Indeterminate or aggressive appearance for malignancy. Next imaging study. Lesions seen on radiographs that are not definitely benign often require additional characterization using advanced imaging studies such as MRI or CT. The next best imaging examination is not always clearly defined because the choice will be influenced by the radiographic appearance of the lesion, location, number of lesions, availability of imaging equipment, plan for biopsy/treatment, as well as underlying patient-specific clinical parameters. CT Area of Interest CT continues to play a role in the evaluation of indeterminate bone lesions discovered on radiographs, particularly in lesions with mineralized matrix or in suspected cases of osteoid osteoma (see Variant 4). Both MRI and CT have been used to evaluate the degree of cortical involvement in chondroid lesions [20]. In comparison with radiographs and MRI, CT has been shown to better delineate the presence of cortical destruction and the character of matrix mineralization patterns in patients with clear cell chondrosarcoma [21]. In a retrospective review of 40 pathologically confirmed telangiectatic osteosarcomas, Murphey et al [22] noted that CT was the optimal imaging modality for demonstration of subtle matrix mineralization seen in 85% of cases in the intraosseous or soft-tissue components of the lesion. Not all studies conclude that one modality, CT or MRI, is better than the other. A multi- institutional collaborative study assessing the relative accuracy of CT and MRI in the local staging of primary malignant musculoskeletal neoplasms showed no statistically significant difference between CT and MRI in determining tumor involvement of muscle, bone, joints, or neurovascular structures. Furthermore, the combined interpretation of CT and MRI did not significantly improve accuracy [23].
Primary Bone Tumors. Indeterminate or aggressive appearance for malignancy. Next imaging study. Lesions seen on radiographs that are not definitely benign often require additional characterization using advanced imaging studies such as MRI or CT. The next best imaging examination is not always clearly defined because the choice will be influenced by the radiographic appearance of the lesion, location, number of lesions, availability of imaging equipment, plan for biopsy/treatment, as well as underlying patient-specific clinical parameters. CT Area of Interest CT continues to play a role in the evaluation of indeterminate bone lesions discovered on radiographs, particularly in lesions with mineralized matrix or in suspected cases of osteoid osteoma (see Variant 4). Both MRI and CT have been used to evaluate the degree of cortical involvement in chondroid lesions [20]. In comparison with radiographs and MRI, CT has been shown to better delineate the presence of cortical destruction and the character of matrix mineralization patterns in patients with clear cell chondrosarcoma [21]. In a retrospective review of 40 pathologically confirmed telangiectatic osteosarcomas, Murphey et al [22] noted that CT was the optimal imaging modality for demonstration of subtle matrix mineralization seen in 85% of cases in the intraosseous or soft-tissue components of the lesion. Not all studies conclude that one modality, CT or MRI, is better than the other. A multi- institutional collaborative study assessing the relative accuracy of CT and MRI in the local staging of primary malignant musculoskeletal neoplasms showed no statistically significant difference between CT and MRI in determining tumor involvement of muscle, bone, joints, or neurovascular structures. Furthermore, the combined interpretation of CT and MRI did not significantly improve accuracy [23].