Objective: To investigate the value of susceptibility weighted imaging (SWI) in evaluating the histopathologic grade of cerebral astrocytomas and compare the relative value of SWI and conventional magnetic resonance imaging (MRI) sequences.
Materials and methods: This is an analysis of 26 untreated patients with pathologically confirmed astrocytomas. The tumors were classified as low grade (grade I-II: 12 cases) or high grade (grade III-IV: 14 cases). Imaging was performed with a 3.0 T MRI scanner. Conventional sequences [T1-weighted imaging (T1WI), contrast enhanced T1WI (CE-T1WI), T2-weighted imaging (T2WI), and T2 FLuid Attenuated Inversion Recovery (T2FLAIR)] and SWI sequence (including CE-SWI) were done. The number of small vessels and the amount of blood products in the tumors were determined for each sequence. Differences between the two groups were analyzed statistically.
Results: SWI was more sensitive than conventional sequences (T1WI, CE-T1WI, T2WI, and T2FLAIR) in visualizing small vessels and microhemorrhages in cerebral astrocytomas (P < 0.01). CE-SWI was better than CE-T1WI sequences for visualizing tumor small vessels and microhemorrhages. SWI visualized greater numbers of small vessels and areas of microhemorrhages in high-grade tumors than in low-grade tumors (P < 0.01). This was especially true after contrast administration (P < 0.01).
Conclusion: SWI plays an important role in astrocytoma grading, especially for enhanced astrocytomas after contrast injection. CE-SWI was better than CE-T1WI in visualizing tumor architecture.