Functional magnetic resonance imaging in adult craniopagus for presurgical evaluation

2005 ◽  
Vol 103 (5) ◽  
pp. 910-916 ◽  
Author(s):  
Yi-Ching Lynn Ho ◽  
Keith Yu-Ching Goh ◽  
Xavier Golay ◽  
Wee-Tin Hong ◽  
Shih-Hui Lim ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Parietal Lobe ◽  
Inferior Frontal Gyrus ◽  
Preoperative Evaluation ◽  
Blood Oxygen Level Dependent ◽  
Conjoined Twins ◽  
Functional Magnetic Resonance ◽  
Language Mapping ◽  
Imaging Evaluation ◽  
Content Type

✓ Cranially conjoined twins are rare and pose unique challenges in the preoperative evaluation of cerebral language function. The authors report on their experience in the functional magnetic resonance (fMR) imaging evaluation of adult craniopagus (temporoparietooccipital fusion) to evaluate hemispheric language dominance and the eloquent language areas in the preoperative planning stages. Conventional clinical imaging hardware originally designed for individuals was adapted and tailored for use in the twins. They were assigned a selection of language tasks while undergoing fMR imaging. Significant blood oxygen level—dependent activations were detected in the main language regions in each twin, that is, the inferior frontal gyrus (around the Broca area), the middle and superior temporal lobes (around the Wernicke area) together with the inferior parietal lobe, and the middle and superior frontal gyri. Overall, the right-handed twin was strongly left lateralized for language, whereas the left-handed twin showed more bilateral activation during language tasks. Noninvasive language mapping with the aid of fMR imaging has been demonstrated for the first time in total craniopagus.

Discordance between functional magnetic resonance imaging during silent speech tasks and intraoperative speech arrest

2005 ◽  
Vol 103 (2) ◽  
pp. 267-274 ◽  
Author(s):  
Nicole Petrovich ◽  
Andrei I. Holodny ◽  
Viviane Tabar ◽  
Denise D. Correa ◽  
Joy Hirsch ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Inferior Frontal Gyrus ◽  
Hemispheric Dominance ◽  
Cortical Mapping ◽  
Precentral Gyrus ◽  
Functional Magnetic Resonance ◽  
Content Type ◽  
Neurosurgical Planning ◽  
Silent Speech ◽  
Fine Print

Object. The goal of this study was to investigate discordance between the location of speech arrest during awake cortical mapping, a common intraoperative indicator of hemispheric dominance, and silent speech functional magnetic resonance (fMR) imaging maps of frontal language function. Methods. Twenty-one cases were reviewed retrospectively. Images of silent speech fMR imaging activation were coregistered to anatomical MR images obtained for neuronavigation. These were compared with the intraoperative cortical photographs and the behavioral results of electrocorticography during awake craniotomy. An fMR imaging control study of three healthy volunteers was then conducted to characterize the differences between silent and vocalized speech fMR imaging protocols used for neurosurgical planning. Conclusions. Results of fMR imaging showed consistent and predominant activation of the inferior frontal gyrus (IFG) during silent speech tasks. During intraoperative mapping, however, 16 patients arrested in the precentral gyrus (PRG), well posterior to the fMR imaging activity. Of those 16, 14 arrested only in the PRG and not in the IFG as silent speech fMR imaging predicted. The control fMR imaging study showed that vocalized speech fMR imaging shifts the location of the fMR imaging prediction to include the motor strip and may be more appropriate for neurosurgical planning.

Comparative localization of auditory comprehension by using functional magnetic resonance imaging and cortical stimulation

1999 ◽  
Vol 91 (4) ◽  
pp. 626-635 ◽  
Author(s):  
Michael J. Schlosser ◽  
Marie Luby ◽  
Dennis D. Spencer ◽  
Issam A. Awad ◽  
Gregory McCarthy
Keyword(s):  
Magnetic Resonance ◽  
Language Processing ◽  
Cortical Stimulation ◽  
Spatial Extent ◽  
Auditory Comprehension ◽  
Functional Magnetic Resonance ◽  
Language Mapping ◽  
Technical Problems ◽  
Content Type ◽  
Fine Print

Object. The authors previously described a functional magnetic resonance (fMR) imaging task for the localization of auditory comprehension in which focal activation of posterior temporal and inferior frontal regions of the left hemisphere was reliably demonstrated. Because this study was conducted in neurologically normal volunteers, it was not possible to determine whether the activated regions were critical to the performance of language tasks; that is, whether the fMR imaging activations provided a valid measure of language processing. A direct comparison of fMR imaging language activation with cortical stimulation must be completed before it can be used with confidence in presurgical planning, and this comparison is performed in the present study.Methods. The authors report on a series of 33 consecutive patients who underwent dominant hemisphere resection and in whom fMR imaging mapping of auditory comprehension was performed at the Yale neurosurgical program.In 23 of the 33 patients fMR imaging activation was consistent with the typical results obtained in normal participants in the earlier study. In 16 of these 23 patients language mapping was performed using either intra- or extraoperative cortical stimulation. Cortical stimulation failed to localize language areas in two of the 16 patients. Electrical stimulation that was performed in proximity to the fMR image activations interfered with auditory comprehension, object naming, or speech production in 12 of the remaining 14 patients. Five of the 10 cases in which evocation of reliable fMR imaging activation failed were attributable to technical problems and/or patient head movement.Conclusions. Cortical stimulation results and fMR imaging findings were consistent in all but two patients. However, the spatial extent of the activation produced by fMR imaging and the spatial extent of stimulation-induced language disruption that was caused by direct cortical stimulation did not always correspond. Problems in defining the extent of activation by both methods are discussed.

Somatosensory representation in patients who have undergone hemispherectomy: a functional magnetic resonance study imaging

2000 ◽  
Vol 92 (1) ◽  
pp. 45-51 ◽  
Author(s):  
Richard G. Bittar ◽  
Alain Ptito ◽  
David C. Reutens
Keyword(s):  
Magnetic Resonance ◽  
Parietal Lobe ◽  
Sensory Stimulation ◽  
Functional Magnetic Resonance ◽  
Somatosensory Stimulation ◽  
Content Type ◽  
Parietal Lobes ◽  
Cortical Regions ◽  
Fine Print ◽  
Stimulation Of

Object. Removal or disconnection of an entire cerebral hemisphere is occasionally used to treat refractory seizures. Patients who have undergone a hemispherectomy provide useful models to study the reorganization of cortical somatosensory representation. This plasticity may be a consequence of the pathological lesion, the hemispherectomy itself, or both.Methods. Three patients who had undergone hemispherectomy were studied with functional magnetic resonance (fMR) imaging. Responses to sensory stimulation in normal hands and hands opposite the lesioned hemisphere were studied. Multislice T2*-weighted gradient-echo echoplanar images were obtained using a 1.5-tesla MR imager. The activation condition consisted of somatosensory stimulation of the index finger. A T1-weighted anatomical MR image was acquired. The fMR and anatomical MR images were coregistered, and statistically significant activation foci (p < 0.01) were identified. Stimulation of the normal hand produced activation in the primary somatosensory cortex (SI) in all patients. Stimulation of the impaired hand resulted in activation of the ipsilateral parietal operculum (second somatosensory area [SII]) and posterior parietal lobe (Brodmann's Area 7) in all cases, but no activation was elicited in the SI in any patient. In addition, other areas within the ipsilateral frontal and parietal lobes were activated in some individuals.Conclusions. Residual somatosensory function in the hand opposite the lesioned hemisphere is mediated by the SII and other cortical regions in the intact hemisphere, without involvement of the SI.

Investigating the Neural Correlates of the Affect Heuristic Using Functional Magnetic Resonance Imaging

2021 ◽  
pp. 1-14
Author(s):  
Kenny Skagerlund ◽  
Mikael Skagenholt ◽  
Paul J. Hamilton ◽  
Paul Slovic ◽  
Daniel Västfjäll
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Functional Magnetic Resonance Imaging ◽  
Inferior Frontal Gyrus ◽  
Neural Correlates ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Left Inferior Frontal Gyrus ◽  
Affect Heuristic ◽  
Medial Frontal Gyrus

Abstract This study investigated the neural correlates of the so-called “affect heuristic,” which refers to the phenomenon whereby individuals tend to rely on affective states rather than rational deliberation of utility and probabilities during judgments of risk and utility of a given event or scenario. The study sought to explore whether there are shared regional activations during both judgments of relative risk and relative benefit of various scenarios, thus being a potential candidate of the affect heuristic. Using functional magnetic resonance imaging, we developed a novel risk perception task, based on a preexisting behavioral task assessing the affect heuristic. A whole-brain voxel-wise analysis of a sample of participants (n = 42) during the risk and benefit conditions revealed overlapping clusters in the left insula, left inferior frontal gyrus, and left medial frontal gyrus across conditions. Extraction of parameter estimates of these clusters revealed that activity of these regions during both tasks was inversely correlated with a behavioral measure assessing the inclination to use the affect heuristic. More activity in these areas during risk judgments reflect individuals' ability to disregard momentary affective impulses. The insula may be involved in integrating viscero-somatosensory information and forming a representation of the current emotional state of the body, whereas activity in the left inferior frontal gyrus and medial frontal gyrus indicates that executive processes may be involved in inhibiting the impulse of making judgments in favor of deliberate risk evaluations.

Sources of error in comparing functional magnetic resonance imaging and invasive electrophysiological recordings

2000 ◽  
Vol 93 (2) ◽  
pp. 214-223 ◽  
Author(s):  
Derek L. G. Hill ◽  
Andrew D. Castellano Smith ◽  
Andrew Simmons ◽  
Calvin R. Maurer ◽  
Timothy C. S. Cox ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Healthy Volunteers ◽  
Hand Movement ◽  
Epileptogenic Zone ◽  
Imaging Data ◽  
Functional Magnetic Resonance ◽  
Reliable Technique ◽  
Content Type ◽  
The Brain ◽  
Fine Print

Object. Several authors have recently reported studies in which they aim to validate functional magnetic resonance (fMR) imaging against the accepted gold standard of invasive electrophysiological monitoring. The authors have conducted a similar study, and in this paper they identify and quantify two characteristics of these data that can make such a comparison problematic.Methods. Eight patients in whom surgery for epilepsy was performed and five healthy volunteers underwent fMR imaging to localize the part of the sensorimotor cortex responsible for hand movement. In the patient group subdural electrode mats were subsequently implanted to identify eloquent regions of the brain and the epileptogenic zone. The fMR imaging data were processed to correct for motion during the study and then registered with a postimplantation computerized tomography (CT) scan on which the electrodes were visible. The motion during imaging in the two groups studied, and the deformation of the brain between the preoperative images and postoperative scans were measured.The patients who underwent epilepsy surgery moved significantly more during fMR imaging experiments than healthy volunteers performing the same motor task. This motion had a particularly increased out-of-plane component and was significantly more correlated with the stimulus than in the volunteers. This motion was especially increased when the patients were performing a task on the side affected by the lesion. The additional motion is hard to correct and substantially degrades the quality of the resulting fMR images, making it a much less reliable technique for use in these patients than in others. Also, the authors found that after electrode implantation, the brain surface can shift more than 10 mm relative to the skull compared with its preoperative location, substantially degrading the accuracy of the comparison of electrophysiological measurements made in the deformed brain and fMR studies obtained preoperatively.Conclusions. These two findings indicate that studies of this sort are currently of limited use for validating fMR imaging and should be interpreted with care. Additional image analysis research is necessary to solve the problems caused by patients' motion and brain deformation.

Clinical application of functional magnetic resonance imaging in presurgical identification of the central sulcus

1998 ◽  
Vol 88 (5) ◽  
pp. 863-869 ◽  
Author(s):  
Jesús Pujol ◽  
Gerardo Conesa ◽  
Joan Deus ◽  
Luis López-Obarrio ◽  
Fabián Isamat ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Three Dimensional ◽  
Functional Magnetic Resonance ◽  
Central Sulcus ◽  
Clinical Context ◽  
Content Type ◽  
Sensorimotor Region ◽  
Specific Factors ◽  
Eloquent Cortex ◽  
Fine Print

Object. The authors sought to evaluate the advantages and limitations of functional magnetic resonance (fMR) imaging when it was used regularly in the clinical context to identify the central sulcus. Methods. A 1.5-tesla MR system comprising a spoiled gradient recalled acquisition in the steady-state functional sequence and a cross-hand cancellation analysis method were used to evaluate 50 surgical candidates with centrally located space-occupying lesions in the brain. Three-dimensional (3-D) models of the patient's head and brain showing the relative position of the tumor and the eloquent cortex were obtained in each case. A selective and reproducible focal activation was found, indicating the probable central sulcus position in 41 patients (82%). Direct cortical stimulation confirmed the fMR findings in 100% of 22 intraoperatively assessed patients. Failure to identify the central sulcus occurred in 18% of cases and was mainly a consequence of intrinsic damage in the primary sensorimotor region that resulted in severe hand paresis. Conclusions. Although specific factors were identified that contributed to reduced sensitivity of fMR imaging in the clinical context, the present study supports functional assessment and 3-D representation of specific surgical situations as generally feasible in common practice.

Localization of human frontal eye fields: anatomical and functional findings of functional magnetic resonance imaging and intracerebral electrical stimulation

2001 ◽  
Vol 95 (5) ◽  
pp. 804-815 ◽  
Author(s):  
Elie Lobel ◽  
Philippe Kahane ◽  
Ute Leonards ◽  
Marie-Hélène Grosbras ◽  
Stéphane Lehéricy ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Eye Movements ◽  
Magnetic Resonance ◽  
3 Tesla ◽  
Frontal Eye Fields ◽  
Precentral Gyrus ◽  
Functional Magnetic Resonance ◽  
Content Type ◽  
Cortical Areas ◽  
Fine Print

Object. The goal of this study was to investigate the anatomical localization and functional role of human frontal eye fields (FEFs) by comparing findings from two independently conducted studies. Methods. In the first study, 3-tesla functional magnetic resonance (fMR) imaging was performed in 14 healthy volunteers divided into two groups: the first group executed self-paced voluntary saccades in complete darkness and the second group repeated newly learned or familiar sequences of saccades. In the second study, intracerebral electrical stimulation (IES) was performed in 38 patients with epilepsy prior to surgery, and frontal regions where stimulation induced versive eye movements were identified. These studies showed that two distinct oculomotor areas (OMAs) could be individualized in the region classically corresponding to the FEFs. One OMA was consistently located at the intersection of the superior frontal sulcus with the fundus of the superior portion of the precentral sulcus, and was the OMA in which saccadic eye movements could be the most easily elicited by electrical stimulation. The second OMA was located more laterally, close to the surface of the precentral gyrus. The fMR imaging study and the IES study demonstrated anatomical and stereotactic agreement in the identification of these cortical areas. Conclusions. These findings indicate that infracentimetric localization of cortical areas can be achieved by measuring the vascular signal with the aid of 3-tesla fMR imaging and that neuroimaging and electrophysiological recording can be used together to obtain a better understanding of the human cortical functional anatomy.

Discrepant findings for Wada test and functional magnetic resonance imaging with regard to language function: use of electrocortical stimulation mapping to confirm results

2005 ◽  
Vol 102 (1) ◽  
pp. 169-173 ◽  
Author(s):  
Kuan H. Kho ◽  
Frans S. S. Leijten ◽  
Geert-Jan Rutten ◽  
Jan Vermeulen ◽  
Peter van Rijen ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Right Hemisphere ◽  
Test Results ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Wada Test ◽  
Content Type ◽  
Language Functions ◽  
Imaging Results ◽  
The Right

✓ The Wada test is still considered the gold standard for determining the language-dominant hemisphere prior to brain surgery. The authors report on a 34-year-old right-handed woman whose Wada test results indicated that the right hemisphere was dominant for language. In contrast, functional magnetic resonance (fMR) imaging was indicative of bilaterally represented language functions. Activation in the left hemisphere demonstrated on fMR imaging was most pronounced in the Broca area. Importantly, fMR imaging results in this area were confirmed on electrocortical stimulation mapping. These contradictory findings indicated that a right hemispherre dominance for language according to the Wada test should be questioned and verified using electrocortical stimulation. Nonetheless, the question remains whether involvement of these areas in the left frontal hemisphere is critical for language, as these were spared during surgery.

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