title: Antivascular ultrasound therapy: magnetic resonance imaging validation and activation of the immune response in murine melanoma.
abstract: OBJECTIVE
  The purpose of this study was to investigate the treatment effects of antivascular ultrasound (US) with dynamic contrast-enhanced magnetic resonance imaging (MRI), contrast-enhanced sonography, and histopathologic analysis in a murine melanoma model.
  
  
  METHODS
  Subcutaneous K1735 murine melanoma tumors were grown in syngeneic C3H/HeN mice. Quantitative tumor perfusion characteristics were measured before antivascular US treatment with both dynamic contrast-enhanced MRI and high-resolution contrast-enhanced sonography. Tumors were subsequently treated with 1 or 3 minutes of continuous low-intensity US after intravenous administration of a US contrast agent. Treatment effects were assessed by quantitative dynamic contrast-enhanced MRI, contrast-enhanced sonography, histopathologic analysis, and immunohistochemistry.
  
  
  RESULTS
  Low-intensity antivascular US treatment resulted in approximately a doubling and tripling of the time to peak enhancement on dynamic contrast-enhanced MRI in the 1- and 3-minute treatment groups, respectively, along with a significant decrease in contrast wash-out (P < .01). There was a potent reduction in tumor perfusion on contrast-enhanced sonography, with approximately 40% and 70% reductions in the tumor area perfused as assessed by contrast-enhanced sonography after 1 (P < .05) and 3 (P < .01) minutes of antivascular US. The pathologic and histologic changes spatially correlated with the regions of diminished perfusion seen on contrast-enhanced sonography and dynamic contrast-enhanced MRI. Antivascular US therapy resulted in a significant increase in the number of hypoxia-inducible factor 1A(+) cells, indicating tumor hypoxia (P < .01), and of CD45(+)/CD3(+) cells in tumors after treatment, in keeping with increased T-cell infiltration (P < .01).
  
  
  CONCLUSIONS
  Antivascular US treatment effects extend beyond direct cytotoxicity from hemorrhagic necrosis to include ischemia-mediated cytotoxicity, enhanced small molecule retention, and intratumoral immune activation.
authors.affiliation: Department of Radiology (S.J.H., T.G., M.C.S., S.P., C.M.S.), Penn Image-Guided Interventions Laboratory (S.J.H., T.G.), and Penn Ultrasound Research Laboratory (S.J.H., C.M.S.), Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania USA. stephen.hunt@uphs.upenn.edu.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Hunt
authors.affiliation: Department of Radiology (S.J.H., T.G., M.C.S., S.P., C.M.S.), Penn Image-Guided Interventions Laboratory (S.J.H., T.G.), and Penn Ultrasound Research Laboratory (S.J.H., C.M.S.), Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania USA.
authors.forename: Terence
authors.initials: T
authors.lastname: Gade
authors.affiliation: Department of Radiology (S.J.H., T.G., M.C.S., S.P., C.M.S.), Penn Image-Guided Interventions Laboratory (S.J.H., T.G.), and Penn Ultrasound Research Laboratory (S.J.H., C.M.S.), Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania USA.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Soulen
authors.affiliation: Department of Radiology (S.J.H., T.G., M.C.S., S.P., C.M.S.), Penn Image-Guided Interventions Laboratory (S.J.H., T.G.), and Penn Ultrasound Research Laboratory (S.J.H., C.M.S.), Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania USA.
authors.forename: Stephen
authors.initials: S
authors.lastname: Pickup
authors.affiliation: Department of Radiology (S.J.H., T.G., M.C.S., S.P., C.M.S.), Penn Image-Guided Interventions Laboratory (S.J.H., T.G.), and Penn Ultrasound Research Laboratory (S.J.H., C.M.S.), Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania USA.
authors.forename: Chandra M
authors.initials: CM
authors.lastname: Sehgal
mesh_terms: D000818:Animals; D014408:Biomarkers, Tumor / Q000276:immunology*; D045744:Cell Line, Tumor; D018810:Magnetic Resonance Angiography / Q000379:methods; D008545:Melanoma / Q000276:immunology / Q000473:pathology* / Q000628:therapy*; D051379:Mice; D008809:Mice, Inbred C3H; D009389:Neovascularization, Pathologic / Q000276:immunology / Q000473:pathology* / Q000628:therapy*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D014464:Ultrasonic Therapy / Q000379:methods*
chemical_list: D014408:Biomarkers, Tumor
keywords: cancer; dynamic contrast-enhanced magnetic resonance imaging; immune; microbubble; therapeutic ultrasound