Study compares PET and standing MRI in horses with foot lameness
Bottom line
Version 1 — Brief
A new study in Veterinary Radiology & Ultrasound compared dual-tracer positron emission tomography, using ^18F-FDG and ^18F-NaF, with low-field standing MRI in 14 horses with forelimb lameness localized to the foot. The goal was to see how well PET’s metabolic information aligned with MRI’s structural detail in a clinical population of lame horses. The work builds on UC Davis-led research into equine PET imaging and adds clinical evidence that the two modalities can identify overlapping lesions while also contributing different kinds of information, particularly around active bone and soft tissue change. (pubmed.ncbi.nlm.nih.gov)
Why it matters: For equine veterinarians, foot lameness remains one of the most common and frustrating diagnostic problems, and MRI has long been a mainstay because it can visualize soft tissue and osseous structures within the hoof capsule in standing horses. But prior UC Davis background on PET suggests PET may detect metabolically active lesions, including small areas of abnormal bone, that MRI can miss or characterize differently. In practice, that means PET and low-field MRI may be less competitors than complements, especially in horses with persistent foot pain, multiple concurrent lesions, or questions about which imaging finding is actually active. (vetmed.ucdavis.edu)
What to watch: Watch for larger clinical studies, outcome data, and clearer guidance on when PET should be added after MRI in horses with foot pain. (pmc.ncbi.nlm.nih.gov)
Key facts
- Study
- Compared dual-tracer PET with low-field standing MRI
- Tracers
- ^18F-FDG and ^18F-NaF
- Sample size
- 14 horses
- Population
- Horses with forelimb lameness localized to the foot
- Journal
- Veterinary Radiology & Ultrasound
- PET purpose
- Soft tissue metabolic activity and osseous activity
- MRI type
- Low-field standing MRI
Version 2 — Full analysis
A new equine imaging study in Veterinary Radiology & Ultrasound examined how positron emission tomography and low-field standing MRI correlate in horses with forelimb lameness localized to the foot, an area where diagnosis is often difficult even after a thorough workup. The study evaluated 14 horses and compared dual-tracer PET, using ^18F-FDG for soft tissue metabolic activity and ^18F-NaF for osseous activity, with low-field standing MRI, which remains a widely used advanced imaging option for the equine foot. (learn.aaep.org)
That question matters because foot pain is a major source of forelimb lameness in horses, and advanced imaging has steadily reshaped how veterinarians approach it. MRI has become central to diagnosis because it can assess both soft tissues and bone within the hoof capsule, often in the standing horse, avoiding general anesthesia. Earlier work has shown that standing low-field MRI can identify lesions in most horses with chronic foot pain, with navicular bone lesions, navicular bursitis, deep digital flexor tendon injury, and distal interphalangeal collateral ligament disease among the common findings. (vetmed.ucdavis.edu)
At the same time, PET has emerged as a newer functional imaging tool in equine lameness. Reviews of equine nuclear medicine describe PET as a higher-resolution, cross-sectional modality that can identify areas of increased metabolic activity in the distal limb, and UC Davis has been a major driver of that work, including development of standing equine PET applications. A UC Davis research summary tied to this line of investigation reported that, in horses imaged for foot pain, PET and MRI identified the same injuries in most cases, but PET sometimes added information, including detection of small abnormal areas in the coffin bone that MRI might not show as clearly. (pmc.ncbi.nlm.nih.gov)
The new paper appears to extend that concept into a direct clinical comparison of PET and low-field standing MRI in the same horses. Based on the abstract information available, the authors assessed how PET findings from ^18F-FDG and ^18F-NaF aligned with MRI findings in horses whose lameness had already been localized to the foot. That framing is important: PET is not replacing the lameness exam or diagnostic analgesia, but being tested as an additional tool once clinicians have narrowed the source of pain. Earlier methodological work from the same research group also established a sequential dual-tracer PET protocol for the equine foot, supporting the feasibility of assessing both osseous and soft tissue lesions in one imaging workflow. (pubmed.ncbi.nlm.nih.gov)
Industry and clinical commentary around equine foot imaging has consistently emphasized that MRI findings must be interpreted in context, because many horses have more than one abnormality within the foot. AAEP and The Horse coverage has similarly noted that MRI is especially valuable for soft tissue lesions, but often reveals multiple changes, not all of which are necessarily the active pain generator. That’s where PET may be especially useful: not just showing that a lesion exists, but suggesting whether it is metabolically active. That interpretation is an inference from the available literature and background reporting, rather than a direct claim from the new paper alone. (aaep.org)
Why it matters: For veterinary professionals, the practical question is not whether PET or MRI is “better” in the abstract, but which modality answers the clinical question in front of them. Low-field standing MRI remains more established and accessible for evaluating foot lameness, particularly for soft tissue pathology and structural change. PET may be most helpful when clinicians need to prioritize among several lesions, look for early osseous change, or clarify whether a suspicious finding on MRI is likely to be active. In referral settings, the combination could improve diagnostic confidence, prognosis discussions, and treatment planning for pet parents managing chronic or high-value performance horses. (onlinelibrary.wiley.com)
There are still important caveats. The study population was small, at 14 horses, and access to PET remains limited compared with MRI. Even UC Davis has presented PET as a targeted advanced imaging tool rather than a front-line test for every lame horse. Cost, equipment availability, and the need for specialized interpretation will likely keep PET concentrated in referral hospitals for now. (ceh.vetmed.ucdavis.edu)
What to watch: The next step is whether larger studies can show how PET-MRI correlation changes case management or outcomes, not just lesion detection. Clinicians will also want clearer evidence on which lesion types benefit most from PET, whether standing PET expands access, and how dual-tracer protocols fit into real-world referral workflows. (pmc.ncbi.nlm.nih.gov)