[Clinical applications of apparent diffusion coefficient value for evaluation of hip joint of ankylosing spondylitis...

To evaluate the apparent diffusion coefficient (ADC) value in differential diagnosis of ankylosing spondylitis active lesions.

A total of 68 patients with AS involving hip joint who were diagnosed in Third Affiliated Hospital of Southern Medical University form March 2010 to December 2014 were evaluated by MRI. The ADC values of the hip joint lesions were measured and compared in 38 cases of ankylosing spondylitis active lesions (active group) and 30 cases of ankylosing spondylitis in stable period (stable group), all cases were confirmed by clinical diagnosis.

There are 238 lesions were detected demonstrating hyperintens in DWI and ADC picture. The mean ADC values of active group and stable group were (1.00 ± 0.13) × 10⁻³ mm²/s and (0.65 ± 0.12) × 10⁻³ mm²/s (t=-11.85, P=0.00). The correlation coefficient between ADC and BASDAI score is 0.831 (P<0.01). ROC curve showed that the threshold ADC value differentiating active group and stable group was 0.81 × 10⁻³ mm²/s, with a sensitivity of 94.7%and specificity of 90%.

The ADC value of hip joint lesion of AS patient can help to determine the nature of the ankylosing spondylitis.