Divya S Bolar, HMSIV Gillian Lieberman, MD 1 Pre Pre - - surgical planning for surgical planning for brain tumor resection brain tumor resection using functional MRI using functional MRI Divya Divya S. S. Bolar Bolar , HMS IV , HMS IV Gillian Lieberman, MD Gillian Lieberman, MD June 2011
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Divya S Bolar, HMSIVGillian Lieberman, MD
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PrePre--surgical planning for surgical planning for brain tumor resection brain tumor resection using functional MRIusing functional MRI
DivyaDivya S. S. BolarBolar, HMS IV, HMS IVGillian Lieberman, MDGillian Lieberman, MD
June 2011
Divya S Bolar, HMSIVGillian Lieberman, MD
Our patient: clinical historyOur patient: clinical history8585--yearyear--old rightold right--handed woman presents handed woman presents s/ps/p fall fall
with occipital head strikewith occipital head strike
Denies LOC or preDenies LOC or pre--syncopalsyncopal symptoms. Endorses eight symptoms. Endorses eight month history of falls secondary to progressive leftmonth history of falls secondary to progressive left--sided sided weakness and loss of balance.weakness and loss of balance.
Differential Differential DxDx::1.1. Hemorrhagic infarctHemorrhagic infarct2.2. Hemorrhage into Hemorrhage into
underlying mass underlying mass lesionlesion
WellWell--circumscribed circumscribed lesion, lesion, chronicitychronicity of of symptoms => symptoms => suspect hemorrhage suspect hemorrhage into massinto mass
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Our patient: Our patient: Intracranial hemorrhage on CIntracranial hemorrhage on C-- MRIMRI
Mild degree of T1 Mild degree of T1 hyperintensityhyperintensity
MRI head T1/ C-
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Our patient: Our patient: Intracranial hemorrhage on C+ MRIIntracranial hemorrhage on C+ MRI
Moderate degree Moderate degree of lesion of lesion enhancement enhancement
Uncharacteristic of Uncharacteristic of hemorrhagic hemorrhagic infarctinfarct
Consistent with Consistent with contrast uptake by contrast uptake by abnormal tumor abnormal tumor vasculaturevasculature
MRI head T1/ C+
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Our patient: Approach to management
Additional body imaging with CT:Additional body imaging with CT:
Masses found in lung & breastMasses found in lung & breast
No masses found in remaining kidney or at prior No masses found in remaining kidney or at prior surgical sitesurgical site
Etiology of brain tumor unclearEtiology of brain tumor unclear
Metastasis from occult RCC?Metastasis from occult RCC?
New primary brain tumor?New primary brain tumor?
Metastasis from other site?Metastasis from other site?
Neurosurgical resection was recommended to Neurosurgical resection was recommended to decompress, reduce edema, improve local decompress, reduce edema, improve local control, and biopsycontrol, and biopsy
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FrontoparietalFrontoparietal tumorstumors
Neurosurgical resection often indicated, but Neurosurgical resection often indicated, but carries risk of injury to:carries risk of injury to:
Primary motor cortex in Primary motor cortex in precentralprecentral gyrusgyrus and/or and/or descending descending corticospinalcorticospinal tracttract
Frontal language regions if lesion is in dominant Frontal language regions if lesion is in dominant hemisphere (hemisphere (BrocaBroca’’s area in s area in orpeculumorpeculum))
Chief concern is paralysis and loss of speech and Chief concern is paralysis and loss of speech and languagelanguage
Preoperative mapping of these areas could assist Preoperative mapping of these areas could assist in surgical planning and reduce risk of injuryin surgical planning and reduce risk of injury
Divya S Bolar, HMSIVGillian Lieberman, MD
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PrePre--surgical planning: surgical planning: What does the neurosurgeon want to know?What does the neurosurgeon want to know?
Distance between tumor margin and essential functional Distance between tumor margin and essential functional areasareas
““Golden ruleGolden rule”” says minimum distance 10 mm to preserve says minimum distance 10 mm to preserve functionfunction
Trajectory to tumor that avoids functional area (if one Trajectory to tumor that avoids functional area (if one exists)exists)
With this information surgeon can:With this information surgeon can:1.1. Determine if tumor is amenable for resectionDetermine if tumor is amenable for resection2.2. Decide if Decide if intraoperativeintraoperative cortical stimulation is needed cortical stimulation is needed 3.3. Better navigate surgical procedure itselfBetter navigate surgical procedure itself
SoSo--called called ““functional MRIfunctional MRI”” is a noninvasive approach is a noninvasive approach that can safely identify essential functional areas in that can safely identify essential functional areas in advance of surgical interventionadvance of surgical intervention
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What is functional MRI (What is functional MRI (fMRIfMRI)?)?
““ fMRIfMRI is a technique for determining is a technique for determining which parts of the brain are activated by which parts of the brain are activated by different types of physical sensation or different types of physical sensation or activity, such as sight, sound or the activity, such as sight, sound or the movement of a subject's fingers.movement of a subject's fingers.””
-- Steve Smith, FMRIB, OxfordSteve Smith, FMRIB, Oxford
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Approach to Approach to fMRIfMRI
Subjects are continuously imaged while Subjects are continuously imaged while performing specifically timed performing specifically timed ““taskstasks””
Tasks are chosen based on neural system we Tasks are chosen based on neural system we wish to interrogate. Examples include:wish to interrogate. Examples include:
Motor => Finger or footMotor => Finger or foot--tappingtapping
Analysis of images allows creation of statistical Analysis of images allows creation of statistical maps that maps that localize tasklocalize task--based neural activity to based neural activity to corresponding brain regionscorresponding brain regions
Divya S Bolar, HMSIVGillian Lieberman, MD
How is neural activity reflected How is neural activity reflected in the MRI signal?in the MRI signal?
(i.e. how does (i.e. how does fMRIfMRI work!!)work!!)
From neural activity to MRI signal: From neural activity to MRI signal: Oxygen delivery via cerebral blood flow IOxygen delivery via cerebral blood flow I
At baseline, cerebral At baseline, cerebral blood flow (CBF) supplies blood flow (CBF) supplies oxygenoxygen--rich blood to rich blood to capillary bedcapillary bedO2
From neural activity to MRI signal: From neural activity to MRI signal: Oxygen delivery via cerebral blood flow IIOxygen delivery via cerebral blood flow II
Chief oxygenChief oxygen--carrier is carrier is macromolecule macromolecule hemoglobinhemoglobin in red blood in red blood cell (RBC)cell (RBC)
Oxygenated hemoglobin Oxygenated hemoglobin is called is called oxyoxyhemoglobinhemoglobin (HbO(HbO 22 ))
From neural activity to MRI signal: From neural activity to MRI signal: Oxygen extraction and consumptionOxygen extraction and consumption
As blood traverses As blood traverses capillary bed, oxygen is capillary bed, oxygen is extractedextracted from HbOfrom HbO 22 into into tissue and consumedtissue and consumed
From neural activity to MRI signal: From neural activity to MRI signal: Secondary increase in CBF flushes out Secondary increase in CBF flushes out dHbdHb
O2
O2
A secondary increase in A secondary increase in CBF followsCBF follows
Increased CBF delivers Increased CBF delivers more HbOmore HbO 2 2 and and flushes flushes out venous out venous dHbdHb
From neural activity to MRI signal: From neural activity to MRI signal: Reduction in Reduction in dHbdHb increases MR signalincreases MR signal
Decreased Decreased dHbdHb results in results in aa smaller smaller field field perturbation perturbation and and an an increaseincrease in MR signalin MR signal
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MR signal intensity:MR signal intensity: Baseline StateBaseline State
Activation seen in Activation seen in operculum operculum frontalefrontale; ; location consistent with location consistent with BrocaBroca’’s Areas Area
Suggests patient has Suggests patient has left left hemispheric dominancehemispheric dominance
Reduced risk of language Reduced risk of language impairment with resection impairment with resection of rightof right--sided lesion. sided lesion.
Operculum frontale
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Our patient: Surgical planning
Tumor margin Tumor margin 5 mm 5 mm away from motor away from motor activation stripactivation strip
UnobscuredUnobscured oblique oblique trajectory trajectory available available for direct approachfor direct approach
5 mm
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Our patient: Pre-post op comparison
PRE
POST
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Our patient: Post-operative changes
T1 T1 hyperintensityhyperintensity consistent with postconsistent with post-- operative blood and operative blood and proteinaceousproteinaceous material material
Thin rim of Thin rim of enhancement could enhancement could be postbe post--op change, op change, but residual tumor but residual tumor cannot be excludedcannot be excluded
Divya S Bolar, HMSIVGillian Lieberman, MD
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Our patient: Outcome
Patient initially had increased leftPatient initially had increased left--sided sided weakness postweakness post--operativelyoperatively
Not surprising given proximity of tumor to motor Not surprising given proximity of tumor to motor cortexcortex
She was discharged and will see oncology to She was discharged and will see oncology to discuss chemotherapy optionsdiscuss chemotherapy options
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Summary
Functional MRI can be useful tool for preoperative Functional MRI can be useful tool for preoperative planning and assessment for brain tumor resectionplanning and assessment for brain tumor resection
fMRIfMRI creates creates ““activation mapsactivation maps”” which correlate to which correlate to neural activity patternsneural activity patterns
Link between neural activity and MRI signal arises from Link between neural activity and MRI signal arises from increased blood flow flushing out paramagnetic increased blood flow flushing out paramagnetic dHbdHb during stimulationduring stimulation
Use of maps allow surgeons to: Use of maps allow surgeons to: 1.1. Assess Assess resectabilityresectability of tumors near essential functional areasof tumors near essential functional areas2.2. Decide if Decide if intraoperativeintraoperative cortical stimulation is neededcortical stimulation is needed3.3. Better navigate surgical procedureBetter navigate surgical procedure
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References
Buxton RB. Introduction to Functional Magnetic Resonance Imaging. Second Edition. New York, NY: Cambridge University Press; 2009.
Hoa D. Functional MRI of the Brain. http://www.imaios.com/en/e-Courses/e- MRI/Functional-MRI/introduction, Accessed 6/16/2011.
Holodny AI. Functional Neuroimaging: A Clinical Approach. New York, NY: Informa Healthcare; 2008.
Smith S. Brief Introduction to FMRI. http://www.uib.no/med/avd/miapr/arvid/bfy- 361/fmri_smith_1998.pdf. Accessed 6/16/2011.
Sunaert S. Presurgical planning for tumor resectioning. JMRI. 2006; 23:887-095.
van Zijl PC, Eleff SM, Ulatowski JA, Oja JM, Ulug AM, Traystman RJ, Kauppinen RA. Quantitative assessment of blood flow, blood volume and blood oxygenation effects in functional magnetic resonance imaging. Nat Med 1998;4:159–167.Brugge WR, Van Dam J.