DWI在胶质瘤与单发转移瘤及其瘤周水肿中的诊断价值

Diffusion Weighted Imaging of High Grade Gilomas and Solitary Metastases and Peritumoral Edema

目的:探讨DWI在颅内肿瘤及其瘤周水肿中的诊断价值和病理生理机制。材料和方法:分析ADC值在高级别胶质瘤和颅内单发转移瘤的病灶实质及水肿带中的改变(36例)。感兴趣区取病灶实质部分(病灶强化部分)及病灶周围水肿带(将水肿带三等份,分别作为近瘤周区、居中及远瘤周区水肿带),分别测定前述感兴趣区ADC值,测定对侧正常颞叶脑皮质ADC值作为参照值,测定相对ADC值(rADC值)作为分析指标。结果:转移瘤病灶实质及水肿带的ADC值均高于胶质瘤,即在DWI图上前者与后者相比为稍低信号,两者水肿带间ADC值有显著差异。胶质瘤居中水肿带ADC值最低,低于近瘤周区及远瘤周区水肿带,有统计学差异。转移瘤居中水肿带ADC值稍低于近瘤周区及远瘤周区水肿带,但无统计学差异。结论:转移瘤病灶实质及水肿带ADC值均高于胶质瘤。胶质瘤水肿带成因除血管源性水肿之外,尚有部分原因为瘤细胞的浸润所致,肿瘤细胞阻碍了水分子的运动,此点有助于术前在DWI上鉴别两种肿瘤。

To discuss the diagnostic value and the pathophysiolgic principle of diffusion weighted imaging in brain solitary tumor and peritumoral edema. Materials and Methods： A 1.5 T Philips MR scanner was used to perform diffusion imaging and conventional MR sequence on 36 patients who had primary high grade gliomas or solitary metastases. The ROIs were set on the enhancement regions and the peritumoral areas which were cut to three equal parts named as close, middle and far area. The relative ADC value of interest regions was analyzed and the ADC value of normal tempora cortex was set to be reference. Resuits： The ADC value in tumor and peritumoral regions of metastases was significantly higher than that of primary gliomas. So the signal intensity on diffusion weighted image of tumor and peritumoral regions of metastases were slightly lower than that of primary gliomas. The ADC value in the middle peritumoral regions of gliomas were significantly less than that in close and far area. The ADC value in the middle areas of methstases were not significantly less than other area. Conclusion： The ADC value of tumor and peritumoral regions of metastases were significantly higher than that of gliomas because there were some tumor cells in the peritumoral area of gliomas except edema and the tumor cells resisted against the diffusion of water molecule. The characteristic of ADC value can be used to distinguish metastases and primary gliomas before surgery.