title: Diffusion-weighted magnetic resonance imaging using different b-value combinations for the evaluation of treatment results after volumetric MR-guided high-intensity focused ultrasound ablation of uterine fibroids.
abstract: OBJECTIVE
  To assess the value of diffusion-weighted magnetic resonance imaging (DWI) and apparent diffusion coefficient (ADC) mapping using different b-value combinations for treatment evaluation after magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) of uterine fibroids.
  
  
  METHODS
  Fifty-six patients with 67 uterine fibroids were treated with volumetric MR-HIFU. Pre-treatment and post-treatment images were obtained using contrast-enhanced T1-weighted MRI (CE-T1WI) and DWI using b = 0, 200, 400, 600, 800 s/mm(2). ADC maps were generated using subsets of b-values to investigate the effects of tissue ablation on water diffusion and perfusion in fibroids treated with MR-HIFU. Four combinations of b-values were used: (1) all b-values; (2) b = 0, 200 s/mm(2); (3) b = 400, 600, 800 s/mm(2); and (4) b = 0, 800 s/mm(2).
  
  
  RESULTS
  Using the lowest b-values (0 and 200 s/mm(2)), the mean ADC value in the ablated tissue reduced significantly (p < 0.001) compared with baseline. Calculating the ADC value with the highest b-values (400, 600, 800 s/mm(2)), the ADC increased significantly (p < 0.001) post-treatment. ADC maps calculated with the lowest b-values resulted in the best visual agreement of non-perfused fibroid tissue detected on CE images. Other b-value combinations and normal myometrium showed no difference in ADC after MR-HIFU treatment.
  
  
  CONCLUSIONS
  A decrease in contrast agent uptake within the ablated region on CE-T1WI was correlated to a significantly decreased ADC when b = 0 and 200 s/mm(2) were used.
  
  
  CONCLUSIONS
  DWI could be useful for treatment evaluation after MR-HIFU of uterine fibroids. The ADC in fibroid tissue is influenced by the choice of b- values. Low b-values seem the best choice to emphasise perfusion effects after MR-HIFU.
authors: Department of Radiology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands, m.ikink@umcutrecht.nl.
authors: Marlijne E
authors: ME
authors: Ikink
authors: Marianne J
authors: MJ
authors: Voogt
authors: Maurice A A J
authors: MA
authors: van den Bosch
authors: Robbert J
authors: RJ
authors: Nijenhuis
authors: Bilgin
authors: B
authors: Keserci
authors: Young-sun
authors: YS
authors: Kim
authors: Koen L
authors: KL
authors: Vincken
authors: Lambertus W
authors: LW
authors: Bartels
mesh_terms: D000328:Adult; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D057086:High-Intensity Focused Ultrasound Ablation / Q000379:methods*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007889:Leiomyoma / Q000473:pathology / Q000601:surgery*; D009215:Myometrium / Q000473:pathology; D012372:ROC Curve; D015203:Reproducibility of Results; D025321:Surgery, Computer-Assisted / Q000379:methods*; D016896:Treatment Outcome; D047368:Tumor Burden; D014594:Uterine Neoplasms / Q000473:pathology / Q000601:surgery*