title: Prediction of cell necrosis with sequential temperature mapping after radiofrequency ablation.
abstract: OBJECTIVE
  To assess the feasibility of magnetic resonance (MR) thermometry after thermoablative therapy and to quantitatively evaluate the ability of two sequence types to predict cell necrosis.
  
  
  METHODS
  Twenty patients with hepatic tumors were treated by MR-guided radiofrequency ablation. For each 10 patients, postinterventionally performed gradient echo and segmented echo planar imaging sequences were used to calculate temperature maps based on the proton resonance frequency shift method. Contrast-enhanced images acquired 1 month after therapy were registered on the temperature maps and the necrotic, nonenhanced area was segmented and compared to the area with a displayed temperature above 60 degrees C. Sensitivity and positive predictive value of the temperature map was calculated, using the follow-up imaging as the gold standard.
  
  
  RESULTS
  Temperature mapping reached acceptable image quality in 45/47 cases. Sensitivity, ie, the rate of correctly detected coagulated tissue was 0.82 +/- 0.08 for the gradient echo imaging (GRE) sequence and 0.81 +/- 0.14 for the echo planar imaging (EPI) sequence. Positive predictive value, ie, the rate of voxel in the temperature map over 60 degrees C that actually developed necrosis, was 0.90 +/- 0.07 for the GRE sequence and 0.84 +/- 0.11 for the EPI sequence.
  
  
  CONCLUSIONS
  Sequential MR temperature mapping allows for the prediction of the coagulation zone with an acceptable sensitivity and positive predictive value using EPI and GRE sequences.
authors.affiliation: Department on Diagnostic and Interventional Radiology, University of Tübingen, Germany. hansjoerg.rempp@med.uni-tuebingen.de
authors.forename: Hansjörg
authors.initials: H
authors.lastname: Rempp
authors.forename: Stephan
authors.initials: S
authors.lastname: Clasen
authors.forename: Andreas
authors.initials: A
authors.lastname: Boss
authors.forename: Jörg
authors.initials: J
authors.lastname: Roland
authors.forename: Antje
authors.initials: A
authors.lastname: Kickhefel
authors.forename: Christina
authors.initials: C
authors.lastname: Schraml
authors.forename: Claus D
authors.initials: CD
authors.lastname: Claussen
authors.forename: Fritz
authors.initials: F
authors.lastname: Schick
authors.forename: Philippe L
authors.initials: PL
authors.lastname: Pereira
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001831:Body Temperature; D006528:Carcinoma, Hepatocellular / Q000473:pathology* / Q000601:surgery*; D017115:Catheter Ablation / Q000379:methods*; D003287:Contrast Media / Q000008:administration & dosage; D017352:Echo-Planar Imaging / Q000379:methods; D005240:Feasibility Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D008113:Liver Neoplasms / Q000473:pathology* / Q000601:surgery*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009336:Necrosis; D009942:Organometallic Compounds / Q000008:administration & dosage; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; C090600:gadobutrol