mri technique to measure CSF flow

2. Basic principles :-
 CSF circulation is related to the cardiac cycle.
 During systole as blood flow into the brain…, CSF
flows down the aqueduct of sylvius.
 During diastole the reverse occurs.
 So, CSF systole is characterized by caudal CSF
motion
 & CSF diastole by cranial CSF motion

3.  Routine MRI Brain : Is done including sagittal T2, axial
T1,T2, FLAIR , coronal T2
 Flow Studies : The direction of velocity encoding is
caudo-cranial , so…
Any caudal flow --- low SI (systole)
& any cranial flow --- high SI (diastole)
 Retrospective cardiac gating is applied (EGG
Synchronization)

4. A) Qualitative Study
 Provides visual appreciation of the CSF flow through the
aqueduct & basal cisterns.
 A sagittal midline image is taken as a reference image, a
midline vertical phase is placed passing through the
aqueduct.
 Phase images are then obtained, again displaying caudal
CSF systole flow as low S.I & cranial CSF diastolic flow as high
S.I

5. B) Quantitative Study
 We take a midline sagittal T2 image as reference image.
 An Image Plane is drawn perpendicular to the proximal
third of the cerebral aqueduct.
 Then the cursor is placed at its level in the center of the
aqueduct (O).
 Axial phase images are then obtained showing the
aqueduct as a rounded structure (in cross section). (12-16
phase image are obtained alternating systole & diastole)
=Systolic images =Diastolic images
=CSF flow in aqueduct =CSF has in aqueduct
=Is of low S.I =is of high S.I

6.  An annular ROI is then placed within the aqueduct on
one of the phase image. The ROI should include more of
the aqueduct area(excluding brain tissue).
 The ROI area (determined by the (right click, Statistics)
pixel area) represents the aqueduct area (usually 1-5mm2)
 After placing the ROI , copy all is applied to all phase
images
 Then right click → intensity wave option is selected so that
we obtain the velocity of CSF as a curve.

7.  The curve displaying the velocity & flow values
along the cardiac cycle.
(Down flow) represent CSF wave during systole (-ve values)
(Up flow) represent wave during diastole (+ve values )

8. • Each curve has a corresponding table
(obtained by right click & select table option)

9. The following parameters must then be calculated & obtained
from the table.
1- End diastolic peak velocity (cm/sec)
2- Peak systolic velocity (cm/sec)
3- Mean systolic velocity (obtained by
calculating the mean value of all systolic
velocities in the table)
4- Peak systolic flow (cm/sec) (table)
5- Mean systolic flow(ml/cm/sec) calculated
from table)
6- Onset of CSF systole (msec)
7- Duration of CSF systole (msec)
8-Aqueducted area (see above)
Finally 9- Calculation of the aqueduct stroke volume (SV)
SV = Mean systolic flow x duration of CSF systole (& is
expressed in micro liters)

10. Indications :
 The main value of the study is to identify patients
with normal pressure hydrocephalus (NPH)
 NPH is associated with a classic triad of dementia, gait
disturbance, and urinary incontinence.
 NPH patients are candidates to shunting procedures with
marked improvement while patients with atrophy are
not.

11. NPH
 During systole… blood goes to the brain, but the
marked ventriculomegaly prevents any outward
expansion of the brain. ….So expansion is directed
inwards , squeezing the ventricles & expressing a
large amount of CSF through the aqueduct,
resulting into elevated stroke volume (SV) valves :
 These is called HYPERDYNAMIC CSF CIRCULATION.
 (SV)> 42 is usually found in such patients.

12. Atrophy
 Blood flow to the brain is reduced , therefore CSF
flow & velocities are usually close to base- line
values(< 1cm /sec) :
 This is called HYPODYMAMIC CSF CIRCULATION

13. Summary
 NPH all values are elevated  (HYPERDYNAMIC
CIRCULATION)
 Atrophy: all values are reduced (HYPODYMAMIC
CIRCULATION)

14. Normal patients of CSF flow quantification (according to a study conducted by
schcecle HWS et al 2000) ( Mean +/-SD)
End diastolic peak velocity 4.73+/-1.73cm/sec
Systolic peak velocity 5.56+/- 1.87 cm/sec
Mean systolic velocity 3.07 +/- 1.09 cm/sec
Mean systolic flow 0.06 +/- 0.06 cm/sec
Duration of CSF systole 465 +/- 84msec
Systolic SV 28 +/- 28.4 cm/sec

15. CASE 1
Dilated supra and infra tentorial ventricular system out of proportion to the
degree of the cortical atrophic changes.

16. Calculated mean systolic flow (summation of all –ve flow values /
their number) = 0.617 cm/sec
Aqueduct stroke volume (SV) = Mean systolic flow x duration of
CSF systole = 0.617x 320 = 197 microliters (hyperdynamic
circulation).

17. Report example
 Technique (at our hospital)
Axial FLAIR
Sagittal T2
Axial images showing CSF flow at the Aqiduct of sylvius.
 CSF flow curve:-
 End diastolic peak velocity = the highest positive velocity value in the table Cm/sec.
 Peak systolic velocity = the highest negative velocity value in the table Cm/sec.
 Mean systolic velocity= Summation of all positive velocity values / their number Cm/sec.
 Peak systolic flow= the highest negative flow value in the table ml/sec
 Mean systolic flow = Summation of all the negative flow values/ their number ml/sec.
 Onset of CSF systole = From beginning of the 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 microliters. …(the most important
value)

18.  The conventional MR images show:-
- Dilated supra and infra tentorial ventricular system out of
proportion to the degree of the cortical atrophic changes.
 Conclusion:-
Elevated stroke volume denoting hyperdynamic
circulation, being in favor of normal pressure
hydrocephalus, for clinical correlation.

20. PATIENT NAME:
DATE:
PROF. DR.:
Trans rectal US for the prostate and seminal vesicles
revealed:
•Urinary bladder shows normal wall thickness with no stones or masses
seen.
•Average size prostate measuring ……… mm, volume … cm3, with no foci
of calcifications.
•The central and the peripheral zones show homogenous echopattern with
no focal lesions.
•No periprostatic congestion.
•Normal seminal vesicles.
OPINION
Normal transrectal ultrasound study.