Musculoskeletal neoplasms: static and dynamic Gd-DTPA--enhanced MR imaging

Static and dynamic magnetic resonance imaging studies were performed in 69 patients with bone and soft-tissue tumors. T1-weighted spin-echo (SE) imaging after intravenous administration of gadolinium diethylenetriaminepentaacetic acid (DTPA) improved the differentiation of necrotic from viable areas; the contrast-to-noise ratio (C/N) between tumor and muscle was an average of 44% lower compared with that in T2-weighted SE imaging. The C/N between tumor and bone marrow or fatty tissue was 43% and 37% lower, respectively, compared with that in nonenhanced T1-weighted SE imaging. Dynamic changes of signal intensity (SI) after Gd-DTPA enhancement were assessed with fast low-angle shot imaging. Of malignant tumors, 84.1% exhibited slopes higher than 30% per minute; 72% of benign tumors showed slopes lower than 30% per minute. The dynamic technique enabled assessment of the malignant potential of a tumor with some overlap (accuracy, 79.7%). Necrotic areas and peritumorous edema showed significantly lower and more gradual increases in SI than adjacent neoplastic tissue.