Ultrasound Tissue Characterization of Human Achilles Tendon by Stability Quantification of Echo Patterns

We aim to describe a standardized protocol using ultrasound tissue characterization to assess Achilles tendon structure and to support its application, both in research and clinical practice for diagnosing injuries and monitoring treatment response. Many approaches for the assessment of tendon disorders have been proposed, the most recent advance is inside the area of ultrasound imaging, which provides an accessible approach for evaluating tendon size and structure. We address the need for a standardized operator independent method to quantitatively assess the tendon structure, overcoming key limitation of traditional ultrasound imaging.

Among the many new questions to the method that we described will put forward to the questions of what echo types are associated with various disease states. Do echo type changes precede and predict the occurrence of clinical symptoms? To begin, unscrew the two metal screws underneath the tracker to release the standoff.

Cover the superior surface of the standoff with a thick layer of acoustic gel. Then, reattach the standoff to the tracker. Unscrew the two black screws of the transducer strap and the locking screw of the transducer holder base.

Insert the transducer into the transducer holder base and fasten the locking screw and the two strap screws. Next, unscrew the two black screws securing the transducer holder. Adjust the holder height so the transducer runs half a millimeter to one millimeter above the standoff, remaining in contact with the acoustic gel.

Connect the tracker using the USB cable and attach the transducer to the smart system. Plug in the power brick to supply power. Press the power button on the top left edge of the smart system until the blue indicator lights up.

A few beeps will be heard. Double-click on the Ultrasound software icon on the desktop to launch it. Then, minimize the ultrasound screen from the smart system toolbar.

Press the on/off button to power on the tracker. Position the subject in a comfortable prone position with the bare foot relaxed and dangling off the end of the table. Apply a thick layer of acoustic gel to the skin on the distal posterior part of the leg to ensure good contact with the transducer.

Then, push the knee against the subject's metatarsal heads to passively dorsiflex the ankle until it reaches maximum dorsiflexion. Next, double-click on the analysis software icon on the smart system. Then, click the red acquisition button on the upper toolbar.

When the message Tracker initialization ok"appears, click OK.When the Acquisition Control window opens, click Start US to display the ultrasound image from the ultrasound software. In the Acquisition Control window, click Acquisition. When prompted with Press the start button on the tracker to start the acquisition, click OK.Place the tracker on the calcaneal region so that it is perpendicular to the long axis of the Achilles tendon.

Then, press the start button on the tracker to begin the acquisition. The transducer begins to move automatically along the tracker over the length of the tendon. Monitor the full scanning procedure on the ultrasound scanner screen of the smart system.

At the end of data collection, click OK on the Acquisition Control window. Then, click Exit to close the window. Click on the transverse cross section in the top left of the Analysis software screen to refresh and display acquired images.

From the file dropdown menu, select Save Scan, and save images into the designated folder. Click the appropriate button on the upper toolbar of the analysis software to switch from qualitative to quantitative parameter set. Then, press the UTC Quantitative Analysis Properties setting button on the toolbar to open the window.

Now, flag Customize Set 1 from the Settings window. Set the sample window to 25. Click Save All Settings to save changes, and then click OK to close the window.

Next, press the Show or Edit Contour button on the upper toolbar to open the Contour Mode window and Flag Contour. Click the Analysis 1 button on the toolbar to start contouring. Slide through sagittal scans and click at intervals to draw a contour around the tendon in the transverse cross section, starting from the edge of the calcaneus bone, switching from analysis to ultrasound mode to properly identify tendon margins.

Continue drawing a contour every 25 images while moving through the sagittal section. Once all contours are completed, select Save UTC Contour from the file dropdown menu to save all drawn contours. Click the specific Analysis Launch button, which corresponds to the sample window ideal for general analysis for statistics on the toolbar to start a new analysis.

Then, press the statistics button on the toolbar to open the statistical graph window. Click Contour to display graphs for all drawn and interpolated contours. For reporting, navigate to the sagittal cross section of the tendon and click the star button on the toolbar to select reference image at significant positions.

Press the Export PDF button on the toolbar to import images and statistics into the PDF editor. The normal Achilles tendon showed homogeneous echogenicity in both longitudinal and transverse scans with the thickest region measured at 4 millimeters. at position number 2.

UTC Analysis of the normal tendon revealed a high percentage of echo type 1 indicating intact and aligned tendon bundles across all three positions. The pathological Achilles tendon showed moderate hypoechogenic regions proximally and extensive hypoechogenic areas in both the mid portion and distal positions. UTC analysis of the pathological tendon showed a reduced percentage of echo type 1 and a high presence of echo types 3 and 4, especially in the central and distal portions.

The echo type 1 percentage in the normal tendon was consistently high, ranging from 86.9%to 90.3%at all positions and remained elevated in the total tendon volume at 83.8%In contrast, the pathological tendon exhibited a much lower echo type 1 percentage at all positions while echo types 3 and 4 were significantly elevated, comprising 50.7%of the total volume.