Image interpretation: spine

Dr David Lisle Brisbane Private Imaging

Image interpretation

•  Anatomy •  Cross sectional techniques:

–  CT –  MRI

•  Nomenclature of disc herniations and spinal stenosis

•  A few cases

Image interpretation

•  Anatomy •  Cross sectional techniques:

–  CT –  MRI

•  Nomenclature of disc herniations and spinal stenosis

•  A few cases

Image interpretation

•  Anatomy •  Cross sectional techniques:

–  CT –  MRI

•  Nomenclature of disc herniations and spinal stenosis

•  A few cases

Development of CT

•  70’s •  Each slice 60secs •  20-30 mins/ head scan

•  70’s – 80’s •  5-10 secs/ slice •  5 mins/ head scan •  Longer for body and spine: up to 20 mins

1974 1988

Spiral (helical) CT

•  90’s •  Speed

–  Patient acceptance –  Different phases of contrast

enhancement

•  Volumetric data set –  Multiplanar and 3D

reconstructions

Multidetector (multislice) CT

•  Late 90’s to present •  0.175 - few seconds scan

time •  Overlapping =

reconstructions •  Contiguous = speed •  Original: 4 slice •  2nd generation: 16, 64 •  New: 256; 320

Workstation reporting

MRI: T1

–  Fat bright •  Bone marrow

–  Bone cortex black –  Anatomy

MRI: T2

–  Bone cortex black –  Anatomy –  Fluid bright –  Fat bright

•  Bone marrow –  Oedema bright

•  Difficult to differentiate

MRI: STIR or T2FS

–  Fat ‘saturated out’ •  Bone marrow black

–  Fluid bright –  Differentiate oedema

from marrow

T1 T2 STIR

MRI: T1FS-Gd

–  Fat ‘saturated out’ •  Bone marrow and other

fat black –  Non-fat T1 bright • Haemorrhage • Movement • Enhancement

Ø Pathology Ø Veins Ø Nerve root ganglia

T1

T1

Image interpretation

•  Anatomy •  Cross sectional techniques:

–  CT –  MRI

•  Nomenclature of disc herniations and spinal stenosis

•  A few cases

NOMENCLATURE

•  Consistent •  Reflect common usage where appropriate •  Surgically relevant •  ‘Able to visualize over the phone’ •  2 morphological characteristics:

–  Nature of disc pathology –  Location

•  Able to add further descriptors –  Neural structures –  Clinical context

•  www.asnr.org/spine_nomenclature/reporting

Disc bulge

•  Generalised extension of disc tissue beyond intervertebral disc space

•  ‘Generalised’ = >50% circumference (>1800) •  Relatively short distance, <3mm

Herniated disc •  Localised displacement of disc material beyond

intervertebral disc space (ie bony margins excluding osteophytes) OR break in vertebral end plate (Schmorl’s node)

•  ‘Localised’ = <50% circumference (<1800) –  ‘Broad based’ = 25 - 50% circumference (>900) –  ‘Focal’ = <25% circumference (<900)

•  ‘HNP’ not accurate –  Herniation may include NP, cartilage, annulus, bone

•  ‘Rupture’ tends to refer to trauma/ acute event •  ‘Prolapse’ and ‘bulging disc’ outdated •  ‘Localised disc bulge’ = oxymoron

Extruded disc

•  Greatest distance in any plane between edges > base

T1

Sequestered disc

•  Extruded disc material that has no continuity with the disc of origin

•  = free fragment •  Migrated disc:

–  Disc material displaced away from site of extrusion

T2 T2

T1

Location of herniation

•  Anatomic system that correlates with surgery •  Landmarks, transverse plane:

–  Sagittal and coronal planes at centre of disc –  Medial edge of articular facet –  Medial, lateral borders of pedicles

Location of herniation •  Locations, transverse plane:

–  ‘Central’ = midline –  ‘Right central’ & ‘left central’ =

paracentral/ posterolateral –  ‘Subarticular’ = lateral recess –  ‘Foraminal’ –  ‘Extraforaminal’ = far lateral

Location of herniation •  Locations, transverse plane:

–  ‘Central’ = midline –  ‘Right central’ & ‘left central’ =

paracentral/ posterolateral –  ‘Subarticular’ = lateral recess –  ‘Foraminal’ –  ‘Extraforaminal’ = far lateral

Location of herniation •  Locations, transverse plane:

–  ‘Central’ = midline –  ‘Right central’ & ‘left central’ =

paracentral/ posterolateral –  ‘Subarticular’ = lateral recess –  ‘Foraminal’ –  ‘Extraforaminal’ = far lateral

Location of herniation •  Locations, transverse plane:

–  ‘Central’ = midline –  ‘Right central’ & ‘left central’ =

paracentral/ posterolateral –  ‘Subarticular’ = lateral recess –  ‘Foraminal’ –  ‘Extraforaminal’ = far lateral

Location of herniation •  Locations, transverse plane:

–  ‘Central’ = midline –  ‘Right central’ & ‘left central’ =

paracentral/ posterolateral –  ‘Subarticular’ = lateral recess –  ‘Foraminal’ –  ‘Extraforaminal’ = far lateral

Volume: degree of canal compromise

•  X-sectional area at site of maximal narrowing •  ‘Mild’: <1/3 •  ‘Moderate’: 1/3 – 2/3 •  ‘Severe’: > 2/3 •  Same grading for foraminal narrowing as seen in

sagittal plane •  Other descriptors such as compression of

specific neural structures

Mild Moderate Severe

Image interpretation

•  Anatomy •  Cross sectional techniques:

–  CT –  MRI

•  Nomenclature of disc herniations and spinal stenosis

•  A few cases

•  85 year old female •  Severe acute on chronic mechanical back pain

–  Can’t sleep –  Limited walking to only a few steps

•  Spontaneous onset •  No known trauma

What is the most likely diagnosis?

1.  Acute disc herniation 2.  Facet joint degeneration 3.  Crush fracture secondary to osteoporosis 4.  Metastatic cancer

What is the most appropriate imaging modality?

1.  Plain film 2.  CT 3.  Scintigraphy (bone scan) 4.  MRI

24/3/2012

24/3/2012 16/12/2011

MRI: pre-vertebroplasty

STIR

2

3

2

3

T1 STIR

•  68M •  Sudden onset bilateral leg pain and weakness •  Urinary retention

What is the most likely diagnosis?

1.  Guillain Barre syndrome 2.  Cauda equina syndrome 3.  Crush fracture secondary to osteoporosis 4.  Discitis/ osteomyelitis

What is the most appropriate imaging modality?

1.  Plain film 2.  CT 3.  Scintigraphy (bone scan) 4.  MRI

•  Dx: Cauda equina syndrome •  Cause: massive sequestration •  Other causes:

–  Tumour •  Primary of lower cord: ependymoma •  Primary of nerve: BPNST •  Primary of dura: meningioma •  Primary of vertebral body: chordoma, giant cell

tumour •  Secondary

–  Trauma