Diagnosis and progression of sacroiliitis in repeated sacroiliac joint computed tomography

Addition of CT to Improve the Diagnostic Confidence for the Detection of Sacroiliac Joint Erosions in Patients with Equivocal MRI Findings

PURPOSE

To determine if CT can improve the diagnostic confidence for the detection of sacroiliac joint (SIJ) erosions in patients with equivocal MRI findings.

METHODS

A retrospective analysis of adult patients who had an SIJ MRI and a subsequent SIJ CT within 12 months was conducted. Using a 5-point Likert scale, two reviewers evaluated the de-identified MRI and CT images in randomized order and in separate sessions to answer the question: "Does the patient have SIJ erosions?". A Fisher's exact test was used to analyze the difference in diagnostic confidence, and intraclass correlation coefficient (ICC) was used to determine interrater reliability.

RESULTS

54 patients were included in the analysis (average age, 43.9 years). The average time interval between initial SIJ MRI and subsequent CT was 14.4 weeks (range, 5.6-50.3 weeks). CT resulted in significantly more cases with definitive diagnostic confidence than cases with probable or equivocal confidence compared to MRI (P < .001). Amongst cases with equivocal findings on MRI, 73.2% of cases had definitive diagnoses on CT. There was moderate interrater agreement for MRI, with an ICC of .490 [95% CI, .258-.669], and excellent agreement for CT, with an ICC of .832 [95% CI, .728-.899].

CONCLUSION

Overall, CT led to significantly increased diagnostic confidence and higher interrater reliability for the detection of SIJ erosions compared to MRI. Judicious use of CT may be useful in detecting SIJ erosions in patients with equivocal MRI findings.

Sacroiliac joint in sarcoidosis on computed tomography: a monocentric retrospective study (SISTER)

Sacroiliitis and spondyloarthritis (SpA) have been associated to sarcoidosis. Sarcoidosis bone involvement of the sacral or iliac bones has been reported to mimic SpA. We aimed to evaluate the prevalence of structural sacroiliitis and structural changes of the sacroiliac joints (SIJ) in patients with sarcoidosis by abdominal-pelvic computed tomography (AP-CT). In this monocentric retrospective study, three blinded readers evaluated AP-CT that had already been performed on patients with sarcoidosis and classified them as normal, degenerative, or inflammatory. A consensus was reached for the divergent cases. Erosion, ankylosis, and sclerosis, classically associated with sacroiliitis, were noted. SpA was defined according to the ASAS 2009 classification criteria. We identified 217 patients with proven sarcoidosis who underwent AP-CT. Only three patients had sacroiliitis by CT and four had SpA, representing 1.38% and 1.85% of the patients, respectively. Degenerative SIJs represented 28.1% of patients and were significantly associated with age, at least one pregnancy, rural lifestyle, ankylosis, diffuse idiopathic skeletal hyperostosis, sclerosis, and the presence of osteophytes. Four patients had axial bone sarcoidosis. Sacroiliitis, SpA, and degenerative changes of the SIJ have been highlighted by AP-CT in patients with sarcoidosis. Osteoarthritis of the SIJ in sarcoidosis was associated with age, pregnancy, and rural lifestyle. Further studies are needed to assess the link between SpA and sarcoidosis.

The Prevalence and Clinical Associations of Subclinical Sacroiliitis in Inflammatory Bowel Disease

BACKGROUND

Sacroiliitis, an inflammatory arthropathy associated with ankylosing spondylitis (AS), is found in patients with inflammatory bowel disease (IBD) but may go undiagnosed. The aims of this study were to assess prevalence of sacroiliitis in IBD and to determine association between clinical characteristics of IBD and sacroiliitis.

METHODS

Inflammatory bowel disease patients undergoing abdomino-pelvic computed tomography (CT) for any indication (2006-2015) were identified. Using standardized CT scoring, sacroiliitis was confirmed. Two blinded readers used a standardised model where presence of ankylosis or erosion score >3 indicated sacroiliitis. Inflammatory bowel disease scoring was blinded to the presence of sacroiliitis. Demographics, IBD characteristics, clinical activity (Harvey Bradshaw Index >4, Mayo >2, as denoted by attending physician), endoscopic activity (Simple Endoscopic Score for Crohn's Disease >4/Mayo subscore >1), and arthritis/extraintestinal manifestations (EIMS) were recorded. Comparisons were made between those with/without sacroiliitis.

RESULTS

Three hundred sixteen patients were included (50% male; 74% Crohn's disease [CD]). Computed tomography scoring identified 49 (16%) with sacroiliitis. Radiologists had reported sacroiliitis in 33% of these. Five patients had been to a spondylitis clinic. Thirty-three of 49 had abdominal x-rays; 64% of these fulfilled the imaging component of Modified New York criteria for AS. More than 5 sacroiliac erosions were associated with radiologist-reported sacroiliitis (P < 0.0001). There was no difference in prevalence between CD and ulcerative colitis. Sacroiliitis was associated with male sex (63.3% vs 47.9%; odds ratio [OR], 1.8; P = 0.04), known arthritis (41% vs 12%; OR, 4.7; P < 0.0001), pain as an IBD symptom (77.7% vs 56.9%; P = 0.03), and CD inflammatory phenotype (P = 0.01). Endoscopic activity, location, and extent were not associated.

CONCLUSIONS

Sacroiliitis is underdiagnosed in IBD and is associated with male sex, arthritis, and inflammatory CD. Data support targeted screening in at-risk patients.

Interrater reliability and radiation dosage of oblique coronal computed tomography for sacroiliitis in comparison with axial computed tomography

OBJECTIVE

Sacroiliitis, a prerequisite to the diagnosis of ankylosing spondylitis, can be ascertained by CT when MRI is not available. Oblique coronal CT is an increasingly popular approach when examining sacroiliitis. The goal of this study was to understand how oblique coronal CT compared with axial CT scanning in terms of raters' concordance when diagnosing sacroiliitis.

METHODS

52 subjects < 45 years of age at onset of their chronic lower back pain were sequentially scanned by X-ray, axial CT and oblique coronal CT. The acquired images were graded by two experienced, double-blinded physicians.

RESULTS

Sacroiliitis in the oblique coronal view was sensitive enough for grading disease severity and/or detecting improvement. Interrater reliability for CT (axial + oblique coronal) was higher than X-ray. The diagnosis based upon oblique coronal CT was consistent, while the radiation dose delivered to the gonads was significantly reduced, compared with axial CT.

CONCLUSION

When MRI is not available, oblique coronal CT should replace axial CT when diagnosing sacroiliitis. Advances in knowledge: When evaluating sacroiliitis, oblique coronal CT is as accurate as conventional axial CT, yet more advantageous owing to reduced radiation dosage.