Two gifts enhance diagnostic imaging
A $500,000-scanner takes sharper images, and new tools improve noninvasive procedures
[From Tufts March 2010 Issue]
A new high-performance CT scanner at Cummings School delivers three-dimensional images and enables veterinarians, among other advantages, to see soft-tissue structures, such as tumors, that would be less visible with older technology. The $500,000-scanner can create images in half the time the school’s previous scanner required.
In addition, equipment as seemingly basic as a new video monitor and overhead light at the school are helping veterinarians pursue cutting-edge procedures, such as treating dogs with collapsing tracheas without invasive surgery. The ongoing trend toward technology provides more tools to improve diagnoses and treatments and, in some cases, offer cures.
It’s not uncommon for veterinary schools today to have state-of-the-art equipment, including sophisticated ultrasound machines and $1.5-million MRI machines. Veterinarians at Cummings School of Veterinary Medicine at Tufts University also use quantitative electroencephalograms, or EEGs, which evaluate brain wave function, and nuclear imaging technology, which is capable of identifying certain cancers at a very early stage.
The new CT scanner can take a complete series of cross-sectional images, or “slices,” of animal’s body in minutes. The former scanner took twice as long; an older CT might take several minutes. The difficulty is, the longer a scan takes, the more difficult it is to obtain clear images, particularly of moving structures such as the chest.
“We can’t ask the animal to hold its breath for five minutes,” says radiologist Amy Sato, DVM. Using older-generation scanners, the anesthetized animal would breathe constantly during the scan, creating blurred images. The new scanner is so fast that, when an animal is under anesthesia, the chest can be scanned during the short intervals between breaths. “The images come out very crisp,” Dr. Sato says.
The scanner – paid for with the help of a $250,000 bequest from the late Zelda Cushner, a cocker spaniel breeder who took many of her dogs to the school’s Foster Hospital for Small Animals for care – also helps owners better understand their dog’s problem.
The cross-sectional images can be “reconstructed” to create a life-like three-dimensional image, Dr. Sato says. “Previously, it was hard to show owners small cross-sections of their dog and have them understand that this meant that their dog had, for example, a vascular anomaly. Now I can show them a picture of a 3-D model, and I can spin it on the computer, and they can see the abnormal vessel from all angles. It is easy for the owner to see and understand the abnormality.”
The 3-D models also help surgeons to better plan procedures. The reconstructions are especially valuable before complex tumor resections – accurate information about the involved structures improves the chance of controlling the tumor and reduces the length of the surgery. Shorter surgeries often lower the risk of complications. In some cases, when images have shown a lesion couldn’t be repaired, the surgeon has called off the procedure. “It’s so much better to know that ahead of time instead of finding out during surgery,” Dr. Sato says.
The new CT scanner has particular advantages over X-rays and the old scanner in cancer detection. X-rays create a two-dimensional image of a three-dimensional animal – essentially flattening the image, so that adjacent structures overlie one another.
“If, for example, a little nodule in the lung is superimposed over a rib, we might not be able to see it,” Dr. Sato says. The old CT scanner did provide better images than X-rays because the ribs were not superimposed over the lung in the cross-sectional images. But the new scanner is far better in part because it obtains very thin slices – one-half a millimeter, or half as thick as a dime. That’s superior to the prior scanner’s thinnest slice of one millimeter and results in sharper images. “We definitely can see tiny things much better now,” Dr. Sato says.
The images from the scanner go into a computer, where veterinarians can manipulate them at will using specialized software. For example, superimposed structures, such as bones, can be made to completely disappear so that only the structures of interest are visible.
A second diagnostic imaging technology has also benefited from a donation. The Foster Hospital’s fluoroscopy suite has a new overhead-mounted light and high-quality monitor that were bought with a $20,000 donation from an anonymous couple. The donors cited the professionalism and skill of the cardiology team in treating their cat’s heart disease, which helped him live two additional years.
In fluoroscopy, veterinarians use X-rays to display real-time video images on a monitor. These images are particularly helpful during minimally invasive interventional cardiology and radiology procedures. Veterinarians can use the images to guide the placement of metal, tube-like stents, which are sometimes used to keep the body’s normal passages open. For example, a urethra that is blocked by a tumor can continue to function normally after placement of a stent.
The techniques have been lifesaving for some dogs with blockages that make it impossible to urinate. “Before, they would just be put to sleep,” says cardiologist Suzanne Cunningham, DVM.
In another example, Yorkshire terriers and other small dogs with cases of collapsing tracheas formerly had one option for treatment – to undergo surgery, which has a variable success rate. Now veterinarians often prefer a non-surgical treatment. They use fluoroscopy to guide insertion of a self-expanding metallic stent into the trachea to prevent it from collapsing, often providing dogs with a debilitating cough and life-threatening respiratory distress an improved quality and length of life. Other uses of fluoroscopy include placing coils to stop blood flow through abnormal vessels and treating inoperable cancers by delivering chemotherapy directly into the tumor.
“In most cases, these interventional procedures are performed either with no incisions or very small incisions over a blood vessel of interest,” Dr. Cunningham says about the value of most fluoroscopy-guided procedures. “That’s the beauty of it. We can use fluoroscopy to help us drive catheters to places that were typically accessible only via invasive surgical procedures, and by doing so, we are often able to dramatically reduce both morbidity and mortality in our patients.”
The donors’ gift resulted in an important upgrade in their work, Dr. Cunningham says. “We basically had this old light that had to be hovering over our shoulders, and we couldn’t touch it during the procedure, and the monitor was inconveniently located. We had to crane our necks around to be able to see it.” That was no easy feat while the veterinarians wore protective lead aprons.
The new light’s handle can be sterilized, so that surgeons can control it during procedures. An eye-level video monitor permits them to easily watch their work in progress. “I can’t stress enough how much it has improved our visualization during the procedure,” Dr. Cunningham says, “both on the surgery side and what it is we’re actually doing during the procedure. It’s just made things 100 times easier.”
Dr. Cunningham envisions veterinarians’ greater use of fluoroscopy in the future. One current application is installing pacemakers to correct a dog’s abnormally slow heart rate. “Owners find the dogs weak or collapsed, bring them in and they have extremely slow heart rates. They come in fainting, sometimes having near-death episodes,” she says. “They’re at risk of dying from their arrhythmia. But you put a pacemaker in those animals, and you take a dog that has complete heart block, which is at imminent risk of death, and those dogs can go on to live years after the procedure, with the pacemaker controlling the heart rate.”
Among all the happy endings that can result from new technology, Dr. Cunningham says, “that’s probably one of the most dramatic.”