N EURO -R ADIOLOGY R AJ R EDDY Neurosurgery Prince of Wales Hospital SPINE.
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Transcript of N EURO -R ADIOLOGY R AJ R EDDY Neurosurgery Prince of Wales Hospital SPINE.
NEURO-RADIOLOGY
RAJ REDDYNeurosurgery
Prince of Wales Hospital
SPINE
Objectives
Review spine anatomy on X-ray, CT and MRI Approach to interpretation of imaging Differential diagnoses for common spine
lesions
Imaging Modalities
Basic Imaging Types
X-ray CT (Computed Tomography) MRI (Magnetic Resonance Imaging) Angiography
X-ray
Limited Use Evaluation of:
Bones (fractures) Calcification
Computed Tomography
http://fitsweb.uchc.edu/student/selectives/TimHerbst/intro.htm
Computed Tomography (CT)
Tomography Imaging in sections, or slices
Computed Geometric processing used to reconstruct an
image Computerized algorithms
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
CT Image Formation
X-ray detectorX-ray
X-ray tube
CT Image Formation
Backprojection
CT Image Reconstruction – 6 Slices
CT Image Reconstruction – 12 Slices
CT Image Reconstruction – Final
Magnetic Resonance Imaging
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
Angiography
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.
Angiography
AP Right ICA Lateral Right ICA
Angiography
AP Right Vertebral
Planes of Section
Axial (transverse) Sagittal Coronal Oblique
Anatomy
Radiographic Anatomy
Cervical Spine – AP View
Cervical Spine – Lateral View
Cervical Spine – Open-Mouth (Dens) View
Cervical Spine – Oblique View
Lumbar Spine – AP View
Lumbar Spine – Lateral View
Approach to Xrays
Approach to Spine Imaging
A – adequacy/alignment
B – bone
C – cord/canal/cartilage
D – disc
E – extras
C7-T1
Alignment
1. prevertebral 2. anterior spinal 3. posterior spinal 4. spino-laminar
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
Cartilage
Disc Spaces Should be
uniform Assess spaces
between the spinous processes
Soft tissue
Nasopharyngeal space (C1) - 10 mm (adult)
Retropharyngeal space (C2-C4) - 5-7 mm
Retrotracheal space (C5-C7) - 14 mm (children), 22 mm (adults)
Extremely variable and nonspecific
CT Anatomy
CT
MRI Anatomy
Compartments of the Spine
a. Intradural, intramedullaryb. Intradural, extramedullaryc. Extradural, extramedullary
a. c.b.
…
Pathology
Spine Pathology
Trauma
Degenerative disease
Tumors and other masses
Inflammation and infection
Vascular disorders
Congenital anomalies
Trauma
Evaluating Trauma
Fracture – plain film / CT
Dislocation – plain film / CT
Ligamentous injury – MRI
Cord injury – MRI
Nerve root avulsion – MRI
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. 2003.
NEXUS C-Spine Rules
Canadian C-Spine Rules (CCR)
Stiell IG. The CCR in Alert and Stable Trauma Patients. JAMA. 2001.
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. 2003.
Plain film findings may be very subtle or absent!
Anterolisthesis of C6 on C7
(Why?)
CT
Fractures of C6 left pedicle and lamina
CT – 2D Reconstructions
Acquire images axially…
…reconstruct sagittal / coronal
26M MVA
Vertebral body burst fx with retropulsion into spinal canal
2D Reformats
Vertebral Artery Dissection/Occlusion Secondary to C6 Fracture
Hyperflexion fx with ligamentous disruption and
cord contusion
Nerve root avulsion
Axial Coronal Sagittal
Degenerative Disease
Degenerative Disc (and Facet Joint) Disease
Foraminal stenosis
Thickening/Buckling of Ligamentum
Flavum
Degenerative Disc (and Facet Joint) Disease
Degenerative Disc (and Facet Joint) Disease
Lumbar Spinal Stenosis
Lumbar Spinal Stenosis
Lumbar Spinal Stenosis
Lumbar Spinal Stenosis
Lumbar Spinal Stenosis
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
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
Foraminal Stenosis
Neural foramen
Cervical Spinal Stenosis
MRI - Degenerative Disc Disease
20-40 36% have degenerated disc
50 85-95% have degenerated disc
60-80 98% have degenerated disc
<60 20% have asymptomatic disc herniation
Age:
Conclusion: Abnormal findings on MRI frequently DO NOT relate to symptoms (and vice versa) !
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
Annular
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.
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.
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.
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.
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.
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.
Protrusion Protrusion w/migration
Protrusion w/migration +
sequestration
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.
Abnormal Disc
Bulge
Symmetric Asymmetric
Herniation
Broad-based Focal
Extrusion Protrusion
Sequestered Migrated Neither
> 180º< 180º
< 90º90º–180º
No waistWaist*
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.
*(In any plane)
Central Disc Protrusion
L5-S1 Disc Extrusion Into Lateral Recess with Impingement of R S1 Nerve Root
L-S1DiscR-S1
Schmorl’s Nodes
Cervical Radiculopathy
Lumbosacral Radiculopathy (Sciatica)
Important: A herniated disc at (e.g.) L4-5 may impinge either the L4 or L5 nerve roots!
L5-S1 Disc Extrusion Into Lateral Recess with Impingement of R S1 Nerve Root
L-S1DiscR-S1
Spondylolysis / Spondylolisthesis
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)
Tumors and Other Masses
Extradural = outside the thecal sac (including vertebral bone lesions)
Intradural / extramedullary = within thecal sac but outside cord
Intramedullary = within cord
Classification of Spinal Lesions
Herniated disc
Vertebral hemangioma
Vertebral metastasis
Epidural abscess or hematoma
Synovial cyst
Nerve sheath tumor (also intradural/extramedullary) Neurofibroma Schwannoma
Common Extradural Lesions
Nerve sheath tumor (also extradural)
Neurofibroma
Schwannoma
Meningioma
Drop Metastasis
Common Intradural Extramedullary Lesions
Astrocytoma
Ependymoma
Hemangioblastoma
Cavernoma
Syrinx
Demyelinating lesion (MS)
Myelitis
Common Intramedullary Lesions
Classification of Spinal Lesions
Extradural IntramedullaryIntraduralExtramedullaryDuraCord
Extradural: Vertebral Body Tumor
Extradural: Vertebral Metastases
T2 (Fat Suppressed) T1 T1+C (fat suppressed)
Extradural: Vertebral Metastases
T2 (Fat Suppressed) T1 T1+C (fat suppressed)
?
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
Vertebral Hemangiomas
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
Extradural: Vertebral Metastases
Extradural: Epidural Abscess
Extradural: Nerve Sheath Tumor(Schwannoma)
Intradural Extramedullary: Meningioma
Intradural Extramedullary: Meningioma
Intradural Extramedullary: Nerve Sheath Tumor(Neurofibroma)
Intradural Extramedullary: “Drop Mets”
T2 T1 T1+C
Intradural Extramedullary: “Drop Mets”
Intradural Extramedullary: Arachnoid Cyst
T2 T1
Intramedullary: Astrocytoma
Intramedullary: Astrocytoma
Intramedullary: Cavernoma
Intramedullary: Ependymoma
Seen with:• congenital lesions
• Chiari I & II• tethered cord
• acquired lesions• trauma• tumors• arachnoiditis
• idiopathic
Intramedullary: Syringohydromyelia
Seen with:• congenital lesions
• Chiari I & II• tethered cord
• acquired lesions• trauma• tumors• arachnoiditis
• idiopathic
Intramedullary: Syringohydromyelia
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
Infection and Inflammation
Infectious Spondylitis / Diskitis
Common chain of events (bacterial spondylitis): 1. Hematogenous seeding of subchondral VB2. Spread to disc and adjacent VB3. Spread into epidural space epidural abscess4. Spread into paraspinal tissues psoas abscess5. May lead to cord abscess
Infectious Spondylitis / Diskitis
T2 T1 T1+C T1+C
Infectious Spondylitis / Diskitis
Pyogenic Spondylitis / Diskitis with Epidural Abscess
T1
T2
T1 + C
Spinal TB (Pott’s Disease)
• Prominent bone destruction• More indolent onset than pyogenic• Gibbus deformity• Involvement of several VB’s
Spinal TB (Pott’s Disease)
• Prominent bone destruction• More indolent onset than pyogenic• Gibbus deformity• Involvement of several VB’s
Transverse Myelitis
Inflamed cord of uncertain cause Viral infections Immune reactions IdiopathicMyelopathy progressing over hours to weeksDDX: MS, glioma, infarction
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
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
Cord Edema
As in the brain, may be secondary to ischemia (e.g. embolus to spinal artery)
or
venous hypertension (e.g. AV fistula)
Spine Imaging Guidelines1. Uncomplicated LBP usually self-limited, requires no imaging
2. Consider imaging if:
• Trauma
• Cancer
• Immunocompromise / suspected infection
• Elderly / osteoporosis
• Significant neurologic signs / symptoms
3. 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
4. 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)
5. MRI for sx of radiculopathy, cauda equina syn, cord compression, myelopathy
6. Fusion hardware is safe for MRI but may degrade image quality; still worth a try
7. Indications for IV contrast in MRI:
• Tumor, infection, inflammation (myelitis), any cord lesion
• Post-op L-spine (discriminate residual/recurrent disk herniation from scar)
8. Emergent or scheduled? Emergent only if immediate surgical or radiation therapy
decision needed (e.g. cord compression, cauda equina syndrome)
9. Difficult to image entire spine in detail; target study to likely level of pathology
10. CT chest/abdomen/pelvis includes T-L spine (no need to rescan trauma pts*)
* If image data still on scanner (24-48 hours)
Spine Imaging Guidelines