Introducing the MILE-PET Scanner at Fairfield Equine

We are excited to announce the arrival of the MILE-PET scanner from LONGMILE Veterinary Imaging this spring (May 2025).

This cutting-edge technology allows for positron emission tomography (PET), enabling functional imaging of the distal limbs (from the carpus and tarsus down).

What Makes MILE-PET Imaging Unique?

PET offers significant advantages over traditional imaging methods:

• Increased Spatial Resolution: Provides clearer, three-dimensional images.
• Longitudinal Follow-up: Easy to repeat scans over time to monitor changes.
• Soft Tissue and Bone Tracers: Specialized options for both tissue types.
• Co-Registration with Other Imaging: Combine PET with MRI or CT scans to show functional changes and activity in the distal limb.

PET can be used as a screening tool or in combination with other imaging techniques to provide more detailed insights into your horse's condition. It helps identify sources of lameness, especially when other imaging methods have been inconclusive, and can differentiate the activity of multiple lesions when blocking patterns aren't specific enough.

Why Choose PET Imaging?

PET scanning is particularly beneficial in the following cases:

• Inconsistent Distal Limb Blocking Patterns: When standard lameness evaluations are unclear.
• Multiple Lesions: Differentiates which lesions are causing issues when blocking patterns fail to pinpoint the problem.
• Long-Term Monitoring: Ideal for tracking osseous lesions over several months—PET scans are faster and more affordable for follow-up imaging.
• Cases Where Other Modalities Haven't Worked: When advanced imaging techniques like MRI or CT don’t provide answers, PET can offer a new perspective.

CT image with PET overlay

When to Consider PET Scanning

PET imaging is ideal for cases involving:

• Unclear or Inconsistent Blocking Patterns: Difficulty pinpointing which part of the distal limb is problematic.
• MRI Findings: When MRI identifies osseous lesions that require ongoing monitoring.
• Multiple Lesions: When other imaging methods fail to determine which lesion is clinically significant.
• Failure of Other Imaging Modalities: When advanced imaging techniques like MRI or CT haven’t been able to provide a diagnosis.

While PET is a powerful tool, it is not a replacement for nuclear scintigraphy. PET is limited to imaging the distal (lower) limb, and cases requiring broader imaging (e.g., axial or proximal limb issues) are better suited for nuclear scintigraphy.

How PET Imaging Works

PET scans are performed with the horse standing, and horses can be released from radiation restrictions the same day—allowing for repeat imaging without long hospitalization periods. This makes it easier to track the recovery progress and determine when it's safe to resume or increase exercise.

Contact Us for More Information

We are thrilled to offer this advanced imaging service to the veterinary community.

If you are considering whether PET is the right choice for your patient, or if you have any questions, please don’t hesitate to reach out to our team

• Dr. Ryland Edwards: redwards@fairfieldequine.com
• Dr. Alycia Crandall: acrandall@fairfieldequine.com

 

We look forward to working with you to provide the best care for your patients!

 

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PET FAQ’s

 

1) What is a PET scan and how does it work?

a) A PET scan is a cross-sectional nuclear imaging modality where the horse is injected with a radiotracer. Then the mobile scanner is brought over to the desired limb and 3-dimensional images are obtained of the leg. The image created on the screen is representative of the degree of radiotracer taken up in the bones and/or soft tissues.

 

2) What does PET stand for?

a) Positron emission tomography

 

3) How can a PET scan help diagnose an injury in my horse?

a) The scan shows where areas of increased radiotracer are present, which correlates with an area of injury.

 

4) What is the difference between PET scans and other diagnostic imaging techniques?

a) PET scanning is most similar in application to nuclear scintigraphy or a “bone scan”. The difference is that a PET scan results in a 3-dimensional image, whereas nuclear scintigraphy produces 2-dimensional images. This is like comparing radiography to computed tomography (CT).

b) The image created from PET scanning is based on uptake of a radiotracer, so it does not show structurally what the fetlock or other region scanned looks like but rather creates an image representative of the fetlock based on the functional activity of the tracer within the bony or soft tissue structures.

 

5) Which areas of my horse can be scanned using PET?

a) The machine is able to image as high as the carpus in the forelimb and tarsus in the hindlimb. The height restriction of the machine prevents us from imaging any higher due to the positioning of the abdomen and stifle.

 

6) What do the colors in PET scan images represent?

a) These colors represent the intensity of the radiation received by the scanner. These can be programmed to a specific color pattern. Generally, what is used is a color scheme resembling fire, where whiter = “hotter”; however, a grayscale can also be used.

 

7) What are the unique benefits of PET scanning for horses?

a) PET scanning is a functional imaging modality, meaning that it can provide us with additional information regarding abnormal lesions that we find in a lame horse. The functional nature allows us to determine if abnormalities identified on other imaging modalities (MRI, CT) are “active” or not. This additional puzzle piece is used alongside our clinical exam and diagnostic blocking that has been performed to help nail down what is a horse’s cause of lameness if there are multiple lesions present or even just one lesion with questionable significance.

b) One of the benefits is that this can be performed standing with light sedation. Another benefit is that many horses can have this performed as an outpatient procedure and do not require extensive hospitalization.

c) The benefit of PET scanning versus nuclear scintigraphy is the advantage of obtaining a 3-dimensional image that more accurately tells us which structure and even which particular portion of a structure is affected.

8) How many equine PET scanners are available in the US?

a) The number increases each year! There are currently a dozen facilities in the United States that offer this imaging modality. We are currently the only facility in the Northeast that will be offering these services year-round.

 

9) Are PET scans used for humans as well?

a) PET imaging was adapted for horses based off of success using it in human medicine. This imaging is typically used for oncology to identify bony metastasis and osteomyelitis but is also used to assess osteoarthritis, response to treatment, and exercise-induced bone remodeling.

 

10) Can PET scan imaging alone diagnose lameness, or is additional imaging required

a) PET scanning alone can help us determine what is affected; however, anatomic specifics generally require an additional imaging modality. Depending on the intensity and location of the lesion, we can coregister or overlay the image with a radiograph or ultrasound, but frequently we coregister these images with other 3-dimensional modalities like CT or MRI.

 

11) What advancements in equine care have PET scans contributed to?

a) There are several novel locations for bone, joint, tendon, and ligamentous injuries that we have been able to identify as sources of lameness since instituting this modality of imaging. Previously undiagnosed lamenesses that simply improved (or didn’t) with extended periods of rest can now have more focused treatment and rehabilitation protocols when we have a specific diagnosis.

 

12) Can PET scans detect conditions that other imaging methods might miss?

a) Yes! This is part of the reason this technology has become so widely adapted.

 

13) How often should a horse undergo a PET scan?

a) Depending on the lesion, a second scan is usually recommended 3-4 months after the first scan. Certain scenarios and cases will have monthly follow up scans (laminitis, chronic lesions, cases where we’re trying to return to work as soon as possible).

 

14) Does my horse need to be sedated for a PET scan?

a) Yes, light sedation is used similar to what you might see your horse receive for joint injections. This is different from a standing MRI or standing surgical procedure where your horse may require a continuous infusion of sedation because these take several hours. A PET scan usually does not require heavy sedation for most horses.

 

15) How quickly will I receive the results from a PET scan?

a) The initial impressions from the scan can usually be determined the day of the scan. Sometimes if coregistration with other advanced imaging modalities is required, then a complete report may take 2-3 days to finalize.

 

16) What is the preparation process for a horse undergoing a PET scan?

a) A physical examination is performed to ensure there are no immediate concerns with performing the procedure and sedating the horse. An intravenous catheter is placed both to facilitate sedation and to administer the radioisotope safely.

b) No fasting or other preparations need to take place prior to the exam. Depending on severity of lameness many horses are in work up until the day of the exam.

 

17) Are there any risks associated with PET scans for horses?

a) The machine is very safe to use and designed to work with horses. There is a safety release if they attempt to step out of the machine while it is scanning. The only risks are those associated with any form of sedation, which includes gastrointestinal upset, or colic. We have a cautious refeeding protocol and strictly monitor water intake on all of our patients, and as such have an extremely low rate of post procedural colic for our hospitalized patient population.

 

18) How long does a typical PET scan take?

a) This depends on the number of limbs and regions scanned. Sometimes it can be as fast as 5-10 minutes. Bilateral scans of several sites can sometimes take an hour with positioning.

 

19) What should I expect during my horse's PET scan appointment?

a) The same excellent quality care they receive for other advanced imaging appointments! Horses receive a full physical examination and are groomed thoroughly. An intravenous catheter is placed to facilitate sedation. Your horse will be kept in wraps and soft ride boots for the procedure. Once the imaging is acquired, the catheter is removed, your horse will be monitored after a few hours to ensure that they have cleared radiation. They will then receive a bath if they became sweaty from sedation or are groomed fully again and can be sent back home the same day in most cases!

 

20) How does Fairfield Equine Hospital ensure the safety and comfort of horses during PET scan?

a) Our team has 35 years of experience in handling horses of all backgrounds for the purposes of performing advanced imaging with multi-modal sedation techniques. We work patiently to ensure not just your horse’s safety, but to instill a positive experience in their mind so that they do not become recalcitrant to veterinary work in the future. Having a physical exam prior to assess patient attitude and apprehension, placing an intravenous catheter to minimize needle pokes, and fluid team work to ensure our staff move slowly and patiently all help us achieve these outcomes.