A New Way to “See” Your Leg’s Health: How a Bone Scan is Helping Fight Peripheral Artery Disease
Featured paper: Quantification of Skeletal Muscle Perfusion in Peripheral Artery Disease Using 18F-Sodium Fluoride Positron Emission Tomography Imaging
Disclaimer: This content was generated by NotebookLM and has been reviewed for accuracy by Dr. Tram.
Imagine you are going for a brisk walk in your neighborhood. After just a few blocks, your calves start to ache, feeling heavy or cramped. You stop, the pain fades, but it comes back as soon as you start moving again. For over 230 million people globally, this isn’t just a sign of getting older—it is a condition called Peripheral Artery Disease (PAD).
PAD happens when the arteries in your legs become clogged with plaque, much like old water pipes getting filled with gunk. This narrows the “pipes,” making it harder for oxygen-rich blood to reach your muscles. If left untreated, PAD can lead to serious problems, including the risk of losing a limb (amputation) or even death.
While doctors have ways to check for PAD, they aren’t always perfect. However, a groundbreaking new study published in the Journal of the American Heart Association by Dr. Mitchel R. Stacy and his team has found a way to use a common medical imaging tool to see exactly how much blood is reaching a person’s muscles.
The Trouble with Current Tests
Right now, if a doctor thinks you have PAD, they usually perform a test called the Ankle-Brachial Index (ABI). This involves putting blood pressure cuffs on your arms and ankles to compare the pressure. It’s a bit like checking the water pressure at the main valve of a house to see if there’s a leak.
The problem? Many people with PAD also have diabetes or kidney disease. These conditions can make the arteries in the legs very stiff—almost like concrete pipes. When the arteries are that hard, the blood pressure cuff can’t squeeze them properly, which leads to a “fake” normal reading. This means a person could have severe blockages, but the standard test says they are fine.
Doctors have been searching for a better way to measure perfusion—which is the scientific word for how much blood is actually soaking into the muscle tissue to keep it alive.
A New Imaging Superpower: 18F-NaF PET
The researchers decided to try something different. They used a technology called Positron Emission Tomography (PET). PET scans use a tiny amount of a radioactive “tracker” injected into the blood to show how organs and tissues are working.
Specifically, they used a tracker called 18F-sodium fluoride (18F-NaF). Usually, this tracker is used to look at bones or to see where arteries are hardening (calcification). The researchers had a clever idea: because this tracker travels through the blood before it sticks to bone, they could use that first “trip” through the legs to measure exactly how much blood the muscles were getting.
One of the biggest advantages of 18F-NaF is that it is “off-the-shelf”. Some other trackers used in PET scans have to be made in a massive, expensive machine called a cyclotron right at the hospital because they “expire” in just a few minutes. But 18F-NaF lasts long enough that it can be ordered from a central lab and shipped to almost any hospital with a PET camera.
From Pigs to People: Testing the Theory
Before trying this on humans, the team tested the method on a group of eight pigs. Scientists use pigs for heart and blood research because their circulatory systems are very similar to ours.
In the study, the researchers briefly blocked blood flow to one of the pig’s legs to mimic PAD. They used the PET scan to measure the blood flow immediately and then again two weeks later. They found that the PET scan was incredibly accurate at showing the “dip” in blood flow and the subsequent recovery as the pig’s body grew new, tiny blood vessels (called microvascular remodeling) to bypass the blockage. To be absolutely sure, they compared the PET results to a “gold standard” laboratory method using tiny microspheres, and the results matched perfectly.
Real-World Results for Patients
After the success with the pigs, the team moved to a clinical trial with 39 human patients who had different stages of PAD. The results were impressive:
- Mapping the Damage: The PET scans created detailed “perfusion maps” of the calf. These maps showed exactly which muscles were “thirsty” for blood and which were healthy.
- Matching the Symptoms: The PET scans were much better than the old blood pressure tests (ABI) at telling how severe a patient’s symptoms were. In fact, while the old tests often missed the mark, the PET scans showed a clear drop in blood flow as the disease got worse.
- Seeing the Cure Work: In one case, a 44-year-old patient with diabetes had a procedure to open up a blocked artery (revascularization). Just six days after the surgery, a follow-up PET scan showed a huge jump in blood flow to his leg muscles, proving the surgery worked.
Why This Matters for Your Future
This study is a big deal because it offers a “one-stop shop” for leg health. Because 18F-NaF is already used to look for hardening of the arteries, a doctor could potentially give a patient one injection and get two answers: how badly the arteries are clogged and how much blood is actually reaching the muscles.
Having an accurate, easy-to-access scan means doctors can make better decisions. They can decide who needs surgery right away and who can be treated with exercise or medicine. Most importantly, it gives a voice to patients whose symptoms are real but whose traditional tests might be coming back “normal.”
As the researchers noted, this is the first time this specific method has been tested and translated for use in humans. While they still want to test it on larger groups of people, this study opens a new door for millions of people living with PAD, helping them keep their legs healthy and stay on the move.