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The National Neuroscience Institute (NNI) studied whether the use of intraoperative MRI (iMRI) would improve the extent of surgical resections of intracranial pathology in patients which could lead to better patient outcomes.

The surgeries were performed in our BrainSuite operating theatre, which has an intraoperative high field 1.5T maganetom (iMRI) with complete surgical navigation capabilities (Vector Vision, BrainLab). The patients operated on had either gliomas or arteriovenous malformations (AVMs).

30 cases of gliomas and 9 cases of arteriovenous malformations were performed in the BrainSuite over a one year period.


Gliomas: 21 out of 30 cases of gliomas, following what would normally and subjectively be thought to be a complete surgical excision, were found to have unexpected residual tumour identified on a "post-surgical" MRI scan using the intraoperative MRI scan. These patients then had the residual tumours resected in the same sitting leading to complete tumour excision for this group of patients.

AVMs: 2 out of the 9 AVM cases had an unexpected residual nidus detected following what was thought to be complete excisions after "post-surgical" scans in the intraoperative MRI scan. These were then immediately resected.

Overall, 23 out of the 39 cases had benefited from the use of iMRI which had identified incomplete resections and consequently, were saved from having a repeat surgery at a later date. The use of iMRI allowed the neurosurgeon to objectively determine the completeness of surgical excision. If the resection was incomplete, then the surgery was continued. The iMRI did not add to surgical morbidity or mortality, but instead, using updated image guidance from the post-surgical scan, it allowed complete resection to be done safely.

Table: Cases performed in the iMRI operating theatre over a 1-year period

​Intracranial Pathology​Gliomas
​No. of patients​30​9​39
​No. of patients who had immediate further surgery for unexpected residual lesion detected on iMRI​21​2​23
​% of patients who benefited70%​22.2%​59%


The use of Intraoperative Magnetic Resonance Imaging has significantly improved outcome of surgical resection in our neurosurgical practice. It helps the neurosurgeon to objectively determine the completeness of surgical excision during surgery. Any residual lesion can be removed at the same sitting, negating the need for repeat surgery at a later date. More than half of our patients had a direct benefit from the use of this technology which allowed for safe and complete resections of their intracranial pathology.