title: Focal laser ablation of prostate cancer: numerical simulation of temperature and damage distribution.
abstract: BACKGROUND
  The use of minimally invasive ablative techniques in the management of patients with low grade and localized prostate tumours could represent a treatment option between active surveillance and radical therapy. Focal laser ablation (FLA) could be one of these treatment modalities. Dosimetry planning and conformation of the treated area to the tumor remain major issues, especially when, several fibers are required. An effective method to perform pre-treatment planning of this therapy is computer simulation. In this study we present an in vivo validation of a mathematical model.
  
  
  METHODS
  The simulation model is based on finite elements method (FEM) to solve the bio-heat and the thermal damage equations. Laser irradiation was performed with a 980 nm laser diode system (5 W, 75 s). Light was transmitted using a cylindrical diffusing fiber inserted inside a preclinical animal prostate cancer model induced in Copenhagen rats. Non-enhanced T2-weighted and dynamic gadolinium-enhanced T1-weighted MR imaging examinations were performed at baseline and 48 hours after the procedure. The model was validated by comparing the simulated necrosis volume to the results obtained in vivo on (MRI) and by histological analysis. 3 iso-damage temperatures were considered 43° C, 45° C and 50° C.
  
  
  RESULTS
  The mean volume of the tissue necrosis, estimated from the histological analyses was 0.974 ± 0.059 cc and 0.98 ± 0.052 cc on the 48 h MR images. For the simulation model, volumes were: 1.38 cc when T = 43° C, 1.1 cc for T = 45°C and 0.99 cc when T = 50 C°.
  
  
  CONCLUSIONS
  In this study, a clear correlation was established between simulation and in vivo experiments of FLA for prostate cancer.Simulation is a promising planning technique for this therapy. It needs further more evaluation to allow to FLA to become a widely applied surgical method.
authors.affiliation: Inserm (French National Institute of Health and Medical Research), U703, 152 rue du Docteur Yersin, 59120 Loos, France.
authors.forename: Mohamad-Feras
authors.initials: MF
authors.lastname: Marqa
authors.forename: Pierre
authors.initials: P
authors.lastname: Colin
authors.forename: Pierre
authors.initials: P
authors.lastname: Nevoux
authors.forename: Serge R
authors.initials: SR
authors.lastname: Mordon
authors.forename: Nacim
authors.initials: N
authors.lastname: Betrouni
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D006801:Humans; D053685:Laser Therapy / Q000009:adverse effects*; D008297:Male; D008954:Models, Biological; D011471:Prostatic Neoplasms / Q000473:pathology / Q000601:surgery*; D051381:Rats; D015203:Reproducibility of Results; D013696:Temperature