[Chondrosarcoma of the bone. Differential pre- and postoperative diagnosis using magnetic resonance].

Twelve patients were studied by means of Magnetic Resonance Imaging (MRI) in order to demonstrate either loco-regional recurrence of central chondrosarcomas or degenerative evolutions of exostoses. MRI findings were compared with plain film, scintigraphy, and Computed Tomography. MRI showed loco-regional recurrences by demonstrating their site, extent, and relationship with adjacent structures. In showing the degenerative evolution of exostoses MRI--confirmed at surgery--was superior to plain film in 3 cases out of 7, and to Computed Tomography in 2 cases. The authors discuss MRI findings: chondrosarcomas have low-intensity signal in T1-weighted sequences and high-intensity signal in T2-weighted. Thanks to its high contrast resolution MRI always allowed the detection of the chondrosarcoma. Nevertheless, MRI did not allow the tumor grading--which is due either to a difficult evaluation of the morphology of neoplastic calcifications, or to non-specific-intensity signal.