Peripheral artery disease (PAD), a narrowing of arteries in the arms and legs, is an all too frequent result of runaway diabetes, sometimes even leading to amputations. Symptoms like foot pain and numbness are often the first signs that patients have PAD. An earlier diagnosis would be extremely helpful for thousands, long before meaningful intervention becomes useless.
A new technique called dynamic diffuse optical tomography imaging (DDOT) from a research team at Columbia University may do just that. DDOT uses near-infrared light to visualize hemoglobin within tissue, providing an indication of how well blood is moving below the probe. The technique doesn’t require the injection of risky contrast agents nor the use of X-ray radiation, potentially helping make it perfect for a screening test.
From the announcement:
Michael Khalil, a Ph.D. candidate working with Hielscher [Andreas Hielscher, Ph.D., professor of Biomedical and Electrical Engineering and Radiology, and director of the Biophotonics and Optical Radiology Laboratory] at Columbia. “One key reason why DDOT shows so much promise as a diagnostic and monitoring tool is that, unlike other methods, it can provide maps of oxy, deoxy and total hemoglobin concentration throughout the foot and identify problematic regions that require intervention.”
“Using instrumentation for fast image acquisition lets us observe blood volume over time in response to stimulus such as a pressure cuff occlusion or blockage,” said Hielscher.
“In the case of tissue, light is absorbed by hemoglobin. Since hemoglobin is the main protein in blood, we can image blood concentrations within the foot without using a contrast agent,” Hielscher points out. Contrast agents pose the risk of renal failure in some cases, so the ability to monitor PAD without using a contrast agent is a great advantage.