Sacral Insufficiency Fracture after Radiotherapy for Cervical Cancer: Appearance and Dynamic Changes on 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography

Figure 1

A 71-year-old woman who underwent pelvic radiotherapy for cervical cancer developed hip pain at 9 months after radiotherapy. Diffuse, mild, linear FDG uptake (SUVmax, 3.2) parallel to the sacroiliac joint in the left sacral ala (yellow arrow) was found in the fused axial image, while the low-dose CT image was normal. Follow-up FDG PET/CT at 12 months after diagnosis of SIF. The SIF became bilateral and showed FDG uptake (left SUVmax, 2.6; right SUVmax, 2.4); the low-dose CT image showed increased bone density and a new anterior sacral fracture line (white arrow).