title: Advantages of high b-value diffusion-weighted imaging to diagnose pseudo-responses in patients with recurrent glioma after bevacizumab treatment.
abstract: BACKGROUND
  The diagnosis of pseudo-responses after bevacizumab treatment is difficult. Because diffusion-weighted imaging (DWI) is associated with cell density, it may facilitate the differentiation between true- and pseudo-responses. Furthermore, as high b-value DWI is even more sensitive to diffusion, it has been reported to be diagnostically useful in various clinical settings.
  
  
  METHODS
  Between September 2008 and May 2011, 10 patients (5 males, 5 females; age range 6-65 years) with recurrent glioma were treated with bevacizumab. All underwent pre- and post-treatment MRI including T2- or FLAIR imaging, post-gadolinium contrast T1-weighted imaging, and DWI with b-1000 and b-4000. Response rates were evaluated by MacDonald- and by response assessment in neuro-oncology working group (RANO) criteria. We also assessed the response rate by calculating the size of high intensity areas using high b-value diffusion-weighted criteria. Prognostic factors were evaluated using Kaplan-Meier survival curves (log-rank test).
  
  
  RESULTS
  It was easier to identify pseudo-responses with RANO- than MacDonald criteria, however the reduction of edema by bevacizumab rendered the early diagnosis of tumor progression difficult by RANO criteria. In some patients with recurrent glioma treated with bevacizumab, high b-value diffusion-weighted criteria did, while MacDonald- and RANO criteria did not identify pseudo-responses at an early point after the start of therapy.
  
  
  CONCLUSIONS
  High b-value DWI reflects cell density more accurately than regular b-value DWI. Our findings suggest that in patients with recurrent glioma, high b-value diffusion-weighted criteria are useful for the differentiation between pseudo- and true responses to treatment with bevacizumab.
authors.affiliation: Department of Neurosurgery, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan.
authors.forename: Fumiyuki
authors.initials: F
authors.lastname: Yamasaki
authors.forename: Kaoru
authors.initials: K
authors.lastname: Kurisu
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Aoki
authors.forename: Masami
authors.initials: M
authors.lastname: Yamanaka
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Kajiwara
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Watanabe
authors.forename: Takeshi
authors.initials: T
authors.lastname: Takayasu
authors.forename: Yuji
authors.initials: Y
authors.lastname: Akiyama
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Sugiyama
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D020533:Angiogenesis Inhibitors / Q000627:therapeutic use; D061067:Antibodies, Monoclonal, Humanized / Q000627:therapeutic use*; D000068258:Bevacizumab; D001932:Brain Neoplasms / Q000188:drug therapy* / Q000473:pathology*; D002648:Child; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005188:False Negative Reactions; D005189:False Positive Reactions; D005260:Female; D005910:Glioma / Q000188:drug therapy* / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000473:pathology* / Q000517:prevention & control*; D017063:Outcome Assessment, Health Care / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D020533:Angiogenesis Inhibitors; D061067:Antibodies, Monoclonal, Humanized; D000068258:Bevacizumab