This document describes the process and parameters analyzed in quantitative cerebrospinal fluid (CSF) flow studies using phase contrast MRI. CSF flow is analyzed both qualitatively and quantitatively by measuring flow velocities and calculating stroke volume in the cerebral aqueduct. Elevated stroke volume is indicative of normal pressure hydrocephalus, while reduced values suggest cerebral atrophy. Key parameters including peak systolic and diastolic velocities, mean systolic flow, duration of CSF systole, and aqueduct stroke volume are calculated to differentiate normal, hyperdynamic, and hypodynamic CSF circulation.

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.