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CSF Flow Study In MRI
1. CSF FLOW STUDY IN MRI
Mohit Deswal
Assistant Professor
Radio Imaging Technology
2. Cerebro Spinal Fluid
• Cerebrospinal fluid (CSF) is a clear, colorless bodily fluid
that occupies the subarachnoid space and the ventricular
system around and inside the brain and spinal cord.
• The CSF occupies the space between the arachnoid mater and
the pia mater.
• Total volume
– Adults: 140-170 ml
– Children:10-60 ml
3. • 50 to 70% of CSF is produced
in the brain by modified
ependymal cells in the choroid
plexus.
• Remainder is formed around
blood vessels and along
ventricular walls.
• Reabsorbion of CSF occurs
at the aracnoid villi projects
in the venous sinuses in the
duramater.
Production of CSF
5. • Two components can be distinguished in CSF circulation:
– (i) bulk flow (circulation)
– (ii) pulsatile flow (back and forth motion).
• In bulk flow, CSF is produced by choroid plexus and
absorbed by arachnoid granulations.
• In pulsatile flow, CSF movement is pulsatile and results from
pulsations related to cardiac cycle.
• Because very little CSF circulates through the subarachnoid
space, pulsatile flow can be measured and demonstrated by
PC MRI.
6. • Protection: CSF protects the brain tissue from injury.
• Chemical stability.
• Prevention of brain ischemia.
• Clearing waste.
Functions of CSF
12. • Two techniques are used
Time resolved 2DPhase Contrast MRI
Time Spatial Labeling Inversion Pulse(Time-SLIP)
Imaging sequences
13. • CSF flow is pulsatile and synchronous with the cardiac
cycle,
cardiac gating can be used to provide increased sensitivity.
• Retrospective gating – follows
the R wave and entire cardiac
cycle
is sampled.
• Prospective gating – Partial
cardiac cycle is sampled.
• Most accurate results are obtained
in retrospective gating.
Cardiac Gating
14. • The PC MRI generates signal contrast between flowing and
stationary nuclei by sensitising the phase of the transverse
magnetisation to the velocity of motion.
• Before PC MRI data are acquired, the anticipated maximum
CSF flow velocity must be entered (velocity encoding
(VENC)).
– For optimal signal, the CSF flow velocity should be the
same as, or slightly less than, VENC.
– velocities greater than VENC can produce aliasing artifacts.
– velocities much smaller than VENC result in a weak signal.
Phase Contrast technique
15. • Standard VENC value : 5 – 8 cm/s
• Low VENC values (2–4 cm/s) : Discrimination of
communicating and non-communicating arachnoid cysts and
assessment of the VP shunt patency.
• Higher VENC values (20–25 cm/s) : For hyper dynamic
CSF flow within the cerebral aqueduct in normal pressure
hydrocephalus.
16. • Two data sets are acquired with opposite sensitization.
• For stationary nuclei, the net phase is zero, and their signal is
eliminated.
• However, flowing nuclei move from one position to another
between the time of the first sensitization and that of the
second sensitization.
• Because phase varies with position, the net phase after
subtraction of the two data sets is non-zero, and there is
residual signal from flowing CSF.
• The combination of PC MRI acquisitions results in
magnitude
and phase images.
17. Magnitude image is a magnitude
of difference signal. In this image
the flow is bright and the
background is suppressed
Phase image is a phase of difference
signal. In this image forward flow is
bright, reverse flow is black and
background is mid-grey.
18. • Two series of PC imaging techniques are applied
• Flow quantification - In the axial plane, with through-plane
velocity encoding.
• Qualitative assessment - In the sagittal plane, with in-plane
velocity encoding.
Through-plane is performed in
axial oblique plane perpendicular
to the aqueduct.
19. In plane is performed in
sagittal plane parallel to the
aqueduct .
20. The sequence of timeresolved 2D phase contrast MRI with
velocity encoding help us in two ways
1.Quantitatively
2.Qualitatively
21. ForQuantitative
Axial technique: CSF flow dynamics were
quantitatively studied by using a cardiac gated
(Peripheral ECG gating being used for cardiac
synchronization) high resolutionaxial phasecontrast.
23. For qual i t at i ve assessm
ent of C
SF f l ow
For qualitative
assessmentof CSFflow,
midsagittalphase
contrast images were
obtained with in-plane
velocity encoding in the
caudocranial direction
which signs low signal
to craniocaudal CSF
displacement
25. • Take axial phase images obtained from through plane.
• Draw an ROI at the level of aqueduct.
• Then intensity wave option is selected so that CSF flow
velocity is obtained as a curve.
Flow Quantification
26. •From the curve, flow velocity
table is obtained.
•The following parameters
must be then calculated and
obtained from the table.
End diastolic peak velocity = the highest positive velocity value in the
table (cm/s )
Peak systolic velocity = the highest negative velocity value in the table (cm/s )
Mean systolic velocity = summation of positive velocity values / their numbers
(cm/sec )
Peak systolic flow = the highest negative value in the table (ml/s )
Mean systolic flow = summation of all negative flow values / their numbers (ml/s )
Onset of CSF flow = from beginning of curve till the end of the diastole (msec )
Duration of CSF systole = from the end of diastole till end of the systole (msec)
Systolic stroke volume = mean systolic flow x duration (micro liters )
27. • Time SLIP can be used to capture CSF flow.
• It is based on the arterial spin labeling technique.
• Unlike PC MRI, 2D Time SLIP acquisitions are incremental,
allowing the bulk flow using Fast Advanced Spin Echo
(FASE) sequence.
• A series of single shot images with incremental inversion
recovery delay times are acquired.
• CSF flow can be acquired in any plane.
Time Spatial Labeling Inversion
Pulse
28. A non selective IR pulse is
applied ,inverting all signal
in the field of view.
A second
specially
selective
inversion pulse
is applied to
the region of
interest.
After a short
period, tagged
CSF is seen
moving in to
the non tagged
background.
Time SLIP
29. • Aqueduct : Sagittal acquisition with axial tag
Imaging planes
30. • Chiari : Sagittal acquisition with axial tag
39. Data for healthy volunteers
Analysis revealed that in the control group, the mean
systolic velocity at the level of the aqueduct was around
1.18 cm/sec (+/- 0.47).
The peak systolic velocity was around 2.27 cm/sec (+/-
0.94).
Also we obtained a mean value of 27.26microliters (+/- 3.5)
for the aqueductal systolic stroke volume in healthy
volunteers.
40. velocity(cm/s)
velocity(cm/s)
velocity(cm/s)
systole(mm/s)
systole(mm/s)
(mm/s)
systole(mm/s)
(mm)
(ml/s)
volume (μl/s)
Parameters 1 2 3 4 5
End diastolic peak
0.37 1.68 1.91 4.02 2.36
Systolic peak
0.69 2.54 2.41 3.24 2.49
Systolic mean
0.35 1.455 1.50 1.346 1.251
Time of CSF peak
218 190 258 339 214
Onset of CSF
125 120 120 120 577
End of CSF systole
270 440 480 450 299
Duration of CSF
145 320 360 330 363
Aqueductal area
0.053 0.054 0.055 0.051 0.125
Mean systolic flux
0.018 0.885 0.087 0.08 0.066
Systolic stroke
26 28.3 32 26 24
An overview of the measured and calculated parameters of
the aqueductal CSF flow in normal volunteers.
41. In NPH cases
Pathological CSF flow dynamics in normal pressure
hydrocephalus, The systolic peak velocity and the systolic
stroke volume values were statistically significantly higher
than those of the normal controls, these results indicate that
patients with normal pressure hydrocephalus have
hyperdynamic aqueductal CSF flow. In NPH cases ,
systolic stroke volume are above 60 microliters
42. velocity(cm/s)
velocity(cm/s)
velocity(cm/s)
systole (mm/s)
(mm/s)
(mm/s)
systole (mm/s)
(mm)
(ml/s)
volume (μl/s)
Parameters 1 2 3 4 5 6 7 8 9
End diastolic peak
4.31 3.86 3.85 2.74 2.68 1.48 3.51 2.82 2.72
Systolic peak
4.27 4.27 4.79 6.97 3.87 2.26 5.32 3.78 4.42
Systolic mean
1.91 2.473 12.94 3.918 2.09 1.264 6.34 5.54 6.76
Time of CSF peak
225 305 401 351 307 296 505 440 385
Onset of CSF systole
149 200 260 175 160 162 180 170 135
End of CSF systole
449 520 640 550 620 592 510 550 620
Duration of CSF
300 350 380 375 460 430 330 380 485
Aqueductal area
1.58 0.124 0.148 0.117 0.098 0.155 0.198 1.231 1.553
Mean systolic flux
0.304 0.332 0.304 0.489 0.206 0.275 0.339 0.335 0.195
Systolic stroke
91 106 116 183 94 118 112 135 95
An overview of the measured and calculated parameters ofaqueductal
CSF flow in NPH patients with very high stroke volume.
43. In Cerebral atrophy
In cerebral atrophy, blood flow to the brain is decreased; we
found markedly lower systolic peak velocity, systolic mean
velocity and stroke volume values in comparison to healthy
volunteers indicating a hypodynamic CSF circulation.
Systolic stroke volume are around 10 microliters
44. • 73-year-old male with the diagnosis of normal pressure hydrocephalus
presented with urinary incontinence and dementia.
• Axial and sagittal T2 weighted images show enlarged ventricles, upward
bowing of corpus callosum consistent with transependimal CSF leakage/gliosis
and normal cerebral sulci.
• Quantitative cerebrospinal fluid (CSF) flow analysis graphic reveal
hyperdynamic flow rates in the aqueduct
Clinical Studies
45. • A 24-year-old female with the diagnosis of Chiari 1 malformation presented
with sub occipital headache.
• Pre-operative and post-operative sagittal T2 weighted MRI show a large syrinx
in association with cerebellar tonsillar ectopia.
• Pre- and post-operative cerebrospinal fluid (CSF) flow MRI show no association
between cervical subarachnoid space and cisterna magna. No symptomatic
improvement was observed after the surgery. Both pre-operative and post-
operative CSF flow MRI show pulsatile CSF flow in the syrinx.
46. A series of single shot 2D Time SLIP images are shown in the coronal view
before and after the shunt placement. In the pre shunt series CSF is unable
to flow in to the lateral ventricles and after shunt placement CSF flow into
the lateral ventricles.
47. Summary
Formation and absorption of CSF
Conditions changing CSF flow dynamics
Quantitative & qualitative assessment
Selection of sequence
Survey
CSF drive
CSF QF
CSF PCA
Post processing
Systolic stroke volume
Normal case (27.26 micro liters) NPH
case (>60 micro liters) Cerebral
atrophy (10 micro liters)
48. • Until now, the only MR imaging technique to visualize CSF
movement is phase-contrast (PC) MR imaging.
• Time–spatial labeling inversion pulse(Time-SLIP)is another
option, which makes it possible to noninvasively select CSF
at any region in the CNS and visualize its movement for up
to 5 seconds, providing information about CSF dynamics
even in slow-flowing regions.
• Time-SLIP is expected to have widespread application for
diagnosis and evaluation of response to treatment of
abnormal CSF movement.
Conclusion
