radiology 3b

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radiology 3b
2013-02-18 12:48:32

radiology spring 2013
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  1. the thing about "moment arms"
    • the longer the arm, the more force is needed to hold the same wt
    • so, if yr arm is outstretched and you're holding even a small wt, the paraspinal muscles have to create a lot of force to stabilize the spine, bc these muscles (erector spinae) have short moment arms
    • the forces are transmitted to vertebral discs
  2. which abs contract to support the spine
    • transverse abdominus
    • with multifidus
  3. DDD almost always happens at which disc space?
  4. stress riser effect
    location in an object where stress is concentrated, so the object is likely to fail there
  5. name something that creates stress risers in the spine
    • surgical fusion
    • this results in acceleration of degenerative changes adjacent to the sites of fusion
  6. 3 characteristics of lumbar vertebrae
    • large bodies
    • large facet joints and SPs
    • neural foramina exit in coronal plane
  7. coronal plane
    divides bony in to dorsal/ventral sides
  8. in which plane do the neural foramina exit in the lumbar vertebrae
  9. in a lateral view of lumbar vert, as you move more laterally, posteriorly you'll first see the SPs, then what?

    • sup/inf articular facets
    • pars interarticularis (btwn the above 2 on one vert)

    • neural foramen 
    • pedicle

    • 12th rib
    • TPs
  10. par interarticularis
    • it's part of the lamina
    • btwn sup and inf articular facets
    • weakest part of the lamina
  11. where's the ligamentum flavum?
    • connects lamina of adjacent vertebrae
    • in a lat view of the lumbar spine it's posterior of the spinal foramen
  12. interspinous lig
    • concects the SPs along their bodies, not at their ends
    • on a lat lumbar x-ray visible btwn SPs
  13. epidural space is where on a lumbar vert x-ray?
    it's dark, you can see it just post of the body of L5, it's a line ant to the cord
  14. in an axial CT, where is the aorta?
    ant and a bit off center from the vertebral body
  15. on an axial CT how do you recognize the paraspinal muscles?
    they're the lighter blobs posterolat to the SP
  16. vertebral body endplate
    neural foramen
     on  an axial CT
    • endplate is the edge of the vertebral body
    • neural foramen is the gap post to the body, ant to the SP
  17. looking at facet joints on an axial CT, where is the "superior articular facet" and which facet belongs to the sup ver?
    • the sup art facet is more lateral
    • the sup vert's facets (it's inf art facets) are medial
  18. how to find an intervertebral disc on an axial CT?
    if you can't see the vert body, just a darkish outline of it, and if you're simultaneously seeing the facets, then that shadow of the body is the intervertebral disc
  19. on a coronal view of the lumbar spine, what's directly sup and inf to a pedicle?
    neural foramen
  20. on a coronal CT of the lumbar spine, where is the pars interarticularis?
    it looks like it's between the TP and the lamina
  21. tell me about spotting the 12th rib in a coronal CT of the lumbar spine
    • it'll be in a very posterior view, where you're only seeing the SPs
    • the 12th ribs will appear as 2 SP-ish dots lat to T1
  22. what to order for back pain w no recent trauma?
    • nothing - it'll usually heal by itself
    • BUT, when imaging is needed, go w MIR first
    • x-rays "may be sufficient ofr the initial eval of the following red flags:" recent trauma, osteoporosis, age > 70
  23. 10 red flags for back problems
    • recent significant trauma (or milder trauma if >50 y/o)
    • unexpained wt loss
    • unexplained fever
    • immunosuppression (from a disease or drugs)
    • history of cancer
    • IV drug use
    • prolonged use of corticosteroids or hx of osteoporosis
    • age > 70
    • focal neurologic deficit w progressive or disabling symptoms
    • duration > 6 weeks
  24. 2 slides on pg 5 w details about what to order for specific complaints
    I'm not typing these. Just review them before exams
  25. lumbar views, and which 3 are the standards?
    • AP
    • lateral
    • spot lumbosacral
    • oblique
    • flex/ext

    it's the first 3
  26. how to find L5/S1 - 3 methods
    • best method: count from the top
    • or look for 12thr rib on lat or AP - it ends by the 1st lumbar vert
    • look for the L/S junction (meeting of the arc of the sacrum and arc of the curving lumbar spine)
  27. in a lat view what's a trick for identifying T12?
    it has a white cloud cutting through the post portion of the body
  28. you must go back to the slides and review the "be able to identify" lists on on pg 7
  29. anatomy of the scotty dog
    • eye = pedicle
    • head/nose = TP
    • neck = pars interarticularis
    • ear = sup art facet
    • front leg = inf art facet
    • hindmost leg = SP
    • other hind leg = inf art facet
  30. spondylolisthesis vs spondylolysis
    • movement of one vert body with respect to another
    • fracture thru pars interarticularis
    • lysis can lead to listhesis
    • DDD can result in spondylolistheis w/o spondylolysis -- this is associated w spinal canal stenosis
  31. breaking the spotty dog's neck is called what?
    spondylolysis (spondylolisthesis is when there's movement of one vertebral body w respect to another)
  32. gradings of spondylolisthesis
    • <25% dislocation - grade 1
    • 50% - grade 2
    • 100 % (the post of the upper vert body is at ant spot of inf vert body) - grade 4
  33. vacuum disc phenomenon
    • happens w DDD
    • when body moves w/o a disc this creates a vacuum that sucks gas from nearby structures, creating a very dark line btwn bodies
  34. 4 things that come with lumbar DDD
    • disc space narrowing
    • hypertrophic changes or osteophytes
    • endplate sclerosis
    • vacuum disc phenomenon
  35. a visiple feature of anklylosing spondylitis
    fusion of SPs
  36. discitis/osteomyelitis
    • mostly a soft tissue process
    • on x-ray, look for destruction of endplates (they'll be concave)
    • get MRI w contrast! but can still see some findings on x-ray
  37. what to do if you suspect a tumor in the lumbar spine
    get MRI or CT -usually don't need contrast w MRI if just assessing for cord compression
  38. common causes for thoracic/lumbar spine injuries
    • MVI > 35 mph
    • falls > 15 ft
    • MVP w pedestrian thrown > 10 ft
    • assault w depressed consciousness
    • known cervical spin injury
    • rigid spine disease
  39. bottom line for what to order fro T/L spine supsected blunt trauma
    get CT first
  40. where are most lumbar spine injuries?
    thoracolumbar junction (stress riser)
  41. for lumbar spine injuries get CT after abnormalx-ray except _ _ _
    • stable compression fx
    • isolated SP and TP fx
    • spondylolysis
  42. 5 categories of lumbar spine injuries
    • compression fractures - ant wedge or biconcave
    • burst fx (axial load)
    • chance fracture
    • fracture-dislocations
    • minor fractures (TP, SP, pars interarticularis)
  43. lumbar ant compression fracture - 3 things to ask
    • how much loss of ht?
    • has there been a change in alignment?
    • does the post wall of vert body look like it's encroaching on the spinal canal?
  44. what's happening in an ant compression fx - what to do?
    • mid and post columns intact
    • nonoperative management
    • stable if >40% loss of height, consider Burst or Chance fracture
  45. chance fracture
    • classic injury from lap seatbelt
    • fulcum is ant to spine and results in distraction injury involving all 3 columns
    • unstable

    it's a horizontal fx thru the vertebra
  46. in scoliosis, meaning of dextro, levo, apex, cobb angle
    • dextro: right
    • levo: left
    • apex: peak of curvature
    • cobb angle: A line is drawn along the superior end plate of the superior end vertebra and a
    • second line drawn along the inferior end plate of the inferior end vertebra. If
    • the end plates are indistinct the line may be drawn through the pedicles. The
    • angle between these two lines (or lines drawn perpendicular to them) is measured
    • as the Cobb angle.
  47. unique characteristics of thoracic spine
    • more supported than lumbar spine
    • smaller articular processes
    • seperate articular facet for ribs (on lat/post body and lat TP)
    • upper 4 are more like c-vert, lower 4 like L-verts, middle 4 are a combo
  48. on an AP view of the thoracic spine where is the clavicle?
    btwn T3 and T4, lower than the first 2 ribs
  49. DISH
    • diffuse idiopathic skeletal hyperostosis
    • flowing ossification of the ant long lig
    • the disc space is preserved
    • usually asymptomatic save some loss of mobility which is protective against DDD
  50. ivory vertebrae
    • one vert that comes up white (trabecular looks same as cancellous)
    • could be: osteoblastic metastasis, lymphoma, Paget's disease, fluorosis, osteopetrosis
  51. sacroiliitis - def and possible causes
    • inflam of the SI joint
    • ankylosing spondylitis
    • inflam bowel disease
    • Reiter's disease
    • rheumatoid
    • psoriasis
    • infection