The Value Of T2WI-Dixon Sequences In The Diagnosis Of Axial Spondyloarthritis

Objective: To compare the diagnostic efficiency between single T2 weighted imaging(T2WI)-Dixon sequences and routine protocols(spectral attenuated inversion recovery(SPAIR)-T2 WI sequences and T1 weighted imaging(T1WI)sequences)in the diagnosis of axial Spondyloarthritis(ax Sp A),and to explore the diagnostic value of MRI examination with single T2WI-Dixon sequence in the diagnosis of ax Sp A.Materials and methods: This prospective study comprised suspected ax Sp A patients who underwent magnetic resonance imaging(MRI)of the sacroiliac joints in a 3.0-T scanner from June 2017 to January 2018.Based on the Assessment of Spondyloarthritis International Society(ASAS)classification criteria,two rheumatologists divided the patients into ax Sp A group and non-ax Sp A group according to clinical symptoms,imaging and laboratory examinations.MRI scanning sequences included routine protocols(SPAIR-T2 WI and T1 WI sequences)and T2WI-Dixon sequences.The T2WI-Dixon sequences consisted of in-phase,opposed-phase,fat-only,and water-only images.Images obtained from the routine protocols were analyzed firstly by two independent radiologists.Then,the T2WI-Dixon images were reviewed separately two weeks later.The analyses included “positive MRI”,active sacroiliitis,chronic sacroiliitis,SPARCC scores,and SSS scores.Signal-to-noise ratios(SNRs)and contrast-to-noise ratios(CNRs)of bone marrow edema and fat deposition were measured by the second radiologist.Using clinical diagnosis as the gold standard,the diagnostic performances of “positive MRI” were compared between T2WI-Dixon sequences and routine sequences.The intraobserver and interobserver agreement of active sacroiliitis and chronic sacroiliitis were assessed by Kappa test.The intraobserver and interobserver agreement of the SPARCC scores and the SSS scores were evaluatedby the intraclass correlation coefficient(ICC).Paired t test was used to compare SNR data and CNR data between routine protocols and T2WI-Dixon sequences.Results: 88 patients were included in the study.The “positive MRI” on the T2WI-Dixon sequences in the diagnosis of ax Sp A provided a sensitivity and specificity of 70% and 77%-82%,respectively.The “positive MRI” on the routine sequences in the prediction of ax Sp A provided a sensitivity and specificity of 64%-68% and 77-86%,respectively.For active sacroiliitis,chronic sacroiliitis,fat deposition and ankylosis,intraobserver and interobserver agreements were good(k=0.814-1.000).Intraobserver and interobserver agreements on erosion and backfill were fair to good(k=0.656-0.750).For SPARCC scores,SSS scores,SSS fat scores and SSS ankylosis scores,intraobserver and interobserver agreements were very good to excellent(ICC=0.812-0.998).Intraobserver and interobserver agreements on SSS erosion score and SSS backfill scores were moderate to good(ICC=0.575-0.762).For bone marrow edema and fat deposition,the SNR and CNR were significantly higher on the T2WI-Dixon sequences than that on the routine sequences.Conclusions: The T2WI-Dixon sequences provide the similar diagnostic performance in comparison with the routine sequences(SPAIR-T2 WI and T1WI)in the diagnosis of ax Sp A.Therefore,the T2WI-Dixon sequences as a single sequence could be a convenient and effective radiological method for the diagnosis,evaluation and follow-up of ax Sp A.