Can we distinguish conventional osteosarcoma subtypes (osteoblastic and chondroblastic) based on their magnetic resonance signal intensities?

Introduction/Objectives. Osteosarcoma (OS) is the most common primary malignant bone tumor in adolescents and young adults, with a tendency to produce variable amounts of osteoid, cartilage, and fibrous matrices. The objective of this study is to differentiate between osteosarcoma subtypes osteoblastic and chondroblastic according to their magnetic resonance (MR) signal intensities and X-ray findings. Methods. We performed a retrospective analysis for 21 pathologically proven osteosarcoma subtypes: osteoblastic (n = 14) and chondroblastic (n = 7). Conventional images of the bone of origin, periosteal reactions, lytic and sclerotic features, the presence of calcification, and pathological fractures were investigated with X-rays. We measured the mean ROI values for each lesion with MRI sequences. Results. Among the osteosarcoma lesions, 57% were localized at the knee. X-ray evaluations of the osteoblastic osteosarcomas revealed pure lytic lesions in 35.7% and pure sclerotic lesions in 35.7%. Chondroblastic osteosarcomas revealed pure lytic lesions in 14.3% and pure sclerotic lesions in 42.9%. Due to variable osteoblastic, chondroblastic, and fibroblastic areas and proportions of the ossified matrix, osteosarcoma lesions have a heterogeneous MR signal. However, no statistically significant value was detected. Conclusion. According to our results, MRI signal characteristics and X-ray findings may not be able to distinguish osteosarcoma subtypes, so prospective studies with larger patient cohorts are needed.