Normal MRI Appearance and Motion-Related Phenomena of CSF
Christopher Lisanti1,
Carrie Carlin1,
Kevin P. Banks2 and
David Wang3
1 Department of Radiology, Wilford Hall Medical Center, Lackland AFB, TX.
2 Department of Radiology, Fort Sam Houston, MCHE-DR, 3851 Roger Brooke Dr.,
Fort Sam Houston, TX 78234.
3 Department of Radiology, University of Colorado Health Sciences Center,
Denver, CO.
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Fig. 1A —Schematic representation of factors involving occurrence and degree
of time-of-flight (TOF) losses. Portion of excited mobile protons within CSF
move out of slice volume between 90° and 180° pulse applications
(TE/2). Only those protons subjected to both pulses will yield signal.
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Fig. 1B —Schematic representation of factors involving occurrence and degree
of time-of-flight (TOF) losses. More mobile protons move out of slice volume
between 90° and 180° pulses as CSF flow velocity increases, which
results in increasing TOF losses. Same effect occurs with increasing TE
because mobile protons have more time to move out of slice volume before
application of 180° refocusing pulse.
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Fig. 1C —Schematic representation of factors involving occurrence and degree
of time-of-flight (TOF) losses. Decreasing CSF flow angle relative to imaging
plane results in lower effective velocity relative to slice volume, which
results in decreasing TOF losses. Veffective = effective velocity,
Vactual = actual velocity, COS = cosine.
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Fig. 1D —Schematic representation of factors involving occurrence and degree
of time-of-flight (TOF) losses. With increasing slice thickness, fewer mobile
protons move out of slice volume between 90° and 180° pulses, which
results in decreased TOF signal loss.
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Fig. 2 —Healthy 26-year-old female volunteer. Axial T2-weighted image
through level of lateral ventricles shows two foci of decreased CSF signal
just superior to foramen of Monro (arrows) secondary to time-of
flight losses.
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Fig. 3A —65-year-old woman with hepatitis and pancreatitis undergoing MR
cholangiopancreatography. T2-weighted single-shot fast spin-echo image
acquired during systole shows time-of-flight signal losses (arrows)
in ventral and lateral subarachnoid space.
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Fig. 3B —65-year-old woman with hepatitis and pancreatitis undergoing MR
cholangiopancreatography. Same sequence acquired during diastole shows normal
bright CSF signal surrounding thoracic spinal cord.
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Fig. 4A —71-year-old man with cervical spine pain after fall. Axial
T2-weighted image through cervical canal shows foci of signal loss in
subarachnoid space (arrows) due to to-and-fro motion of CSF and
associated time-of-flight (TOF) losses.
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Fig. 5 —21-month-old male infant with seizures and developmental delay.
Axial T2-weighted image through third ventricle shows darker signal centrally
(arrow) and brighter signal peripherally (arrowheads). This
is common appearance of CSF in this region due to laminar flow effects.
Laminar flow results in slower flow peripherally (less time-of-flight [TOF]
loss) and faster flow centrally (more TOF loss).
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Fig. 6A —45-year-old man with left sensorineural hearing loss. Axial
T2-weighted image at cerebellopontine angle shows signal loss anterior to
basilar artery (arrows) due to time-of-flight losses.
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Fig. 7 —63-year-old man with vertigo. Coronal postgadolinium T1-weighted
image through third ventricle shows bright CSF signal (arrow) due to
flowrelated enhancement (FRE) on entry slice. FRE rapidly diminished on deeper
coronal slices (not shown.)
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Fig. 8A —Healthy subject. Axial T2-weighted image through upper cervical
spine shows multiple areas of abnormal bright CSF signal within periphery of
subarachnoid space (arrows) due to flow-related enhancement, No
saturation band was applied.
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Fig. 8B —Healthy subject. Axial T1-weighted image shows marked decrease in
intensity of multiple foci of bright signal (arrows) in CSF due to
application of superiorly placed saturation band. TR and TE remained
unchanged.
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Fig. 9 —Healthy subject. Axial FLAIR image through level of lateral
ventricles illustrates high signal (arrows) seen in lateral
ventricles just superior to foramen of Monro due to flow-related
enhancement.
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Fig. 10 —19-year-old woman with headaches. Midline sagittal FLAIR image shows
flow-related enhancement (arrow) at foramen magnum initially thought
to be Chiari I malformation. Sagittal T1-weighted images (not shown) showed
normal dark CSF signal at foramen magnum.
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Fig. 11B —57-year-old man with remote history of left cerebellar astrocytoma
resection. Axial T2-weighted image shows time-of-flight (TOF) loss
(arrow) in exact location of FRE in A. This example nicely
shows importance of background signal and sequence type on whether moving CSF
protons will result in bright signal (FRE) or dark signal (TOF loss).
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Fig. 12A —8-year-old girl with history of right frontal lobe glioma resection.
Axial FLAIR image at level of lateral ventricles shows marked bright signal
(arrows) secondary to flow-related enhancement (FRE) in enlarged
right lateral ventricle and surgical defect with minimal FRE in normal-sized
left lateral ventricle.
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Fig. 13 —25-year-old man with thoracic spine pain. Sagittal T2-weighted image
through thoracic spine shows globular signal loss in dorsal subarachnoid space
(arrows) resulting from turbulence and time-of-flight effects
associated with complex CSF flow.
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Fig. 14 —70-year-old man with normal pressure hydrocephalus. Midline sagittal
3D fast spin-echo T2-weighted image shows significant loss of signal
associated with increased velocities and turbulent flow in superior aspect of
fourth ventricle (arrows). Corresponding sagittal T1-weighted image
(not shown) shows normal dark CSF signal.
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Fig. 15A —32-year-old woman with butterfly vertebral body and scoliosis. Axial
T2-weighted image at level of thoracic cord shows significant asymmetric
time-of-flight signal losses in CSF (arrows).
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Fig. 16 —Healthy 32-year-old man. Axial T2-weighted image through cerebellum
shows focus of near-complete signal loss adjacent to basilar artery
(arrow) from transmitted turbulence from artery and some
time-of-flight (TOF) losses resulting in appearance of artifactual basilar
aneurysm. Notice also mild TOF losses in CSF (arrowheads).
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Fig. 18A —Healthy 2-year-old boy. As TE increases, ghosting artifact becomes
more conspicuous due to increased brightness of ghosting source. Axial
proton-density-weighted image (TR/TE, 3,000/30) shows dark and bright ghosting
(arrows) due to CSF flow within fourth ventricle.
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Fig. 18B —Healthy 2-year-old boy. As TE increases, ghosting artifact becomes
more conspicuous due to increased brightness of ghosting source. By increasing
TE to 120 milliseconds, image shows dark and bright ghosting (arrows)
become more evident.
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Fig. 19 —48-year-old woman. Axial fast spin-echo T2 image shows bright
ringshaped lesion (black arrows) in left lobe of liver due to
ghosting of CSF motion. Notice faint ring ghost more posteriorly and more
conspicuous ghost posterior to patient (white arrow). Ghosts and
spinal canal are all in anteroposterior phase-encoding direction, which
confirms identity of this lesion as ghosting artifact.
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Copyright © 2007 by the American Roentgen Ray Society.
