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Advanced MR imaging

combined with

Intraoperative MRI for

Brain Tumors

Mahmoud Nagib, MD

Neurosurgical Associates

Mark C. Oswood, MD, PhD

Consulting Radiologists, Ltd

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Techniques

Functional MRI (fMRI)

Diffusion tensor imaging (DTI)

Intraoperative MRI (iMRI)

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Functional MRI

Shows areas of brain activated during specific tasks

Can be done on many MR scanners with appropriate software

More activation seen at 3T

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Functional MRI Benefits

May lead to more complete resection or shorten OR time.

Perform biopsy instead of resection.

Supplemented with intra-operative mapping.

Petrella, et. al. Radiology 240, 793 (2006).

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Clinically Useful fMRI Paradigms

Motor

Visual

Language

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fMRI: Motor

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fMRI: Visual

3.1

19.6

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fMRI: Language

Case Example of fMRI

Cavernous Malformation

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Cavernous Malformation

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Susceptibility Weighted Imaging

(SWI)

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Diffusion Tensor Imaging

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fMRI Right Finger

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fMRI Tounge

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fMRI Language

Story Reading

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fMRI Language Lateralizaiton

fMRI shows greater activation on left

Suggests left hemisphere dominance

WADA confirms left hemisphere dominance

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Diffusion Weighted Imaging

Image water movement on microscopic level

Water moves at different speeds along versus across white matter bundles

Determine predominant direction of axon bundles in brain

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Diffusion Tensor Imaging

Trace white matter tracts through brain

May be able to follow tracts in areas of infiltrative tumor

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Can we see fibers from

diffusion imaging?1. diffusion along fiber axis > diffusion across fiber axis

2. search for and connect directions with highest diffusivity

3. acquire >> 6 gradient directions in order to solve fiber crossing sections

4. algorithms under development; no unambiguous solution to problem up to now

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Fiber tracking

Image from PhD-Thesis of David Tuch, MGH Boston shows projections from rostral pons into the corona radiata via thalamus (blue fibers). Red fibers are the cerebellar pontine fibers projecting into the middle cerebellar peduncle.

Data acquired on a 3T Allegra with 258 different diffusion gradient directions at a strength of 40mT/m, b-values 20,000 s/mm2, TE = 140 ms, gradient pulse length 60 ms

Intraoperative MRI Guided

Resection of Brain Tumors at

Abbott-Northwestern Hospital

Case Examples

What is Intraoperative MRI?

Operating Room with attached MRI scanner bay

MRI scanner is suspended on rails from ceiling

Scanner moves to patient during surgery

iMRI Operating Suite

History of iMRI Program

In 2007, under the leadership of Dr. Douglas Yock the intraoperative MRI program was instituted on the Abbott Northwestern Hospital campus

Since then, over one thousand neurosurgical interventions have been completed

The patient ages ranged from early infancy (2 months) up to the 7th and 8th decade of life

Pathology including entire

spectrum of neurosurgery Congenital anomaly

Craniocervical pathology and approaches through the transoral route

Infectious disease

Vascular abnormalities, aneurysm/arteriovenous malformation/cavernous angiomas

Neoplastic disease, malignant and benign

Over 1000 iMRI cases

completed As the neurosurgical team, including the nursing staff and surgeon, gained experience,

More complex cases have been completed with greater proficiency

More than one major surgical intervention can be completed in the intraoperative MRl suite per day.

As more experienced gained

The length of surgery was curtailed

Potential for complications related to long surgeries decreased

We can demonstrate a cost benefit to the use of the intraoperative MRl

Is iMRI essential to a good

outcome? The answer: in our opinion, it is certainly not essential for a good outcome

We believe it enhances the possibility of a good outcome

The early recognition of complications

And the early attempts at resolving these complications

iMRI cases

We are going to proceed with some illustrative cases to demonstrate the value of the intraoperative MRI in enhancing the patient’s outcome.

Cerebellar tumor

iMRI post resection

iMRI post resection

Follow up MRI

Improved outcome after early recognition of hemorrhage

Intraventricular tumor

?Location of speech and optic tracts

Diffusion Tensor and Functional

Imaging DTI/fMRI

(DTI) Optic tracts and speech cortex

DTI fiber tracking

iMRI resection

Frontal tumor

iMRI after resection

Repeat iMRI after additional

resection

Tumor near corticospinal tract

DTI to localize corticospinal tract

Tumor location

iMRI resection with

Intraoperative DTI

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Conclusions

Use advanced MR imaging for pre-operative evaluation of brain lesions

fMRI to locate functional areas of cortex

DTI to locate white matter tracts

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Conclusions

Use intraoperative MRI to improve outcomes of brain surgery patients

More complete resection of lesions

Early recognition of complications

Avoid repeat surgery