Clinical advances in musculoskeletal imaging: spondylodiscitis and pediatric oncology

This thesis focused on two subjects in the field of musculoskeletal imaging: spondylodiscitis and bone tumors in children. Clinical imaging data were analyzed and correlated with patient characteristics, laboratory values, pathological results, and follow-up. We found that in patients with a suspicion of spondylodiscitis on MRI, the culture yield of CT-guided biopsy was rather low: only one out of three biopsies was positive for a certain micro-organism, both for the initial and repeat biopsy. Moreover, more than 95% of patients with suspected spondylodiscitis would have been adequately treated with empiric antibiotics, regardless of the biopsy result (excluding immunocompromised patients). This questions the need for routine CT-guided biopsy in these patients. In children with bone tumors, we found that two MRI findings are helpful in differentiating Ewing sarcoma from osteomyelitis, namely the presence of a soft-tissue mass and a sharp transition zone from pathologic to normal bone. Furthermore, a CT-guided biopsy of a bone lesion in a child with an indeterminate result of pathologic examination virtually always proved to indicate benignancy. Finally, in Ewing sarcoma, tumor volume measurements are subject to some degree of observer variability but this does not affect prognostic stratification, FDG-PET/CT may potentially replace invasive bone marrow biopsy for staging, and surveillance MRI after completion of treatment proved to be futile. These findings can improve the use of imaging and CT-guided biopsy for diagnosis, staging, follow-up and consultation of patients (and their parents) with bone tumors and Ewing sarcoma in particular