CT-like images of the sacroiliac joint generated from MRI using susceptibility-weighted imaging (SWI) in patients with axial spondyloarthritis

Abstract

BackgroundTo analyse the added value of susceptibility-weighted imaging (SWI) compared with standard T1-weighted (T1) MRI for detecting structural lesions of the sacroiliac joint (SIJ) in patients with axial spondyloarthritis (axSpA) using CT as reference standard.Material and methodsSixty-eight patients with suspected or proven axSpA underwent both MRI and CT of the SIJ on the same day. Two readers separately scored CT, T1 and SWI for the presence of erosions, sclerosis and joint space changes using an established 24-region SIJ model. Disagreement was resolved by a third reader. Diagnostic accuracy (McNemar test), Cohen’s kappa (k), sensitivity (SE) and specificity were calculated on the joint level using CT as reference.ResultsIn CT, 38 joints showed erosions, 67 sclerosis and 37 joint space changes. Agreement with CT for erosions was 92.6% (k=0.811 (0.7–0.92)) in SWI and 87.5% (k=0.682 (0.54–0.82)) in T1 (p=0.143) and agreement for sclerosis 84.6% (k=0.69 (0.57–0.81)) and 62.5% (k=0.241 (0.13–0.35)) (p<0.001), respectively. This resulted in superior SE of SWI (81.6% vs 73.7%) for erosions and sclerosis (74.6% vs 23.9%) at a minor expense of SP. No differences were detected for joint space changes.ConclusionIn patients with axSpA, SWI depicts erosions and sclerosis more accurately than T1 spin echo MRI at 1.5 T.

What amount of structural damage defines sacroiliitis: a CT study

“…Included in this analysis were patients from three study cohorts: the SacroIliac MAgnetic resonanace and Computed Tomography study (SIMACT) (n=110)5 6 10 and the Virtual Non-Calcium - Susceptibility Weighted Imaging-study (n=72),11 both prospective studies on patients with chronic LBP and possible axSpA, as well as the SacroIliac Changes in the Normal Population (SICC-NP) study, a retrospective investigation, including 818 patients from the general population 12. All patients from the two prospective cohorts received standardised laboratory testing (including HLA-B27 and C reactive protein) and clinical questionnaires (eg, Bath Ankylosing Spondylitis Disease Activity Index) as described in detail in the respective publications.…”

CT-like images in MRI improve specificity of erosion detection in patients with hand arthritis: a diagnostic accuracy study with CT as standard of reference

“…9 Another promising method is offered by new pulse sequences with ultrashort TEs or zero ZTE, which allow direct visualisation of bone by more precise representation of its water content. [21][22][23] The feasibility of erosion detection by SWI has been demonstrated for anatomically complex regions such as the hand 24 and the sacroiliac joint 25 before. In the present study, we further optimised the sequence parameters and adapted them for hand imaging so that all regions could be imaged and assessed.…”

MRI in axial spondyloarthritis: understanding an ‘ASAS-positive MRI’ and the ASAS classification criteria

“…Some authors have proposed a minimum MRI protocol for the SIJ of an oblique coronal T1 and STIR sequence with sufficiently high resolution, before suggesting the diagnosis of axSpA [41]. However, this consensus is already out of date with increasing recognition by many radiologists that the minimum standard for an MRI protocol of the SIJ for diagnostic purposes should include at least 4 sequences: 3 in the semicoronal plane-(1) a T1-weighted sequence sensitive for marrow fat signal (such as T1 spin echo), (2) a T2-weighted water-sensitive sequence for BME (such as STIR or equivalent), (3) a sequence designed for optimal depiction of the bone-cartilage interface (articular surface) to allow improved visibility of erosion [12,42,43]; plus 1 sequence in the semiaxial plane that is orthogonal to the semicoronal sequences. This latter sequence has been shown to greatly assist in the ascertainment of BME patterns [44], and using only the coronal sequences will reveal patterns of BME that may appear to meet the 2009 ASAS definition of active sacroiliitis in 30-41% of athletes [26].…”