title: Computed Tomography Imaging of Solid Tumors Using a Liposomal-Iodine Contrast Agent in Companion Dogs with Naturally Occurring Cancer.
abstract: OBJECTIVE
  Companion dogs with naturally occurring cancer serve as an important large animal model in translational research because they share strong similarities with human cancers. In this study, we investigated a long circulating liposomal-iodine contrast agent (Liposomal-I) for computed tomography (CT) imaging of solid tumors in companion dogs with naturally occurring cancer.
  
  
  METHODS
  The institutional animal ethics committees approved the study and written informed consent was obtained from all owners. Thirteen dogs (mean age 10.1 years) with a variety of masses including primary and metastatic liver tumors, sarcomas, mammary carcinoma and lung tumors, were enrolled in the study. CT imaging was performed pre-contrast and at 15 minutes and 24 hours after intravenous administration of Liposomal-I (275 mg/kg iodine dose). Conventional contrast-enhanced CT imaging was performed in a subset of dogs, 90 minutes prior to administration of Liposomal-I. Histologic or cytologic diagnosis was obtained for each dog prior to admission into the study.
  
  
  RESULTS
  Liposomal-I resulted in significant (p < 0.05) enhancement and uniform opacification of the vascular compartment. Non-renal, reticulo-endothelial systemic clearance of the contrast agent was demonstrated. Liposomal-I enabled visualization of primary and metastatic liver tumors. Sub-cm sized liver lesions grossly appeared as hypo-enhanced compared to the surrounding normal parenchyma with improved lesion conspicuity in the post-24 hour scan. Large liver tumors (> 1 cm) demonstrated a heterogeneous pattern of intra-tumoral signal with visibly higher signal enhancement at the post-24 hour time point. Extra-hepatic, extra-splenic tumors, including histiocytic sarcoma, anaplastic sarcoma, mammary carcinoma and lung tumors, were visualized with a heterogeneous enhancement pattern in the post-24 hour scan.
  
  
  CONCLUSIONS
  The long circulating liposomal-iodine contrast agent enabled prolonged visualization of small and large tumors in companion dogs with naturally occurring cancer. The study warrants future work to assess the sensitivity and specificity of the Liposomal-I agent in various types of naturally occurring canine tumors.
authors.affiliation: The Singleton Department of Pediatric Radiology, Texas Children's Hospital, Houston, Texas, United States of America.
authors.forename: Ketan B
authors.initials: KB
authors.lastname: Ghaghada
authors.affiliation: Department of Clinical Sciences, Tufts Cummings School of Veterinary Medicine, North Grafton, Massachusetts, United States of America.
authors.forename: Amy F
authors.initials: AF
authors.lastname: Sato
authors.affiliation: The Singleton Department of Pediatric Radiology, Texas Children's Hospital, Houston, Texas, United States of America.
authors.forename: Zbigniew A
authors.initials: ZA
authors.lastname: Starosolski
authors.affiliation: Department of Clinical Sciences, Tufts Cummings School of Veterinary Medicine, North Grafton, Massachusetts, United States of America.
authors.forename: John
authors.initials: J
authors.lastname: Berg
authors.affiliation: Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, United States of America.
authors.forename: David M
authors.initials: DM
authors.lastname: Vail
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage* / Q000737:chemistry; D004283:Dog Diseases / Q000000981:diagnostic imaging*; D004285:Dogs; D005260:Female; D007455:Iodine / Q000008:administration & dosage* / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry; D008099:Liver / Q000000981:diagnostic imaging; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000662:veterinary*; D008168:Lung / Q000000981:diagnostic imaging; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000662:veterinary*; D008321:Mammary Glands, Animal / Q000000981:diagnostic imaging; D015674:Mammary Neoplasms, Animal / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D008081:Liposomes; D007455:Iodine