POSITRON EMISSION TOMOGRAPHY OF THE EQUINE DISTAL LIMB: EXPLORATORY STUDY.

This research is on the use of a portable, high-resolution positron emission tomography (PET) scanner to image the lower limb of a horse. The study shows that this imaging technique not only makes it possible to visualize biological functions of tissue, but it does so with minimal harm to the patient or risk to medical staff involved.

Objective of the Research

• The primary aim of the study was to ascertain the effectiveness of a high-resolution PET scanner for imaging the lower part of a horse’s leg (distal limb). Before this research, there was no documented use of PET imaging in horses.

Methodology

• The research team conducted scans on the front feet and fetlocks (the equivalent of a human ankle) of three horses. All these horses had known issues located in their distal front limbs.
• The horses were put under general anesthesia and doses of F-fluorodeoxyglucose (F-FDG), varying from 1.5 to 2.9 MBq/kg, were administered. F-FDG is a radiopharmaceutical used in PET scans as a tracer.

Observations

• The researchers found that the radiation exposure during imaging was slightly higher than with Technetium scintigraphy, another common imaging technique. However, the fact that the horses were under general anesthesia minimized the duration of contact with the patient and, consequently, the risk to staff.
• The team noted that the uptakes of F-FDG were evident throughout the soft tissues, with the highest uptake in the coronary band and the lowest in the tendons. This allowed for high contrast imaging between soft tissue and bone, facilitating the differentiation of normal and problematic anatomic structures.
• Among the issues identified were degradation of the flexor cortex of the navicular bone, damages to the flexor tendons and suspensory ligament, and abnormal uptake through the lamina of a laminitic (a severe foot condition in horses) subject.

Implications

• From the research findings, it suggests that molecular tomographic imaging, specifically PET scans, is feasible for use in the distal limb of a horse.
• The researchers expect that this technique could be useful in both clinical and research settings, especially for studies involving tendon and ligament injuries (tendinopathy/desmopathy) and laminitis.