2. Magnetic Resonance Imaging
All MRI machines work on hydrogen atom as
hydrogen is considered the most common atom
in the body, 90% of body is water (H20). The
movement of the hydrogen protons in the
magnetic field is the basis of MRI imaging. The
protons are stimulated by a Radiofrequency (RF)
coil and then left to relax in the direction of the
magnetic field creating energy that is used for
development of the image.
3. MRI of Spinal Cord and CSF flow
Non-invasive
–Provides anatomic detail of brain, spinal
cord, intravertebral disc spaces, and CSF
within subarachnoid space
–Does not require intrathecal injection
–Does not have bone artifacts
Contraindications to MRI
• Pacemakers
• Ferromagnetic aneurysm clips
• Metallic spinal fusion rods
4. Preference of MRI
• MRI is the preferred modality for middle and
posterior cranial fossa of brain.
– In CT these structures are obscured by bone
artifacts
• Spinal cord
– Allows direct visualization of spinal cord, nerve
roots, and surrounding CSF
– Can be done in various planes
– Aid in diagnosis and treatment of neuro-
disorders
5. Usefulness of MRI
• Assessing demyelinating • Herniated disks
disease
– Such as MS • Congenital abnormalities
of vertebral column
• Spinal cord compression • Metastatic disease
• Post radiation therapy • Para spinal masses
changes of spinal cord
tumors
6. Not valuable for diagnosing:
• Osseous bone abnormalities of skull
• Intracerebral hematomas
• Subarachnoid Hemorrhage
– CT preferred for these 3 illnesses
7. MRI Magnetic Resonance Imaging
• MRI do not use ionizing radiation [ X-Rays ] for
imaging
• It can provide 3 dimensional imaging in the
axial, sagittal, coronal and oblique projections.
• MRI gives high resolution images.Both T1 AND T2
weighted images are essential for diagnosis.
• MRI can show the following ;
1. The fractured vertebra and its displacement
2. Ligamentous injury
3. Cord parenchymal lesions [specially in T2 WIs ]
4. Blood collections inside the spinal canal &
paravertebrally.
8. Any MRI examination should include:
• T1 weighted images [T1WIs] show (anatomy)
• T2 weighted images |T2Wls]
show(Pathology)
• Contrast used in MRI is Gadolinium PTPA
injected in an a dose of 0.1-0.2mL/kgm body
weight
• MR can obtain sections in any plane as
axial, sagittal and coronal.Oblique sections
can also be performed
9. Diagnosis by MRI
MRI Sections:
• Coronal Like X ray A-P
• Sagittal Like X ray lateral.
• Axial Like C.T.
11. Common MR appearance in T1 and T2 WIs
1) Low signal in T1 & low signal in T2 WIs (non
mobile protons)
a-Cortical bone e.g. edges of vertebrae
b- Mature fibrous tissues e.g. ligament and
tendons
c- Calcifications either normal or pathological
2) High signal in T1 & high signal T2Wis
Subacute hematoma
12. 3) High signal in T1 & low signal in T2 WIs
Fat and fat like structure e.g. lipoma
4) Low signal in T1 & high signal in T2 WIs
The most common signal behavior
Example: CSF, infarction, most of
tumors.
13. Please remember;
1) Bone marrow contains fat so appear bright
in T1 and darker in T2 WI
2) Thrombus = Subacute blood so appear white
in T1 & White T2 WIs
3) Normal flowing blood gives no signal so
appear Black in T1, Black in T2
4) Intervertebral disc: Nucleus pulposus
(contains water) black in T1, white T2,
Annulus fibrosus (mature fibrous tissue)
black in T1, black in T2
14. Imaging Technology
1. X-RAYS: These show (1) disc narrowing, (2) bone spurs
(osteophytes), and (3) vertebrae slipping off another
(spondylo-lithesis)
2. CAT SCAN: This is a computerized X ray that shows how
much the diameter of the canal is reduced and how far
out the discs are
3. M.R.I. (Magnetic Resonance Imaging): It produces
picture like the CAT scan but they are generated using a
magnetic field (instead of radiation) – not needed if the
CAT scan shows the problems. 14
15. MRI (magnetic resonance imaging):
• Image is produced due to reaction between
magnetic field inside the body & the magnetic
field of the device.
• This magnetic field inside the body is produced
due to movement of Hydrogen ions as H+ protons
are the most found ions in the body.
16. No image is obtained incase of:
1. Site without hydrogen ions.
2. If the hydrogen ions aren’t moving.
There are 2 types of images:
1-T1 image:
• All fluids as C.S.F. black
• Fats are white
• Brain & spinal cord are dark grey
17. 2-T2 image:
• All fluids as C.S.F. is white
• Fats are black
• Brain & spinal cord are light grey
There are 3 views:
• Sagittal: as lateral image in x-ray.
• Axial: as in CT.
• Coronal: used to detect scoliosis, Intraspinal
tumor, Para spinal soft tissue
N.B. : the slide is taken every 4 mm in the whole column
(cervical,dorsal, and lumbar) unlike CT
19. Types of MRI
1. Open MRI
2. Closed MRI
3. Extremity MRI or for pediatric head.
Surface coil:
Is a device used for imaging & the patient must lie on
it, it is used to produces a large image with high
resolution.
N.B :There was a coil used for imaging cervical
spine but it is not used nowadays as it moves with
breathing so the image becomes unclear.
20. What is seen in MRI
1. Bone: vertebral endplate is black while in CT is white
2. Disc
3. Paravertebral soft tissue
4. Bone marrow indicated for MRI only
5. Spinal cord indicated for MRI only
N.B.:
MRI takes slides from left to right, so when we detect the
midline image we choose the picture which contains the
clearest image of spinal cord & conus medularis & what is
before it is left & what is after it is right.
21. 1. Spinal canal (in axial image)
If the thecal sac is circled & the epidural fat is found
normal.
2. Cauda Equina (in axial image)
Is more obvious in T2 more than T1 as in T2 C.S.F is
white & nerve roots are grey in colour as well as it‘s
not obvious in CT.
3. Spinal cord (in sagittal image)
Spinal cord must be enveloped with C.S.F. anteriorly
& posteriorly
Mild stenosis: if C.S.F is found in one direction only
anterior Or posterior.
Moderate stenosis: C.S.F isn’t found at all.
22. 4. Bone marrow
Contains fat & fat is white in T1 & black in T2
5. Disc (in midline sagittal T2 image)
IF:
a. Disc contains water it is white & it’s edge is within
the vertebral edgeNORMAL.
b. Disc doesn’t contain water (becomes black) & it’s still
within the vertebral edge DEGENERATED.
c. Disc doesn’t contain water (becomes black) & it’s edge
isn’t within the vertebral edge it may be
PROTRUDED OR HERNIATED.
24. 1. spinal canal stenosis: (SCS)
a) Idiopathic or Congenital SCS:
< 13 mm reduced sagittal diameter
Relative 11-12 mm / Absolute 8-9-10 mm
b) Developmental SCS:
Increases by time inspite of normal diameter which due
to
i) Hypertrophy of the lamina (becomes thick & short) &
the angle becomes acute instead of being obtuse
ii) Articular facet hypertrophy
iii) Ligamentum flava hypertrophy
25. c- Acquired not discogenic:
as there are many causes
I) Disc lesions
ii) Osteophytes
Usually the patient has all types of spinal canal
stenosis
N.B.
Captious spinal canal: very wide canal
The canal diameter > 21 mm & it’s painful also as the
thecal sac becomes more free instead of being
fixed
I can appreciate SCS of lumbar spine in axial more
sagittal view .
26. -Ligaments, tendons and cortical bone are usually black in T1
& T2 images as they contain a lot of hydrogen ions but
they aren’t moving that is why they are black all the time.
-Ligamentum flava appears normally as a thin rope &
appears abnormally as a thick rope.
- Lateral recess measurement normally it measures about
0.5 cm or 5 mm if there is narrowing it compresses the
nerve roots.
27. Cervical spinal canal stenosis
We can detect it in sagittal T2 MRI image
1. Normally there’s C.S.F anterior & posterior to the cord
2. Mild there’s C.S.F only anterior or posterior to the cord
3. Moderate No C.S.F anterior or posterior to the cord
4. Severe No C.S.F & the cord is compressed as well
But in CT
Normally the cord is kidney shaped & there’s no idiopathic
SCS
Developmental SCS no disc & no C.S.F
Acquired SCS C.S.F disappears due to disc
28. Spinal Stenosis
Spinal stenosis is a progressive narrowing of the opening
in the spinal canal, which places pressure on the spinal
cord (nerve roots)
Pressure on nerve roots causes
chronic pain, and
loss of control over some
functions because
communication with the
brain is interrupted
29. Spinal Stenosis
Cervical spinal stenosis: Stenosis (narrowing) is located in
the neck
Lumbar Spinal Stenosis: Stenosis is located on the lower
part of the spinal cord
75% of cases of spinal stenosis occur in the low back
(lumbar spine), and legs are affected
Produce pain in the legs with walking, and the pain is relieved
with sitting
30. Summary
Disc Space Narrowing may be due to bulging and
herinated discs
Posterior osteophytes – bone spurs
Posterior Apophyseal Arthropathy – abnormal growth on
facet joints
Spondylolisthesis – vertebral slippage
We detect these conditions using X ray
59. Lung Metastasis. Post-contrast axial CT image showing a lung
metastasis in the right hemisphere adjacent to the falx with
surrouding edema and effacement of the sulci in the right hemisphere
secondary to the mass effect.
70. Olfactory Groove Meningioma. Post-contrast CT with multiple views displaying a
large olfactory meningioma expanding around the internal carotids and as far as the
clivus. Note the mass effect displacing the corpus callosum superiorly and posteriorly
and erosion of the anterior fossa floor
71. Posterior Fossa Meningioma. T1-weighted coronal MRI with contrast. A large tumour
is highlighted in the right posterior fossa and bilateral dilatation of the lateral
ventricles is evident (likely secondary to compression of the 4th ventricle or Sylvian
aqueduct)
72. Cauda Equina. T2-weighted axial MRI image showing a central disc
herniation compressing the cauda equina.
74. Central Disc Herniation. T2-weighted axial MRI showing a central disc
herniation compressing the cord (note the minimal amount of CSF and
change in cord morphology)
75. Cord Compression. T2-weighted sagittal MRI showing compression of
the L1 vertebra with posterior displacement vertebral body disrupting
the posterior spinal line
76. Far Lateral Disc Herniation. T2-weighted axial MRI
image showing a right-sided far lateral disc
herniation compressing the nerve root
78. Subarachnoid hemorrhage. Axial CT image with blood filling
the suprasellar cistern, ambient cisterns, interhemispheric
fissure, and sylvian fissures in the classic star pattern
79. Subarachnoid hemorrhage and Aneurysm. Axial non-contrast CT image
showing a SAH and right MCA aneurysm with mild hydrocephalus seen
by the prominent temporal horns of the lateral ventricles
80. Acute Subdural Hematoma. Non-contrast axial CT showing a left hemispheric
subdural hematoma with some blood tracking along the falx and concurrent
intracerebral hemorrhage on the right. Some compression is seen on the left with
decreased visibility of sulci and soft tissue swelling on the posterior left occipital lobe
81. Chronic Subdural Hematoma. Axial CT image showing left hemispheric
chronic subdural hematoma with neomembrane and compression of
the left hemisphere.
