title: A preliminary analysis and model of prostate injection distributions.
abstract: OBJECTIVE
  Understanding the internal dynamics of prostate injections, particularly injection pattern distribution is a key step to developing new therapies for prostate disease that may be best served with a direct injection approach. Due to excellent properties involving liquid contrast agents, MRI can be used for targeting and monitoring of injections into organs and tissues.
  
  
  METHODS
  Eleven intraprostatic injections were performed in vivo with canines using a custom transrectal guiding and imaging system for use in a standard 1.5 T MR scanner. In addition, 25 injections were performed on excised cadaveric human prostates, using a MedRad Spectris injector system. MRI was used to guide the injections and monitor intraparenchymal injection distribution.
  
  
  RESULTS
  T1 and T2-weighted MR images were correlated with histology to produce three-dimensional data sets that can be used to analyze trends in injection patterns. This analysis was used to develop strategies for injection prediction such as gadolinium pre-injections and diffusion-weighted imaging guidance. In addition, a rough model of prostate injections is described, and a preliminary injection guide is developed that takes into account the individual clinician's goals for therapy.
  
  
  CONCLUSIONS
  MR visualization of injected therapeutic agents allows for prediction and monitoring of drug distributions, possibly improving efficacy and reducing side effects. Injection analysis and modeling may be used to assist in optimizing clinical treatments that require or would benefit from focal parenchymal injections into the prostate.
authors.affiliation: Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA. schowning@mri.jhu.edu
authors.forename: Scott L
authors.initials: SL
authors.lastname: Chowning
authors.forename: Robert C
authors.initials: RC
authors.lastname: Susil
authors.forename: Axel
authors.initials: A
authors.lastname: Krieger
authors.forename: Gabor
authors.initials: G
authors.lastname: Fichtinger
authors.forename: Louis L
authors.initials: LL
authors.lastname: Whitcomb
authors.forename: Ergin
authors.initials: E
authors.lastname: Atalar
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000493:pharmacokinetics* / Q000494:pharmacology*; D004285:Dogs; D005544:Forecasting; D008279:Magnetic Resonance Imaging; D008297:Male; D008962:Models, Theoretical; D011467:Prostate; D011471:Prostatic Neoplasms / Q000188:drug therapy*; D012007:Rectum
chemical_list: D000970:Antineoplastic Agents