432PRole of Intraoperative MRI (iMRI) in neurosurgery, potential imaging tool for maximizing gross total resection (GTR) rate of CNS tumours

Abstract Background High field iMRI with integrated neuronavigation system is an advanced diagnostic tool gives information about extent of resection allowing immediate update of neuronavigation parameters after anatomic changes occuring as a result of tumour resection, cerebrospinal fluid evacuation and brain shift. Methods 20 CNS tumour cases underwent Brain suite MRI prior to surgery, then surgery was done after patient registration in navigation system using iMRI. Preoperative tumor volume was manually segmented, compared with intraoperative volume after first resection attempt and final post operative volume after surgical closure to calculate extent of resection (EOR).Descriptive statistics were used to find mean, SD, frequency, percentage of variables. Normally distributed interval data reported as means by two-sample t- test. Non-normally distributed interval/ordinal data reported as median{inter-quartile ranges} and compared among groups by Wilcoxon exact test to obtain EOR values. Results 20 cases allocated to two groups (G), 1st in whom surgery was complete after first iMRI and 2nd who underwent further tumour removal. In G1 surgery was terminated in 11 cases after iMRI, GTR in 81.8% cases. iMRI showed subtotal resection(STR) in 18.2% patients but surgery stopped owing to infiltration of eloquent brain. Median preoperative tumour volume was 40.8cm3. Median postoperative tumour volume was 0.81cm3 with a significant p value ( Conclusions iMRI has potential role in maximizing gross total resection rates of CNS tumours which has an overall great prognostic impact. Legal entity responsible for the study Institutional ethics committee, Max Superspeciality Hospital, New Delhi. Funding Has not received any funding. Disclosure All authors have declared no conflicts of interest.