Whole‐lesion ADC histogram analysis and the spondyloarthritis research consortium of canada (SPARCC) MRI index in evaluating the disease activity of ankylosing spondylitis

Background

Conventional MRI is limited in quantitative evaluation of ankylosing spondylitis (AS) activity states. A comparison of the effectiveness of the whole‐lesion apparent diffusion coefficient (ADC) histogram analysis with the Spondyloarthritis Research Consortium of Canada (SPARCC) MRI index in evaluating the disease activity of AS might aid in this assessment.

Purpose

To compare the effectiveness of the whole‐lesion ADC histogram analysis with the SPARCC MRI index in evaluating the disease activity states of AS.

Study Type

Prospective.

Population

A total of 57 AS patients and 27 healthy matched volunteers were included.

Field Strength/Sequence

3.0T MR including a diffusion‐weighted imaging (DWI) sequence (b = 0, 1000 s/mm²).

Statistical Tests

One‐way analysis of variance (ANOVA) and Scheffe's post‐hoc was used to compare the parameters among different groups. A receiver operating characteristic (ROC) analysis and the Spearman rank correlation were performed to test the diagnostic performance of all parameters in distinguishing different disease activity states and determining the correlations between them.

Assessment

AS disease activity states was evaluated according to the Ankylosing Spondylitis Disease Activity Score (ASDAS). Initial DWI images and corresponding ADC maps were imported into our in‐house software. Regions of interest (ROIs) were drawn in all slices and the relevant parameters were derived simultaneously. The SPARCC MRI index scores were counted artificially based on T₂‐PDW‐SPAIR images.

Results

The ADC_mean, ADC percentiles, and SPARCC MRI index of the active group were significantly higher than the inactive and control groups (all P < 0.001). The 90th percentile could differentiate the inactive from the control group and the low disease activity group from the inactive group (P = 0.011 and 0.006, respectively). The 50th percentile of the high disease activity group was significantly higher than the low group (P = 0.004), while the SPARCC MRI index of the very high disease activity group was higher than the high group (P < 0.001).

Data Conclusion

The whole‐volume ADC histogram analysis was superior to the SPARCC MRI index in assessing AS activity states.

Level of Evidence: 1

Technical Efficacy: Stage 2

J. Magn. Reson. Imaging 2018.

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