Predicting the probability of meningioma recurrence based on the quantity of peritumoral brain edema on computerized tomography scanning

Object. The goal of this study was to determine whether the quantity of per itumoral brain edema displayed on computerized tomography (CT) scanning cou ld be correlated with brain invasion and subsequent recurrence of meningiom as. Methods. One hundred thirty-five patients who underwent resection of intrac ranial meningiomas at the Ottawa Civic Hospital were followed during the pe riod 1980 to 1998. A complete resection was defined as one in which tumor, invaded bone, and involved dura were removed. Tumors were examined microsco pically for evidence of brain invasion. The mean follow-up period was 9 +/- 4 years (standard deviation [SD]) and the mean time to recurrence was 5 +/ - 4 years (SD). The authors used a simple grading system based on the avera ge thickness tin centimeters) of edema seen on an axial CT slice showing th e most tumor. Edema grade was linearly related to edema volume determined by digitizing t he scans (r = 0.96; 29 cases). The chance of brain invasion increased by 20 % for each centimeter of edema (r(s) = 1, p < 0.0001; 124 cases). The prese nce of brain invasion was predictive of recurrence after complete resection with an accuracy of 83%, a sensitivity of 89%, and a specificity of 82%. T he chance of recurrence within 10 years after complete resection was given by the equation: percentage chance of recurrence = (centimeter of edema)(3) x 0.7, which can be used to predict the chance of recurrence based on find ings on CT scans (r(s) = 1, p < 0.0001; 86 patients). Statistical significa nce was confirmed using Kaplan-Meier and univariate and multivariate analys es. Completeness of resection was the most powerful predictor of recurrence (p < 0.00001, r = 0.6), followed by edema grade and brain invasion (both p = 0.02, r = 0.1). Patient age and gender and tumor location, size, and his tological subtype were nonsignificant factors. Conclusions. Brain invasion causes peritumoral edema. Invaded brain tissue is also the source of residual cells in cases of tumor recurrence after gro ss-total resection.