Assessment of Locally Recurrent Disease, Response to Chemo- and Radiotherapy, and Special Considerations

This chapter gives a short overview of the expected imaging appearance of postoperative findings, postoperative recurrence, and potential postoperative complications that may occur after treatment of tumors of the osseous spine. Furthermore, assessment of response to chemo- and radiotherapy is discussed. Magnetic resonance imaging (MRI), including morphological sequences, dynamic contrast-enhanced imaging, and diffusion-weighted imaging, is the preferred technique to differentiate expected postoperative changes such as edema and fibrosis from local recurrence. Complementary computed tomography (CT) may add information by demonstrating osteolysis, detection of chondroid calcifications in recurrent cartilage tumors of chordoma, and calcified osteoid matrix in recurrent osteosarcoma. Positron emission tomography (PET)/CT and WBMRI have a complementary role in the posttreatment evaluation of lymphoma. PET/CT also has a role in the evaluation of posttreatment response of plasmacytoma. Complications such as damage to neural structures, flap reconstruction failure, CSF leak with formation of pseudomeningocele, vascular injury, wound-related complications such as tissue necrosis, wound dehiscence, hematomas, seromas, infections, and development of extensive fibrosis are also best evaluated on MRI. CT is, however, the mainstay for hardware and bone graft failure. Mimickers of poor response to chemotherapy include early granulation tissue, bone marrow changes due to chemotherapy or irradiation, radiation necrosis, and insufficiency fractures.