Abstract
Anatomical variants are frequently encountered when assessing the sacroiliac joints
(SIJ) using magnetic resonance imaging. When not located in the weight-bearing part
of the SIJ, variants associated with structural and edematous changes can be misinterpreted
as sacroiliitis. Their correct identification is necessary to avoid radiologic pitfalls.
This article reviews five SIJ variants involved in the dorsal ligamentous space (accessory
SIJ, iliosacral complex, semicircular defect, bipartite iliac bony plate, and crescent
iliac bony plate) and three SIJ variants involved in the cartilaginous part of the
SIJ (posterior dysmorphic SIJ, isolated synostosis, and unfused ossification centers).
Keywords
anatomy - magnetic resonance imaging - sacroiliac joint - spondylarthritis - variant
