1. Prince of Wales Hospital
Neuro-Radiology
SPINE
Raj Reddy
Neurosurgery
Prince of Wales Hospital

2. Objectives Review spine anatomy on X-ray, CT and MRI
Approach to interpretation of imaging
Differential diagnoses for common spine lesions

3. Imaging Modalities

4. Basic Imaging Types X-ray CT (Computed Tomography)
MRI (Magnetic Resonance Imaging)
Angiography

5. X-ray
Limited Use
Evaluation of:
Bones (fractures)
Calcification

6. Computed Tomography

7. Computed Tomography (CT)
Imaging in sections, or slices
Computed
Geometric processing used to reconstruct an image
Computerized algorithms

8. Computed Tomography Uses X-rays
Dense tissue, like bone, blocks x-rays
Gray matter weakens (attenuates) the x-rays
Fluid attenuates even less
A computerized algorithm (filtered backprojection) reconstructs an image of each slice

9. CT Image Formation
X-ray tube
X-ray
X-ray detector

10. CT Image Formation
Backprojection

11. CT Image Reconstruction – 6 Slices

12. CT Image Reconstruction – 12 Slices

13. CT Image Reconstruction – Final

14. Magnetic Resonance Imaging

15. What is MR? Not an X-ray, electromagnetic
Electromagnetic field aligns all the protons in the brain
Radiofrequency pulses cause the protons to spin
Amount of energy emitted from the spin is proportional to number of protons in the tissue
No ferromagnetic objects

16. Angiography

17. Angiography Real time X-ray study
Catheter placed through femoral artery is directed up aorta into the cerebral vessels
Radio-opaque dye is injected and vessels are visualized
Gold standard for studying cerebral vessels.

18. Angiography
AP Right ICA
Lateral Right ICA

19. Angiography
AP Right Vertebral

20. Planes of Section
Axial (transverse)
Sagittal
Coronal
Oblique

21. Anatomy

26. Radiographic Anatomy

27. Cervical Spine – AP View

28. Cervical Spine – Lateral View

29. Cervical Spine – Open-Mouth (Dens) View

30. Cervical Spine – Oblique View

31. Lumbar Spine – AP View

32. Lumbar Spine – Lateral View

33. Approach to Xrays

34. Approach to Spine Imaging
A – adequacy/alignment
B – bone
C – cord/canal/cartilage
D – disc
E – extras

35. C7-T1

36. Alignment 1. prevertebral 2. anterior spinal 3. posterior spinal
4. spino-laminar

37. Cartilage
Predental Space should be no more than 3 mm in adults and 5 mm in children
Increased distance may indicate fracture of odontoid or transverse ligament injury

38. Cartilage Disc Spaces Assess spaces between the spinous processes
Should be uniform
Assess spaces between the spinous processes

39. Soft tissue Nasopharyngeal space (C1) - 10 mm (adult)
Retropharyngeal space (C2-C4) mm
Retrotracheal space (C5-C7) - 14 mm (children), 22 mm (adults)
Extremely variable and nonspecific

40. CT Anatomy

43. CT

44. MRI Anatomy

55. Compartments of the Spine
a. Intradural, intramedullary
b. Intradural, extramedullary
c. Extradural, extramedullary a. b. c.

56. …

61. Pathology

62. Spine Pathology Trauma Degenerative disease Tumors and other masses
Inflammation and infection
Vascular disorders
Congenital anomalies

63. Trauma

64. Evaluating Trauma Fracture – plain film / CT
Dislocation – plain film / CT
Ligamentous injury – MRI
Cord injury – MRI
Nerve root avulsion – MRI

65. To x-ray or not to x-ray?
13 million trauma patients at risk for cervical spine injury
very low incidence of cervical spine fracture
In alert and stable trauma patients:
x-rays performed on 69%
CT performed in 5%
acute injury in 2.6%
stabilization in 2.2%
Stiell IG et al. The Canadian C-Spine Rule versus NEXUS
in Patients with Trauma. N Engl J Med

66. NEXUS C-Spine Rules

67. Canadian C-Spine Rules (CCR)
Stiell IG. The CCR in Alert and Stable Trauma Patients. JAMA

68. Which one is better? NEXUS Pro: easy to use
Con: poor sensitivity and specificity (90.7% and 36.8%)
Con: more x-rays (67%)
CCR
Pro: great sensitivity and specificity (99.4% and 45.1%)
Pro: less x-rays (55.9%)
Con: more difficult to remember and use
Stiell IG et al. The Canadian C-Spine Rule versus NEXUS
in Patients with Trauma. N Engl J Med

69. Plain film findings may be very subtle or absent!
Anterolisthesis of C6 on C7
(Why?)

70. Fractures of C6 left pedicle and lamina

71. CT – 2D Reconstructions Acquire images axially…
…reconstruct sagittal / coronal

72. 26M MVA

73. Vertebral body burst fx with retropulsion into spinal canal
2D Reformats

76. Vertebral Artery Dissection/Occlusion Secondary to C6 Fracture

77. Hyperflexion fx with ligamentous disruption and cord contusion

78. Nerve root avulsion
Axial Coronal Sagittal

79. Degenerative Disease

80. Degenerative Disc (and Facet Joint) Disease
Foraminal stenosis
Thickening/Buckling of Ligamentum Flavum

81. Degenerative Disc (and Facet Joint) Disease

82. Degenerative Disc (and Facet Joint) Disease

84. Lumbar Spinal Stenosis

85. Lumbar Spinal Stenosis
MR#

86. Lumbar Spinal Stenosis

87. Lumbar Spinal Stenosis

88. Lumbar Spinal Stenosis

89. Lumbar Spinal Stenosis
Disc bulge, facet hypertrophy and flaval ligament thickening frequently combine to cause central spinal stenosis
Note the trefoil shape of stenotic spinal canal

90. Lumbar Spinal Stenosis
Disc bulge, facet hypertrophy and flaval ligament thickening frequently combine to cause central spinal stenosis
Note the trefoil shape of stenotic spinal canal

92. Foraminal Stenosis
Neural foramen

93. Cervical Spinal Stenosis

95. MRI - Degenerative Disc Disease
Age:
% have degenerated disc
% have degenerated disc
% have degenerated disc
<60 20% have asymptomatic disc herniation
Conclusion: Abnormal findings on MRI frequently DO NOT relate to symptoms (and vice versa) !

96. MRI – Herniated Disc Levels
85-95% at L4-L5, L5-S1
5-8% at L3-L4
2% at L2-L3
1% at L1-L2, T12-L1
Cervical: most common C4-C7
Thoracic: 15% in asymptomatic pts. at multiple levels, not often symptomatic

97. Schematic sagittal anatomical sections showing the differentiating features of an annular tear (radial tear in this case) and a disc herniation. The term "tear" is used to refer to a localized radial, concentric, or horizontal disruption of the anulus without associated displacement of disc material beyond the limits of the intervertebral disc space. Nuclear material is shown in black, and the annulus (internal and external) corresponds to the white portion of the intervertebral space. The same convention is used in Figures 3, 12, 13, and 14. (Adapted from Milette PC. The proper terminology for reporting lumbar intervertebral disk disorders. AJNR Am J Neurorad 1997;18: ; with permission.)
Annular

98. Symmetrical presence (or apparent presence) of disc tissue "circumferentially" (50-100%) beyond the edges of the ring apophyses may be described as a "bulging disc" or "bulging appearance", and is not considered a form of herniation. Furthermore, “bulging” is a descriptive term for the shape of the disc contour and not a diagnostic category.
Adapted from: “Nomenclature and Classification of Lumbar Disc Pathology: Recommendations of the Combined Task Forces of the North American Spine Society, American Society of Spine Radiology, and American Society of Neuroradiology,” 2001.

99. Asymmetrical bulging of the disc margin (50%-100%), such as is found in severe scoliosis, is also not considered a form of herniation.
Adapted from: “Nomenclature and Classification of Lumbar Disc Pathology: Recommendations of the Combined Task Forces of the North American Spine Society, American Society of Spine Radiology, and American Society of Neuroradiology,” 2001.

100. By convention, a "broad-based" herniation involves between 25% and 50% (90-180) of the disc circumference.
Adapted from: “Nomenclature and Classification of Lumbar Disc Pathology: Recommendations of the Combined Task Forces of the North American Spine Society, American Society of Spine Radiology, and American Society of Neuroradiology,” 2001.

101. By convention, a "focal herniation" involves less than 25% (90) of the disc circumference.
Adapted from: “Nomenclature and Classification of Lumbar Disc Pathology: Recommendations of the Combined Task Forces of the North American Spine Society, American Society of Spine Radiology, and American Society of Neuroradiology,” 2001.

102. Herniated discs may take the form of protrusion or extrusion, based on the shape of the displaced material (see definitions in text).
Adapted from: “Nomenclature and Classification of Lumbar Disc Pathology: Recommendations of the Combined Task Forces of the North American Spine Society, American Society of Spine Radiology, and American Society of Neuroradiology,” 2001.

103. Protrusion Extrusion Extrusion
When a relatively large amount of disc material is displaced, distinction between protrusion (A) and extrusion (B or C) will generally only be possible on sagittal MR sections or sagittal CT reconstructions. In Figure C, although the shape of the displaced material is similar to that of a protrusion, the greatest cranio-caudal diameter of the fragment is greater than the cranio-caudal diameter of its base at the level of the parent disc, and the lesion therefore qualifies as an extrusion. In any situation, the distance between the edges of the base, which serves as reference for the definition of protrusion and extrusion, may differ from the distance between the edges of the aperture in the anulus, which cannot be assessed on CT images and is seldom appreciated on MR images. In the cranio-caudal direction, the length of the base cannot exceed, by definition, the height of the intervertebral space (Adapted from Milette PC. Classification, diagnostic imaging and imaging characterization of a lumbar herniated disc. Radiol Clin North Am 2000; 38: )
Protrusion Extrusion Extrusion
Adapted from: “Nomenclature and Classification of Lumbar Disc Pathology: Recommendations of the Combined Task Forces of the North American Spine Society, American Society of Spine Radiology, and American Society of Neuroradiology,” 2001.

104. Protrusion w/ migration + sequestration Protrusion w/ migration
Schematic representation of various types of posterior central herniations. A, Small sub-ligamentous herniation (or protrusion) without significant disc material migration. B, Sub-ligamentous herniation with downward migration of disc material under the posterior longitudinal ligament (PLL). C, Sub-ligamentous herniation with downward migration of disc material and sequestered fragment (arrow). (From Milette PC. Classification, diagnostic imaging and imaging characterization of a lumbar herniated disc. Radiol Clin North Am 2000; 38: )
Protrusion w/
migration +
sequestration
Protrusion w/
migration
Protrusion
Adapted from: “Nomenclature and Classification of Lumbar Disc Pathology: Recommendations of the Combined Task Forces of the North American Spine Society, American Society of Spine Radiology, and American Society of Neuroradiology,” 2001.

105. Abnormal Disc Herniation Bulge Broad-based Focal Symmetric Asymmetric
< 180º
> 180º
Herniation
Bulge
90º–180º
< 90º
Broad-based
Focal
Symmetric
Asymmetric
Waist*
No waist
Extrusion
Protrusion
Sequestered
Migrated
Neither
*(In any plane)
Adapted from: “Nomenclature and Classification of Lumbar Disc Pathology: Recommendations of the Combined Task Forces of the North American Spine Society, American Society of Spine Radiology, and American Society of Neuroradiology,” 2001.

106. Central Disc Protrusion

107. L5-S1 Disc Extrusion Into Lateral Recess with Impingement of R S1 Nerve Root
MR#

108. Schmorl’s Nodes

109. Cervical Radiculopathy

110. Lumbosacral Radiculopathy (Sciatica)
Important:
A herniated disc at (e.g.) L4-5 may impinge either the L4 or L5 nerve roots!

111. L5-S1 Disc Extrusion Into Lateral Recess with Impingement of R S1 Nerve Root
MR#

112. Spondylolysis / Spondylolisthesis

113. Confusing “Spondy-” Terminology
Spondylosis = “spondylosis deformans” = degenerative spine
Spondylitis = inflamed spine (e.g. ankylosing, pyogenic, etc.)
Spondylolysis = chronic fracture of pars interarticularis with nonunion (“pars defect”)
Spondylolisthesis = anterior slippage of vertebra typically resulting from bilateral pars defects
Pseudospondylolisthesis = “degenerative spondylolisthesis” (spondylolisthesis resulting from degenerative disease rather than pars defects)

114. Tumors and Other Masses

115. Classification of Spinal Lesions
Extradural = outside the thecal sac (including vertebral bone lesions)
Intradural / extramedullary = within thecal sac but outside cord
Intramedullary = within cord

116. Common Extradural Lesions
Herniated disc
Vertebral hemangioma
Vertebral metastasis
Epidural abscess or hematoma
Synovial cyst
Nerve sheath tumor (also intradural/extramedullary)
Neurofibroma
Schwannoma

117. Common Intradural Extramedullary Lesions
Nerve sheath tumor (also extradural)
Neurofibroma
Schwannoma
Meningioma
Drop Metastasis

118. Common Intramedullary Lesions
Astrocytoma
Ependymoma
Hemangioblastoma
Cavernoma
Syrinx
Demyelinating lesion (MS)
Myelitis

119. Classification of Spinal Lesions
Dura
Cord
Intradural
Extramedullary
Extradural
Intramedullary

120. Extradural: Vertebral Body Tumor

121. Extradural: Vertebral Metastases
MR#
T2 (Fat Suppressed) T T1+C (fat suppressed)

122. Extradural: Vertebral Metastases?
T2 (Fat Suppressed) T T1+C (fat suppressed)

123. Vertebral Metastases vs. Hemangiomas
Hemangiomas (Benign, usually asymptomatic, commonly incidental):
Bright on T1 and T2 (but dark with fat suppression) Enhancement variable
Metastases:
Dark on T1, Bright on T2 (even with fat suppression) Enhancement

124. Vertebral Hemangiomas

125. Extradural: Vertebral Metastases
Diffusely T1-hypointense marrow signal may represent widespread vertebral metastases as in this patient with prostate Ca
This can also be seen in the setting of anemia, myeloproliferative disease, and various other chronic disease states

126. Extradural: Epidural Abscess

127. Extradural: Nerve Sheath Tumor
(Schwannoma)

128. Intradural Extramedullary: Meningioma

129. Intradural Extramedullary: Meningioma

130. Intradural Extramedullary: Nerve Sheath Tumor
(Neurofibroma)

131. Intradural Extramedullary: “Drop Mets”
MR#
T T T1+C

132. Intradural Extramedullary: “Drop Mets”

133. Intradural Extramedullary: Arachnoid Cyst
T T1

134. Intramedullary: Astrocytoma

135. Intramedullary: Astrocytoma

136. Intramedullary: Cavernoma

137. Intramedullary: Ependymoma

138. Intramedullary: Syringohydromyelia
Seen with:
congenital lesions
Chiari I & II
tethered cord
acquired lesions
trauma
tumors
arachnoiditis
idiopathic

139. Intramedullary: Syringohydromyelia
Seen with:
congenital lesions
Chiari I & II
tethered cord
acquired lesions
trauma
tumors
arachnoiditis
idiopathic

140. Confusing “Syrinx” Terminology
Hydromyelia: Fluid accumulation/dilatation within central canal, therefore lined by ependyma
Syringomyelia: Cavitary lesion within cord parenchyma, of any cause (there are many). Located adjacent to central canal, therefore not lined by ependyma
Syringohydromyelia: Term used for either of the above, since the two may overlap and cannot be discriminated on imaging
Hydrosyringomyelia: Same as syringohydromyelia
Syrinx: Common term for the cavity in all of the above

141. Infection and Inflammation

142. Infectious Spondylitis / Diskitis
Common chain of events (bacterial spondylitis):
Hematogenous seeding of subchondral VB
Spread to disc and adjacent VB
Spread into epidural space  epidural abscess
Spread into paraspinal tissues  psoas abscess
May lead to cord abscess

143. Infectious Spondylitis / Diskitis
T T T1+C T1+C

144. Infectious Spondylitis / Diskitis

145. Pyogenic Spondylitis / Diskitis with Epidural Abscess

149. T1 T2

150. Spinal TB (Pott’s Disease)
Prominent bone destruction
More indolent onset than pyogenic
Gibbus deformity
Involvement of several VB’s
T1 + C

151. Spinal TB (Pott’s Disease)
Prominent bone destruction
More indolent onset than pyogenic
Gibbus deformity
Involvement of several VB’s

152. Transverse Myelitis Inflamed cord of uncertain cause Viral infections
Immune reactions
Idiopathic
Myelopathy progressing over hours to weeks
DDX: MS, glioma, infarction

153. Multiple Sclerosis
Inflammatory demyelination eventually leading to gliosis and axonal loss
T2-hyperintense lesion(s) in cord parenchyma
Typically no cord expansion (vs. tumor); chronic lesion may show atrophy

154. Multiple Sclerosis
Inflammatory demyelination eventually leading to gliosis and axonal loss
T2-hyperintense lesion(s) in cord parenchyma
Typically no cord expansion (vs. tumor); chronic lesion may show atrophy

155. venous hypertension (e.g. AV fistula)
Cord Edema
As in the brain, may be secondary to ischemia (e.g. embolus to spinal artery) or
venous hypertension (e.g. AV fistula)
Dural AVF
MR#

156. Vascular

157. Spinal AVM / AVF

158. Congenital

159. MR# Lipomyelomeningocele with tethered cord, mistaken for myelomenigocele at birth and partially resected without untethering cord. Now 11 y/o with progressive cavovarus deformity, LE weakness and incontinence.

160. Spine Imaging Guidelines
Uncomplicated LBP usually self-limited, requires no imaging
Consider imaging if:
Trauma
Cancer
Immunocompromise / suspected infection
Elderly / osteoporosis
Significant neurologic signs / symptoms
Back pain with signs / symptoms of spinal stenosis or radiculopathy, no trauma:
Start with MRI; use CT if:
Question regarding bones or surgical (fusion) hardware
Resolve questions / solve problems on MRI (typically use CT myelography)
MRI contraindicated

161. Spine Imaging Guidelines
Begin with plain films for trauma; CT to solve problems or to detail known fractures; MRI to evaluate soft-tissue injury (ligament disruption, cord contusion)
MRI for sx of radiculopathy, cauda equina syn, cord compression, myelopathy
Fusion hardware is safe for MRI but may degrade image quality; still worth a try
Indications for IV contrast in MRI:
Tumor, infection, inflammation (myelitis), any cord lesion
Post-op L-spine (discriminate residual/recurrent disk herniation from scar)
Emergent or scheduled? Emergent only if immediate surgical or radiation therapy decision needed (e.g. cord compression, cauda equina syndrome)
Difficult to image entire spine in detail; target study to likely level of pathology
CT chest/abdomen/pelvis includes T-L spine (no need to rescan trauma pts*)
* If image data still on scanner (24-48 hours)