title: Assessment of breast lesions with diffusion-weighted MRI: comparing the use of different b values.
abstract: OBJECTIVE
  Our purpose was to study the utility of diffusion-weighted MRI in differentiating benign from malignant breast lesions by assessing the best b values.
  
  
  METHODS
  Forty-five women (mean age, 46.1 years) with 52 focal mass breast lesions underwent diffusion-weighted imaging with different b values. The apparent diffusion coefficient (ADC) value of each lesion was calculated from the ADC maps done using five b values (0, 250, 500, 750, and 1,000 s/mm(2)) and using b values of 0 s/mm(2) with each other b value separately (0 and 250 s/mm(2), 0 and 500 s/mm(2), 0 and 750 s/mm(2), 0 and 1,000 s/mm(2)). The mean ADC values were correlated with imaging findings and histopathologic diagnoses. The cutoff ADC value, sensitivity, and specificity of diffusion-weighted imaging to differentiate benign and malignant lesions were calculated in all b value combinations. A p value of < 0.05 was considered statistically significant.
  
  
  RESULTS
  The mean ADC value was significantly lower for malignant lesions compared to benign lesions (p < 0.0001) in all b value combinations. No statistical difference was seen between the ADC obtained from different b value combinations (p = 0.2581) in the differentiation between benign and malignant lesions. The ADC calculated from b 0 and 750 s/mm(2) was slightly better than the other b value combinations, showing a sensitivity of 92.3% and a specificity of 96.2%.
  
  
  CONCLUSIONS
  Diffusion-weighted imaging is a potential resource as a coadjutant of MRI in the differentiation between benign and malignant lesions. Such imaging can be performed without a significant increase in examination time, especially because it can be done with lower b values.
authors.affiliation: Clínica de Diagnóstico Por Imagem, Rua Ataulfo de Paiva, 669, 2nd floor, Leblon, Rio de Janeiro, RJ, Brazil, 22649-900. fephila@gmail.com
authors.forename: Fernanda Philadelpho Arantes
authors.initials: FP
authors.lastname: Pereira
authors.forename: Gabriela
authors.initials: G
authors.lastname: Martins
authors.forename: Eduardo
authors.initials: E
authors.lastname: Figueiredo
authors.forename: Marisa Nassar Aidar
authors.initials: MN
authors.lastname: Domingues
authors.forename: Romeu Cortes
authors.initials: RC
authors.lastname: Domingues
authors.forename: Lea Mirian Barbosa
authors.initials: LM
authors.lastname: da Fonseca
authors.forename: Emerson Leandro
authors.initials: EL
authors.lastname: Gasparetto
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001943:Breast Neoplasms / Q000175:diagnosis*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult