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Brain Tumor Treatments
Once a brain tumor is diagnosed, the physician
determines the best way to treat it. Often, surgery
is the best option for removing as much of the tumor
as possible. Radiation or chemotherapy may be used after
surgery to destroy any remaining cells, or, in cases
where the brain tumor is inoperable, may become the
primary method of treatment.
Intraoperative
MRI
Intraoperative MRI refers to the use of MRI technology
to obtain images of the brain during surgery. Real-time
visualization allows surgeons to confirm the location
of lesions, plan and reconfirm the optimal surgical
approach, and verify complete lesion removal prior to
closure.
Conventional surgical navigation systems rely on images
obtained prior to surgery and cannot account for movement
of the brain during the surgery that could result simply
from exposure or from tumor removal. With the use of
MRI images obtained during various points in the surgery,
the navigation system continuously adjusts to account
for any brain shift, thereby minimizing harm to healthy
and/or eloquent areas of the brain.
University Hospital is the hospital in the world to
utilize a compact OR-based MRI system (PoleStar N-10)
that successfully addresses the problems associated
with early versions of intraoperative MRI systems, including
cumbersome design, limited application, and high cost.
The Brain Tumor Program is conducting clinical studies
to confirm the efficacy of this revolutionary new technology.
Stereotactic Surgery
The current gold standard in surgery involves the innovative
use of stereotactic techniques. Instead of a "flat"
image of the brain, computer-based technology provides
a three-dimensional perspective to the surgeon.
Conventional stereotaxis attaches a metal frame
to the patient's skull to create a fixed reference point
or system of coordinates. This fixed reference point,
combined with a three-dimensional image of the brain
provided by a computer and MRI scanning, allows for
precise mapping and visualization of the tumor and surrounding
tissue.
Once the brain has been mapped, precise navigation
to the tumor site and optimal tumor resection is possible
using a variety of surgical devices attached to the
frame. The result is accurate, minimally invasive surgery
that maximizes tumor resection, while minimizing injury
to surrounding healthy tissue and functional losses
in movement, sight, hearing, and speech.
Frameless Stereotactic Surgery
Frameless stereotactic surgery provides the same precision
without the need to attach a heavy metal frame to the
patient's skull. Frameless systems substitute a reference
system created by "wands," plastic guides,
or infrared markers. The Brain Tumor Program uses an
infrared-based Stealth surgical navigation system for
frameless, image-guided surgical approaches, and employs
it when a frame-based system would be unnecessarily
cumbersome or time consuming. Certain tumors–such as
those with irregular margins–may be treated more effectively
with the use of frameless stereotactic surgery.
The Stealth Station®, which works together
with MRI, CT scans, or ultrasound, limits the size of
cranial openings and removes much of the guesswork from
cerebral localization. The Stealth uses sensor-based
"optical tracking" computer technology to
accurately pinpoint areas of the brain. It is precise
within one millimeter. Images, produced in "real
time," are updated every eight seconds. This sophisticated
system reduces surgical morbidity, operation time, and
for some, length of hospitalization.
Functional
Image-Guided Surgery (FIGS)
Surgical resection of a brain tumor is a common and
often effective treatment. But sometimes the tumor’s
location near "eloquent" areas of the brain–those
that control movement or speech–poses a dilemma. Removing
the tumor may also result in taking away some of the
healthy tissue surrounding it, causing a neurological
deficit.
The Brain Tumor Program is a pioneer in the use of
Functional Image-Guided Surgery (FIGS), a technique
that combines Functional MRI (fMRI) with frameless stereotactic
surgery to optimize the safety and efficacy of treatment
for patients with tumors located in the cerebral hemispheres.
During a FIGS procedure, fMRI is used to map the
functional area of a patient's brain. While the MRI
is scanning, the patient is asked to perform a series
of activities and movements, such as reading a list
or tapping fingers. The areas of the brain that correlate
to those movements "light up" on the scan and create
an image. This information is sent to a surgical navigation
computer located in the operating room. Neurosurgeons
use a special pointer positioned on the patient’s head
to guide incisions, skull openings, and brain tumors
based on corresponding points of the MRI image. The
added degree of precision in guidance and navigation
provided by this technique maximizes tumor resection
while minimizing the possibility of weakness, blindness,
and speech loss.
FIGS offers non-invasive preoperative assessment
and planning for brain tumor surgery. This technology
also is being applied to stereotactic radiosurgery,
where FIGS’ precision tremendously reduces the chance
that radiation will be applied to eloquent areas of
the brain.
MR SPECT
MR SPECT is a new and highly effective method of scanning
the brain. In many cases, it detects tumors that were
unfound in earlier brain scans.
A conventional MR scan uses nuclear magnetic resonance
imaging. This means that echoes of radio waves are sent
to the brain to image a picture of the brain. As the
radio waves encounter different densities, images are
mapped out. Sometimes the images indicate masses or
tumors. MR SPECT takes this mapping a step further and
uses state of art software to analyze radio waves for
signature patterns called spectra.
Different chemicals produce different types of spectra.
So once the radio waves indicate a change in density,
the spectra is analyzed. The presence of certain chemicals
can tell physicians if there are tumors growing in the
brain. The chemicals provide a more accurate indication
for mapping. MR SPECT is a noninvasive test, that offers
results in real time, decreasing the need for biopsies
and other surgeries. It also offers physicians a quicker
method of detection and enables treatment plans to be
created sooner.
Skull Base Surgery
Many different types of tumors may be located at the
brain’s undersurface, or skull base. Tumors in this
area are not only deep-seated, they also are located
near nerves associated with vision, hearing, and other
functions. In the past, many of these tumors were considered
inaccessible to the surgeon. Today, however, there are
new approaches that enable neurosurgeons to remove skull
base tumors without having to lift the brain. These
operations, combined with advanced instrumentation and
an emphasis on a multidisciplinary approach, have made
skull base surgery a specialty in itself.
A comprehensive, "team" approach to skull
base surgery is in place at University Hospital, and
its importance cannot be overstated. With the skull
base positioned near the eyes, ears, nose, and throat,
there’s a need for specialists such as plastic surgeons,
otolaryngologists, opthalomologists, neuroradiologists,
and oncologists to be involved in the planning of the
surgery and during the procedure itself. While one goal
of the team is to remove as much of the tumor as possible,
another is to retain the function of organs and nerves
that may be affected by the surgery.
Plastic surgeons have adapted methods to skull base
surgery that were initially used to repairing craniofacial
deformities. Otolaryngologists, with their expertise
in disorders of the head and neck, work closely with
neurosurgeons in the care of patients with a range of
anterior skull-based lesions. If a tumor is adjacent
to an optic nerve, an opthalmolgist’s expertise may
be needed to preserve the patient’s vision.
Stereotactic Radiosurgery
(SRS)
Computer-based technology, which provides a three-dimensional
perspective to the surgeon, is at the core of stereotactic
techniques that are now the gold standard in brain tumor
treatment. Not only can stereotaxis be used for conventional
surgery, but also to deliver radiation to selected sites
in the brain.
Stereotactic radiosurgery delivers focused, multiple
beams of radiation to areas where they are needed–a
single point on a tumor site–while avoiding healthy
tissue. This procedure does not involve surgical incision
and is often an excellent treatment alternative to surgery,
or an option for patients who are not candidates for
surgery. The Brain Tumor Program pioneered a radiosurgical
technique that significantly reduces the treatment time
required for complex lesions.
Stereotactic Radiation
Therapy (SRT)
After surgical removal of a brain tumor, doctors want
to make certain they have removed every tumor cell possible.
Post-operative radiation treatments are commonly used
to destroy microscopic cells or any part of the tumor
that was inaccessible through surgery. Traditionally,
radiation has been delivered to the whole brain–tumor
site and normal tissue alike. But with today’s technology,
the delivery of radiation can be focused on the tumor
area.
Stereotactic radiation therapy uses frameless stereotaxis
to deliver small doses of radiation therapy to tumor
sites. Fractionated SRT is the method of delivering
doses of radiation in daily treatments in order to increase
the total amount of radiation directed to a tumor site.
Brachytherapy, or interstitial radiation, utilizes
stereotactic techniques to implant radioactive "seeds"
directly into a tumor. The seeds remain there for a
period of time, enabling delivery of radiation across
several stages of tumor growth and increasing the efficacy
of treatment.
Stereotactic placement of brachytherapy sources
is done in conjunction with physicians and assistance
from radiation oncology.
GliSite® Radiation Therapy
System
GliaSite is designed to be used after tumor removal
surgery or tumor resection. After the surgery, an uninflated
balloon catheter is placed inside the space left by
the removed tumor (the tumor resection cavity). The
other end of the catheter extends out under the scalp.
The balloon is filled with a solution (contrast medium)
that is visible on an MRI. This allows the physician
to verify that the balloon fits the cavity left by the
resected tumor.
Once the patient has recovered from the tumor resection
surgery, the contrast medium is removed from the balloon
and a liquid radiation source is inserted into the catheter
and into the balloon.
The radioactive fluid delivers radiation to the edges
of the tumor cavity, targeting places where cancer may
remain. It stays in the catheter for approximately three
to seven days until the right amount of radiation is
delivered. It is then removed from the catheter and
then catheter is removed during a brief surgical procedure.
Because of the precision of the catheter, the risks
to healthy tissue are minimized.
The Gliadel® Wafer
The Gliadel® Wafer is a complementary therapy used
in the treatment of certain brain tumors. The Brain
Tumor Program was part of a national study involving
Gliadel and patients with recurrent glioblastoma multiforme
(GBM) tumors. It currently is the principal investigator
in a new multicenter study of the combined treatment
of Gliadel, radiation therapy, and radiosurgery in patients
with newly diagnosed malignant gliomas. Patients are
being accepted into the trial study.
With the use of Gliadel in recurrent GBM tumors, up
to eight dime-sized wafers are implanted following surgery.
They slowly erode, delivering high concentrations of
a chemotherapeutic drug, carmustine, at the tumor site.
Because of the blood-brain barrier–a protective
wall of blood vessels and cells–IV-delivered chemotherapy
has difficulty reaching brain tumors. Additionally,
Gliadel does not have the side effects commonly found
with chemotherapeutic agents delivered through an IV.
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Brain
Tumor Treatments
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