Study to evaluate the role of MRI in cases of primary malignant bone tumors

Background: Radiographs are the primary screening technique used for bone tumours and tumor-like lesions. When a lesion is indeterminate or shows signs of aggressiveness, magnetic resonance imaging (MRI) is indicated for further characterisation. Contrast-enhanced MRI (CEMRI) can reveal the most vascularised parts of the tumour and MRI guidance makes it possible to avoid biopsing necrotic areas. Objective: The purpose of this study was to evaluate the role of MRI in cases of primary malignant bone tumors and to determine the MRI characteristics of different primary malignant bone tumor and correlate and compare the imaging findings with surgical and gross pathological findings wherever possible. Materials and methods: We prospectively evaluated forty patients of suspected primary malignant skeletal neoplasms for two year period. Plain radiograph both antero-posterior and lateral projections were taken. Once the tumor was diagnosed on plain radiography, Magnetic Resonance Imaging (MRI) was performed in forty consecutive patients with malignant bone tumors. There were 21 males and 19 females. Results: Out of the 40 cases, thirteen were Osteosarcomas, eight were Ewing’s sarcomas, six were Chondrosarcomas, eight were Giant cell tumours, three were Chordomas, and two were multiple myelomas. Out of the thirty one cases operated, cortical involvement was seen in 27 cases and was absent in 4 cases. Thus sensitivity, specificity, positive predictive value and negative predictive value of MRI in detecting cortical involvement in our study were 96.2%, 100%, 100% and 80% respectively. Marrow involvement was seen in all cases on MRI and was confirmed by surgical and pathological findings in thirty one cases. Extra osseous soft tissue involvement was seen in 34 cases out of 40 cases. Soft tissue involvement was not seen 4 cases of GCT, two cases of Ewing’s sarcoma. Out of total forty cases, 12 cases showed joint involvement on MRI 32.5% cases demonstrated involvement of joint and 67.5% cases did not show joint involvement on MRI. The sensitivity was 100%, specificity 90.4%, positive predictive value 83.3% and negative predictive value 100%. Out of a total of forty cases, MRI showed neurovascular bundle involvement in four, so 10% cases demonstrated involvement of neurovascular bundle. The sensitivity in our study was 100%, specificity 96.2%, positive predictive value 100 % and negative predictive value was 96.2%. Conclusion: MRI is the modality of choice for determining local extent and tumour staging.