Sacral Stress Fracture following the Bone Union of Lumbar Spondylolysis

Figure 3

Magnetic resonance image of the sacrum at the first visit to our hospital. (a) Coronal plane on a T1-weighted image. (b) Coronal plane on a T2-weighted image. (c) Coronal plane on a short TI inversion recovery (STIR) image. (d) Axial plane at the S2 level on a STIR image. The left sacral ala on a T1-weighted image shows a low intensity (a), a T2-weighted image shows a high intensity (b), and on a STIR image shows a high intensity (c) compared with the right sacral ala. These radiological findings indicated bone marrow edema. Oblique lineal signal void (white arrows) can be seen in the bone marrow edema; these are fracture lines. An axial plane on a STIR image shows a low-intensity area (white arrow) surrounded by a high-intensity area in the left ventral surface of the sacral ala (d).

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