Radiology of Spine

– begins with GOOD rads
– center over specific region of spine you are interested in –> if zoom out, see artifacts causing disk spaces to be narrow
– obtain multiple rads when there is a need to review multiple segments of the spine (don’t just take one large one)
– know NORMAL radiographic anatomy
– have a method for review
– know what to look for AND recognize what you see

– ends of vertebrae forming the disk space

– on lumbar vertebrae
– see on lateral view as an opacity in the foramen (NORMAL)

C7 – T13 – L7 – S3 – Cd(variable)

C7 – T13 – L7 – S3 – Cd(variable)

C7 – T18 – L6 – S3 – Cd(variable)

C7 – T13 – L6 – S3 – Cd(variable)

– evaluate spaces in the *middle 2/3* of the radiograph
– as get farther out on edge of radiograph, the spaces get narrowed (like looking at a picket fence)
– compare space with the one cranial to it and the one caudal to it

– usually incidental — though can be so severe that it causes narrowing and cord compression
– may affect surgical planning

1. transitional vertebrae
2. hemivertebra
3. block vertebra
4. spina bifida

– vertebra has anatomic characteristics of ADJACENT spinal regions
– use the last pair of ribs as a landmark for surgery in TL area (should be T13) –> use to tell if disk protrusion and where
– if in lumbar region, count from end of last ribs and beginning of sacrum to tell which is transitional vertebra

– see with bulldogs and boston terriers
– wedge shaped vertebrae
– occur due to failure of formation
– can see as fused dorsal processes possibly

– vertebrae did not develop right
– look like butterfly with wings
– congenital anomaly

– congenital anomaly
– dorsal arching of spine
– can compress cord if severe
– can see on PE –> don’t know how bad until radiograph spine
– use contrast to tell where compression is occurring because contrast outlines spinal canal

– congenital anomaly
– dorsal process does NOT properly fuse –> see 2 dorsal processes when look on VD view
– incidental finding usually unless causes herniation (common in lumbar)

– congenital anomaly
– 2 vertebrae are fused together during development
– could act as fulcrum to cause protrusions and problems
– see no disk space or partial disk space

– disease of attachment of vertebral joints associated with disk space
– usually clinically insignificant by itself
– may be associated with chronic disk disease or infection in disk space
– does NOT cause neuro deficits — chronic degenerative disease or instability when see it
– see in middle to older gods

– see proliferative bone ventrally off end plates
– *excessive proliferation under vertebrae* — can see at multiple spots

– *dorsally displaced axis relative to atlas*
– usually congenital
– may have absence or hypoplasia of dens (underdeveloped or no dens)
– lateral view best to see
– widening of space between spinous process of C2 and vertebral arch of C1
– lack of parallelism between dorsal lamina of C2 and dorsal lamina of C1
– means something when we see it
– see in smaller breeds like yorkies and poodles –> see problems with limbs
– see in younger dogs

– widened space between dorsal arch (dens) of C2 and C1 vertebral arch –> compression of cord (should be small space)
– angle opens up between dorsal aspect of C1 and C2
– VD view = can see rounded front of C2 which indicates NO dens (agenesis) — or could see hypoplastic dens

– FLEX the dog’s neck if cannot tell if normal or abnormal distance between C1 and C2
– when flex, space will increase between vertebrae
– don’t just flex the neck to look for this because could cause acute compression of the cord –> BAD

– narrowed disk space
– sclerosis of vertebral endplates (ends of vertebrae that make up either side of disk space)
– ventral displacement of S1 relative to L7
– ventral spondylosis deformans if chronic enough
– see in older dogs
– see in larger breeds

– *narrowed disk space with sclerosis*
– can see irregular bone proliferative ventral that is spondylosis deformans
– see degenerative changes on outside so do CT cross-section to see what is going on

– closed up vertebral canals due to proliferative bone
– see nerve roots trapped inside spinal canal
– look on soft tissue window and bone window
– can’t tell what is going on just by radiographs, so do CT –> see *nerve compression and narrowing of canal*

– hypointense material see in vertebral canal
– sclerosis
– compression on nerve roots due to lot of tissue filling up canal

– infection of the disk itself
– infection or inflammation of the intervertebral disk and adjacent endplates
– irregular endplate lysis — should normally be opaque, so lysis indicates aggressive lesion
– narrowed disk space
– sclerosis
– spondylosis if more chronic infection
– more aggressive with lysis and proliferative bone

– *sclerosis and lysis of endplates*
– irregular appearance of endplate, especially on the cranial edge of the caudal vertebra
– can be in single or multiple places or in other regions of the spine
– can see some spondylosis deformans on ventral aspect as well
– common to see in *lumobsacral junction*
– appearance can resemble brucella canis, so need to differentiate since this is zoonotic

– suspect spinal trauma
– may want to get laterals first to avoid manipulation
– may be at or near regional junctions commonly
– if present, have to assume there is cord injury due to movement of spinal canal –> may not actually look bad, but could see canal damage
– can be catastrophic

– can see displacement of vertebrae with fracture line
– describe displacement based on movement of the fractured portion

– traumatic or pathologic fracture causes compression
– vertebrae should be similar size –> see compression fracture that can be confused with congenital anomaly (because compression caused small vertebra)
– neoplastic process could cause vertebrae to collapse = PATHOLOGIC fracture
– vertebral body could appear small and narrow due to compression from fracture

– may find proliferative bone, lytic bone or may be mixed
– may involve body, lamina, pedicle and/or processes
– usually limited to ONE vertebra, but metastatic neoplasia can affect multiple vertebrae

– *marked sclerosis and proliferation of bone*
– see lytic changes in vertebra on MRI
– could just be a lucent change on vertebra (subtle change)
– can cause cord compression that will be seen on MRI

– extension of disk material into the canal
– protrusion, herniation, prolapse OR extrusion of material
– can’t determine type of disease (above 4) on radiographs

1. disc space (between endplates)

2. intervertebral foramen (horse head)

3. dorsal articular facet space (half-moon shaped radiolucent area between dorsal articulations)

1. NARROWED intervertebral disk space

2. WEDGE-shaped intervertebral disk space

3. DECREASED size of intervertebral foramen

4. INCREASED opacity of intervertebral foramen

5. MINERAL opacity at level of intervertebral foramen (disk mineralized)

6. DECREASED dorsal articular facet space

(best for LATERAL view only)

– *concentrate on vertebrae in the middle of radiograph due to bad angle of vertebrae at the edge*
– narrowed intervertebral disk space, wedge-shaped disk space, etc.
– compare vertebrae to the one in front and the one behind it
– if see mineral opacity in disk space, this is degenerative disease due to mineralization and NOT protruded disk because mineralization does NOT cause disk protrusion

1. mineral opacity (hyperattenuating) mass in canal –> increased opacity displaces cord to one side

2. loss of visualization of epidural fat (dark gray)

3. distortion of cord

– easier to see disk disease on CT
– on CT, protrusion appears as increased opacity and displaced cord due to mineralized mass
– if think see signs on rads, DO CT because better to see what is going on in cross-section

1. NARROWED intervertebral disk space

2. MINERALIZED area at level of neural canal (protruding dorsally)

– not as many signs to look for in cervical region because intervertebral foramen not very visible
– do CT to determine protrusion or not

C2-C3

1. hypointense material in canal (relative to other structures)

2. loss of visualization of usual hyperintense signal of fat and CSF surrounding cord

3. displacement of cord

– *T2 saggital* = money shot because fluid is BRIGHT and fat is not as bright — can see disruption of area with hypointensity above disk space

– *STIR saggital* = suppresses fat so can see hypointense area that is protrusion

– transverse sections show cord being compressed to the side of canal

CT

– because MRI is sensitive whether the disk is mineralized or not

– little white line below the spinal cord

– can tell is disk if messed up if do not see normal white hydrated disk

– *determines the site of cord compression*
– put contrast into subarachnoid space to outline the cord –> shows compressed areas

– do with myelography
– put in ceromedullary cistern above C1
– use spinal needle with stylet and iodine contrast specific to myelography
– can collect CSF from here too

– fingers on widest portions of wings of atlas and look for external occipital protuberance off back of skull
– go halfway between EOP and wings of atlas dead on midline (so ensure correct positioning)
– feel resistance as go through
– feel pop when go through dura and should be in subarachnoid space (where CSF is)

– radiopaque line around cord –> should see thickness of contrast
– see dorsal and ventral columns on lateral view
– see right lateral and left lateral columns on VD view
– want columns to appear with uniform thickness and appearance
– contrast tapers off normally at cauda equina and goes into sacral area

– put contrast media in subarachnoid space
– move up from LS junction to do at *L5-L6 space*
– find wings of ileum and feel L7 dorsal process between them and move cranially to L6 and insert spinal needle cranial to L6 dorsal process
– back stylet out to check for CSF bubbling out
– SAFER to do than cervical tap because cervical area has lot of respiratory centers up there (though lumbar tap harder to do)

1. extradural

2. intramedullary

3. intradural-extramedullary

– shows disk protrusion if affected area is over disk space and there is dorsal deflection of contrast
– contrast DORSALLY reflected due to disk protrusion on lateral view
– dorsal contrast column is affected and gets thin
– on VD view, contrast column bulges out and thins in affected area
– something outside the dura is causing pressure on the cord (tumor from pedicle or body, abscess or hemorrhage outside cord OR *disk protrusion*)

– something from inside of the cord causes the cord to push outward in all directions
– on lateral view = see dorsal and ventral deflection of cord and thinning of contrast
– on VD view = contrast column bulges out

– arises from subarachnoid space (nerve sheath tumor or meningioma protruding into space)
– need BOTH views to see what is happening
– on lateral view = see small bulge that causes ventral and dorsal thinning of contrast
– on VD view = flares out to one side like a “golf ball on a tee” and see filling defect

– SEIZURES
– need to keep head elevated to keep contrast away from brain to prevent seizures

– wobbler
– see in young Danes and older animals
– all limbs are affected
– usually *mid to lower cervical spine*
– see disk protrusion associated or hypertrophy of dorsal longitudinal ligament
– flexion or extension can exacerbate radiographic appearance

– narrowed disk space
– malformation of vertebrae (cranioventral margin could be rounded off)
– degenerative changes
– narrowed vertebral canal (front part of vertebral body lamina gets narrowed)
– malalignment of vertebrae
– enlarged articular processes (can compress on cord)

– can see medial displacement as hourglass shape
if use contrast, see contrast changing — dorsal elevation of ventral column
– bone can be funnel shape (or more narrow)

– see compression and displacement of cord
– compression occurs due to dorsal articular processes

– see compression of cord
– see changes in cord as increased signal intensity (do not see these changes on CT)
– see cord pushed from side to side on transverse section