Improving Your Plantar Fascia Images

Some best settings, tips, images, and videos …

The plantar fascia is a hyperecheoic (white) fibrillar structure covering the Abductor Hallucis, the Flexor Digitorum Brevis, and ultimately the proximal half of the Digiti Quinti muscle. Plantar fasciitis is identified by a hypoechoic (darker) thickening of the fascia trailing off from the calcaneus (itself a particularly unmistakable hyperechoic white arch, which you will use as a landmark) and flairing out along the bottom of the foot. The upper and lower edges of the fascia will be hyperechoic (white) while the inflammation between will be hypoechoic (darker gray to black). A normal plantar fascial band should measure about 3.5 to 4.5 mm in thickness. The most common purpose of your scan is to measure the thickness of the fascia and look for swelling and inflammation.

Here are your primary settings and some tips on technique for acquiring a good image of the plantar fascia:

  1. Frequency: Press your frequency button ("Freq") until your frequency is set to 7.5 MHz. This will almost always be best for fascia.
  2. Focus: Press your focus button ("Focus" — just below Frequency) until you have only two pointers on the right side of your screen, then roll your trackball to point them at the region of the image where the fascia is apt to be found. This is usually one to two centimeters down from the top of the screen.
  3. Depth: Normally you will tend to get the best images of the fascia with your Depth knob set to 6.3 cm or 4.7 cm.
  4. Gain: Set your master B-Gain knob to 75, then fine-tune the image with your TGC gain sliders in order to make the upper and lower edges of the fascia stand out more clearly. You don’t want it too bright (washed out) or too dark (obscure); you are looking for a comfortable balance.
  5. Technique: It’s possible to image the fascia along the transverse plane (and I suppose you might do so during an occasional guided injection of the fascia), but it is by far easiest (and most accurate) to visualize and measure when imaged along the longitudinal plane. I tend to have the little gray orientation dot at the top left on the screen and orient the dot-end of the probe (the "notch") distally, pointing toward the patient’s toes. Always use plenty of gel, and come up over the patient’s heel and identify the calcaneus as it comes into view. You should then see, trailing out from it, the hyperechoic (lighter) bands of the fascia and, if inflamed, the vertically-thickened hypoechoic (darker) region between. A good tell-tale indicator is to look for a hyperechoic line just above the white arc of the calcaneus. Keep in mind that you may need to correct the angle of the probe to maintain a 90-degree angle to what you are imaging, and also take a moment to move the probe to the left or the right to observe (and align yourself along) the three bands of the plantar fascia. After bringing the fascia into view, tweak your settings (Depth knob and Focus pointers if necessary, then the TGC Gain Sliders), and with the settings now set where you think best, begin again and come back up over the heel, repeatedly if necessary, watching the calcaneus come into view and, trailing away from it, the fascia itself … correcting your angle and position as needed, until you pull in a clear image of the fascia … then press "Freeze." Scroll the trackball to the left, backing up in your cineloop, to find the clearest frame from which to make your measurements.

 

Probe Orientation …

Probe Orientation

 

Most Common Mistake …

The most common mistake in imaging the fascia (and I have made it myself, indeed even when first constructing this page!) is to visually lock in on the muscle layer beneath the fascia, and think because it is particularly hypoechoic (dark, and easy to spot) that you have found what you are looking for, when in fact you have only found a valuable clue to where to look for the lower edge of the actual fascia coursing above this muscle layer. Look at the following image. In it you will see the fascia trailing off from the calcaneal tuberosity, demarcated by a hyperechoic line above and below, with a rather hypoechoic (darker) area between. This is the fascia being measured. Below the fascia, off to the left, is an even darker area — this is the muscle layer, and it is often mistaken for the fascia.

Here is something to try if you are trying to distinguish between the fascia and the muscle beneath it. Zoom in your Depth to 4.7 cm and look for the fibrous texture evidenced in the fascia, which should contrast with the more uniformally homogenous hypoechoic Flexor Digitorum Brevis. Repeatedly come up over the calcaneus and try to identify the bands of the fascia while paying close attention to the angle at which you are holding the probe. It’s the combination of these factors that will translate into an accurate image of the plantar fascia. Just be warned: that muscle layer is often much more hypoechoic, and in the beginning — eager to capture an image and get some measurements — it’s easy to be misled.

Common mistake

 

What you should be looking for — 1st, 2nd, and 3rd …

1.) You are coming up over the heel longitudinally, so the first thing you are looking for is the calcaneous (which should be a very clear and obvious hyperechoic curve). It’s almost impossible to miss the calcaneous.

2.) Now, at this point you should turn your attention to the top, left side of the calcaneous where you should see the hyperechoic (white) leading edge of the plantar fascia trailing just below the calcaneous (which is to say, just above it on the screen). This is our landmark for where we should see the bottom edge of the fascia.

3.) With the bottom edge of the fascia identified, we now look for the hypoechoic (darker) muscle layer above the fascia (which is to say, below it on the screen). This is our landmark that should help us identify the hyperechoic upper edge of the fascia trailing over the muscle layer. (And remember, as covered in a section above, you don’t want to confuse this muscle layer with the fascia itself. It is, however, a very helpful visual guide for where you can find the upper edge of the fascia.)

 

Step 1
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Step 1

Step 2
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Step 2

Step 3, first part …
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Step 3a

Step 3, second part …

Step 3b

 

Quick TGC Gain Slider Tip …

Keeping in mind the caveat given above (the warning to avoid mistaking the darker muscle beyond the fascia for the fascia itself), it is always helpful to adjust your gain sliders when fine-tuning the clarity of your plantar fascia images.

One way to do so is to increase the gain above and below the inflammation once you feel you have identified it (making the hyperechoic bands even brighter), while lowering the gain a bit in the region of the inflammation itself (making what might otherwise be a dark gray even darker). This can be a helpful technique in better clarifying the borders of the fascia you will be measuring.

The Split-Screen Technique …

If you would like to compare the left and right feet, side by side, in the same image, or if you would like to get a longer view of the fascia itself (up to 100mm — two probe lengths) all on the screen at the same time, you will want to check out our page on the split-screen technique.

Training Videos

You can access the library of plantar fascia exam training videos by clicking here.