Radiographic Procedures 2 (155) Lumbar Vertebrae, Sacrum, and Coccyx

Lumbar spine

• five total

• occupy posterior abdominal region

• features:

  • transverse processes smaller than T-spine

  • pars interarticularis; part of lamina between articular processes

Lumbar vertebra

• body

• 2 pedicles

• 2 transverse processes

• 2 laminae

• superior and inferior articular processes

• spinous process

• accessory process; formed posterior of the transverse process

• mamillary process; forms off of the superior articular process

Zygapophyseal joint

• shown in an AP or PA oblique projection;

  • AP oblique:

    • LPO, left side

    • RPO, right side

  • PA oblique:

    • RAO, left side

    • LAO, right side

Intervertebral foramina

shown in a lateral projection, 90 degree rotation of patient

Sacrum

• formed by the fusion of five sacral segments into curved, triangular bone

• wedged between iliac bones of the pelvis

  • articulation - sacroiliac (SI) joints

• anatomic features:

  • promontory

  • sacral canal

  • pelvic sacral foramina

  • sacral cornu

• males: longer, narrower, more evenly curved, and more vertical in position

• females: more acutely curved

Coccyx

• formed by fusion of three to five rudimentary vertebrae

• curves inferiorly and anteriorly from articulation with sacrum

• coccygeal cornu

AP L-spine

• patient position:

  • supine or upright

• part position:

  • MSP centered to midline

  • shoulders and hips in same horizontal plane

  • arms crossed on chest

  • reduce lordosis by flexing hips and knees to place lower back closer to table

• respiration:

  • suspended at the end of expiration

• CR:

  • perpendicular to IR

  • for lumbosacral: enters patient at iliac crests (L4)

  • for lumbar: enters 1 ½ inches above iliac crests

• collimation:

  • for lumbosacral: 8 × 17 inches

  • for lumbar: 8 × 14 inches

• SID:

  • 48” to reduce distortion and open intervertebral disk spaces

AP L-spine image criteria

• lumbar bodies

• open intervertebral disk spaces

• interpediculate spaces (between pedicles)

• spinous processes

• transverse processes

• sacrum

• coccyx

• lower thoracic vertebrae

Lateral L-spine

• demonstrates intervertebral foramina

• patient position:

  • recumbent or upright

• part position:

  • true lateral, MCP vertical

  • knees flexed and superimposed

  • arms, with elbows flexed, at right angle to body

  • place place radiolucent support under lower spine to place horizontal, if needed (for perpendicular CR)

• respiration:

  • suspended at the end of expiration

• CR:

  • perpendicular to IR (with sponge)

  • enters MCP at iliac crests (L4)

  • if spine is not horizontal, angle caudad 5-8 degrees (without sponge)

• collimation:

  • 8 × 17 inches

Lateral L-spine image criteria

• all five vertebral bodies

• intervertebral disk spaces

• intervertebral foramen

• upper sacrum

• superimposed posterior margins of bodies

• nearly superimposed iliac crests (if CR is not angled)

• spinous processes in profile

Lateral L5-S1

• patient position:

  • lateral recumbent

• part position:

  • MCP perpendicular to IR

  • hips extended

  • superimposed knees, may be slightly flexed

  • with elbows flexed, place arms at right angle to body

  • support lower spine in horizontal position in same manner as for lateral projection

• respiration:

  • suspended

• CR:

  • when spine is horizontal, perpendicular; 2 inches posterior to ASIS and 1 ½ inches inferior to iliac crest

    • if spine is not horizontal:

      • angle 5 degrees caudad for males

      • angle 8 degrees caudad for females

  • francis method suggests angling caudad for smaller/average waists and angling cephalad for larger waists

• collimation:

  • 6 × 8 inches

Lateral L5-S1 image criteria

• lumbosacral junction

• lower one or two lumbar vertebrae

• upper sacrum

• open lumbosacral intervertebral disk space open

• iliac crests closely superimposing each other (perpendicular CR)

AP oblique L-spine

• demonstrates zygapophyseal joints closest to IR

  • both sides examined for comparison

• patient position:

  • recumbent or upright

• part position:

  • 45 degree rotation

  • radiolucent support under elevated side

• respiration:

  • suspend at the end of expiration

• CR:

  • perpendicular to IR

  • 2 inches medial to elevated ASIS at L3 (1 ½ inches above iliac crests

• collimation:

  • 9 × 12 inches (10 × 12 inch IR)

  • 9 × 14 inches (14 × 17 inch IR)

AP oblique L-spine image criteria

• lumbosacral spine or both

• articular processes

• zygapophyseal joints, closest to IR

  • open and uniformly visible thorugh the vertebral bodies

• Scottie dogs

• when the joint is not well seen, and the pedicle is anterior on the vertberal body, the patient is not rotated enough

• when the joint is not well seen, and the pedicle is posterior on the vertebral body, the patient is rotated too much

PA oblique L-spine

• demonstrates the zygapophyseal joints farthest from IR

  • both sides demonstrated for comparison

• patient position:

  • upright or recumbent

• part position:

  • 45 degree rotation

• respiration:

  • suspended at the end of expiration

• CR:

  • perpendicular to IR

  • enters 2 inches lateral to elevated spinous process and 1 ½ inches above iliac crest

• collimation:

  • 9 × 14 inches

PA oblique L-spine image criteria

• zygapophyseal joints farthest from IR

• T12-L1 articulation

• Scottie dogs

Lateral L-spine (flexion and extension)

• patient position:

  • upright or recumbent

  • MCP centered to midline of the grid

• part position:

  • flexion: patient bends forward

  • extension: patient bends backward

  • IR centered at level of spinal fusion (if present)

• repiration:

  • suspended

• CR:

  • perpendicular to spinal fusion or L3

• collimation:

  • 14 × 17 inches

Lateral L-spine (flexion and extension) image criteria

• motion in the area of a spinal fusion (if present)

• herniated disk (if present)

AP L-spine (left and right bending)

• patient position:

  • upright or supine

  • mSP centered to midline of grid

• part position:

  • first radiograph with maximum right bending

  • second radiograph with maximum left bending

  • cross patient’s leg on the opposite side to be flexed over the other leg

  • move the patient’s heels toward the side that is flexed

  • mvoe the shoulders directly lateral as far as possible without rotating the pelvis

• respiration:

  • suspended

• CR:

  • perpendicular to IR

  • enters L3, 1-1 ½ inches above iliac crests

• collimation:

  • 10 × 12 or 14 × 17 inches

AP L-spine (left and right bending) image criteria

• lumbar vertebrae in maximum bending

• integrity of spinal fusion

  • site centered and including superior and inferior vertebrae

• scoliosis - structural changes in the vertebrae (if present)

• herniated disk (if present)

AP axial SI joints (Ferguson)

• patient position:

  • supine

• part position:

  • MSP centered to IR

  • extend lower limbs, or abduct thighs and place vertical

• respiration:

  • suspended

• CR:

  • cephalad angle

    • 30 degrees in males

    • 35 degrees in females

  • enters MSP at 1 ½ inches above pubic symphysis or

  • 2-2 ½ inches inferior to ASIS

• collimation:

  • 8 × 10 or 10 × 12 inches

AP axial SI joints (Ferguson) image criteria

• lumbosacral joint

• symmetric SI joints

• sacrum

• open intervertebral disk space between L5 and S1

PA axial SI joints

• patient position:

  • prone

• part position:

  • MSP centered

• respiration:

  • suspend

• CR:

  • 35 degrees caudad

  • enters L4 spinous process

• collimation:

  • 6 × 8 inches

PA axial SI joints image criteria

• lumbosacral joint and both SI joints free of superimposition

AP oblique SI joints

• demonstrates SI joint farthest from IR

  • both sides are examine for comparison

• patient position:

  • supine

• part position:

  • 25-30 degree rotation

  • support body in position

  • long axis parallel with table

  • IR centered at level of ASIS

• respiration:

  • suspended

• CR:

  • perpendicular to IR

  • 1 inch nedial to elevated ASIS

• collimation:

  • 6 × 10 or 6 × 12 inches

AP oblique SI joints image criteria

• SI joint farthest from IR

  • RPO, left side

  • LPO, right side

• open SI joint space with minimal overallping of ilium and sacrum

PA oblique SI joints

• demonstrates SI joint closest to IR

• patient position:

  • prone

• part position:

  • 25-30 degree rotation

  • support elevated side

• respiration:

  • suspended

• CR:

  • perpendicular to IR

  • 1 inch medial to ASIS closest to IR

  • PA axial oblique can be obtained with an angle of 25-30 degrees caudad to enter L5 spinous process

• collimation:

  • 6 × 10 inches

PA oblique SI joints image criteria

• SI joint closest to IR:

  • LAO, left side

  • RAO, right side

Scottie dog

AP axial sacrum

• patient position:

  • supine

  • may also be performed with patient prone (PA axial) if needed for comfort

• part position:

  • MSP in midline of table

  • ASIS equidistant from grid

  • arms in comfortable, symmetric position out of field

  • support knees with sponge

• CR:

  • 15 degrees cephalad

    • 15 degrees caudad for PA

  • enters MSP 2 inches superior to pubic symphysis

    • enters MSP at level of sacral curve for PA

• collimation:

  • 10 × 12 inches

AP axial sacrum image criteria

• sacrum free of superimposition

  • free of forshortening, with the sacral curvature straightened

  • pubic bones not overlapping the sacrum

AP axial coccyx

• patient position:

  • supine

  • may also be performed with patient prone (PA axial) if needed for comfort

• part position:

  • MSP in midline of table

  • ASIS equidistant from grid

  • arms in comfortable symmetric positon out of field

  • support knees with sponge

• CR:

  • 10 degrees caudad

    • 10 degrees cephalad for PA

  • enters MSP 2 inches superior to pubic symphysis

    • enters MSP at coccyx for PA

• collimation:

  • 8 × 10 inches

AP axial coccyx image criteria

• coccyx free of superimposition

  • not superimposed by pubic bones/ pubic symphysis

Lateral sacrum

• patient position:

  • recumbent lateral

  • hips and knees flexed for comfort

• part position:

  • arms at right angle to body

  • knees superimposed

  • support spine to horizontal position

  • interiliac plane perpendicular to IR

  • shoulders and pelvis in true lateral

    • MCP vertical

  • sacrum centered to IR

• CR:

  • perpendicular to level of ASIS and to a point 3 ½ inches posterior

• collimation:

  • 10 × 12 inches

Lateral coccyx

• patient position:

  • recumbent lateral

  • hips and knees flexed for comfort

• part position:

  • arms at right angle to body

  • knees superimposed

  • support spine to horizontal position

  • interiliac plane perpendicular to IR

  • shoulders and pelvis in true lateral position

    • MCP vertical

  • sacrum centered to IR

• CR:

  • perpendicular to 3 ½ inches posterior and 2 inches inferior to ASIS

• collimation:

  • 6 × 8 inches

  • closed collimation improves visibility

  • lead rubber behind patient absorbs scatter

Lateral sacrum and coccyx image criteria

• sacrum and coccyx

• no rotation

  • closely superimposed posterior margins of the ischia and ilia, demonstrating no rotation

• often combined for one image rather than two separate ones

Scoliosis radiography

• stitching applications

• demonstrates amount/degree of curvature that occurs with force of gravity acting on body

• also used to evaluate fixation devices, such as Harrington rods

• bending studies used to differentiate between primary and compensatory curves

• variety of devices and IR holders

• all systems allow multiple images encompassing the entire spine to be captured without the need for repositioning the patient

• acquired images combined, or stitched, by the computer system into composite image demonstrating entire spine in one image

• note special radiation requirements

PA thoracolumbar

• patient position:

  • upright, facing vertical grid

• part position:

  • MSP centered to midline of the vertical grid device

  • ASIS equidistant to the IR

  • arms abducted and not in field

• CR:

  • perpendicular to IR

  • centering points for each sequence will be dictated by the system used

  • a two (or three) image sequence is performed

• collimation:

  • depends on the type of system used, as well as the extent of the patient’s scoliosis

PA thoracolumbar image criteria

• entire spine from base of skull to tip of coccyx

  • cervical, thoracic, and lumbosacral spines

  • vertebral column aligned down the center of the image

Lateral thoracolumbar

• patient position:

  • upright, lateral

• part position:

  • MSP centered with the IR

  • MCP perpendicular to midline of grid

  • arms at right angle to body or upward

  • position special ruler adjacent to spine if needed

• CR:

  • perpendicular to IR

  • centering points for each sequence will be dictated by the system used

  • a two (or three) image sequence is performed

• collimation:

  • depends on the type of imaging system used, as well as the extent of the patient’s scoliosis

Lateral thoracolumbar image criteria

• entire spine from base of skull to tip of coccyx

  • entire cervical, thoracic, and lumbosacral spines

  • vertebral column aligned down the center of the image