Lecture 3 - SACRUM, COCCYX, LUMBAR SPINE Flashcards
AP AXIAL SI JOINT
sig:
- to see SI joint spaces
- sacroilitis, osteitis condensans, degenertaion, articulation
tech:
- in bucky
- 18x24 lanscape
- susped on respiration
- exp:
pos:
- supine is preffered
- AP position
- pillow or head
beam:
- cephalad angulation 30deg in males and 35 in females
- 5cm below level of ASIS
collim:
- SI joints
- medial aspects of ilium
- collim to SI joints
POSTERIOR OBLIQUE SI joints
sig:
- to visualise individual joint space
tech:
- 18x24 portrait
- in bucky
- exp:
pos:
- elevate affected hip 25-40 deg
- ask pt to keep affected sides leg flexed only a little ut the other leg can be flexed to provide stability
- sponges if necessary
beam:
- 2.5cm medial to raised ASIS
collim:
- SI joint of int open
- ALA of ilium not overlapping sacrum (then that’s over rotation)
Name the projections done to see the sacrum
AP
LATERAL
Name the projections done to see the lumbar spine
AP
LATERAL
OBLIQUE
Name the projections done to see the coccyx
AP
LATERAL
AP AXIAL SACRUM
sig:
- degeneration, fractures, tumours, infection
tech:
- 24x30 landscape
- yes grid
- in bucky
- suspend on respiration
- exp: 70 kVp, 20-30 mAs, 110
pos:
- supine
- legs extended with support under knee or elevate knee slightly
- midsag plane to CR
rotation? symmetrical iliac crests and SI joints
beam:
- cephalad 15 deg
- between symphysis (GT level) and ASIS level
collim:
- tight collim to region
FOV:
- SACRUM, SI joints and L5/S1 junction
- no foreshortening of sacrum
- sacral foramina
AP AXIAL COCCYX
sig:
- is there real necessity for this projection?
tech:
- in bucky
- 24x30 portrait
- yes grid
- exp: 80 kVp, 15 mAs, 110 cm
- suspend on respiration
pos:
- supine
- legs extended with knee support or flex knee slightly
- midsag plane to midline of table
- no rotation of pelvis
rotation? lateral margin of coccyx is equidistant from pelvic brim
beam:
- caudad 10deg
- 5cm sup to symphysis (GT level)
collim:
- tight collim
FOV:
- coccyx free of superimposition from pubic rami
- free of gas and feces (empty bladder and colon before)
LATERAL SACRUM AND COCCYX
sig:
- usually lateral sacrum and coccyx imaged together (cuz coccyx imaging doesn’t alter the pre-determined treatment)
tech:
- 24x30 portrait
- in bucky
- suspend on respiration
- exp: 80 kVp, 30-40mAs, 110
pos:
- lateral recumbent
- can be left or right (pt pref)
- flex knees add sponge if needed
- long axis of sacrum and coccyx to midline of table
- rotation? greater sciatic notch and femoral heads should be superimposed
beam:
- 3-4” post ASIS
FOV:
- L5/S1
- distal coccyx
- ant and post margin shown
Name the ligs of the lumbar spine?
- Anterior longitudinal lig
- posterior longitudinal lig
- interspinous lig (between spinous process of 2 verts)
- supraspinous lig (lines the length of spinous pocesses)
Explain the neurological and vascular supply of the lumbar spine
- spinal cord ends at L1-2 in adults and forms the conus medullaris then he caudia equina (bundles of spinal erves and nerve rootlets)
- vascular: blood supply to tissues and bones
why is imaging of the spine considered unnecessary?
cuz it does not improve pt outcomes.
Best used when pt has severe or progressive neurologic deficits or in situations of trauma
What is a trauma protocol for the lumbar spine?
- probs go straight to CT
Why is gonadal shielding quite confusing for lumbar spine projections?
because shielding might block out necessary anatomy
Discuss AP vs PA lumbar spine projections
ask pt pres: supine or prone
AP
- lumbar spine closer to IR
- reduce OID
- dose to gonad increased
PA
- reduce dose to gonad.
reason: tissue displacement , where abdominal soft tissue and contents compress.
AP LUMBAR SPINE
sig:
- to see fractures, scoliosis, tumours
- T11 all the way to distal sacrum
tech:
- 35x43 portrait
- suspend on expiration or use breathing tech
- exp: 70-80 kVp, 40-60 mAs , 110 (BT: 75kVp, 35 mAs, 1.6 s)
- yes grid
pos:
- supine
- knees and hips flexed to flatten natural curvature of lumbar spine and open IV disc space
- hands NOT by sides (above head is better)
rotation: - central spinous process and symmetrical appearance of SI and iliac wings
- check pt from bottom to top and line according the midsaggital plane
beam:
- LCM in small pts or centre to iliac crests in bigger pts
collim:
- 5 cm laterally
FOV:
- T12-Sacral region
- TP shown (might be obscurred by bowel gas)
- iV JOINTS
- SI joints
Explain how the anode heel effect can be used to reduce dose for lumbar projections
- head placed towards cathode side of xray tube will lead to a lower dose
LATERAL LUMBAR
sig:
- see T12-sacral region
- frac, degeneration (osteoporosis), vert bodies
- displacement, subluxation
- bone lesions
- spondylolisthesis
- L5/S1 junction
tech:
- 35x43 portrait
- suspend on expiration
- in bucky
- exp: 70-80 kVp, 60-80 mAs, 110cm
- use grid
pos:
- lateral recumbent or erect
- knees flexed and sponge under
- arms drawn into chest (HBL= arms corssed over chest)
- get lumabr spine straight and horizontal by placing sponges a waist
True Lateral?
- superimposition of greater sciatic notches
- superimposition of superior articulating facets
- superimposition of inferior endplates
beam:
- L3: LCM in small pt, iliac crest level big pts
collim:
- skin surface
FOV;
- T12-SACRUM
- IV foramina L1-L4 open
- IV disc spaces open
- facet joints
- SP
- L5/S1
Is the left or right view of the lumbar spine better?
- 38% reduced dose with left lat positioning
- this is due to liver being uppermost when positioned left and so can help absorb the dose.
- THIS ISN’T STANDARD TO LIE ON LEFT
Distinguish between trauma and non-trauma reasons for imaging the lumbar spine
Trauma
- fractures
- dislocations
Non-trauma
- scoliosis
- osteoporosis
- spondylolisthesis/spondylolysis
- ankylosing spondylitis
- degenerative joint disease
- spina bifida (occulta)
How do you asses a pt with spinal trauma?
- Type of injury (mechanism)
- asses 3 columns and notice pathology
- stable or unstable?
- look for more than 1 fracture
- check for spinal canal compression
where in the lumbar region is the most common for a fracture?
T12-L2
- transition region from rigid to flexible
- 75% = compression/wedge fracture
- 20% = fracture/dislocations (involving post elements and vert body)
Don’t only do an AP spine, do a lateral and other projections to notice pathology
Explain what a transverse process fracture is
- avulsion fracture: abnoral tension in paraspinous muscles or direct trauma
- check for psoas muscle bulging (haematoma)
- if fracture in upper lumbar = possible renal damage due to close kidney proximity
explain what are compression fractures of the lumbar spine
- caused by anterior column not being able to withstand the axial force and becomes compressed
- results in educed ant and post vert height and also anterior wedging
- lateral projection is best
- on AP u no longer can see cupid’s bow, and that’s indicative
What’s the cupid bow radiographic component of the AP lumbar spine?
- inferior borders of L3-5
- loss of it is indicative of compression fracture on an AP
