MRI and CT Scans: Area to Visualize
In the absence of reliable evidence, it is the opinion of the work group that MRI or CT scans performed to visualize a potentially malignant bone tumor should include a detailed assessment of the tumor and surrounding soft tissue, with additional sequences that visualize the entire bone compartment, from the proximal joint to the distal joint.
Use of Imaging Prior to Referral to a Musculoskeletal Oncologist
Developed by the Musculoskeletal Tumor Society
Although there is a paucity of reliable literature that directly addresses this question, there remains a long history of clinical acumen and associated recommendations from expert panels to justify visualization of the entire bone when performing an MRI to investigate a potentially malignant bone tumor. The American College of Radiology has created practice parameters to guide practitioners on the appropriate execution of MRI in the setting of bone tumors (https://acsearch.acr.org/docs/69421/Narrative/). The field of view should be chosen based on the size of patient and tumor, commonly requiring an adjustment of the field of view to visualize the entire bone to ensure the extent of intramedullary disease and presence of skip lesions are adequately addressed (Kager, 2006). This may require changes to the coil (e.g. a surface coil for a detailed evaluation of the tumor, with a change to a body coil for visualization of the proximal and distal extent of the bone) or possibly performing two separate studies. The sequences should provide multiple perspectives of the tumor and surrounding tissue (axial, coronal, and sagittal) that allow for complete visualization and planning for biopsy execution and operative strategy. The ordering of advanced imaging for a bone tumor may be an uncommon scenario for many practitioners not specialized in the diagnosis or treatment of neoplastic diseases, and we encourage consultation with or referral to dedicated musculoskeletal radiologists or treating specialists to guarantee the study is performed appropriately. The work group agreed that benign bone tumors and non-neoplastic abnormalities of the bone often do not require extension of the field of view outside of the area of concern, and further supports the recommendation of consultation with specialist practitioners when ordering the study to avoid over-imaging of tumors that are clearly benign. MRI is the preferred imaging study; however, a CT scan is acceptable when an MRI cannot be performed due to patient-specific contraindications (pacemaker, cerebral aneurysm clips).