Overall, MRI had an increased rate of both true-positive and radiographic characterization, the characterization of low-grade chondroid lesions on MRI is challenging because of overlapping features of benign and malignant lesions. MRI is generally considered the preferred imaging modality for staging of bone tumors [14]. Hogeboom et al [36] compared the value of MRI to CT in the evaluation of bone tumors in a prospective study of 25 patients. They found that MRI has better soft-tissue contrast than CT, making it possible to study the relationship of the bone tumor to the soft tissues, bone marrow, and joints more accurately. They found that CT better defines destruction of cortical bone. Specifically, MRI was superior to CT in detecting cortical bone destruction in 4.5% of patients studied and better at evaluating marrow involvement in 25%, soft-tissue involvement in 31%, joint involvement in 36.4%, and invasion of neurovascular structures in 15.3% of patients. MRI and CT were judged equivalent in these categories the majority of the time (ranging from 63% to 82% of the time for the various categories). CT was superior to MRI for some patients in two categories: detecting cortical bone destruction (13.6%) and neurovascular involvement (7.7%). If both modalities are available, the authors suggest that MRI is preferable to CT. A prospective study comparing the staging of primary bone sarcoma with CT, MRI, bone scintigraphy, and angiography in 56 patients showed that MRI was superior in defining tumor length, demonstrating involvement of muscle compartments, and delineating the relationship between tumor and major neurovascular bundles [37]. In the same study, MRI was shown to be comparable to CT in demonstrating cortical bone and joint involvement [37].
Primary Bone Tumors. Overall, MRI had an increased rate of both true-positive and radiographic characterization, the characterization of low-grade chondroid lesions on MRI is challenging because of overlapping features of benign and malignant lesions. MRI is generally considered the preferred imaging modality for staging of bone tumors [14]. Hogeboom et al [36] compared the value of MRI to CT in the evaluation of bone tumors in a prospective study of 25 patients. They found that MRI has better soft-tissue contrast than CT, making it possible to study the relationship of the bone tumor to the soft tissues, bone marrow, and joints more accurately. They found that CT better defines destruction of cortical bone. Specifically, MRI was superior to CT in detecting cortical bone destruction in 4.5% of patients studied and better at evaluating marrow involvement in 25%, soft-tissue involvement in 31%, joint involvement in 36.4%, and invasion of neurovascular structures in 15.3% of patients. MRI and CT were judged equivalent in these categories the majority of the time (ranging from 63% to 82% of the time for the various categories). CT was superior to MRI for some patients in two categories: detecting cortical bone destruction (13.6%) and neurovascular involvement (7.7%). If both modalities are available, the authors suggest that MRI is preferable to CT. A prospective study comparing the staging of primary bone sarcoma with CT, MRI, bone scintigraphy, and angiography in 56 patients showed that MRI was superior in defining tumor length, demonstrating involvement of muscle compartments, and delineating the relationship between tumor and major neurovascular bundles [37]. In the same study, MRI was shown to be comparable to CT in demonstrating cortical bone and joint involvement [37].