Ultrasonography in Rheumatic / Musculoskeletal Disease
Musculoskeletal ultrasound (MSUS) includes 2 principal modes: B-mode (or gray scale) that provides morphological information of the anatomic structures and Doppler mode (color Doppler or power Doppler) that allows evaluation of blood flow.
MSUS should be performed with high-resolution linear transducers (ie, probes) with frequencies between 6 and 14 MHz for deep/intermediate areas to ≥15 MHz for superficial areas.
Tissue harmonic imaging, spatial compound imaging, extended field of view (panoramic), and virtual convex imaging are some of the software capabilities that may be useful in MSUS.
When scanning a joint, the probe should be oriented as perpendicular or parallel to the bony cortical surface (bony acoustic landmark) so that the cortical margin appears bright, sharp, and hyperechoic.
A dynamic scanning technique by means of slight movements of translation (side-to-side, back-to-front), angulation, and rotation of the probe should be carried out to allow the best visualization of the structure(s) of interest.
MS structures should be evaluated as they move smoothly either actively or passively.
To avoid anisotropy (ie, hypoechoic/anechoic appearance of a normally hyperechoic structure that mainly affects tendons) and the common pitfalls that accompany it, the probe should be continuously adjusted to maintain the beam perpendicular to the tendon fibers, especially in insertional regions.
When the long axis of the structure of interest corresponds to the cranial-caudal orientation of the anatomic position, the most proximal aspect of the structure is usually placed on the left-hand side of the screen. However, other options are acceptable as long as the movement of the image on the screen is kept parallel to the direction of the probe on the patient. Our preference for short axis is to align the structure of interest on the screen as if the observer is looking at the patient.
Probe compression can be helpful in distinguishing a compressible liquid collection from a non-compressible solid. Little or no compression is important when performing Doppler examination to avoid cessation of flow in small vessels.
A generous amount of gel should be used for superficial structures especially when little or no pressure is indicated.
The machine setting for B-mode and Doppler mode should be properly adjusted to optimize the US image acquisition process.
For further reading, see Joint Assessment Using Bedside Ultrasonography
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Any views expressed above are the author's own and do not necessarily reflect the views of WebMD or Medscape.
Cite this: John Anello, Brian Feinberg, John Heinegg, et. al. New Clinical Practice Guidelines, September 2017 - Medscape - Sep 15, 2017.