SAT0392 The diagnostic accuracy of existing grading criteria of sacroiliac joint ct in ankylosing spondylitis

Abstract

BackgroundImaging modalities are essential for the diagnosis of ankylosing spondylitis (AS) due to the absence of specific clinical manifestations. Sacroiliac Joint (SIJ) CT has been used to identify sacroiliitis for decades with a higher diagnostic accuracy than radiography in detecting structural changes, and not reducing the specificity like MRI. However, no well-accepted grading system for SIJ CT existed.ObjectivesWe evaluated the diagnostic accuracy of existing grading criteria of sacroiliitis, aiming to provide references for future better reading of SIJ CT in AS.MethodsA total of 2714 patients who had received CT scanning for any reasons with complete SIJ structures displaying between June 2012 and December 2015 were included. The CT scans were read by 2 rheumatologists together who had received professional training in radiology. Patients with sacroiliitis were selected and bilateral SIJs of each patient were evaluated separately by the 1984 modified New York (mNY) criteria, the criteria proposed by Lee (Lee criteria)[1] and the criteria from Innsbruck workshop report (Innsbruck criteria)[2], respectively. The grading differences among these criteria were analyzed.ResultsAmount to 509 patients were detected having sacroiliitis with an average age of 34 years and 64% of male. Among 1018 SIJs of these patients, 45 SIJs graded 1∼3 by mNY criteria were graded 0 by Lee criteria, indicating the better specificity of Lee criteria. Lee criteria was much more convenient and reliable than mNY criteria for its more explicit definitions. The SIJs with definite sacroiliitis estimated by mNY and Lee criteria were 79.37% and 82.91%, respectively, and simply divided into grade 3 or grade 4. Conversely, 85.27% SIJs were identified as definite sacroiliitis and classified into 5 grades, from grade IIB to grade IVB, by Innsbruck criteria, and the percentages of each grade were 8.94%, 26.82%, 20.92%, 10.12% and 18.47%, respectively, which means a higher discrimination capability than the other two criteria. Other than graded by the extent of lesions in mNY criteria or Lee criteria, the grading assessment by Innsbruck criteria was based on the lesion types, which was more consistent with the natural progression of sacroiliitis.Table 1.The existing grading criteria of SIJ CTmNY criteriaLee criteriaInnsbruck criteria 0 = Normal1 = Suspicious for erosions or sclerosis2 = Mildly abnormal with definite erosions or sclerosis, but without alteration in the joint width3 = Moderately abnormal with erosions or sclerosis, joint space narrowing or widening and/or partial ankylosis4 = Complete ankylosis0 = Normal1 = Focal erosions seen on only one of either semi-coronal or axial images2 = ≤25% erosions*, but without alteration in the joint width3 = ≥25% erosions*, joint space alteration and/or partial ankylosis4 = Complete ankylosisIA = SIJ>4 mmIB = SIJ<2 mmIIA = Contour irregularitiesIIB = ErosionIIIA = Subchondral sclerosisIIIB = Spur formationIVA = Transarticular bony bridgesIVB = Ankylosis*Extent of erosions; (%) = number of slices wit...

The value of the sacroiliac joint area as a new morphological parameter of ankylosing spondylitis

“…[4][5][6] The evolution of the symptoms and signs of AS is very much related to decreases in spinal mobility, column stiffness, function, and pain. [7][8][9] Radiographic images show minimal changes in response to earlier acute inflammation. Thus, the detection of radiographic abnormalities is frequently delayed.…”

“…In the spine, abnormalities progress from reactive sclerosis (Romanus lesion or "shiny corner") and erosions and squaring at the edge of the vertebral bodies to bony bridging and syndesmophyte formation. [7][8][9] Magnetic resonance imaging (MRI) is sometimes considered when there is a high clinical suspicion of AS but previous X-rays were normal. MRI can facilitate earlier AS diagnoses, but the results can be normal even in patients with active AS, and the chronic changes of sacroiliac joint inflammation are better seen on standard X-rays.…”

“…Previous studies assessed sacroiliac joint thickness (SIJT) using a single measurement point, described as the approximate halfway, middle or any location on the sacroiliac joint (SIJ). [7,8,10] However, new bone formation, inflammatory changes, deformity, and asymmetrical narrowing of the SIJ have been reported to occur throughout the SIJ. [11,12] Thus, different findings may result from the use of different measurement locations.…”