Updated: Feb 16, 2022
At PICSM we pride ourselves in offering the highest quality of ultrasound imaging to diagnose injuries to muscles, tendons, and ligaments. Not only do we have the most advanced imaging in the Helena area, in Montana, and in our entire region, we are also the first to offer Shear Wave Elastography to help identify diseased or damaged tissue. Because high resolution ultrasound imaging
is a functional exam when compared to MRI, we now have multiple tools at our disposal to help identify and treat damaged tissues. Shear Wave Elastography is the newest tool that separates PICSM from other clinics by looking at the stiffness of the tissue.
Simply, Shear Wave identifies tissue that has become too elastic (hypermobile), or torn, versus too stiff (scar tissue). Although MRI is good for looking at the big picture, Shear Wave Elastography helps us to focus on small areas of damage and determine the health of the collagen fibers that make up muscular, tendon, and ligamentous tissue. This allows us to identify damaged tissue that would be called "normal" with MRI imaging, whereas elastography allows PICSM, as a provider of Shear Wave, to identify and treat areas that are creating chronic pain and disfunction.
Why Shear Wave Elastography Instead of MRI?
Although nothing beats MRI for the big picture (view from 1000 feet up), after a whiplash injury, Shear Wave Elastography can help identify the injury to tissues that are typically not well visualized with routine MRI imaging. MRI does assess
the quality of bone and disk spaces, but
has a limited role in determining the functionality of the soft tissues around the neck after a whiplash injury, as an example. Many so-called "normal MRIs" fail to adequately evaluate the muscular and ligamentous attachments with movement, because MRI is a static study. Shear Wave Elastography allows PICSM to evaluate tissue both in a relaxed and active phase movement. Elastography evaluates tissue based on compliance (flexibility) so that we can determine subtle tears, hypermobile versus tissue that is too stiff or scarred. With Shear Wave Elastography we are looking directly at the tissue in question, giving us
a close to ground-level view of the damage. MRI of the median nerve is seen on the black and white image and shear wave is shown on the color images. The white arrow points to the median nerve in cross section of the left and longitudinal of the right. Red areas of the elastography image shows stiffness of the nerve and surrounding tissue during wrist extension.
Shear Wave Elastography Helps Identify Damaged Nerves
Shear Wave Elastography is a new technique to identify damaged nerves, such as the median nerve found in carpel tunnel syndrome. Pulsed ultrasound waves will rebound off tissues with different speeds depending on the compliance of the tissue, or the elasticity of the tissue. Using this latest technology helps us to identify the health of any tissue, but can be used to help identify damage to nerves. Normally nerves are very supple and with chronic compression, entrapment, or neuropathy, they become stiff. Normal elastic values for a healthy median nerve run about 32kPa (kilopascal), and a diseased carpel tunnel nerve runs upwards 66kPa. In severe cases, the median nerve stiffness can run well over 100kPa. The lower the kPa, the softer, or more compliant the nerve is. High kPa confirms stiffness and loss of glide through tissue. With normal movement, the extremities, nerves glide in fascial planes, smoothly allowing muscle contraction and joint movement without compression or stretching of nerves. In diseased states, nerves become entrapped or adhered to the surrounding tissue showing poor compliance and stiffness. Elastography can be used to confirm where nerve entrapment is occurring and guide treatments.