Ultrasound: why its the best imaging modality for feet!
Ok, so maybe the title is a little contekntious. Sonography isn’t better per se, but it is pretty awesome and is super accurate in the limbs when compared to other modalities.
What is sonography?
Sonography is the practice of using ultrasound to look inside the body.
I'll be you're thinking… isn’t that what they use for looking at babies?
You're right, it is. We can use that very same and very safe technology to look inside of our feet and legs to see pathologies that are affecting us on a day-to-day basis.
How does ultrasound work?
The ultrasound machine creates an electric current which is then passed through a crystal in a probe causing it to vibrate at a specific frequency. The vibrations are then sent into the body and bounce off of structures of different densities and the sound waves bounce back to the probe which then turns the vibrations into a picture.
Clear as mud, right? Check this video out, the first few seconds are tricky but it makes more sense, eventually!
What can be seen with ultrasound?
Ultrasound can see bones, tendons, ligaments, muscles, blood vessels, nerves and cartilage. This being said, the ability to see the structures can be limited by the type of machine, the probe, the patient and the location that is injured. Structures that are very deep or that are in awkward to get to places can be hard to see with ultrasound because the image loses quality as the sound waves pass through thicker tissues.
Ultrasound can see bones, tendons, ligaments, muscles, blood vessels, nerves and cartilage.
Also, a big struggle with ultrasound is that it can only see whatever is directly in front of it, and so if something is at an angle, around a corner or behind a very solid structure (like bone), then it might not be suitable to use ultrasound and other modalities could be more useful.
What can be diagnosed with ultrasound?
Lumps and bumps like ganglions, cysts and abscesses
What happens after an ultrasound scan?
The ultrasound scan may be used to confirm or rule out a diagnosis. Once this has been done, your clinician will be able to direct your treatment plan more specifically. Whilst ultrasound is an amazing modality that can quickly aid diagnosis, it can sometimes raise more questions for the patient and clinician and so further imaging may be required such as X-rays, MRIs and or CT scans. If you are privately funding, this can understandably be frustrating, but it is down to the clinician whom you see to ensure that you get the correct imaging performed.
Is ultrasound always accurate?
In the immortal words of Alanis Morissette: “It’s like having 10,000 spoons when all you need is a knife” ... and sometimes, ultrasound can be the spoon, and other times it can be the knife!
Ultrasound is user dependent, so the accuracy relies on who is scanning you:
Recognising what is normal or abnormal on the scan
Knowing what to look for based on
What the imaging request asks them to look for (so that's why it's important to make sure your health professional is good at diagnosing foot pain!)
What you have said to the sonographer (be clear in where you get your symptoms and how the symptoms feel)
What the scan has shown is / is not there and if that means they should be scanning other things too
The sonographer understanding variations in foot anatomy
Is up-to-date and well practiced in scanning feet.
So, the accuracy for ultrasound can be excellent, but may be dependent on the person scanning you.