectric transducer, a miniature device that bends in response to electrical current, allowing a laser-light emitting optical fiber to be rapidly scanned over the area to be imaged.
So far, the device, which must be further reduced in size before it can be deployed with standard endoscopes, has only been used in animal models and in samples of human colons that had been removed during surgical procedures.