Transcript Primary Motor Cortex

The expected and unexpected:
Initial experiences in a de novo fMRI program
Tannenbaum AD, Sakai O, Jara H, Barest G, Norbash AM, Mian AZ
Department of Radiology
Boston University School of Medicine
Boston Medical Center
Boston, MA
Introduction
Basic Principles
Normal Anatomy
Paradigms
Unusual Patterns
Discussion
Functional
magnetic resonance imaging (fMRI) of the
_
brain allows for identification of eloquent areas for
preoperative planning and for various psychiatric and
neurological disorders.
-Predominantly used for preoperative planning
-Localization is achieved using various paradigms designed to
stimulate specific areas such as motor, speech, and sensory
regions
-Precise preoperative localization enables maximal resection and
may also help predict postoperative deficits
-High concordance rates with Wada testing and intraoperative
cortical stimulation
-Has been shown to alter surgical management
-Data is generated using paradigms and BOLD imaging
Mahvash, M., Maslehaty, H., Jansen, O., Mehdorn, H. M., & Petridis, A. K. (2014). Functional magnetic resonance imaging of motor and language for preoperative planning of neurosurgical procedures adjacent to functional areas. Clinical Neurology and Neurosurgery, 123, 72–
77. doi:10.1016/j.clineuro.2014.05.011
Medina, L. S., Aguirre, E., Bernal, B., & Altman, N. R. (2004). Functional MR imaging versus Wada test for evaluation of language lateralization: cost analysis. Radiology, 230(1), 49–54. doi:10.1148/radiol.2301021122
Petrella, J. R., Shah, L. M., Harris, K. M., Friedman, A. H., George, T. M., Sampson, J. H., et al. (2006). Preoperative functional MR imaging localization of language and motor areas: effect on therapeutic decision making in patients with potentially resectable brain
tumors. Radiology, 240(3), 793–802. doi:10.1148/radiol.2403051153
Introduction
Basic Principles Normal Anatomy
BOLD Hardware/Software
Paradigms
Unusual Patterns
Discussion
_Blood Oxygen Level-dependent Imaging (BOLD)
Basic Principles of BOLD
-Originally discovered in 1990 by Ogawa et al
-Deoxyhemoglobin (deoxyHb) acts as an endogenous
paramagnetic contrast agent for BOLD
-Images are acquired using echoplanar imaging
-Cortical activation leads to a drop in oxyHB and increase in
CO2 with a compensatory increase in blood flow, leading to
higher oxyHb and dilution of deoxyHb
-BOLD relies on the gradient of oxyHb:deoxyHb to generate
functional data
Kim, S.-G., & Ogawa, S. (2012). Biophysical and physiological origins of blood oxygenation level-dependent fMRI signals. Journal of Cerebral Blood Flow and Metabolism : Official Journal of the International Society of Cerebral Blood Flow and Metabolism, 32(7), 1188–1206.
doi:10.1038/jcbfm.2012.23
Introduction
_
Basic Principles Normal Anatomy
BOLD Hardware/Software
fMRI Paradigm
Paradigms
Unusual Patterns
Discussion
Stimulus
Short
Long T2*:
T2*:
deoxygenated
oxygenated
MRI Pulse Sequence
Stimulus-dependent
MRI signal change
Neurovascular
Coupling
Hemodynamic
Response
Main BOLD response
T2* 
T2* 
Fig.1: Schematic showing the time course of BOLD response to a
short stimulus. The fast response has a negative peak at about
two seconds poststimulus due to brief decrease in blood
oxygenation after neural activity. The main BOLD response peaks
at about five seconds with FWHM(full width at half maximum) of
about four seconds. The signal takes about a minute to return to
baseline.
Introduction
Basic Principles Normal Anatomy
BOLD Hardware/Software
_Schematic of BOLD
Paradigms
Unusual Patterns
Discussion
Increased oxyHb
signal generation
Increased blood flow
Cortical
Stimulation
Increased Neuronal
Activity
Decreased
deoxyHb
concentration
Increased O2
Extraction
Increased deoxyHb
fMRI
signal
deoxyHb has a
paramagnetic effect;
Increased blood flow is
sufficient to dilute
deoxyHb concentration
Introduction
Basic Principles Normal Anatomy
BOLD Hardware/Software
Paradigms
Unusual Patterns
Discussion
Blood Oxygen Level-dependent Imaging (BOLD)
Resting state schematic illustrating the paramagnetic effect of deoxyHb
HbO2
Hb
HbO2
HbO2
Hb
Hb
Distorted
field lines
Activated state with increase in oxyHb. Measurement of the gradient between oxyHb and
deoxyHb will yield BOLD signal.
HbO2
HbO2
HbO2
Adapted from Daniel Marcus PhD., “Brain Imaging for fun and Profit”
HbO2
HbO2
Hb
Introduction
Basic Principles Normal Anatomy
BOLD Hardware/Software
Paradigms
Unusual Patterns
Discussion
_Blood Oxygen Level-dependent Imaging (BOLD)
Limitations of BOLD
-Relies on T2* imaging which is sensitive to magnetic field
inhomogeneity
-Very sensitive to patient motion
-An indirect measurement of cortical neuronal activity.
Data reflects changes in blood flow rather than direct
neuronal activity
Kim, S.-G., & Ogawa, S. (2012). Biophysical and physiological origins of blood oxygenation level-dependent fMRI signals. Journal of Cerebral Blood Flow and Metabolism : Official Journal of the International Society of Cerebral Blood Flow and Metabolism, 32(7), 1188–1206.
doi:10.1038/jcbfm.2012.23
Introduction
Basic Principles Normal Anatomy
BOLD Hardware/Software
Paradigms
Unusual Patterns
Discussion
At our institution we employ the following system
-GE Discovery 750W 3 Tesla MRI
-Sensavue fMRI by Invivo Corp.
-Images processed in DynaSuite by Invivo Corp.
Typical fMRI Acquisition Parameters
-TR = 2000 ms
-Number of volumes 120
-Control 10 repetitions
-Stimulus 10 repetitions
Each volume takes 2 seconds to acquire and the first 4 volumes
are discarded. Total scan time is 4 min 8 sec for each of our
paradigms.
Introduction
Basic Principles Normal Anatomy
BOLD Hardware/Software
Paradigms
Unusual Patterns
Discussion
Acquisition Parameters, continued
FSPGR BRAVO (IR-prep fast SPGR) image for anatomic localization
Images are obtained using a 256 x 256 matrix with 1.2 mm slice
thickness. 1 slab is obtained with 16 locs per slab.
TE = 3.3, TR = 8.5, NEX = 1, Flip Angle = 12
Diffusion Tensor Imaging (DTI) 4mm
Images are obtained using a 129 (freq.) x 128 (phase) matrix with 5
mm slice thickness with 1 mm spacing. 29 slices are obtained.
TEmin = 98.6, TR = 8000, NEX = 1, B = 1000
Introduction
Basic Principles
Normal Anatomy Paradigms
Language Motor
Unusual Patterns
Discussion
_I Broca’s Area
Classically located in the left
frontal lobe, refers to the pars
triangularis(red) and the pars
opercularis(blue) of the inferior
frontal gyrus
Wernicke’s Area
Classically located in the
posterior portion of the left
superior temporal gyrus
Arcuate Fasciculus
A segment of the superior
longitudinal fasciculus that
connects Wernicke’s and
Broca’s
Image source: https://en.wikipedia.org/wiki/Broca%27s_area#mediaviewer/File:Broca%27s_area_-_lateral_view.png.
Licensed under CC-BY-SA-2.1-jp
Introduction
Basic Principles
Normal Anatomy Paradigms
Language Motor
_I Broca’s Area
Classically located in the left
frontal lobe, refers to the pars
triangularis and the pars
opercularis of the inferior
frontal gyrus
Wernicke’s Area
Classically located in the
posterior portion of the left
superior temporal gyrus
Arcuate Fasciculus
A segment of the superior
longitudinal fasciculus that
connects Wernicke’s and
Broca’s
Unusual Patterns
Discussion
Introduction
Basic Principles
Normal Anatomy Paradigms
Language Motor
Unusual Patterns
Discussion
_I Broca’s Area
Classically located in the left
frontal lobe, refers to the pars
triangularis(red) and the pars
opercularis(blue) of the inferior
frontal gyrus
Wernicke’s Area
Classically located in the
posterior portion of the left
superior temporal gyrus
Arcuate Fasciculus
A segment of the superior
longitudinal fasciculus that
connects Wernicke’s and
Broca’s
Modified from: https://en.wikipedia.org/wiki/Broca%27s_area#mediaviewer/File:Broca%27s_area__lateral_view.png. Licensed under CC-BY-SA-2.1-jp
Introduction
Basic Principles
Normal Anatomy Paradigms
Language Motor
Unusual Patterns
Discussion
_I Broca’s Area
Classically located in the left
frontal lobe, refers to the pars
triangularis and the pars
opercularis of the inferior
frontal gyrus
Wernicke’s Area
Classically located in the
posterior portion of the left
superior temporal gyrus
Arcuate Fasciculus
A segment of the superior
longitudinal fasciculus that
connects Wernicke’s and
Broca’s
Receptive
language
center In
this
healthy
volunteer
did not
localize to
the classic
location
Introduction
Basic Principles
Normal Anatomy Paradigms
Language Motor
Unusual Patterns
Discussion
_I Broca’s Area
Classically located in the left
frontal lobe, refers to the pars
triangularis(red) and the pars
opercularis(blue) of the inferior
frontal gyrus
Wernicke’s Area
Classically located in the
posterior portion of the left
superior temporal gyrus
Arcuate Fasciculus
A segment of the superior
longitudinal fasciculus that
connects Wernicke’s and
Broca’s
Modified from: https://en.wikipedia.org/wiki/Broca%27s_area#mediaviewer/File:Broca%27s_area__lateral_view.png. Licensed under CC-BY-SA-2.1-jp
Introduction
Basic Principles
Normal Anatomy Paradigms
Language Motor
_I Broca’s Area
Classically located in the left
frontal lobe, refers to the pars
triangularis(red) and the pars
opercularis(blue) of the inferior
frontal gyrus
Wernicke’s Area
Classically located in the
posterior portion of the left
superior temporal gyrus
Arcuate Fasciculus
A segment of the superior
longitudinal fasciculus that
connects Wernicke’s and
Broca’s
Unusual Patterns
Discussion
Introduction
Basic Principles
Normal Anatomy Paradigms
Language Motor
Unusual Patterns
Discussion
_I Primary Motor Cortex
Classically located in the dorsal
aspect of the precentral gyrus of
the frontal lobe. Primary
coordinator of movement.
Premotor Cortex
Located just anterior to the primary
motor cortex. Function uncertain,
may play a role in planning.
Supplementary Motor Area
Located at the medial surface of
the hemispheres just anterior to
the primary motor cortex.
Contributes to control of
movement.
Image source: http://www.neuroscientificallychallenged.com/glossary/primary-motor-cortex
Introduction
Basic Principles
Normal Anatomy Paradigms
Language Motor
_I Primary Motor Cortex
Classically located in the dorsal
aspect of the precentral gyrus of
the frontal lobe. Primary
coordinator of movement.
Premotor Cortex
Located just anterior to the primary
motor cortex. Function uncertain,
may play a role in planning.
Supplementary Motor Area
Located at the medial surface of
the hemispheres just anterior to
the primary motor cortex.
Contributes to control of
movement.
Unusual Patterns
Discussion
Introduction
Basic Principles
Normal Anatomy Paradigms
Language Motor
Unusual Patterns
Discussion
_I Primary Motor Cortex
Classically located in the dorsal
aspect of the precentral gyrus of
the frontal lobe. Primary
coordinator of movement.
Premotor Cortex
Located just anterior to the primary
motor cortex. Function uncertain,
may play a role in planning.
Supplementary Motor Area
Located at the medial surface of
the hemispheres just anterior to
the primary motor cortex.
Contributes to control of
movement.
Image modified from: http://www.neuroscientificallychallenged.com/glossary/premotor-cortex/
Introduction
Basic Principles
Normal Anatomy Paradigms
Language Motor
Unusual Patterns
Discussion
_I Primary Motor Cortex
Classically located in the dorsal
aspect of the precentral gyrus of
the frontal lobe. Primary
coordinator of movement.
Premotor Cortex
Located just anterior to the primary
motor cortex. Function uncertain,
may play a role in planning.
Supplementary Motor Area
Located at the medial surface of
the hemispheres just anterior to
the primary motor cortex.
Contributes to control of
movement.
Approximate location of premotor
cortex highlighted in red
Introduction
Basic Principles
Normal Anatomy Paradigms
Language Motor
Unusual Patterns
Discussion
_I Primary Motor Cortex
Classically located in the dorsal
aspect of the precentral gyrus of
the frontal lobe. Primary
coordinator of movement.
Supplementary
motor area
Primary motor
cortex
Premotor Cortex
Located just anterior to the primary
motor cortex. Function uncertain,
may play a role in planning.
Supplementary Motor Area
Located at the medial surface of
the hemispheres just anterior to
the primary motor cortex.
Contributes to control of
movement.
Image modified from: http://www.arts.uwaterloo.ca/~bfleming/psych261/lec16no9.htm
Introduction
Basic Principles
Normal Anatomy Paradigms
Language Motor
_I Primary Motor Cortex
Classically located in the dorsal
aspect of the precentral gyrus of
the frontal lobe. Primary
coordinator of movement.
Premotor Cortex
Located just anterior to the primary
motor cortex. Function uncertain,
may play a role in planning.
Supplementary Motor Area
Located at the medial surface of
the hemispheres just anterior to
the primary motor cortex.
Contributes to control of
movement.
Unusual Patterns
Discussion
Introduction
Basic Principles
Normal Anatomy
Paradigms
Unusual Patterns
Discussion
Overview Motor Language Other
_fMRI Paradigms
-A paradigm is an activity or stimulus designed to elicit a
specific cortical response
-Typically target visual, speech, motor, or memory areas
-Successful localization of eloquent areas requires that the
patient is able to comply with the paradigm
-Block design: the most common type during which a
specific stimulus is repeated over a stimulus-rest cycle
-Event related design: single events designed to elicit a
cortical response
ASFNR Paradigms. Available at http://www.asfnr.org/paradigms.html. Date accessed 03/10/2015.
Introduction
Basic Principles
Normal Anatomy
Paradigms
Unusual Patterns
Discussion
Overview Motor Language Other
Activation
_
_time
Block design paradigm schematic
showing 20 second rest/stimulus
cycles
Stimulus
Rest
20
40
60
80
100
120
Time (sec)
Actual recorded data showing a
block design paradigm with the
smoothed predicted value and
the actual recorded values (here
labeled R3)
Introduction
Basic Principles
Normal Anatomy
Paradigms
Unusual Patterns
Discussion
Overview Motor Language Other
Motor
Paradigms
_
-Designed to stimulate motor, pre-motor and supplementary
motor areas
-Typically block design paradigms
-Examples include:
o
o
o
o
Bilateral complex finger tapping
Unilateral sequential finger tapping
Tongue movement/lip puckering
Toe motion
-Requires adequate patient dexterity and ability to cooperate (if
lacking dexterity hand-grip can be attempted)
-Physician or technologist can actively assist patient with finger
motion or toe motion if patient unable to follow command in a
timely fashion
ASFNR Paradigms. Available at http://www.asfnr.org/paradigms.html. Date accessed 03/10/2015.
Introduction
Basic Principles
Normal Anatomy
Paradigms
Unusual Patterns
Discussion
Overview Motor Language Other
Motor
Paradigms – Our methods
_
-At our institution we begin every fMRI with tongue movement
to help separate this from the later language paradigms (if
necessary)
The patient is asked to move their tongue side to
side in 20 second rest-stimulus intervals
-Bilateral toe-motion
The patient is asked to move their toes randomly in 20
second rest-stimulus intervals. It is important patients
not move feet excessively to avoid head motion artifact
-Bilateral finger tapping
Rapid finger tapping over 20 second rest-stimulus
cycles
Introduction
Basic Principles
Normal Anatomy
Paradigms
Unusual Patterns
Discussion
Overview Motor Language Other
I
Tongue
movement
(pink) with
motor cortex
activity
Toe motion
(yellow) with
motor
activity
Introduction
Basic Principles
Normal Anatomy
Paradigms
Unusual Patterns
Discussion
Overview Motor Language Other
_Language Paradigms
-Designed to lateralize and stimulate Broca’s area,
Wernicke’s area and the arcuate fasciculus
-Examples include:
o
o
o
o
o
Sentence completion
Verb generation (i.e. Ball  “throw”)
Passive listening (Wernicke’s area)
Word naming (i.e. think of words that start with “A”)
Object naming
-Typically a block design paradigm
Introduction
Basic Principles
Normal Anatomy
Paradigms
Unusual Patterns
Discussion
Overview Motor Language Other
_Language Paradigms
-Requires the patient to be literate and able to recognize
and read the letters on the display
-It is essential that patients do not actually move their
tongue/lips during the procedure to avoid confounding
activation
Gracco, V. L., Tremblay, P., & Pike, B. (2005). Imaging speech production using fMRI. Neuroimage, 26(1), 294–301. doi:10.1016/j.neuroimage.2005.01.033
Introduction
Basic Principles
Normal Anatomy
Paradigms
Unusual Patterns
Discussion
Overview Motor Language Other
Language
Paradigms – Our methods
_
We employ the following standardized paradigms:
-Verb generation
The patient is shown a noun and asked to think of a
verb such as “car”  “drive”
-Word generation
The patient is asked to think of as many words as
they can that start with a specific letter
-Sentence completion
The patient is given a sentence and asked to complete it
-Object naming
The patient is shown various objects (e.g. house, chair)
and asked to recognize and name them
Introduction
Basic Principles
Normal Anatomy
Paradigms
Unusual Patterns
Discussion
Overview Motor Language Other
I
Word
generation
(orange)
showing activity
in Broca’s area
in a left
language
dominant
subject.
Sentence
completion
paradigm
showing
activity in
Wernicke’s
area (red)
Introduction
Basic Principles
Normal Anatomy
Paradigms
Unusual Patterns
Discussion
Overview Motor Language Other
_fMRI Paradigms – Other uses
-Script-driven fMRI has been used to investigate patterns of
activation in PTSD
-Alzheimer’s disease characterization via parahippocampal
and hippocampal activation in memory tasks
-Assessment of addiction with focus on prefrontal cortex
-Evaluation of traumatic brain injury (TBI), able to show
subtle changes in mild TBI in the absence of structural
defects on static images. Dependent on site of injury
Hughes, K. C., & Shin, L. M. (2011). Functional neuroimaging studies of post-traumatic stress disorder. Expert Review of Neurotherapeutics, 11(2), 275–285. doi:10.1586/ern.10.198
Sperling, R. (2011). The potential of functional MRI as a biomarker in early Alzheimer's disease. Neurobiology of Aging, 32, S37–S43. doi:10.1016/j.neurobiolaging.2011.09.009
Luijten, M., Machielsen, M., Veltman, D., Hester, R., de Haan, L., & Franken, I. (2014). Systematic review of ERP and fMRI studies investigating inhibitory control and error processing in people. Journal of Psychiatry & Neuroscience, 39(3), 149–169. doi:10.1503/jpn.130052
McDonald, B. C., Saykin, A. J., & McAllister, T. W. (2012). Functional MRI of mild traumatic brain injury (mTBI): progress and perspectives from the first decade of studies. Brain Imaging and Behavior, 6(2), 193–207. doi:10.1007/s11682-012-9173-4
Introduction
Basic Principles
Normal Anatomy
Paradigms
Unusual Patterns
Discussion
_Hx: 55F Spanish-speaking with glioblastoma multiforme(red arrow) presents for
preoperative evaluation prior to resection. Before starting the test it was discovered she
was illiterate and thus unable to follow written directions.
Presumed Wernicke’s area (blue arrow), slightly more anterior than expected, potentially distorted
by tumor
Challenge: Illiterate Spanish-speaking patient, unable to perform language tasks without
assistance.
Solution: Spanish-speaking interpreter read letters on screen and patient was able to
complete word generation paradigm, resulting in faint activation of Wernicke’s area.
Introduction
Basic Principles
Normal Anatomy
Paradigms
Unusual Patterns
Discussion
_Hx: 51M Cantonese-speaking with complex partial seizures due to a left frontal lobe
mass(red arrow). Pre-operative evaluation given proximity to eloquent areas.
Broca’s area localizes to inferior frontal lobule(blue arrow)
Expected Wernicke’s
area(yellow arrow)
Object naming paradigm
Challenge: Cantonese-speaking patient with limited English fluency.
Solution: To complete object naming paradigm, the patient was shown images and asked to
silently name them in his native language, resulting in activation of the language centers.
Introduction
Basic Principles
Normal Anatomy
Paradigms
Unusual Patterns
Discussion
_Hx: 37F right-handed with intractable epilepsy s/p trauma found to have multiple
prominent areas of left-sided activation during language tasks
Two distinct Broca’s areas(blue arrows)
Single Wernicke’s area(yellow
arrow)
Arcuate
fasciculus
Sentence completion paradigm
Challenge: Multiple areas of activation on language related paradigm.
Solution: Correlate with the patient’s medical record or patient query. We discovered the
patient was trilingual, likely explaining the multiple Broca’s areas.
Introduction
Basic Principles
Normal Anatomy
Paradigms
Unusual Patterns
Discussion
_Hx: 71M right-handed with intractable epilepsy for preoperative evaluation prior to rightsided amygdalohippocampectomy.
Word generation paradigm
Bilateral Broca’s areas (blue arrows)
Challenge: Bilateral language centers with no clear dominant side by fMRI. Evaluation for
Wernickes was inconclusive.
Solution: Confirmatory testing. Post-fMRI preoperative Wada test confirmed bilateral codominant language centers, noting dysphasia with right-sided injection and non-fluency
with left-sided injection. This patient suffered a postoperative right MCA territory infarct
with hemorrhage resulting in severe aphasia consistent with Wada testing.
Introduction
Basic Principles
Normal Anatomy
Paradigms
Unusual Patterns
Discussion
_(Hx: 60M left-handed semi-literate with right frontal glioblastoma multiforme(red arrow),
preoperative evaluation.
Faint Broca’s activation (blue arrow)
DWI showing infarct
Word generation paradigm
Challenge: Semi-literate patient, able to recognize letters.
Solution: The patient was asked to think of any words that came to mind when he saw a
letter on the screen, which resulted in faint Broca’s area activation. This was confirmed by
language deficits after postoperative infarct in this region.
Introduction
Basic Principles
Normal Anatomy
Paradigms
Unusual Patterns
Discussion
_Hx: 70F right-handed with glioblastoma multiforme(red arrow) being evaluated prior to
brain biopsy. fMRI demonstrated robust tongue activation.
Intense motor activity(blue arrow)
Tongue movement paradigm
Wernicke’s with arcuate
fasciculus(yellow arrow)
Word generation paradigm
Challenge: Separate tongue activity from language activity in Wernicke’s area.
Solution: Perform tongue movement paradigm first in order to localize tongue activity. This
will help to differentiate activation of Wernicke’s area in case of inadvertent tongue
movement during language generation paradigm.
Introduction
Basic Principles
Normal Anatomy
Paradigms
Unusual Patterns
Discussion
48M with limited reading capacity, with large left-sided mass(red arrow) for
_Hx:
evaluation prior to resection. fMRI results influenced a change to conservative
management.
Intense motor activity(blue
arrow)adjacent to mass
Right and left corticospinal
tracts(yellow arrows)
Partially visualized left
corticospinal tract(yellow
arrow)
Finger tapping paradigm
Challenge 1: Left corticospinal tract not well visualized adjacent to mass.
Solutions: Review literature and consult experienced colleagues. The mass caused
medialization of the left corticospinal tract and adjacent edema likely altered diffusivity
rendering the fibers unapparent at the level of the motor strip.
Introduction
Basic Principles
Normal Anatomy
Paradigms
Unusual Patterns
Discussion
48M with limited reading capacity, with large left-sided mass for evaluation prior to
_Hx:
resection. fMRI results influenced a change to conservative management.
Broca’s area(blue arrow) visualized using modified word generation paradigm
Challenge 2: Patient had limited ability to recognize letters.
Solution: Patient instructed to think of any word that came to mind regardless of letter
presented in word generation paradigm.
Introduction
Basic Principles
Normal Anatomy
Paradigms
Unusual Patterns
Discussion
_Hx: 29M, right handed, with intractable epilepsy and left mesial temporal sclerosis,
evaluation prior to amygdalohippocampectomy. This patient was able to undergo leftsided resection without postoperative language deficits.
Broca’s area(blue arrow) on the
Wernicke’s area(yellow arrow)
right
& arcuate fasciculus on right
Word generation paradigm
Verb generation paradigm
Challenge: Language center not in the expected location.
Solution: Recognize normal anatomic variation. Approximately 5% of right handed patients
can have right hemisphere language dominance. This was confirmed with a WADA test.
Introduction
Basic Principles
Normal Anatomy
Paradigms
Unusual Patterns
Discussion
Discussion
-fMRI is becoming a standard tool in the preoperative
evaluation of neurosurgical patients and can affect
operative planning
-fMRI must be performed and interpreted in the context
of the patient with attention to pre-existing deficits (i.e.
level of literacy, prior insult, ability to follow directions)
-Unexpected patterns of activation can be challenging in
a de novo fMRI program.
Introduction
Basic Principles
Normal Anatomy
Paradigms
Unusual Patterns
Discussion
Discussion
-Challenging cases we have encountered include bilateral, multiple or
unexpected locations of language centers, and distortion of the usual
anatomy. Additional history from the patient may be helpful.
-Varying levels of literacy or English language proficiency that render
implementation of paradigms challenging. The operator must improvise
to complete the paradigm. Performing object naming tasks or
involvement of interpreters can assist in paradigm completion.
-Different paradigms are used to activate specific language
centers(Brocas, Wernickes) however intensity and center of activation
can be variable. Operator must utilize any available paradigms to obtain
results useful for patient care.
-When in doubt, refer to the literature and consult with experienced
colleagues.