title: [Application of magnetic resonance diffusion weighted imaging in early ankylosing spondylitis].
abstract: OBJECTIVE
  To evaluate the magnetic resonance diffusion-weighted imaging (DWI) in the detection of early ankylosing spondylitis and explore the manifestations of ankylosing spondylitis on whole body DWI (WB-DWI).
  
  
  METHODS
  A total of 16 patients with early ankylosing spondylitis (AS) and 18 patients with low back pain (LBP) were recruited. Subchondral bone marrow apparent diffusion coefficient (ADC) in bilateral ilium and sacrum along sacroiliac joints were compared. An independent sample t-test (SPSS 16.0, SPSS, Chicago, III) was utilized to analyze the ADC value differences between groups. P < 0.05 denoted statistical significance. The mean ADC values of focal lesions in AS patients were also measured. Whole body diffusion weighted imaging was performed in additional 8 clinical confirmed AS patients and analyzed with the techniques of maximum intensity projection (MIP) and multiplanar reconstruction (MPR) in comparison with conventional MRI images to investigate the detectability of AS lesions with whole body DWI.
  
  
  RESULTS
  Mean ADC values in 16 AS patients were (0.51 ± 0.13)×10(-3)mm(2)/s in ilium and (0.49 ± 0.17)×10(-3)mm(2)/s in sacrum. Mean ADC values in 18 LBP patients were (0.32 ± 0.06)×10(-3)mm(2)/s in ilium and (0.31 ± 0.08)×10(-3)mm(2)/s in sacrum. The ADC value in AS patients were statistically significantly greater than those in ilium and sacrum of LBP patients. Whole body DWI detected abnormalities in 8 AS patients within bilateral sacroiliac joints and other sites corresponding to the clinical symptoms of patients. The mean ADC values of focal lesions of this patient cohort were (1.31 ± 0.38)×10(-3)mm(2)/s in sacrum and (1.18 ± 0.27)×10(-3)mm(2)/s in ilium.
  
  
  CONCLUSIONS
  Subchondral marrow ADC values along sacroiliac joints allow the differentiation of patients with early AS from LBP patients. In conjunctions with such post-processing techniques as MIP and MPR, WB-DWI allows a comprehensive assessment of AS patients to guide treatment, evaluate prognosis and follow therapeutic responses.
authors.affiliation: State Key Laboratory of Oncology in Southern China, Department of Medical Imaging & Interventional Radiology, Department of Gynecologic Oncology, Cancer Center, Sun Yat-sen University, Guangzhou 510060, China. aifei1021@163.com
authors.forename: Fei
authors.initials: F
authors.lastname: Ai
authors.forename: Dan
authors.initials: D
authors.lastname: Tian
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Xiao-ming
authors.initials: XM
authors.lastname: Li
authors.forename: Rao-pan
authors.initials: RP
authors.lastname: Wu
authors.forename: Chuan-miao
authors.initials: CM
authors.lastname: Xie
authors.forename: Pei-hong
authors.initials: PH
authors.lastname: Wu
mesh_terms: D000293:Adolescent; D000328:Adult; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000175:diagnosis; D008297:Male; D013167:Spondylitis, Ankylosing / Q000175:diagnosis*; D051598:Whole Body Imaging / Q000379:methods; D055815:Young Adult