New Ways to Picture Your Pets Health
X-ray vision is no longer just a fantasy promised by ads in the back of comic books. Now, veterinarians are able to view detailed images of internal organs and structures, thanks to advanced imaging technologies such as magnetic resonance imaging (MRI) and computed tomography (CT or CAT).These noninvasive technologies provide more information to help veterinarians diagnose problems and better plan for treatment.
“More and more people want the same level of medicine for their pets as they might want for themselves or their families,” according to Dr. David Lee, hospital director for the Veterinary Medical Center (VMC) at the University of Minnesota. The VMC recently installed a $1.7 million MRI machine, the most powerful MR system in a veterinary hospital in the world. “People are far better informed of medical choices than they were in the past, so they are now more likely to request advanced procedures directly,” says Dr. Lee.
PINNING DOWN THE TOUGH DIAGNOSIS
Today, most veterinarians in general practice rely on radiographs, or x-rays, to examine the internal organs and structures of animals. The technology is available in almost every animal hospital, and the procedure can be done quickly. The limitation to this procedure is that it gives a two-dimensional view of three-dimensional objects, and organs and structures may be superimposed on each other, making it difficult to determine the extent of a mass, for instance.
When a diagnosis can’t be made with standard imaging techniques, veterinarians may refer patients to a university hospital or specialty practice for a CT or MRI scan. These advanced imaging procedures can be crucial steps to determining a difficult diagnosis and, ultimately, the proper treatment.
In some cases, CT or MRI scans provide a noninvasive alternative to an exploratory surgery. “In the first few weeks of operation, we had a number of cases where potentially risky surgery was avoided through advanced imaging,” Dr. Lee says. “Our MR system helped us find nonsurgical solutions that were more appropriate.”
CT AND MRI SIMPLIFIED
Computed tomography uses x-rays to provide a cross-sectional view of internal structures that isn’t possible with conventional radiographs. To perform a CT scan, dogs or cats must be sedated or anesthetized to prevent movement. The patient is placed in the opening of the scanner, and an x-ray tube head rotates 360° around the area of interest. Numerous x-ray detectors capture the information and relay it to a computer, which reconstructs the image.
Instead of x-rays, MRI uses high-powered magnetic fields and radio-wave energy to create precise anatomic images. The system is able to produce greater detail than is possible with x-rays or CT scans, thanks to the natural magnetic properties of hydrogen atoms in the body. However, because of the MR system’s powerful magnet, loose metal objects, such as ID collars and even horseshoes, must be removed before animals are imaged.
THE PROS AND CONS
While the applications for CT and MRI scans overlap, CT scans are generally used to examine lung masses and assess skull trauma. The advantages of CT include speed (the average scan takes just a few minutes) and the ability to be used in patients with metal implants.
MRI is usually the preferred modality for brain and spinal cord disorders, musculoskeletal disease, and cancer. This technology offers greater detail than is possible with other modalities. The procedure may take 1 to 2 hours, including preparation, imaging, and recovery. “An MRI scan may actually save lives by reaching a diagnosis faster than would be possible through a litany of other tests,” Dr. Lee says.
Selection of a CT or MRI modality is determined by the veterinarian, depending on the needs of the pet and equipment availability.
ALL MRI SYSTEMS ARE NOT ALIKE
The state-of-the-art MRI unit installed at the VMC can generate a scan faster than other MR systems, so patients are under anesthesia for a shorter amount of time. Because of this powerful system, Dr. Lee says, “we expect that some clients will travel from adjoining states and complex cases that might benefit from our system may travel considerably farther.”
Advanced imaging technology also empowers clinicians to make new medical insights. For example, a decade ago, it was assumed that dogs with seizures were suffering from brain tumors. Because there were no treatment options, it was a poor prognosis. “MRI scans have demonstrated that some dogs suffer seizures because they are having strokes,” says Dr. Travis Saveraid, a radiologist at the University of Minnesota. That diagnosis means a much better potential outcome with proper care.
While CT and MRI scans aren’t necessary for every case, these advanced technologies do offer new hope for pets by helping to pinpoint a diagnosis and, ultimately, the most effective treatment.