磁敏感加权成像对脑肿瘤诊断价值初探

目的探讨磁敏感加权成像（SWI）对脑肿瘤的诊断价值。方法41例脑肿瘤患者行常规横断位（T1WI、T2WI）和横断位SWI检查，其中30例同时行横断位T1WI和SWI增强扫描。观察SWI图像上肿瘤显示、瘤周水肿、肿瘤出血、肿瘤钙化及肿瘤静脉等5个项目，并对所有项目进行评分（0～3），采用析因设计的方差分析及LSD多重检验。结果SWI图像上，脑膜瘤、低级别星形细胞瘤表现为等或稍高信号；复发性脑膜瘤、多数高级别星形细胞瘤及脑转移瘤实性成分表现为稍低信号。脑膜瘤内部新生血管较少，周围静脉呈弧形受压改变；低级别星形细胞瘤肿瘤静脉稀疏、散在分布；复发性脑膜瘤、高级别星形细胞瘤及转移瘤内部静脉血管丰富，瘤周静脉表现各异。相位图上肿瘤钙化以低信号为主，而且钙化灶最外层表现为高信号；出血灶信号与之相反。瘤周水肿表现为高信号。在肿瘤出血、肿瘤钙化及肿瘤静脉显示方面，SWI与T1WI、T2WI评分结果差别具有统计学差异（P〈0．01）；在瘤周水肿显示方面，SWI与T2WI评分结果差别无统计学意义；在肿瘤显示方面，CE-SWI及CE-T1WI与其他序列评分结果的差别有统计学意义（P〈0．01）。结论SWI在显示肿瘤的一般影像特征的基础上突出显示肿瘤静脉、出血代谢物和钙化灶，提供不同于常规MRI序列的肿瘤内部病理信息，相位图像有助于肿瘤出血与钙化的鉴别。

Initial study of susceptibility weighted imaging in brain masses

Objective： To evaluate the value of susceptibility weighted imaging （SWI） in the diagnosis of brain masses. Materials and Methods： Forty-one patients with brain neoplasms underwent conventional MR T1WI, T2WI and SWI scanning. Thirty of them received both contrast enhanced T1WI and SWI （CE-T1WI and CE-SWI）. Tumor visibility, edema, blood products, calcium, and vessels were observed respectively on SWI, the images of all sequences were scored from 0 to 3, according to their ability of depicting the observation projects above. Statistical analysis was conducted to compare the scores among these sequences. Results： Meningiomas and low-grade astrocytomas showed equisignal or mild hypersignal intensity; all recurrent meningiomas, high-grade astrocytomas and metastases in major displayed as mild low signal intensity. Venous vasculature both inside meningiomas and low-grade astrocytomas were relatively poorer than the recurrent ones, high-grade astrocytomas and metastases; perivenous showed arc compressed by the tumor in meningiomas, while displayed variously in other tumors. Calcium within the tumor appeared mainly in hypointense signal intensity surrounded by hyperintense signal ring on phase image, while blood product appeared conversely. Peri-edema displayed as high signal intensity. There was statistical difference of scores between SWI and conventional T1WI, T2WI in displaying blood products, calcium, and venous vasculature （P〈0.01）. There was no significant difference of scores between SWI and T2WI in displaying edema. Significant difference between the scores in detection of tumor visibility was found on the contrast enhanced sequences and non-contrast enhanced sequences （P〈0.01）. Conclusion： SWI sequence not only shows the general imaging features of brain masses but also detects venous vasculature, blood product and calcium within the tumor with superlative contrast. Different from conventional sequences, SWI shows unique details about internal architecture which is determined primarily by blood products. Phase image of SWI is helpful in differentiating blood product and calcium within the tumor.