Value of diffusion-weighted magnetic resonance imaging in early diagnosis of ankylosing spondylitis

Abstract

The objective of this study is to estimate the value of diffusion-weighted MRI (DWI) in the detection of abnormalities in sacroiliac joints in the patients with early ankylosing spondylitis (AS) and investigate the feasibility of whole-body DWI (WB-DWI) in systemic evaluation of AS. Sixteen patients with early AS, 18 patients with simple low back pain (LBP), and 18 healthy volunteers were involved in this study. All subjects underwent conventional MRI and DWI. Apparent diffusion coefficient (ADC) in subchondral bone marrows of sacroiliac joints was measured. Independent-sample t test was used to statistically analyze the difference of ADC values between groups. WB-DWI was performed in additional 12 patients with clinically confirmed AS. The image results were analyzed by multiple post-processing techniques, as compared to conventional MRI. In AS patients, mean ADC values were (0.494 ± 0.170) × 10(-3) mm(2)/s in sacrum and (0.513 ± 0.129) × 10(-3) mm(2)/s in ilium, which were significantly higher than those of LBP ((0.306 ± 0.057) × 10(-3) mm(2)/s in sacrum and (0.323 ± 0.083) × 10(-3) mm(2)/s in ilium) and healthy volunteers ((0.315 ± 0.009) × 10(-3) mm(2)/s in sacrum and (0.319 ± 0.012) × 10(-3) mm(2)/s in ilium). No statistical differences were found between simple LBP and healthy volunteers. Mean ADC value of multiple lesions in AS was (0.932 ± 0.299) × 10(-3) mm(2)/s. By WB-DWI, abnormal signals of sacroiliac joints and extra-sacroiliac joint lesions were demonstrated in the locations corresponding with clinical findings. Mean ADC values of multiple lesions were (1.298 ± 0.323) × 10(-3) mm(2)/s in sacrum and (1.216 ± 0.311) × 10(-3) mm(2)/s in ilium. DWI and WB-DWI were shown to be effective in differentiation and systemic evaluation of early AS. Both techniques are likely to play an importance role in the early diagnosis of AS and assessment of treatment response.

Application of Diffusion-Weighted Imaging in the Detection of Active Sacroiliitis and the Comparison of Apparent Diffusion Coefficient and Relative Apparent Diffusion Coefficient Values

“…There are slight differences in the ADC values in different studies that may be attributed to the different MRI device and different b values. Moreover, similar to the studies of Gezmis et al 6 and Ai et al 15 and unlike the studies of Zhang et al 21 and Sanal et al, 16 the ADC values of unaffected portions of sacroiliac joints in patients with active sacroiliitis were also greater than the ADC values of bone marrow in patients with chronic back pain. This result may be due to the extensive spread of active lesions to the subchondral bone marrow area.…”

“…With the rapid progress of advanced imaging techniques, DWI and whole body-DWI will likely provide a widened application in the early diagnosis and long-term follow-up in AS patients. 15 Moreover, Sanal et al 2,16 performed two studies in 2013 with 21 and 33 patients and stated that DWI is comparable to visual analysis and active lesions in sacroiliitis of AS patients serving an adjunct to STIR. Also, they demonstrated that DWI may reflect the inflammatory state of disease by quantifying the bone marrow changes.…”

“…DWI and dynamic contrast enhanced-MRI were shown to be effective in quantifying changes in inflammation during the treatment of AS and may be convenient for assessing treatment efficacy. 14 Ai et al 15 evaluated 52 patients of whom 16 had early active sacroiliitis. They found that ADC values of inflammatory lesions of AS patients at b values of 600 s/mm 2 were significantly higher than that of adjacent relatively normal regions and also the latter was higher than that of low back pain and control group.…”

Novel Imaging Techniques in Rheumatic Diseases

“…32 Several groups compared sacro-iliac lesions of SpA patients with normal appearing marrow of the same patients and found significantly higher ADC values in lesions then in normal-appearing bone marrow within the same patients. [33][34][35][36] Moreover, ADC is reported to be significantly higher in patients with active ankylosing spondylitis as compared with patients with chronic ankylosing spondylitis or clinically non-active disease. [35][36][37][38] Also, when comparing SpA patients with control patients without inflammatory back pain, higher ADC values were found in bone marrow of sacral and iliac bones of patients as compared with ADC values observed in controls.…”

Advanced Imaging of the Axial Skeleton in Spondyloarthropathy: Techniques, Interpretation, and Utility

“…Attempts to diagnose marrow inflammation by DWI show some promise in the sacrum. 2 Although improved sensitivity with this sequence (even simply using the B0 image; ►Figs. 2B and 3B) may come at the expense of lower specificity, based on correlation with biopsy material, current MRI sequences are relatively insensitive for the detection of inflammation.…”