MR imaging of musculoskeletal sarcomas: the clinical significance of peritumoral low signal intensity lines in planning surgical margins

Abstract

The authors studied 33 musculoskeletal sarcomas, comparing preoperative MRIs with postoperative pathological evaluations based on JOA criteria. Fifty-one sites were investigated to determine the clinical significance of a low signal intensity line (LSL) on the outer margin of the tumor image. LSLs at different sites were counted as individual cases, since they sometimes showed different characteristics at different sites. An LSL showing a consistent width and no change on either of two time-weighted images (T1-W or T2-W) was evaluated as a strong LSL, and was thought to represent a barrier preventing tumor penetration. In cases showing a strong LSL, resection beyond the line can provide a safety margin, even if defind as a marginal procedure according to the JOA criteria. In cases showing only a faint LSL, a high rate of tumor cell presence was observed external to the line; in such cases the surgical plan must be focused on the attainment of a curative margin.