A Quarter horse mare recently underwent a spiral
CT scan to examine a mass near one of the
carotid arteries leading to her head
CT scan to examine a mass near one of the
carotid arteries leading to her head
Washington State University's Veterinary Teaching Hospital (VTH) has installed a new spiral computed tomography (CT) scanner for use in both small and large animals, with funds donated by a generous family.
The VTH has had a CT scanner for more than two decades and a magnetic resonance imaging machine (MRI) since 1996. With the new Toshiba Aquilion 16-slice spiral CT unit operational, both MRI and CT in WSU's veterinary college are among the most advanced complementary tools for diagnostic imaging in the profession.
"Before the new CT, we only imaged a few horses a month (using CT), but now I would expect to do 10 times that," said Professor John Mattoon, a board certified veterinary radiologist and chief of WSU's diagnostic imaging section. "There were limitations with the old technology that hampered its everyday use, but the new CT is truly state-of-the-art, with brand new software that greatly improves its capabilities. Our goal is to examine 100 horses a year with the CT, and several small animals a day."
Speed is one of the new CT's main features. It can scan 1750 millimeters (mm) or about 5.75 feet of a patient's body in 1 mm slices in 38 seconds. Twelve images per second are displayed and all 1750 digital images are delivered within three minutes. The machine's resolution can "see" details as small as 0.35mm; a little more than 13/100ths of an inch. The imaging is produced in a variety of planes as well as in three-dimensional representations of anatomic structures. A small animal can often be imaged in the new CT scanner in seconds, in many cases without general anesthesia.
"A horse with a complex fracture was examined with the new CT in early June and it was completed in a couple of minutes," Mattoon said. "The anesthesia and prep-work it takes to get the horse into the machine takes much longer than the actual exam. By comparison, MRI may take an hour or more. Still, these two imaging modalities are complementary to each other, and one does not necessarily exclude the use of the other."
Horses are too large to fit entirely in the CT scanner, so only the head, upper neck, and lower limbs are imaged. For smaller animals, the entire body can be scanned, and is especially useful for examining the lungs and abdomen.
"CT scans are the first choice in human medicine for imaging the lungs and abdomen, and I think it should become the standard of abdominal imaging in smaller animals as well," said Mattoon, who has practiced radiology for more than 25 years.
As a result of the CT's speed, animals have to spend much less time under anesthesia, if at all. "For horses, we can use a short-acting anesthetic, and some small animals can just be sedated without undergoing anesthesia," Mattoon said. "This is an important advancement because there are always risks associated with anesthetizing an animal.
"Overall, CTs at WSU should be less expensive because exams take less time and anesthesia. This particular new CT scanner should also open up a whole new area of research, including vascular imaging and shunt studies. I imagine that in the beginning we will do a lot of cases in which we use both CT and MRI."
This brief video showcases Washington State's new CT service, as illustrated by the Quarter horse with the cartoid artery mass that needed to be imaged.
19 June 2010 | Fran Jurga's Hoof Blog at Hoofcare.com
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