title: Longitudinal anatomical and metabolic MRI characterization of orthotopic xenograft prostate tumors in nude mice.
abstract: OBJECTIVE
  To assess anatomic and functional magnetic resonance imaging (MRI) for monitoring of tumor volume and metabolism of orthotopic xenograft prostate cancer tumors.
  
  
  METHODS
  Human-derived PC-3M cells were implanted into the prostate in 22 nude mice. Tumor volume and MRI appearance were monitored for up to 29 days. Histology was performed to detect metastases. Hyperpolarized [1-(13) C]pyruvate MRI was used to measure tumor metabolism on day 22.
  
  
  RESULTS
  Tumors were visible by MRI 9 days after tumor cell implantation. Tumor volume increased to 720 ± 190 mm(3) on day 29 of imaging. Metastasis was seen in the iliac lymph nodes at all timepoints, and in more distant lymph nodes at later timepoints, but was not detectable by MRI. Regions with low pyruvate uptake corresponded to regions with necrosis and had a higher lactate/pyruvate ratio (0.98 ± 0.4 vs. 1.6 ± 1.1).
  
  
  CONCLUSIONS
  MRI using the balanced steady-state free precession (bSSFP) sequence can be used to monitor tumor growth in orthotopic PC-3M tumors as early as 9 days post-injection. Hyperpolarized pyruvate MRI has potential to assess tumor metabolism and necrosis.
authors.affiliation: Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada; Department of Medical Biophysics, Western University, London, Ontario, Canada.
authors.forename: Christiane L
authors.initials: CL
authors.lastname: Mallett
authors.forename: Heeseung
authors.initials: H
authors.lastname: Lim
authors.forename: Kundan
authors.initials: K
authors.lastname: Thind
authors.forename: Yuhua
authors.initials: Y
authors.lastname: Chen
authors.forename: Emeline J
authors.initials: EJ
authors.lastname: Ribot
authors.forename: Francisco
authors.initials: F
authors.lastname: Martinez
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Scholl
authors.forename: Paula J
authors.initials: PJ
authors.lastname: Foster
mesh_terms: D000818:Animals; D002247:Carbon Isotopes / Q000493:pharmacokinetics; D045744:Cell Line, Tumor; D003198:Computer Simulation; D003287:Contrast Media / Q000493:pharmacokinetics; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008657:Metabolic Clearance Rate; D051379:Mice; D008819:Mice, Nude; D008954:Models, Biological; D011471:Prostatic Neoplasms / Q000378:metabolism* / Q000473:pathology*; D019289:Pyruvic Acid / Q000493:pharmacokinetics*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D047368:Tumor Burden
chemical_list: D002247:Carbon Isotopes; D003287:Contrast Media; D019289:Pyruvic Acid
keywords: bSSFP; hyperpolarized pyruvate; metastasis; prostate cancer