Background With the advanced MRI techniques, pathologic features can be detected at an early stage and quantitatively evaluated, resulting in the advantages of early diagnosis and prompt treatment.
Objectives This study aimed to determine the value of diffusion-weighted MR imaging (DWI) in determined of ankylosing spondylitis (AS) treatment strategy and assess the role of quantitative MRI in the evaluation of AS treatment outcome.
Methods 18 patients with the diagnosis of early AS were included in this study. Disease activity was measured according to clinical instruments and laboratory tests. For each patient, both inflamed sacroiliac (S-I) joint lesion was checked quantitatively at first diagnosis by diffusion-weighted imaging (DWI) measuring the apparent diffusion coefficient (ADC) and by dynamic contrast-enhanced imaging (DCEI) with evaluation of the enhancement factor (fenh) and enhancement gradient (genh). All patients were revaluated by pelvis computer tomography (CT) for bone change in S-I joint, after two year.
Results Clinical and quantitative MRI parameters diminished significantly with regression of the inflammatory activity. Median ADC values in AS patients were (1.118±0.122)×10-3 mm2/s in S-I joint. The high ADC (>1.118±0.122)×10-3 mm2/s, fenh (>1.65) and genh (2.09%/S) were associated severe disease activity (high BASDIA), and early administration of biologics (p<0.05). In each individual, the high ADC, fenh and genh of S-I joint lesion was associated more severe localized pain than the other S-I joint, despite treatment (p<0.05). Paradoxically, early administration of biologics group that had high ADC, fenh, genh and high disease activity, had minimal bone change of S-I joint, compared to only NSAIDs used group in pelvis CT finding.
Conclusions Diffusion-weighted imaging and DCEI were shown to be effective in quantifying changes in inflammation in S-I joint at the diagnosis of AS, and could be convenient for assessing treatment strategy. To the best of our knowledge this is the first time DWI was used to evaluate the treatment strategy and treatment outcome of AS.
Disclosure of Interest None declared