Neuroendoscopy and high-field intraoperative MRI: first experience.

Abstract

To date, information about the use of intraoperative MRI (iMRI) in patients undergoing neuroendoscopic procedures is sparse. The benefit may be (re)definition of neuronavigation, confirmation of fenestrations and biopsies, detection of complications, and redefinition of anatomical changes during the operation. Our setting consists of a fully integrated high-field 1.5-T MRI into the operating room. The operating room can be functionally divided into (1) the MRI scanner and (2) the operating table outside the 5 Gauss line where ferromagnetic surgical instruments can be used. We included a consecutive series of 11 adult patients who underwent 11 endoscopic operations in the iMRI setting between January 2007 and September 2011. The median age of patients was 54 years (range: 40-69 years). The male-to-female ratio was 4.5:1. Diagnoses leading to endoscopic treatment were aqueductal stenosis (n = 8; caused by tumors in three cases), pineal cyst (n = 1), tumor of the third ventricle (n = 1), and brain abscess with ventriculitis (n = 1). Endoscopic procedures were endoscopic third ventriculostomy with or without tumor biopsy (n = 5), aqueductoplasty (n = 4), tumor biopsy and septostomy (n = 1), and tumor resection (n = 1). All patients were scanned at least once, seven patients twice during surgery. The mean scan time per procedure was 19 minutes. The following sequences were regarded as most useful: T2 axial (placement of catheter, ruling out of complications), T2 sagittal (flow void signal), and true fast imaging (TRUFI) (fenestration defect). iMRI enables high-resolution imaging immediately after endoscopic operation. The combined use is technically feasible and of potential value in selected cases with complex hydrocephalus. In most of these cases, scanning can be limited to T2 axial, T2 sagittal, and TRUFI MR images.