Preoperative Evaluation with fMRI of Patients with Intracranial Gliomas

Abstract

Introduction. Aggressive surgical resection constitutes the optimal treatment for intracranial gliomas. However, the proximity of a tumor to eloquent areas requires exact knowledge of its anatomic relationships to functional cortex. The purpose of our study was to evaluate fMRI's accuracy by comparing it to intraoperative cortical stimulation (DCS) mapping. Material and Methods. Eighty-seven patients, with presumed glioma diagnosis, underwent preoperative fMRI and intraoperative DCS for cortical mapping during tumor resection. Findings of fMRI and DCS were considered concordant if the identified cortical centers were less than 5 mm apart. Pre and postoperative Karnofsky Performance Scale and Spitzer scores were recorded. A postoperative MRI was obtained for assessing the extent of resection. Results. The areas of interest were identified by fMRI and DCS in all participants. The concordance between fMRI and DCS was 91.9% regarding sensory-motor cortex, 100% for visual cortex, and 85.4% for language. Data analysis showed that patients with better functional condition demonstrated higher concordance rates, while there also was a weak association between tumor grade and concordance rate. The mean extent of tumor resection was 96.7%. Conclusions. Functional MRI is a highly accurate preoperative methodology for sensory-motor mapping. However, in language mapping, DCS remains necessary for accurate localization.

Visual Mapping Using Blood Oxygen Level Dependent Functional Magnetic Resonance Imaging

“…Nevertheless, fMRI has been widely implemented for presurgical mapping of both sensorimotor and language areas. Studies comparing fMRI and ICS maps in visual cortex have also reported good correspondence 27,28 . Yet for a variety of reasons, fMRI vision mapping has not been used as widely in the clinic despite its potential utility (see DeYoe et al, 2011 21 ).…”

Combining task-evoked and spontaneous activity to improve pre-operative brain mapping with fMRI

“…However the correspondence between the two techniques is often reported qualitatively and finding metrics to address this quantitatively has been challenging (Vlieger et al, 2004). One approach is to measure the distance between the center of fMRI and ECS localizations (Kapsalakis et al, 2012), however the extent is likely as important as the center when the goal is to avoid postoperative deficits. Other studies have reported the number of ECS points that fall within the activated area of fMRI, however this is critically dependent on the threshold used to differentiate “activated” from “non-activated” voxels and the spatial locations of ECS-negative points are often not recorded (Vlieger et al, 2004).…”

“…Now that our technique is validated with motor mapping, there is good motivation to begin testing it for language and memory. Pre-operative fMRI mapping of these functions tends to be less robust than motor mapping and thus there is greater need for improvement (Hirsch et al, 2000; Kapsalakis et al, 2012; Mehta and Klein, 2010). Further, there is good reason to think our algorithm will prove useful in these other domains.…”

Role of the Wada test and functional magnetic resonance imaging in preoperative mapping of language and memory: two atypical cases

“…They may not be fully reliable and they need future refinement for improved accuracy. While fMRI is helpful in surgical planning (Kapsalakis et al, 2012) and it may predict outcome on a group level after anterior temporal lobectomy, we do not know the optimal set of fMRI memory paradigms, in particular, for cases in who there may be atypical memory dominance or in who there may be a dissociation between memory and language. Thus, Wada test is still necessary to identify rare cases with atypical dominance of cognitive functions.…”