title: Contrast-enhanced transrectal ultrasonography of a novel canine prostate cancer model.
abstract: OBJECTIVE
  This study evaluated the utility of a new animal model for prostate cancer imaging using a new ultrasonographic contrast agent (Sonazoid [NC100100]; Amersham Health, Oslo, Norway), for prostate cancer detection.
  
  
  METHODS
  Twenty-four dogs had a canine transmissible venereal sarcoma cell line injected (50 million cells/mL) directly into the prostate, producing a neoplasm in 15 to 40 days. Transrectal ultrasonography was performed in power Doppler mode on 8 dogs (phase I) and in gray scale phase inversion harmonic imaging mode on 16 animals (including control animals without tumors; phase II). Evaluations were repeated after intravenous injections of the contrast agent (dose, 0.00625-0.20 microL/kg). Histopathologic examination was performed after each study. For the phase II experiments, sensitivity, specificity, and accuracy were calculated.
  
  
  RESULTS
  The contrast agent improved visualization of the prostate cancer vascularity and delineation of tumor size and shape in both power Doppler and phase inversion harmonic imaging modes. Canine transmissible venereal sarcoma tumors ranging from 3 x 5 to 40 x 50 mm were detected. The accuracy for detecting the number of prostate tumors increased (in phase II) from 67% to 87% with the addition of the contrast agent. Histopathologic examination confirmed the ultrasonographic findings and revealed typical canine transmissible venereal sarcoma cells infiltrating the prostate with moderate neovascularity.
  
  
  CONCLUSIONS
  The novel canine tumor model was useful for evaluating ultrasonographic prostate imaging techniques. Improved detection of prostate tumors in dogs was possible with gray scale phase inversion harmonic imaging of the contrast agent. The accuracy of lesion detection increased from 67% to 87%.
authors.affiliation: Department of Radiology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
authors.forename: Flemming
authors.initials: F
authors.lastname: Forsberg
authors.forename: David K
authors.initials: DK
authors.lastname: Johnson
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Merton
authors.forename: Ji-Bin
authors.initials: JB
authors.lastname: Li
authors.forename: Patricia E
authors.initials: PE
authors.lastname: Losco
authors.forename: Else K
authors.initials: EK
authors.lastname: Hagen
authors.forename: Barry B
authors.initials: BB
authors.lastname: Goldberg
mesh_terms: D000818:Animals; D003287:Contrast Media; D004195:Disease Models, Animal; D004285:Dogs; D005290:Ferric Compounds; D007089:Image Enhancement; D007501:Iron; D008297:Male; D010087:Oxides; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging*; D012007:Rectum / Q000000981:diagnostic imaging; D012680:Sensitivity and Specificity; D014463:Ultrasonography
chemical_list: D003287:Contrast Media; D005290:Ferric Compounds; D010087:Oxides; C069727:Sonazoid; D007501:Iron