OBJECTIVE: While diffusion-weighted magnetic resonance imaging (MRI) has been used to study malignant brain tumours, this modality has not been used to study MRI abnormalities surrounding meningiomas. METHODS: We examined intensity and apparent diffusion coefficient (ADC) on diffusion weighted imaging (DWI) for predicting postoperative persistence of MRI abnormalities surrounding meningiomas as well as characterizing the tumours. RESULTS: Of 36 meningiomas who underwent gross total resection, 27 (75%) showed hyperintensity on DWI at b=1100s/mm2. No atypical meningiomas were hypointense on DWI. Of the 26 supratentorial meningiomas, 18 (69.0%) had associated MRI abnormality. No significant correlation was seen between tumour intensity on DWI and existence of surrounding MRI abnormality. Meningothelial meningiomas showed a relatively low prevalence of MRI abnormalities surrounding tumour (30%). Of 11 patients who underwent sequential MRI, all MRI abnormalities surrounding tumour showing isointensity and high ADC on preoperative DWI disappeared after surgery (from 3 weeks to 10 months). All MRI abnormalities surrounding tumour showing hyperintensity and low ADC on preoperative DWI persisted on final follow-up MRI (from 6 months to 20 months). CONCLUSION: The postoperative course of MRI abnormality surrounding tumour might be predictable from the intensity and ADC on preoperative DWI. Since MRI abnormalities associated with meningiomas can cause preoperative neurologic deficits. We hypothesise that abnormalities with restricted diffusion will be more likely to be associated with a preoperative deficit, and more likely to remain after removal of the causative meningioma.
OBJECTIVE: While diffusion-weighted magnetic resonance imaging (MRI) has been used to study malignant brain tumours, this modality has not been used to study MRI abnormalities surrounding meningiomas. METHODS: We examined intensity and apparent diffusion coefficient (ADC) on diffusion weighted imaging (DWI) for predicting postoperative persistence of MRI abnormalities surrounding meningiomas as well as characterizing the tumours. RESULTS: Of 36 meningiomas who underwent gross total resection, 27 (75%) showed hyperintensity on DWI at b=1100s/mm2. No atypical meningiomas were hypointense on DWI. Of the 26 supratentorial meningiomas, 18 (69.0%) had associated MRI abnormality. No significant correlation was seen between tumour intensity on DWI and existence of surrounding MRI abnormality. Meningothelial meningiomas showed a relatively low prevalence of MRI abnormalities surrounding tumour (30%). Of 11 patients who underwent sequential MRI, all MRI abnormalities surrounding tumour showing isointensity and high ADC on preoperative DWI disappeared after surgery (from 3 weeks to 10 months). All MRI abnormalities surrounding tumour showing hyperintensity and low ADC on preoperative DWI persisted on final follow-up MRI (from 6 months to 20 months). CONCLUSION: The postoperative course of MRI abnormality surrounding tumour might be predictable from the intensity and ADC on preoperative DWI. Since MRI abnormalities associated with meningiomas can cause preoperative neurologic deficits. We hypothesise that abnormalities with restricted diffusion will be more likely to be associated with a preoperative deficit, and more likely to remain after removal of the causative meningioma.