title: Optimising diffusion weighted MRI for imaging metastatic and myeloma bone disease and assessing reproducibility.
abstract: OBJECTIVE
  To establish normal bone marrow values of apparent diffusion coefficient (ADC) over an age range, compare them with metastatic and myelomatous involvement, to establish reproducibility and to optimise b values.
  
  
  METHODS
  The ADCs of bone marrow in 7 volunteers (mean age 29.7 years), 34 volunteers (mean age 63.3 years) and 43 patients with metastatic and myelomatous involvement (mean age 65.5 years) were measured. In 9 volunteers diffusion weighted MRI was repeated within 7 days. b values were derived to optimise contrast between normal and pathological marrow.
  
  
  RESULTS
  The mean ADC of bone marrow in younger volunteers was significantly higher than that of older volunteers. The coefficient of reproducibility was 14.8%. The ADC mean of metastatic and myeloma bone disease was 1054 + / -456 x 10⁻⁶mm²s⁻¹. An ADC threshold of 655 × 10(-6) mm(2)s(-1) separated normal and abnormal marrow with a sensitivity and specificity of 90% and 93% respectively. Contrast between normal and abnormal marrow was optimal at b = 1389 smm(-2).
  
  
  CONCLUSIONS
  The reproducibility of ADC measurements in bone is equivalent to published data for soft tissue with a high sensitivity and specificity for separating abnormal from age matched normal bone marrow. A b value of around 1,400 smm(-2) is optimal for imaging bone marrow.
authors.affiliation: Cancer Research UK Clinical Magnetic Resonance Research Group, Institute of Cancer Research and Royal Marsden NHS Foundation Trust, Downs Road, Surrey, SM2 5PT, UK. Christina.Messiou@icr.ac.uk
authors.forename: C
authors.initials: C
authors.lastname: Messiou
authors.forename: D J
authors.initials: DJ
authors.lastname: Collins
authors.forename: V A
authors.initials: VA
authors.lastname: Morgan
authors.forename: N M
authors.initials: NM
authors.lastname: Desouza
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001853:Bone Marrow / Q000473:pathology*; D019046:Bone Marrow Neoplasms / Q000473:pathology*; D001859:Bone Neoplasms / Q000473:pathology*; D016022:Case-Control Studies; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009101:Multiple Myeloma / Q000473:pathology*; D011446:Prospective Studies; D012372:ROC Curve; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity