MR Pathology of Sacrum and Ilium
In a busy radiology practice, imaging of the bony pelvis and lumbosacral spine is commonly requested to investigate the source of lower back and/or hip pain. Radiographs are the initial performed studies. The complex anatomy of the pelvic skeleton, with a number of overlapping structures, makes the imaging assessment and interpretation of many disorders difficult and fraught with the potential to err. Often, pelvic radiographs are suboptimal because of poor positioning of the patient or severe pain. Sacral lesions are frequently overlooked because of the nonspecificity of associated symptoms and because the posterior curvature of the sacrum and the presence of overlying bowel contents obscure anatomic details on plain films. If radiographs are unrevealing, computed tomography (CT) is requested for imaging the sacrum, the presacral space, and the iliac bones. When specific questions arise in cases of suspected trauma or tumor, MR imaging is performed adding multiplanar capability and improved soft tissue contrast.