Conventional agents used in Contrast Enhanced CT scans are often administered multiple times in order to locate a tumor’s precise location due to the brevity of their effect. Veterinarians are currently researching Liposomal-I, a new contrast agent that would lengthen the time that tumors can be seen on scans. Because Liposomal-I consists of iodine-infused liposomes, it remains in the spleen and liver for approximately 24 hours, making tumors in these locations brighter on CECT scans, even as time progresses.
The original study of Liposomal-I was conducted on 13 dogs with masses of varying locations, histology, and stages of metastasis. Researchers administered 275 mg of Liposomal-I per kg of body weight into the blood in their veins. The dogs were scanned prior to, 15 minutes after, and 24 hours after intravenous administration of the contrast agent. Some of the dogs were scanned using conventional CECT imaging methods prior to the study in order to establish a baseline for comparison. The results were evaluated by comparing mean CECT signals for each category of the study, which indicated that the tumors were in fact visible on the scans for more than 24 hours.
Because it remains in the liver and spleen for longer periods of time, Liposomal-I brightens the appearance of smaller tumors on CECT scans; this enables earlier diagnosis and an improved prognosis. Prolonged visibility allows for the tracking of malignancies over time. Furthermore, unlike conventional contrasting techniques where the kidneys excrete the iodine solution, Liposomal-I is excreted through reticuloendothelial systemic clearance. Because this occurs directly in the liver and spleen, where the contrast agent is already located, this option is much safer for patients with renal disease. Prolonged visualization of cancerous tumors would therefore allow for a safer and more precise diagnoses of malignant tumors for veterinary patients, an advantage that with further translational research could be applied to human patients as well. Further research on the advantages and potential risks of Liposomal-I is currently being conducted by a number of veterinarians and pediatricians at research centers which include the Cummings School of Veterinary Medicine at Tufts University, the University of Wisconsin-Madison School of Veterinary Medicine, and the Texas Children’s Hospital.
- Rajewski, Genevieve (Fall 2016). Spotting Cancer. Cummings Veterinary Medicine, Fall 2016, Retrieved from http://sites.tufts.edu/vetmag/fall-2016/spotting-cancer/
- Ghaghada, Ketan B., Sato, Amy F., Starosolski, Zbigniew A., Berg, John, Vail, David M. (2016). Computed Tomography Imaging of Solid Tumors Using a Liposomal-Iodine Contrast Agent in Companion Dogs with Naturally Occurring Cancer. PLOS ONE. doi:10.1371.