Improved detection of subchondral erosions in the sacroiliac joints with T1-weighted fat-suppressed MRI.

OBJECTIVE: To compare the diagnostic performance of two different sets of magnetic resonance imaging (MRI) for the detection of subchondral erosions in the sacroiliac joints regarding the application of fat-water separation techniques when acquiring T1-weighted (T1w) images, using multi-detector computed tomography (MDCT) as the reference standard. METHODS: We retrospectively included 31 consecutive patients having or being suspected for axial spondyloarthritis (SpA) assessed using both MRI and MDCT. Three sets of images were independently assessed for the presence of erosions by two musculoskeletal radiologists (R1, R2): (1) MRI with standard T1w without fat suppression, (2) MRI with both T1w with and without fat suppression, and (3) MDCT. The diagnostic performance of both sets of MRIs was assessed using MDCT as the referent. RESULTS: The assessment of T1w images with fat suppression substantially increased sensitivity (76% vs. 63% R1; 70% vs. 60% R2), specificity (97% vs. 84% R1; 96% vs. 81% R2), positive predictive value (85% vs. 45% R1; 81% vs. 40% R2), and overall accuracy (94% vs. 80% R1; 92% vs. 77% R2) in the detection of erosions when compared to the assessment using T1w images without fat suppression. CONCLUSION: The assessment of T1w images with fat suppression substantially improves the diagnostic performance of MRI in the detection of erosions in the sacroiliac joints. KEY POINTS: • The presence of erosions in the sacroiliac joints may influence the decision on the diagnosis of axial spondyloarthritis. • T1w fat-suppressed MR imaging relatively increases the contrast between the joint space (high signal) and the adjacent subchondral bone (low signal), potentially improving the detection of erosions in the sacroiliac joints. • T1w fat-suppressed images improve the diagnostic performance of MRI in the detection of erosions in the sacroiliac joints compared to T1w without fat suppression, using MDCT as the reference.

CT fluoroscopy-guided transforaminal and intra-articular facet steroid injections for the treatment of cervical radiculopathy: injectate distribution patterns and association with clinical outcome.

OBJECTIVES: To investigate injectate dispersal patterns and their association with therapeutic efficacy during a transforaminal (TFSI) or an intra-articular facet steroid injection (IFSI) to treat cervical radiculopathy. METHODS: This retrospective study examined the post-intervention cervical spine CT of 56 patients randomized to receive one CT fluoroscopy-guided IFSI (29 patients; 10 (34.5%) males; mean age 45.0 years; SD 8.8 years; range 26-61 years) or TFSI (27 patients; 13 (48.2%) males; mean age 51.1 years; SD 11.2 years; range 29-72 years) (December 2010 to August 2013). The presence of contrast within the intra-articular facet, juxta-articular facet, retrodural, epidural, and foraminal and extraforaminal spaces during IFSI, and within the extraforaminal, foraminal, and epidural spaces during TFSI was assessed. Descriptive data are presented as frequencies. The association between injectate dispersal patterns and therapeutic efficacy, 4-week post-intervention, was assessed with ANCOVA models. RESULTS: During IFSI, the injectate predominantly spread to the retrodural (62%; 18/29) or juxta-articular (21%; 6/29) space. During TFSI, the injectate predominantly spread to the extraforaminal/foraminal spaces (41%; 11/27) or to the extraforaminal/foraminal/epidural spaces (33%; 9/27). Injectate presence in the juxta-articular (p = .007) or extraforaminal (p < .001) space was a predictor of therapeutic efficacy but not in the foraminal (p = .54), epidural (p = .89), or retrodural (p = .75) space. CONCLUSIONS: TFSI and IFSI led to preferential extraforaminal and retrodural injectate spread, respectively. Targeting the extraforaminal or juxta-articular facet space improved the clinical efficacy of steroid injections when treating cervical radiculopathy. KEY POINTS: • During intra-articular facet injection, the injectate spreads from the facet joint to the retrodural space and rarely reaches the epidural and/or foraminal spaces. • Epidural spread of the injectate during an anterolateral transforaminal steroid injection is the least effective for pain relief in patients with cervical radiculopathy. • Injection techniques targeting the extraforaminal or juxta-articular facet space are safer than transforaminal injections and effectively relieve pain in patients with cervical radiculopathy.