Equine Nuclear Medicine in 2024: Use and Value of Scintigraphy and PET in Equine Lameness Diagnosis

Simple Summary Nuclear medicine imaging techniques consist of acquiring images after intravenous administration of a small dose of radioactive molecules. Different nuclear medicine techniques are available in the horse. Scintigraphy provides two-dimensional images and has been used for the detection of bone injuries in horses since the late 1970s. This was at the time the only alternative to radiographs to detect bone issues in horses. As other imaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) have developed, the role of scintigraphy in horses has reduced. Scintigraphy remains, however, commonly used in racehorses to detect stress injuries and is also used in other horses to image larger body areas or even the whole body of a horse. In the last 10 years, positron emission tomography (PET) has become available in horses and provides higher resolution three-dimensional images. PET shows promising applications by either replacing the use of scintigraphy for the smaller areas of the limbs or by adding useful information to other imaging techniques. PET allows detection of some injuries prior to their identification with CT or MRI and also helps decide if an injury is active or represents an old scar.Abstract Scintigraphy and Positron Emission Tomography (PET) are both nuclear medicine imaging techniques, providing functional information of the imaged areas. Scintigraphy is a two-dimensional projected imaging technique that was introduced in equine imaging in the late 1970s. Scintigraphy allows imaging of large body parts and can cover multiple areas, remaining the only technique commonly used in horses for whole body imaging. PET is a cross-sectional imaging technique, first used in horses in 2015, allowing higher resolution three-dimensional functional imaging of the equine distal limb. This manuscript will cover current use and values of these two modalities in equine lameness diagnosis.