Post on 16-Jul-2015
transcript
1
Advanced MR imaging
combined with
Intraoperative MRI for
Brain Tumors
Mahmoud Nagib, MD
Neurosurgical Associates
Mark C. Oswood, MD, PhD
Consulting Radiologists, Ltd
2
Techniques
Functional MRI (fMRI)
Diffusion tensor imaging (DTI)
Intraoperative MRI (iMRI)
3
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
4
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).
5
Clinically Useful fMRI Paradigms
Motor
Visual
Language
6
fMRI: Motor
7
fMRI: Visual
3.1
19.6
8
fMRI: Language
Case Example of fMRI
Cavernous Malformation
9
Cavernous Malformation
10
Susceptibility Weighted Imaging
(SWI)
11
Diffusion Tensor Imaging
12
fMRI Right Finger
13
fMRI Tounge
14
fMRI Language
Story Reading
15
fMRI Language Lateralizaiton
fMRI shows greater activation on left
Suggests left hemisphere dominance
WADA confirms left hemisphere dominance
16
17
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
18
Diffusion Tensor Imaging
Trace white matter tracts through brain
May be able to follow tracts in areas of infiltrative tumor
19
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
20
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
44
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
45
Conclusions
Use intraoperative MRI to improve outcomes of brain surgery patients
More complete resection of lesions
Early recognition of complications
Avoid repeat surgery