Nuclear scintigraphy is a highly sensitive, alternative imaging technique that has been used for many years in both human and veterinary medicine. In 1998 the Mid Atlantic Equine Medical Center was one of the first private equine practices in the country to begin offering nuclear scintigraphy to horses. Nuclear medicine can detect changes in your horse's bones and soft tissues before those structural changes can be seen on a radiograph, thereby making an earlier diagnosis of disease possible.
During nuclear scintigraphy, the horse is injected with a radioactive substance (radioisotope). The patient begins emitting radiation in the form of gamma rays (γ-rays), which escape from the body and permit external detection and measurement. Gamma rays are electromagnetic radiation similar to x-rays.
A special camera, called a gamma (or scintillation) camera, is used to detect the distribution of the radioactivity within the patient's body. Hence, unlike radiology where the equipment is the radiation source, the gamma camera is only a radiation detector and the patient is the radiation source.
Bone scintigraphy is the most commonly performed nuclear medicine scan in horses and is indicated in a variety of skeletal disorders because of its high sensitivity and the ease at which the entire skeleton can be imaged. However, it is still recommended that scintigraphy be combined with conventional radiographs or other imaging modality such as CT or MRI to determine the cause of the bony lesion.
All patients that undergo a nuclear medicine procedure must be kept isolated from the general public while they are emitting radioactivity. This is a designated area that can contain and/or facilitate disposal of contaminated material. Clients are not allowed to visit during the period of confinement.
At Mid Atlantic Equine Medical Center, patients can be released to the owners when the radiation they emit is at a low level, which takes approximately 24 hours. During the isolation time, radiation safety measures such as gloves, lab coats, boots, and radiation badges are followed by personnel working with the patients.
Advantages Over Radiology:
- High sensitivity for detecting early disease
- Ease of surveying the entire skeleton
- A negative scan virtually rules out active bone pathology and many forms of joint disease (except osteochondrosis)
- Ability to follow-up lesions for resolution
Disadvantages of Scintigraphy:
- Patient will be radioactive and must be isolated from the general public for 24-36 hours
Indications for Bone Scintigraphy:
- Diagnosis of occult or intermittent lameness
- Bone survey for multiple limb lameness
- Early detection of skeletal injury - occult fracture
- Determining extent and severity of skeletal lesion - activity of radiographic lesions
- Localization of pain but inability to identify cause using radiology and ultrasonography
- Poor performance of ill-defined cause
- Suspected thoracolumbar or pelvic region pain
- Evaluation of healing response
- Evaluation of blood flow to bone
- Diagnosis of aortoiliac thrombosis