Protecting venous structures during radiosurgery for parasagittal meningiomas

Symptomatic edema is a potential complication of meningioma radiosurgery. Parasagittal meningiomas are at aparticular risk for symptomatic edema, suggesting a role for a venous occlusive complication. The authors sought todevelop a strategy to optimize CyberKnife stereotactic radiosurgical treatment parameters to reduce the irradiationof the peritumoral venous system. Multislice CT venography with 3D reconstructions was performed and coregisteredwith thin-section, contrast-enhanced, volumetric MR images. The tumor and critical volumes were contouredon the MR images. Venous anatomical details obtained from the CT venographic study were then exported ontothe MR imaging and fused MR imaging-CT study. Target and critical structure volumes and dosimetric parametersobtained with this method were analyzed. The authors found that reducing the irradiation of veins that course alongthe surface of the meningioma, which may be at risk for radiation-induced occlusion, is feasible in parasagittalmeningioma radiosurgery without compromising other treatment parameters including conformality, homogeneity,and target coverage. Long-term follow-up is needed to assess the clinical validity of this treatment strategy.