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Session ID: eP-4
Sub-Session ID: eP-165
Role of Cerebrospinal Fluid (CSF) Flow Imaging in
Evaluating Distribution of Infused Agents from the 4th
Ventricle to the Total Spine in Treatment of Recurrent
Posterior Fossa Malignant Neoplasms
Rajan Patel, MD; Clarke Sitton, MD; M Kerr, RN;
Stephen Fletcher, DO; Manish Shah, MD;
David Sandberg, MD, FAANS, FACS, FAAP
DISCLOSURE
• None.
INTRODUCTION
• Malignant neoplasms such as medulloblastoma, ATRT,
ependymoma account for 50% of posterior
fossa/infratentorial pediatric brain tumors.
• Approximately 50% of these patients will have
leptomeningeal spread at time of presentation.
• Initial treatment options include Surgery, Craniospinal
Radiation +/- Chemotherapy.
• Survival rates are very poor in these patients when
tumor recur after initial treatment.
PURPOSE
• This IRB approved study is based upon the hypothesis
that infusion of chemotherapy agents directly into the
fourth ventricle may offer an effective new treatment
approach for children with recurrent, infratentorial
malignant brain tumors.
• Infusion into the 4th ventricle will also enable drug
distribution within the spinal subarachnoid space and
help treat leptomeningeal dissemination of the tumor in
the brain and spine.
PURPOSE
• Traditionally the CSF flow distribution is assessed by
nuclear medicine CSF flow study after injection of 111
In-DTPA into spinal canal by lumbar puncture.
• Disadvantages:
– Invasive procedure
– Radiation
– Poor spatial resolution with lack of anatomic
information.
MATERIAL AND METHODS
• Cine phase contrast CSF flow MRI imaging of total spine
was used to assess noninvasively the distribution of the
infused chemotherapy agent from the fourth ventricle
down to the lumbar spine.
• 6 patients with a median age of 12 years who had
previously undergone a posterior fossa craniotomy for
maximal safe surgical resection of a recurrent tumor and
implantation of a 4th ventricular access device (Ommaya
Reservoir).
MATERIAL AND METHODS
• Prior to infusing chemotherapy into the 4th ventricle, all
patients underwent non-invasive Cine phase contrast
CSF flow MRI sequence of the brain and total spine with
Velocity Encoding (VENC) of 5 cm/sec and 10 cm/sec to
confirm CSF flow from the fourth ventricular outlets to
the cervical, thoracic, and lumbar spine.
• CSF flow was assessed by two fellowship trained
neuroradiologists and was characterized qualitatively as
present or absent as well as any obstruction in CSF flow.
Phase Contrast CSF Flow Sequence Acquisition
• FOV 450 Sagittal body coil locator of Entire spine slice
thickness 5mm, 0 mm gap
• FOV 450 Coronal body coil locator of Entire spine slice
thickness 5mm, 0 mm gap
• FOV 380 x 314 Sagittal CSF Flow 1 Slice, slice
thickness 5mm, 0mm gap.
• Check images for any artifacts appear in the cord.
• Placement of the anterior SAT band as close as possible
to spine to reduce heart motion and other artifacts that
may fall into the field of the CSF flow as seen in next
slide.
• FOV is set according to patient size.
Phase Contrast CSF Flow Sequence Acquisition
Sagittal Locator :
• Patient is placed on a Entire
Spine/CTL (Cervical, Thoracic,
Lumbar) coil.
• Sagittal Locator is acquired in 2
Stages and then fused.
• Coronal plane is then Acquired
to check for spine alignment.
Phase Contrast CSF Flow Sequence Acquisition
Sagittal Locator :
• Sagittal Sat Band is placed
anterior to the spine to saturate
out the pulsation artifacts from
Heart as well as Aorta.
Phase Contrast CSF Flow Sequence Acquisition
Coronal Locator :
• Coronal plane is then acquired
to check for spine alignment.
• Sagittal Single Line placement is
setup up from coronal plane.
Phase Contrast CSF Flow Sequence Parameters
Sequence
2D
Plane
Sagittal
VENC
5 cm/sec or 10 cm/sec
FOV
20 - 36 depending upon patient size
TR
20 - 24
TE
4-6
Flip Angle
10 - 12
Matrix
250 x 250
Slice Thickness / Gap
5mm / 0
Scan Time
5 – 6 mins
6 year, male pt. with recurrent medulloblastoma
T2
DWI
ADC
T1 Post
• T2 isointense mass within left sided posterior fossa resection cavity with
associated restricted diffusion and post contrast enhancement.
• Finding suggestive of recurrent medulloblastoma.
6 year, male pt. with recurrent medulloblastoma
T2
T1 Post
T2
• Patient underwent resection of recurrent medulloblastoma and placement of
Ommaya reservoir with catheter ends within resection cavity.
6 year, male pt. with recurrent medulloblastoma
• Whole Spine Cine Phase
Gated CSF flow sequence
demonstrates preservation of
CSF flow from 4th ventricle to
lumbar spine.
• Typically, white represents
caudal to cranial flow, and
black represents cranial to
caudal flow.
RESULTS
• All 6 patients demonstrated CSF flow from the 4th
ventricle to the cervical, thoracic, and lumbar spine with
no evidence of obstruction.
• All sets of images were of diagnostic quality and there
was excellent concordance between the two
neuroradiologists in their interpretation.
• Preliminary results of this study (n=6) demonstrated
stable disease in 4 patients, improvement in 1 patients
and disease progression in 1 patient on follow up MRIs.
Physics of Phase Contrast-MRI
• Until now, the only MR imaging technique to visualize
CSF movement is cardiac gated cine phase contrast MR
sequence (PC-MRI).
• The PC MRI generates signal contrast between flowing
and stationary nuclei by sensitizing the phase of the
transverse magnetization to the velocity of motion.
• Two data sets are acquired with opposite
sensitization/polarity.
Physics of Phase Contrast-MRI
• When the 2 datasets are
subtracted, accumulated net phase
of stationary nuclei will be zero and
signal will be eliminated from final
image.
• However moving nuclei move from
one position in the magnetic field
gradient to another during the time
between the executions of the 2
opposite polarity gradients, the
moving nuclei accumulate a net
phase proportional to the velocity of
the nuclei and there is residual
signal from flowing CSF in final
image.
http://mriquestions.com/phase-contrast.html
Physics of Phase Contrast-MRI
• Before PC MRI data are acquired, the anticipated
maximum CSF flow velocity must be entered into the
pulse sequence protocol which is known as “Velocity
encoding(VENC)”.
• VENC can be adjusted according to the arrangement of
the bipolar gradients.
• PC generates the best results when maximum CSF flow
velocity should be the same as, or slightly less than, the
selected VENC.
• Flow velocities greater than the VENC produce aliasing
artifacts, and velocities much smaller than the VENC
result in poor image quality and weak signal.
Physics of Phase Contrast-MRI
• CSF flow is pulsatile and synchronous with the cardiac
cycle, therefore cardiac gating can be used to provide
increased sensitivity.
• Cardiac gating can be provided with two different
methods: prospective gating and retrospective gating.
• In retrospective gating, the entire cardiac
cycle is sampled while in prospective gating only small
portion of cardiac cycle is sampled.
• Results from retrospective gating are more accurate as
compared with prospective gating.
Physics of Phase Contrast-MRI
• Phase contrast CSF flow sequence contains magnitude
and phase information.
• Magnitude images provide anatomical information.
• Phase images provides velocity information. Greyscale
intensity of each pixel is directly related to the velocity of
CSF.
Study Interpretation
• CSF pulsations are driven by the cardiac cycle.
• During systole, blood rushes into the fixed-volume
cranium, squeezing the ventricles, and causing CSF to
flow caudally out of the brain into the spine and spinal
cord.
• During diastole, CSF flows cranially back into the brain.
• Caudal flow of CSF is conventionally represented as
shades of white on phase images, whereas cranial flow
is by shades of black.
Study Interpretation
(A)
(B)
(C)
(A)Re-phased image is a magnitude of flow compensated signal, in this
image the flow is bright and background is visible
(B)Magnitude image is a magnitude of difference signal, in this image
the flow is bright and the background is suppressed
(C)Phase image is a phase of difference signal, in this image forward
flow is bright, reverse flow is black and background is mid-grey.
CONCLUSION
• CSF flow including the fourth ventricle and the total spine
can be assessed non-invasively with CINE phase
contrast CSF flow sequence.
• This sequence can be served as a new alternative to
nuclear medicine studies for confirmation of CSF flow
before infusion of intrathecal chemotherapy.
• Advantages over nuclear medicine studies include
avoiding an invasive procedure as well as radiation
exposure.
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flow patterns of posterior fossa cystic malformations using CSF flow MR
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Yildiz H, Erdogan C, Yalcin R, Yazici Z, Hakyemez B, Parlak M, et al.
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