When people are sick, they go to see the doctor. The doctor may then decide that they need the information provided by imaging or laboratory tests to better understand the person's illness or disease. Likewise, animals may require a visit to the veterinarian. What many people may not realize, unless it happens with their pet, is that their pets may also require imaging.
In the world of veterinary medical imaging, magnetic resonance imaging (MRI) has become more and more common. Veterinary MRI is extremely similar to MRI for humans, including using the same scanner and techniques. The information provided by the MRI scan can be useful for the treatment of a variety of conditions in animals.
What is magnetic resonance imaging?
Magnetic resonance imaging is a powerful medical imaging technique. A super-conducting magnet inside the doughnut-shaped scanner manages the magnetic field in and around it. When the patient is placed inside the scanner, their protons align to this field. Throughout the scan, pulse sequences affect the magnetic field and the protons realign.
The coils placed near the region of interest (ROI) pick up the signals from the patient's body as these pulse sequences are used. As a result of this, the computer interprets the result, with the help of a radiologist, to create the images associated with MRI.
For patients in a hospital, the images created during the scans provide valuable information to the patient's physician. These images can show detailed images of soft tissue and organs. The pictures may provide information about abnormalities and tumors.
Using certain advanced techniques, the radiologist and physician may be able to detect which abnormalities are malignant. Diffusion weighted imaging, for example, measures the Brownian (random) motion of water molecules, with less motion meaning more viscous areas of liquid. This means that if an area is more viscous than expected, it could be due to a malignancy.
How can MRI be used for animals?
In different areas of the world, veterinarians have begun to see the value of magnetic resonance imaging of animals.1,2 The scan is the same as a basic MR exam, the patient lies on the table and the exam is conducted. In fact, the scanner is often the same model as that used in humans.
The main difference between an adult human and an animal being scanned is that an animal is less likely to be still for the duration of the scan. Like many children who are unable to sit still or who have anxiety about the scanner, animals often need to be sedated for the exam.
There are a variety of uses for veterinary MRI, including small animal brain and spinal diseases, aural, nasal and orbital disorder, planning soft tissue surgery, oncology, orthopedics and cardiac MRI.1,2 The wide variety of uses makes the method important to the field. This is due to its capability to image soft tissue structures. Some common injuries that can be detected using MRI in animals include disc herniation, brain tumors and stroke. Cardiac MRI is still in the research phases but could provide valuable information.1
Veterinary MRI can help veterinarians to better understand diseases that are common in animals. The injuries to the soft tissue are especially visible on MRI, just as they are for human MRI scans. Using the same techniques and scanners as those used for humans, the images may provide treatment guidance. Just as people need tests, both laboratory and imaging, so do injured or ill animals.
- The potential role of MRI in veterinary clinical cardiology. The Veterinary Journal. https://doi.org/10.1016/j.tvjl.2008.11.018. Last accessed August 23, 2019.
- Magnetic resonance imaging (MRI). ivghospitals.com. http://www.ivghospitals.com/service/neurology/magnetic-resonance-imaging-mri/. Last accessed August 23, 2019.