title: Assessment of liver tumor response by high-field (3 T) MRI after radiofrequency ablation: short- and mid-term evolution of diffusion parameters within the ablation zone.
abstract: OBJECTIVE
  To compare the apparent diffusion coefficient (ADC) values of malignant liver lesions on diffusion-weighted MRI (DWI) before and after successful radiofrequency ablation (RF ablation).
  
  
  METHODS
  Thirty-two patients with 43 malignant liver lesions (23/20: metastases/hepatocellular carcinomas (HCC)) underwent liver MRI (3.0 T) before (<1 month) and after RF ablation (at 1, 3 and 6 months) using T2-, gadolinium-enhanced T1- and DWI-weighted MR sequences. Jointly, two radiologists prospectively measured ADCs for each lesion by means of two different regions of interest (ROIs), first including the whole lesion and secondly the area with the visibly most restricted diffusion (MRDA) on ADC map. Changes of ADCs were evaluated with ANOVA and Dunnett tests.
  
  
  RESULTS
  Thirty-one patients were successfully treated, while one patient was excluded due to focal recurrence. In metastases (n=22), the ADC in the whole lesion and in MRDA showed an up-and-down evolution. In HCC (n=20), the evolution of ADC was more complex, but with significantly higher values (p=0.013) at 1 and 6 months after RF ablation.
  
  
  CONCLUSIONS
  The ADC values of malignant liver lesions successfully treated by RF ablation show a predictable evolution and may help radiologists to monitor tumor response after treatment.
authors: Department of Diagnostic and Interventional Radiology, Centre Hospitalier Universitaire Vaudois, University of Lausanne, Rue du Bugnon 46, 1011 Lausanne, Switzerland. tluonmac@gmail.com
authors: Tri-Linh
authors: TL
authors: Lu
authors: Fabio
authors: F
authors: Becce
authors: Pierre
authors: P
authors: Bize
authors: Alban
authors: A
authors: Denys
authors: Reto
authors: R
authors: Meuli
authors: Sabine
authors: S
authors: Schmidt
mesh_terms: D000328:Adult; D000368:Aged; D006528:Carcinoma, Hepatocellular / Q000473:pathology* / Q000601:surgery*; D017115:Catheter Ablation / Q000379:methods*; D005260:Female; D006498:Hepatectomy / Q000379:methods*; D006801:Humans; D008113:Liver Neoplasms / Q000473:pathology* / Q000601:surgery*; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome