Magnetic Resonance Imaging Findings And Basic Studies Of The Dural Tail Sign

Background and objective: The dural tail sign is seen on contrast material-enhanced magnetic resonance images (MRI) as a thickening of the enhanced dura mater that resembles a tail extending from a mass. And the dural tails were considered as a highly specific feature of meningiomas for a time. But there is little report about the histo-pathological proof of the typical dural tail sign. It was initially proposed that dural tails resulted from direct tumor invasion, but many later investigators were able to show little or no direct tumor involvement. It was therefore proposed that dural tails represented non-neoplasm reactive changes to the dura mater, including local reactive hyperemia, tissue hyperplasia, vascular hyperplasia, vascular permeability enhancement, dural vascular dilatation and others. Therefore, any course of stimulus to dural could be produce the enhanced dural tail sign. And it could be appeared in other tumors and inflammatory reaction. As far as meningioma is concerned, it is still controversial that the dural tail sign extended from meningioma mass is the result of whether tumor invasion or inflammatory reaction. And whether the dural tail sign should be routine resection in the operation or not is still controversial. For this reason, the study collected 45 cases dural tail extended from meningioma mass by operation and made pathological basic examination, and attempted to probe the significance of the dural tail and provided the helpful value for the clinical operative program selection.Materials and methods: Forty-five cases of meninigiomas with the dural tail sign on MRI were selected in our hospital from October 2003 to September 2004. The patients comprised 15 males and 30 females, ranging in age from 9 to 80 years (mean, 50.9 ± 12.7 years). Duration of symptoms ranged from 1 day to 2 years, with a mean of 6.3 months. The dural tails were resected during the operation and made pathological examination together with the meningioma mass. MRI including pre-and postcontrast T1-weighted imaging using spin-echo (SE) sequences and T2-weighted imaging using fast spin-echo (FSE) sequences was performed in all of the 45 cases. On MRI, the observation targets included: (1) tumor sole or multiple, tumor shapes and tumor envelope characteristics; (2) the signal intensity of the tumor compared to normal gray matter and the signal homogeneity after contrast administration; (3) the signal homogeneity of contrast enhancement in tumor and dural tail; (4) degree of peritumoral edema; (5) characteristic of tumor margin. Pathological examination of meningiomas included: (1) tumor grading and classification; (2) tumor envelope damage and its component. Pathological examination of the dural tail included: (1) whether tumor cells infiltrated in it or not; (2) the component of the dural tail. Whether there was tumor infiltration or not in dural tail was compared with the tumor position, tumor size, degree of benign or malignancy, classification and peritumoral edema.Statistical analysis was executed by SPSS 10.0 software packages. Significant level was set as a=0.05.Results: all Of the 45 cases of tumors 'shapes were similar round or hemi-round. Tumor size ranged from 2.0X1.8X1.8 cm3 to 8.0X8.0X6.3 cm3 in volume.22 tumors diameter ranged from 3.0 cm to 5.0 cm. 38 possessed intact tumor envelopes and 7 tumor envelopes were damaged. 0~ I degree of peritumoral edema were 73.3% (33/45), II degree were 20.0 % (9/45) and III degree were 11.1 % (3/45). According to statistics, there was no significant correlation between tumor position and tumor size with peritumoral edema. But degree of tumor malignancy was strongly associated with peritumoral edema. Meningiomas incidence of male and female were 1:2.Pathological examination performed that, of the 45 cases, 9 cases were meningothelial meningiomas, 12 were mixed type, 9 were fibrous meningiomas, 2 were malignant, 1 was metaplastic meningioma, 1 was secretory meningioma, 1 was Lymphoplasmocyte-rich meningioma,2 were angiomatous meningiomas, 4 were psammomatous meningiomas, 2 were atypical meningiomas, 1 wes clear cell meningioma, and 1 was chordoma meningioma. But pathological examination of dural tail showed that 37 cases were observed tumor cells infiltration (82.2 %) , 5 were not observed tumor cell infiltration and only seen vessel dilation and inflammatory cell infiltration (11.1 %) and 3 were only fibrous hyperplasia (6.7 %). According to statistics, whether tumor cells infiltration or not in the dural ttissue were no significant correlation with tumor position, tumor size, classification of grade I , but significant correlation with degree of malignancy and peritumor edema. There were a lot of tumor cells in dural tail tissue in grade II and III, but only inflammatory cells in grade I .Conclusion: 1. The contrast MRI is the most effective method to find dural tail sign, it should being the routine method for mengingiomas.2. The dural tail sign is the co-effected results of aggressive infiltration and inflammatory reaction; 3. Of the 45 cases, 37 (82.2 %) dural tail tissue were observed infiltrated tumor cells. It explained that the resection of the dural tail sign is important measure for clearing tumor remain and preventing tumor recurrence;4.Whether tumor infiltration in dural tail sign or not is no significant related to tumor position, tumor size and classification of grade I ; 5.Whether tumor infiltration in dural tail sign or not is significant related to the malignant degree of tumor and the degree of peritumor edema.