MUSCULOSKELETAL NEOPLASM - PERINEOPLASTIC EDEMA VERSUS TUMOR ON DYNAMIC POSTCONTRAST MR-IMAGES WITH SPATIAL-MAPPING OF INSTANTANEOUS ENHANCEMENT RATES

PURPOSE: To evaluate the utility of fast, contrast-enhanced, sequentia l magnetic resonance (MR) imaging in differentiating between extraosse ous tumor and perineoplastic edema. MATERIALS AND METHODS: Fourteen pa tients underwent sequential MR imaging (3.5 seconds per image) after b olus administration of gadopentetate dimeglumine. Initial rates of enh ancement (initial slope) were calculated on a pixel-by-pixel basis and displayed as a ''slope image'' in which pixel intensity reflected the slope value. Close correlation with wedge biopsy specimens was perfor med. RESULTS: Mean initial slope values were viable extraosseous tumor , 9.33 (standard deviation, 2.23); infiltrated muscle, 9.07 (2.31); ed ematous muscle without tumor infiltration, 5.48 (1.27); normal muscle, 1.11 (0.65). Differences in initial slope between all neoplastic and nonneoplastic tissues were statistically significant Within individual patients, initial slope of edematous muscle was always 20% or more lo wer than that of neoplastic tissue. Slope images highlighted areas of viable extraosseous tumor and infiltrated muscle against edematous and normal tissues. CONCLUSION: Computer-generated slope images derived f rom sequential postcontrast MR images allow differentiation between tu mor and nonneoplastic edema and may thereby guide the surgeon in plann ing limb-sparing procedures.