CT Characterization of Sacroiliac Joint Calcium Pyrophosphate Deposition Disease: Association with Structural Imaging Features and Multifocal Pelvic Joint Chondrocalcinosis
2Department of Diagnostic Imaging, Sheba Medical Center, Israel
Background
Calcium pyrophosphate deposition disease (CPPD) classically involves peripheral joints; however, increasing evidence suggests that axial and pelvic joints, including the sacroiliac joints (SIJs), may also be involved.
We aimed to characterize the computed tomography (CT) imaging phenotype of SIJ involvement in CPPD and evaluate its association with structural imaging features and with CPPD involvement of other pelvic joints.
Methods
In this retrospective cross-sectional study, consecutive pelvic CT examinations were retrieved from the imaging archive of Sheba Medical Center (2024-2025), irrespective of the clinical indication for imaging. Of 305 pelvic CT examinations reviewed, 13 were excluded according to predefined criteria, resulting in 292 adults aged ≥50 years (145 men, 147 women) included in the analysis. CT scans were systematically evaluated for predefined structural imaging features associated with SIJ chondrocalcinosis and for chondrocalcinosis in the right/left hip joints and the symphysis pubis. Categorical variables were compared using the χ² test or Fisher`s exact test, and continuous variables using the t-test or Mann–Whitney U test, as appropriate. Multivariable logistic regression was performed to estimate adjusted odds ratios (ORs).
Results
SIJ CPPD involvement was identified in 50 participants (17.1%) and increased significantly with advancing age. Among the structural imaging features assessed, cortical irregularity demonstrated the strongest independent association with SIJ CPPD (adjusted OR 4.7, 95% CI 2.3–9.4; p<0.001). SIJ CPPD was also independently associated with CPPD in the hip joints and symphysis pubis. Subjects with chondrocalcinosis at ≥2 additional pelvic joints had higher odds of SIJ CPPD (adjusted OR 28.0, 95% CI 9.4–83.5; p<0.001), supporting a multifocal pattern of crystal deposition.
Conclusion
SIJ CPPD appears to be part of a multifocal pelvic CPPD phenotype rather than an isolated finding. Recognition of cortical irregularity on CT may facilitate the differential diagnosis of SIJ abnormalities on routine pelvic CT.