UVA Health cardiologists have discovered a new way to track peripheral artery disease (PAD), a serious medical condition characterised by atherosclerosis in the leg arteries that affects more than 200 million people worldwide.

The approach, according to the researchers, will greatly aid efforts to better understand the condition, which reduces blood flow to the limbs and improve treatment options for patients.

At the end of the exercise, the UVA researchers were able to use new magnetic-resonance imaging (MRI) techniques to understand the effects of PAD in the calves of patients with the disease and distinguish them from normal volunteers.

The method they used, known as chemical exchange saturation transfer, or CEST, yielded results comparable to the current gold standard, which does not generate an image. CEST, they discovered, provided additional benefits without requiring highly specialised equipment that many hospitals and researchers do not have.

"The beauty of CEST is that it creates an image of energy stores in the muscle that we can match to images of blood flow," said Christopher M. Kramer, MD, chief of UVA Health's Division of Cardiovascular Medicine and professor of cardiology and radiology at the University of Virginia School of Medicine.

"This provides us with a new understanding of how atherosclerosis in the leg arteries leads to muscle problems downstream."

Understanding Peripheral Artery Disease

PAD affects more than 7% of Americans over the age of 40 and 29% of those over the age of 70. The disease can cause walking pain, lower leg coldness or numbness, painful leg or arm cramps, difficulty sleeping, and erectile dysfunction, among other symptoms, but it can also cause no symptoms at all.

A lack of adequate blood flow to the limbs can make wound healing difficult and, in severe cases, lead to amputation. Existing treatments include medications to improve blood flow and manage pain; in appropriate cases, doctors may also consider surgery or the implantation of a stent to open clogged arteries.

The new diagnostic approach discovered at UVA will help researchers better understand and treat PAD. The research team conducted a clinical trial comparing CEST to the current gold-standard approach, phosphorus magnetic resonance spectroscopy, to see if it would work for this purpose.

The researchers used CEST to image 35 PAD volunteers and compared the results to imaging from 29 control subjects after they performed calf exercise in the MRI scanner.

They discovered that CEST was effective at detecting PAD in the lower legs and distinguishing patients from healthy controls, and that the results compared favourably to phosphorus magnetic resonance spectroscopy.

They concluded that CEST could provide numerous benefits to researchers. CEST has a higher special resolution, generates an image, and does not require the expensive phosphorus magnetic resonance spectroscopy equipment. This means that more centres could benefit from the strategy.

CEST can also be combined with other magnetic resonance imaging methods that measure blood flow in the calf to help researchers better understand the effects of PAD.