title: Imaging tumor variation in response to photodynamic therapy in pancreatic cancer xenograft models.
abstract: OBJECTIVE
  A treatment monitoring study investigated the differential effects of orthotopic pancreatic cancer models in response to interstitial photodynamic therapy (PDT), and the validity of using magnetic resonance imaging as a surrogate measure of response was assessed.
  
  
  METHODS
  Different orthotopic pancreatic cancer xenograft models (AsPC-1 and Panc-1) were used to represent the range of pathophysiology observed in human beings. Identical dose escalation studies (10, 20, and 40J/cm) using interstitial verteporfin PDT were performed, and magnetic resonance imaging with T2-weighted and T1-weighted contrast were used to monitor the total tumor volume and the vascular perfusion volume, respectively.
  
  
  RESULTS
  There was a significant amount of necrosis in the slower-growing Panc-1 tumor using high light dose, although complete necrosis was not observed. Lower doses were required for the same level of tumor kill in the faster-growing AsPC-1 cell line.
  
  
  CONCLUSIONS
  The tumor growth rate and vascular pattern of the tumor affect the optimal PDT treatment regimen, with faster-growing tumors being relatively easier to treat. This highlights the fact that therapy in human beings shows a heterogeneous range of outcomes, and suggests a need for careful individualized treatment outcomes assessment in clinical work.
authors.affiliation: Thayer School of Engineering, Dartmouth College, Hanover, NH, USA. samkoe@dartmouth.edu; pogue@dartmouth.edu
authors.forename: Kimberley S
authors.initials: KS
authors.lastname: Samkoe
authors.forename: Alina
authors.initials: A
authors.lastname: Chen
authors.forename: Imran
authors.initials: I
authors.lastname: Rizvi
authors.forename: Julia A
authors.initials: JA
authors.lastname: O'Hara
authors.forename: P Jack
authors.initials: PJ
authors.lastname: Hoopes
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Pereira
authors.forename: Tayyaba
authors.initials: T
authors.lastname: Hasan
authors.forename: Brian W
authors.initials: BW
authors.lastname: Pogue
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D003287:Contrast Media; D005240:Feasibility Studies; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D051379:Mice; D016513:Mice, SCID; D009336:Necrosis; D010190:Pancreatic Neoplasms / Q000098:blood supply / Q000188:drug therapy* / Q000401:mortality / Q000473:pathology; D010778:Photochemotherapy / Q000379:methods* / Q000401:mortality; D017319:Photosensitizing Agents / Q000008:administration & dosage*; D011166:Porphyrins / Q000008:administration & dosage*; D011879:Radiotherapy Dosage; D047368:Tumor Burden; D000077362:Verteporfin; D023041:Xenograft Model Antitumor Assays
chemical_list: D003287:Contrast Media; D017319:Photosensitizing Agents; D011166:Porphyrins; D000077362:Verteporfin