Wisconsin-Madison Sees Potential in Standing CT

The standing helical computed tomography (CT) scanner is named Equina.

University of Wisconsin-Madison Press Release | Release Date: October 29, 2019

As racing searches for solutions to catastrophic injuries, scientists at the University of Wisconsin-Madison have created a diagnostic imaging tool that could help prevent these injuries through early detection and monitoring: a standing helical computed tomography (CT) scanner named Equina.

It is the first CT scanner on the market to vertically scan the lower legs of a standing, sedated horse and also the first dual-purpose standing CT machine. This means it can scan up and down a patient’s legs and move horizontally to scan the head and neck – three areas of the body where CT is advantageous in teasing out anatomical intricacies.

The system fills a longstanding, unmet need in the diagnosis and treatment of a variety of conditions facing horses and other large animals. Already, more than 150 horses ranging in size from a miniature horse to a draft horse have been scanned at UW Veterinary Care, the teaching hospital of the UW-Madison School of Veterinary Medicine (SVM), using the new system. This has led to findings undetectable by earlier methods, including a brain tumor, an orbital tumor behind the eye, and diseases of the feet, teeth and sinuses.

“The CT has changed the way we can evaluate lameness and orthopedic injury in the distal limb and has virtually replaced radiography (X-rays) as the gold standard diagnostic for disease of the teeth and skull,” says Samantha Morello, clinical associate professor of large animal surgery at the SVM.

The first Equina machine was installed for evaluation in the winter of 2018 at UW Veterinary Care and the service is now available for patients of its Morrie Waud Large Animal Hospital. It is currently the only machine available in Wisconsin.

Standing CT holds several advantages over other diagnostic tools currently available for horses. For one, CT images provide improved imaging of bone and soft tissue compared to traditional X-rays, aiding diagnosis and treatment plans.

The technology, says the SVM’s J.R. Lund, a clinical instructor in diagnostic imaging, also allows for easier and faster imaging, and improves the ability of clinicians to discern what’s happening with their patients.

While X-rays yield a two-dimensional version of a three-dimensional object, which can lead to obscurities, CT “removes that layer of ambiguity” through three-dimensional, cross-sectional images, explains Ken Waller, clinical associate professor and section head for diagnostic imaging.

“To use a loaf of bread analogy, I can slice the loaf, take out a slice and look at it,” Waller says. “Then I can put that slice back, slice the bread in different directions, and take those slices out individually.”
Photo: Two x-ray images.

A comparison of radiograph (X-ray), left, and computed tomography (CT), right, imaging of portions of the coffin bone (on the sides) and navicular bone (centrally located) of a horse. Multiple dark regions within the left side of the navicular bone indicate degenerative change consistent with navicular syndrome. CT is much more sensitive to these changes than radiographs and allows clinicians to evaluate the navicular bone in a three-dimensional manner without superimposition. CT also allows for improved evaluation of the soft tissue structures, such as tendons and ligaments. UW School of Veterinary Medicine

In addition, because a horse can remain standing in the scanner and only requires sedation, there’s no need for general anesthesia – a cost savings for the client and safety advantage for the patient and hospital personnel. Anesthetizing a large patient like a horse is resource-intensive and carries a risk of complications and stress-related injuries, a limitation of conventional CT machines that require the patient to lie recumbent on a table. Clinicians rarely pursue recumbent CT for horses and other large animals unless they are already planning to anesthetize the animals for surgery.

The ability to image horses and other large animals without resorting to general anesthesia makes CT technology available to “almost every patient and client that walks through our door, since it’s safe, fast and cost-effective,” says Morello.

Read the full article online via the bloodhorse.com website

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