title: Role of diffusion-weighted MRI in the detection of early active sacroiliitis.
abstract: OBJECTIVE
  This study proposed to evaluate the value of diffusion-weighted MRI (DWI) to detect active inflammatory changes in the sacroiliac joints of patients with early axial spondyloarthritis (also spelled spondylarthritis).
  
  
  METHODS
  Forty-two patients with chronic low back pain underwent clinical and MRI evaluation for axial spondyloarthritis or early ankylosing spondylitis. STIR, contrast-enhanced T1-weighted, fat-saturated T2-weighted, and diffusion-weighted (b values: 100, 600, 1,000 s/mm(2)) images were obtained. The presence of subchondral bone marrow edema, subchondral fatty marrow infiltration, or contrast enhancement in the sacroiliac joints or adjacent enthesitis sites was considered a marker for active inflammatory changes. All MRI sequences were evaluated for the presence of acute inflammatory changes and inter- and intrarater reliability of the sequences. Mean apparent diffusion coefficient (ADC) values of diffusion-weighted images were calculated from normal and involved iliac and sacral bones of sacroiliac joints.
  
  
  RESULTS
  ADC values measured from the lesions at b values of 1,000 and 600 s/mm(2) in patients with sacroiliitis (n = 13) were significantly higher than values measured from iliac and sacral bones in patients with low back pain of mechanical origin (n = 29). DWI showed sensitivity for detecting acute lesions in early sacroiliitis similar to that of T1-weighted gadolinium images (area under the curve, 0.843-0.971). Intra- and interrater reliability of DWI was acceptable.
  
  
  CONCLUSIONS
  DWI is a sensitive, fast sequence and does not require a contrast agent, which makes it a good and cost-effective alternative for imaging sacroiliac joints. DWI also offers the possibility of quantifying diffusion coefficients of the lesions, which helps to discriminate between normal and involved subchondral bone.
authors.affiliation: Department of Radiology, Faculty of Medicine, Firat University, 23119, Elazig, Turkey. bozgeyik4@hotmail.com
authors.forename: Zulkif
authors.initials: Z
authors.lastname: Bozgeyik
authors.forename: Salih
authors.initials: S
authors.lastname: Ozgocmen
authors.forename: Ercan
authors.initials: E
authors.lastname: Kocakoc
mesh_terms: D000328:Adult; D000465:Algorithms; D003287:Contrast Media; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D012372:ROC Curve; D012446:Sacroiliac Joint / Q000473:pathology*; D012680:Sensitivity and Specificity; D025241:Spondylarthritis / Q000175:diagnosis* / Q000473:pathology; D013167:Spondylitis, Ankylosing / Q000175:diagnosis* / Q000473:pathology; D018709:Statistics, Nonparametric
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA