gms | German Medical Science

Objective: According to the recent literature extensive surgical resection may significantly increase the overall survival in patients with low-grade gliomas (LGGs). Unfortunately, such lesions are often macroscopically difficult to differentiate from normal tissue. Intraoperative magnetic resonance imaging (iopMRI) can be an important support to achieve radical resection with preservation of functionally relevant brain tissue. We present our experience in LGG surgery using iopMRI evaluating the importance of this device to improve the extent of resection (EoR).

Method: We retrospectively reviewed our iopMRI (Siemens 1.5T) surgical database from February 2007 to October 2013. During this period 920 surgical procedures were performed with a histo-pathological diagnosis of LGG in 124 cases. Following functional MR-based brain mapping in every patient, a resection target that would not compromise the neurological function was defined. We analyzed the EoR achieved after each iopMRI control and compared these data with the preoperatively planned grade of resection.

Results: Preoperative MR-based brain mapping suggested that total resection was functionally possible in only 60 patients (53%). Within this group we found that after the first iopMRI – a stage at which the surgeons believed that the tumor was totally removed – an MR-based truly complete tumor removal was documented in only 30 patients (50%). The aim of total tumor resection was eventually achieved in all patients (100%) following one to five MRI controls. Within the group of patients with tailored incomplete resections the preoperative plan could be achieved in all cases (100%) following one to four MRI controls. Overall neurological outcome 3 months following surgery: in 91.2% of the cases the postoperative neurological status was unchanged or improved, in 7.9% there was a postoperative transient worsening of the neurological functions and in 1 patient the deficit was permanent.

Conclusions: These results suggest that intraoperative MRI is a valuable tool to increase the EoR in low-grade gliomas. It allows a precise detection of residual tumor and provides a spatial orientation in relation to functionally relevant structures. Thus intraoperative MRI increases efficacy and potentially the safety in low-grade glioma surgery.