Fig. 2

A 72-year-old woman with sacral insufficiency fracture (SIF) involving the bilateral sacral alae with horizontal component. a Sagittal T1-weighted MR image shows diffuse signal alteration that suggests moderate bone marrow edema at the left sacral ala. b Axial T1-weighted MR image at the proximal S1 level shows moderate bone marrow edema at both sacral alae. c Axial T2-weighted MR image of the same level shows hypointense fracture lines at both sacral alae