Localization of somatosensory function by using positron emission tomography scanning: a comparison with intraoperative cortical stimulation

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>To investigate the utility of [<jats:sup>15</jats:sup>O]H<jats:sub>2</jats:sub>O positron emission tomography (PET) activation studies in the presurgical mapping of primary somatosensory cortex, the authors compared the magnitude and location of activation foci obtained using PET scanning with the results of intraoperative cortical stimulation (ICS).</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>The authors used PET scanning and vibrotactile stimulation (of the face, hand, or foot) to localize the primary somatosensory cortex before surgical resection of mass lesions or epileptogenic foci affecting the central area in 20 patients. With the aid of image-guided surgical systems, the locations of significant activation foci on PET scanning were compared with those of positive ICS performed at craniotomy after the patient had received a local anesthetic agent. In addition, the relationship between the magnitude and statistical significance of blood flow changes and the presence of positive ICS was examined.</jats:p> <jats:p>In 22 (95.6%) of 23 statistically significant (p &lt; 0.05) PET activation foci, spatially concordant sites on ICS were also observed. Intraoperative cortical stimulation was positive in 40% of the PET activation studies that did not result in statistically significant activation. In the patients showing these results, there was a clearly identifiable t-statistic peak that was spatially concordant with the site of positive ICS in the sensorimotor area. All PET activation foci with a t statistic greater than 4.75 were associated with spatially concordant sites of positive ICS. All PET activation foci with a t statistic less than 3.2 were associated with negative ICS.</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Positron emission tomography is an accurate method for mapping the primary somatosensory cortex before surgery. The need for ICS, which requires local anesthesia, may be eliminated when PET foci with high (&gt; 4.75) or low (&lt; 3.20) t-statistic peaks are elicited by vibrotactile stimulation.</jats:p></jats:sec>

Cortical motor and somatosensory representation: effect of cerebral lesions

“…Such a threshold has been previously shown to be biologically significant by correlation with intraoperative cortical stimulation. 2 The peaks were statistically significant (p Ͻ 0.05). Peaks with t-statistic values less than 4.75 may represent regions of increased focal blood flow and neural activity, and we may, therefore, have underestimated the number of cortical areas activated in all groups.…”

A practical procedure for real-time functional mapping of eloquent cortex using electrocorticographic signals in humans

“…Surgical planning of the resection procedure depends substantially on the delineation of abnormal tissue, e.g., epileptic foci or tumor tissue, and on the creation of functional map of eloquent cortex in the area close to that abnormal tissue. Traditionally, different methodologies have been used to produce this functional map: electrical cortical stimulation (ECS) [1, 2, 3], functional magnetic resonance imaging (fMRI) [4], positron emission tomography (PET) [5, 6], magnetoencephalography (MEG) [7], or evoked potentials (EP) [8]. Each of these methods has problems that include morbidity, time consumption, expense, or practicality.…”

Three-dimensional integration of brain anatomy and function to facilitate intraoperative navigation around the sensorimotor strip

“…Transcranial magnetic stimulation (TMS) can locate motor cortex in healthy subjects with 5-22 mm accuracy [Wasserman et al, 1996]; however, we are not aware of TMS's accuracy in neurosurgical patients. About 30% of PET studies fail to produce statistically significant activation by vibrotactile stimulation in the contralateral central region [Bittar et al, 1999]. About 30% of PET studies fail to produce statistically significant activation by vibrotactile stimulation in the contralateral central region [Bittar et al, 1999].…”