What are the commonly used transducers in musculoskeletal Ultrasound?
- The transducer frequency is one important determinant of image quality.
- The higher the frequency, the greater the spatial resolution of the images and the lower the degree of tissue penetration.
- It is important to select the transducer with the highest frequency that still allows penetration to the depth of the structure being imaged.
- Linear probes are preferable to curved probes for musculoskeletal US because the ultrasound waves are propagated parallel to the transducer surface, limiting artifacts during evaluation of linear structures such as tendons.
The most Commonly used transducers in musculoskeletal ultrasound are the below
- Highfrequency (15-7 MHz), smallfootprint, linear array transducer, also called a “hockey stick” transducer – The compact or “hockey stick” linear transducer is ideally suited for the evaluation of small joints and guiding procedures performed on the distal extremities where sharp contours allow for limited contact with the probe surface.
- High-frequency (17-5 MHz) linear array transducer – The linear 12-5 MHz is the workhorse transducer for musculoskeletal US, while the linear 17-5 MHz transducer may be used for the evaluation of more superficial structures.
- Low to medium-frequency (5-2 MHz) curvilinear array transducer – The 5-9 MHz curvilinear transducer is less commonly used in musculoskeletal US but has a role in the evaluation of deep structures or patients with larger body habitus.
- Both linear transducers are used for superficial imaging, whereas the curvilinear transducer’s lower frequency facilitates examination of deeper regions such as the hip
Musculoskeletal ultrasound involves not only the imaging of soft tissues throughout their available range, but also the visualization of elements structurally or functionally connected with them, e.g. the examination of muscle-tendon units should include the tendons at the muscle belly level and the naked (bare) part, their entheses, as well as all peritendinous elements, such as the peritendineum, sheaths, retinaculum, bursa, fascia, subcutaneous tissue, fat folds or bone outlines, main vessels and regional nerves.
Due to the specificity of the diagnosed tissues, musculoskeletal ultrasound requires top-class equipment with the highest quality transducers and, if possible, full software options to improve image quality, i.e. resolution, contrast and the best possible artifact removal.
In addition to providing high quality grayscale images, ultrasound apparatus should also feature the most sensitive color Doppler options