Equine Health Update Issue 2 Volume 19 - Page 20

EQUINE | Equine Disease Update Diagnosing Injury and Disease Article reprinted from The Horse, March 2017, page 22. The Horse is published by The Horse Media Group LLC. Alexandra Beckstett; Erica Larson; Nettie Libert, MS, phd, pas ; Stacey Oke, Dvm, MSc PET Scan: A New Diagnostic Imaging Option for Use in Horses I n August 2016, researchers at the University of Cali- fornia (UC), Davis, performed the first-ever positron emission tomography (PET) scan on a horse. Physi- cians use this technology to diagnose conditions rang- ing from cancer to heart and bone problems. It had never been used in horses for logistical reasons, but a recently developed portable scanner is changing that. Mathieu Spriet, DVM, MS, Dipl. ACVR, ECVDI, associate professor of surgical and radiological sciences at the UC Davis School of Veterinary Medicine, led a study to see whether PET scans could be useful for diagnosing equine lower limb injuries. A PET scan is like a scintigraphic scan, in which the veter- inarian injects a small amount of radioactive tracer into the patient to obtain an image that might reveal “hot spots” of pathology. “But instead of getting a single (twodimensional) im- age, we’re getting a series of images through the body, giving us much more information than the classic scinti- graphic scan,” Spriet said. 20 In their study, he and his colleagues used PET to cap- ture images of the front feet and fetlocks, the knees, and hocks in six research horses with lameness localized to the lower limb. They compared PET findings to those from computed tomography (CT), standing MRI, and scintigraphy. On the PET results they detected early indications of le- sions in areas such as the navicular bone, subchondral bone (located just beneath the joint cartilage), flexor tendon, suspensory ligament, and lamina. Several of these lesions, particularly on ligament attachments and subchondral bone, weren’t visible using the other imag- ing modalities. “PET scan looks at the molecular level and can find some changes that we do not see yet with other modalities,” he said. “The other advantage of PET scan is that you can tell whether the lesion is active or not,” he continued. “Some- times we have old lesions that aren’t causing a problem anymore, and the PET scan helps you distinguish what’s • Equine Health Update •