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DENVER/November 7, 2019 – A new cancer imaging technique could significantly improve the ability to diagnose the disease’s spread to lymph nodes in dogs with head and neck tumors. The technique, which involves injecting iron nanoparticles into a dog then using magnetic resonance imaging (MRI) to detect the particles, is being tested by Morris Animal Foundation-funded researchers at Colorado State University. If successful, it could help guide therapeutic decisions for canine cancer patients.

“Cancer is a game of numbers, and if you want to cure it you have to get rid of 100% of the cancer cells that are in the body,” said Dr. Lynn Griffin, Assistant Professor at Colorado State University’s College of Veterinary Medicine and Biomedical Sciences, and principal investigator on the study. “This method could non-invasively and more accurately determine where cancer is still hiding so we can do something about it.”

The technique would be used during cancer staging, a process to determine the extent of a tumor’s metastasis before undergoing any kind of treatment. This allows veterinarians to develop optimum treatment plans to maximize a patient’s chance for a positive outcome.

For the study, the team injects nanoparticles – in this case, microscopic bits of iron – into a dog’s bloodstream. The particles are then engulfed by macrophages, white blood cells that clear blood of cellular debris, before moving into nearby lymph nodes.

Iron appears black on certain MRI images, so if a completely healthy lymph node is full of the macrophages holding the nanoparticles, it too would appear all black. Cancer cells, though, push macrophages out of lymph nodes. If cancer has invaded even a small portion of a lymph node, that portion should appear white on an MRI. Results would be detectable in less than 48 hours after injection.

In the initial pilot study, the team tested the technique on six dogs, and it was 88% accurate at detecting cancer, which is higher than most previously reported imaging modalities. For the current study, the team just opened enrollment for dogs with oral cancers that have the potential to metastasize to the lymph nodes. They hope to enroll 50 dogs with head and neck cancers.

Current imaging techniques to diagnose cancer spread to lymph nodes in dogs with head and neck cancers, which include palpation and ultrasound, are not very reliable. Cancer cells can sit on one side of an otherwise healthy lymph node without distorting it, allowing it to feel normal to human touch. Similarly, ultrasounds have difficulty spotting the disease if it isn’t blatant.

Head and neck cancers, such as fibrosarcoma and oral melanoma, account for 6% to 7% of canine tumors, according to Withrow and MacEwen’s Small Animal Clinical Oncology.

While this technique could be used in any part of the body, the team is first focusing on head and neck tumors due to the accessibility of that area’s lymph nodes.

“One of the toughest parts about treating cancer is not knowing if you have been aggressive enough to defeat it, while maintaining a good quality of life. This technique could help solve that problem,” said Dr. Janet Patterson-Kane, Morris Animal Foundation Chief Scientific Officer. “With this diagnostic test, we might be able to improve our ability to help owners make the best decisions for their beloved pets, and that would be a good outcome.”

Nanoparticle MRIs were first attempted in human medicine for prostate cancer, but the technique is still being used at an experimental level. If successful in dogs, Dr. Griffin said her team will evaluate its use in detecting the spread of feline oral squamous cell carcinoma, the most common oral cancer in cats.

Morris Animal Foundation, headquartered in Denver, is one of the largest nonprofit animal health research organizations in the world, funding more than $155 million in studies across a broad range of species.

About Morris Animal Foundation

Morris Animal Foundation’s mission is to bridge science and resources to advance the health of animals. Founded by a veterinarian in 1948, we fund and conduct critical health studies for the benefit of all animals. Learn more at