Dural "tail" associated with meningiomas on Gd-DTPA-enhanced MR images: characteristics, differential diagnostic value, and possible implications for treatment.

Gadolinium-enhanced magnetic resonance (MR) imaging studies of 30 histologically proved cranial meningiomas revealed a linear enhanced structure or "tail" extending away from the tumor mass along the dural surface in 18 cases (60%). Contrast material-enhanced computed tomographic studies available in 10 of these 18 cases did not depict this structure. Characteristic features of this MR finding were reviewed, and criteria were defined to distinguish this tail from other enhanced structures. To assess the differential diagnostic value of this finding, gadolinium diethylenetriaminepentaacetic acid-enhanced MR studies of a control group of other extraaxial lesions as well as superficial intraaxial tumors that abut the meninges were reviewed. These cases failed to show this MR feature. Pathologic correlation was available in three meningiomas with the finding of a tail, and these demonstrated meningothelial tumor nodules in the samples taken from areas corresponding to the enhanced regions on MR images. This is in agreement with other recent pathologic studies of the dura mater surrounding meningiomas. The authors believe that the linear enhanced structure described may represent tissue containing tumoral nodules. Awareness of this MR sign may be useful in distinguishing meningiomas from other lesions and in planning total resection of the infiltrated dura mater.