Fig. 5. Comparison between sector (A) and linear (B) transducers to evaluate fiber pattern. Both longitudinal images were obtained at the proximal metacarpus. Image A was obtained with the 7.5 MHz fluid-offset sector transducer shown below the ultrasound image. Note that the fiber pattern can only be evaluated in the central part of the image with this type of transducer. Image B was obtained using the 7 to 10 MHz linear array transducer with a standoff shown below the image. Note the superior evaluation of fiber pattern across the width of the ultrasound image with linear transducers compared to sector transducers. Linear transducers became available in the mid-1990s and have replaced sector transducers for musculoskeletal imaging.
prove resolution of tendons and ligaments (Fig. 7). This began the rapid expansion of equine musculo- skeletal ultrasound, both in terms of diversity and quantity.
Specialists and Education The 1990s and new millennium began to see veter- inarians emerge from the fellowship program at New Bolton Center. Fellows received extensive training for 1 to 2 years, during which time they learned systematic techniques to evaluate a busy
and diverse caseload from the surrounding Chester County horse country. UC Davis followed with its own fellowship program in 2001. Several gradu- ates of these fellowships have gone on to academic positions and some have developed their own pro- grams. Others have set up their own ultrasound consulting services in private practice. The AAEP began holding annual ultrasound wet
labs in association with its annual convention and then in Lexington at the Kentucky Horse Park.
Fig. 6. Abdominal ultrasound images of the spleen and left kidney from 1999 through 2014 with the transducers shown above each image. A, A 2.5 MHz sector transducer from 1999 produces an image of the spleen and left kidney but does not provide substantial detail of the kidney compared with that seen in images B to D. B,A2to5MHz curvilinear transducera detail of the left kidney. C,A2to5MHz curvilinear transducerb compared to the previous images. D,A2to5MHz curvilinear transducerc
from 2001 shows improved
from 2007 produces a softer image with improved resolution from 2012 shows an even softer image. Note that image
quality has improved (more detail and less coarseness), despite the fact that the frequency range of these transducers has remained essentially unchanged.
