A Beloved Rottweiler Demonstrates the Advantage of Using Nuclear Imaging in Cancer Staging
The dark, sleek Rottweiler had been sedated, connected to gas anesthesia and was now being gently positioned into an inflatable, individually pre-formed cushion for the second PET/CT scan of her life. The nuclear medicine team had prepared an injection of special imaging agents, "tracers," that would allow her veterinary oncologists to see, with precision, the location and size of any tumors that had metastasized from Lucy Neu's previous cancer.
Jeffrey Neu had brought Lucy to the Flint Animal Cancer Center at Colorado State University from their home in southern California specifically for this purpose. Lucy lost her right rear leg to osteosarcoma in 2010 and now, a year later, Jeff was acutely aware of the potential for recurrence and spread and was determined to do everything possible to catch any return at its earliest stage. PET/CT scans are often used by physician oncologists to aid in early detection, grading and staging of many cancers, as well as evaluating treatment success. That's what he wanted for Lucy, but found that PET/CT was not as readily accessible in veterinary medicine, except at a handful of teaching and research hospitals such as CSU's Flint Animal Cancer Center.
"The combined PET/CT scanner has been available in human medicine since 2001, but its use with veterinary patients is far more recent," said Dr. Susan Kraft, Professor of Radiology. "A sophisticated system such as ours is available only at the larger veterinary centers engaged in advanced diagnostics and therapy for cancer, as well as developing new treatment options through comparative cancer research."
In Lucy's case, her first PET/CT at CSU FACC confirmed her primary veterinarian's earlier findings, the development of nodules in her lungs which were being treated with chemotherapy. Now, nine months after her first scan, Lucy was stumbling and an MRI revealed a tumor pressing on her cervical vertebrae, which was deemed inoperable. Jeff and Lucy had returned to CSU for this second PET/CT scan, which brought more bad news: in addition to the tumor in her neck, a metastatic tumor had also invaded her pelvis.
Dr. Laura Selmic, one of Lucy's oncologists at the FACC and a research scientist and Fellow in Comparative Oncology, recommended stereotactic radiation therapy, a sophisticated technique used to deliver the maximum dose of radiation to a precisely targeted area while sparing adjacent, healthy tissue. Working with Dr. Jamie Custis, a radiation oncologist, a treatment plan was designed specifically for Lucy. Her recovery exceeded expectations when she began to walk again within just a few days.
"Early detection of cancer, especially metastatic cancer, can be difficult," said Dr. Rodney Page, Director of the Flint Animal Cancer Center. "Veterinary oncology has made great strides in diagnostics and treatments that improve survival and quality of life for pets with cancer. A PET/CT system improves our ability to locate active cancer nodules, and enhances our ability to monitor response to therapeutic interventions."
What is PET/CT?
PET/CT is a nuclear medicine imaging technique that uses a radioactive "tracer" to discern differences in metabolic and physiologic activity in the body - the functional processes. The tracer agent is injected into the body and the system records positrons emitted during the decay of the radioactive material. The tracer agent, usually a form of glucose called FDG (fluorodeoxyglucose), concentrates in the tumor because tumor cells may have a higher metabolic rate than normal cells, requiring higher levels of glucose for energy. With the aid of a computed tomography, or CT scan, performed simultaneously, the system can generate a three-dimensional image that localizes areas of high metabolism to specific anatomic regions.
Computed Tomography, also known as a CT or CAT scan, is a series of x-rays taken in "slices" by a scanner on a rotating frame, or "gantry," used to gather anatomical information about the tumor. On one side of the gantry is an x-ray tube and on the opposite is a detector. The frame rotates 360 degrees around the patient, taking numerous images that are collated serially into a detailed 3D image.
One of the most important advances in medical molecular imaging is the integration of these two imaging modalities. Combining the metabolic data from PET and the anatomical data from CT provides a higher diagnostic accuracy than either one alone, and is especially valuable in staging for many cancers. Combining the technology into one hybrid system also means patients undergo only one, rather than two, procedures.
"Molecular imaging can help us provide individualized medicine. The 3D image gives us the information we need to tailor treatment and management strategies to the individual patient," Dr. Custis explained.
Three months later, another scan showed Lucy's cervical and pelvic tumors were reduced, allowing her to walk without pain or stumbling; but revealed a medium-sized mass on her liver. Jeff knew he could only buy a little more time with his adored Lucy, and he was grateful for the additional months his veterinarian and the veterinary oncologists at the Flint Animal Cancer Center had given them.
Since Lucy had come into Jeff's life as a puppy, they were always together. Lucy accompanied Jeff to work, on trips, and even to fundraising events where she lay quietly under the table, just happy to be with him. Throughout early health scares, including two TPLO surgeries for cruciate ligament tears in her knees, and her battles with cancer, Jeff gave her his love and the best care possible. He would continue to show his love and respect for Lucy after her death by providing a lasting legacy in her name: The Lucy Scholars fund at the Flint Animal Cancer Center.
The Lucy Scholars fund supports oncology specialty training for veterinarians. Lucy helped pioneer a new protocol in early detection of cancer metastasis through the use of serial PET/CT scans. Jeff Neu established the fund in 2011 to support training programs for the FACC specialists who had helped her and who are future pioneers in veterinary oncology.
This fund currently supports a Fellow in comparative oncology, a medical oncology resident and a medical oncology intern.