Role of diffusion-weighted MRI in the detection of early active sacroiliitis

AJR Am J Roentgenol. 2008 Oct;191(4):980-6. doi: 10.2214/AJR.07.3865.


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).

Subjects and 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.

Conclusion: 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.

MeSH terms

  • Adult
  • Algorithms
  • Contrast Media
  • Diagnosis, Differential
  • Diffusion Magnetic Resonance Imaging / methods*
  • Female
  • Gadolinium DTPA
  • Humans
  • Male
  • Predictive Value of Tests
  • ROC Curve
  • Sacroiliac Joint / pathology*
  • Sensitivity and Specificity
  • Spondylarthritis / diagnosis*
  • Spondylarthritis / pathology
  • Spondylitis, Ankylosing / diagnosis*
  • Spondylitis, Ankylosing / pathology
  • Statistics, Nonparametric


  • Contrast Media
  • Gadolinium DTPA