X-ray Measurements
Monday, February 04, 2008
7:49 PM
Trimester 5 Class
Diagnostic Imaging I 5802
Roentgenometrics – Required Material
Definitions
Platybasia=a condition of the posterior fossa of the skull moving cephalic and usually causing basilar impression
Nasion=frontal bone and nasal bone junction
Basion=anterior margin of the foramen magnum
Opisthion=middle point of the rear margin of the foramen magnum
Spondyloptosis=a condition characterized by the 5th lumbar vertebra being anterior to the sacral prominatory
Fovea capitis=hole in the head of the femur
Scheuermann's disease=a condition in which the thoracic kyphosis is increased (‘old lady’s hump’)
Imbrication=having irregular overlapping edges
For the following measurements or assessments of the skeleton you should be able to:
1.
2.
3.
4.
Draw the line or assessment
Recognize the line or assessment
Know how to recognize normal
What are the most likely considerations when the line or assessment is abnormal?
List of measure that are famous but either hard to draw or do not work:
Macrae’s line
o
A line b/t the anterior and posterior margins of the foramen magnum related to the occipital bone and the
odontoid process
o
Basilar impression is present when the occiput lies above this line (may be due to platybasia, occipitalization, RA,
or bone softening disease.
o
If the odontoid apex does not lie in the ventral 1/4 of this line a dislocation of the atlanto-occipital joint or
fracture of the dens may be present.
o
A true lateral w/ no lateral flexion distortion is REQUIRED to perform this measurement
Digastric line
o
A measurement made b/t the odontoid tip and a line formed by connecting the Digastric groove bilaterally. Also
measure b/t the atlanto-occipital joints and the previously mentioned line
o
Both measurements will decrease in basilar impression (due to platybasia, occipitalization, and bone softening
diseases)
Boogard’s line
o
A line drawn b/t the nasion and opisthion
o
Altered in basilar impression (basion will be above Boogard's line
Boogard's angle
o
An angle b/t the basion and the opisthion and the dorsum sella to the basion
o
Altered in basilar impression (angle will be > 135°)
McNab’s line
o
A line through the inferior endplate of the level being evaluated is compared against the adjacent tip of the
superior articular process of the vertebra below
o
Intersection of this line and the superior articular process suggests facet imbrication may be present
o
Relevance is doubtful given high incidence in asymptomatic individuals
Flexion/extension films-lumbar spine (Compression/distraction radiography of the lumbar spine has replaced
flexion/extension films.)
o
Canal measurement
o
A measurement b/t a line drawn through the superior and inferior articular processes at each lumbar level and
the posterior body margin at the midpoint of the same level vertebral body
o
A measurement less than 15 mm indicates possible canal stenosis
Canal/body ratio
o
A ratio b/t the width of the body vs the apparent depth of the spinal canal
o
The higher the ratio the smaller the spinal canal and possible canal stenosis
Skull:
Sella turcica size
o
AP and vertical measurements
o
Enlargement could be due to pituitary neoplasm or extra-pituitary mass
Basilar angle
o
Angle formed by the intersection of the nasion, basion, and the center of the sella turcica
o
Enlargement may be congenital or acquired (Paget's disease, RA, fibrous dysplasia)
McGregor’s line
o
Line from posterosuperior margin of hard palate to the most inferior surface of the occipital bone compared
against the height of the Odontoid process
o
Complications (basilar impression) from superior position could be due to bone softening disorders, platybasia,
or occipitalization of the Atlas
Chamberlain’s line
o
Line from the posterior portion of the hard palate to the posterior aspect of the foramen magnum compared
against the location of the Odontoid process
o
Abnormal position would indicate basilar impression and may be caused by platybasia, atlas occipitalization and
bone softening diseases
Cervical Spine:
Atlantodental interspace (ADI)
o
Distance b/t the posterior margin of the anterior
tubercle of the Atlas and anterior surface of the
Odontoid
o
Decreased space is expect in those with DJD
o
Increased space is associated w/ decreased space in
the neural canal which may be due to trauma,
occipitalization, Down's Syndrome, pharyngeal infection,
and inflammatory arthopathies
George’s line/posterior body line
o
A non continuous series of lines traveling down the
posterior portion of the vertebral bodies and disc spaces
o
A break in George's line is indicative of prior trauma or
may be a sign of instability, especially in cases of
anterolisthesis or retrolisthesis (which may be due to
fracture, dislocation, ligamentous laxity, or DJD)
Posterior cervical line/spinal laminar line / spinolaminar line
o
A non continuous series of lines along the cortical
margin of the laminar/spinous junction throughout the
cervical spine
o
A discontinuity in the lines will indicate an anterior or
posterior displacement of the vertebra (especially useful
when detecting odontoid fractures and atlantoaxial
subluxation). This will also aid in the ID of lower cervical anterolisthesis or retrolisthesis or frank dislocation
Sagittal dimension of the cervical spinal canal
o
A measure of the distance b/t the spinolaminar junction and the posterior surface of the midvertebral body of
the same level
o
Typically this measurement helps determine if canal stenosis may be present or if a potential neoplasm rests
w/in the spinal canal
Atlantoaxial alignment
o
Compare the lateral margins of the Atlas to the lateral corner of the Axis
o
Should these two landmarks not be in vertical alignment a Jefferson's fracture, Odontoid fracture, Alar ligament
instability, or rotatory atlantoaxial subluxation may be present
Cervical gravity line
o
A vertical line drawn through the apex of the Odontoid process
o
Should this line not pass through C7 an indication of non ideal gravitational stresses may be present
Cervical lordosis
o
Dept of the cervical curve
The distance b/t a line drawn from the superior-posterior aspect of the odontoid to the posterior
inferior corner of C7 is measured to the furthest posterior portion of the vertebral body
o
Method of Jochumsen
The distance b/t a line drawn from the anterior border of the Atlas anterior tubercle to the

anterosuperior corner of C7 to the anterior border of the C5 body
o
Angle of cervical curve
The angle formed by a line through and parallel to the inferior endplate of the C7 body intersecting w/ a

line through and parallel to the anterior and posterior tubercles of the Atlas w/ perpendicular lines aiding in
intersection
o
Method of Gore
An angle formed by a line through the posterior surface of the C2 body and another through the

posterior surface of the C7 body
o
All measure the relative amount of lordosis w/ in the gross cervical spine. A trauma, muscle spasm, or
degenerative spondylosis may induce a reversal or decrease in the cervical lordosis
Stress lines of the cervical spine
o
A line is drawn along the posterior surface of the axis and another along the posterior surface of the C7 body
until it intersects the Axis line.
o
When in flexion these lines normally intersect at the C5-C6 disc/facet level. When in extension these lines
should intersect at the C4-C5 disc or facet level
Prevertebral soft tissues
o
Measurements b/t the inferior-anterior most aspects the C1-C7 vertebral bodies and the posterior portion of
the adjacent tracheal shadow
o
Any increase in soft tissue spacing my indicate: post-traumatic hematoma, retropharyngeal abscess, or
neoplasm from adjacent bone or soft tissue structures
Thoracic Spine:
Cobb method of scoliosis measure
o
An angle formed by perpendicular lines along the superior most vertebra of the spinal curvature a line along the
superior end plate and a line along the inferior end plate of the inferior most vertebra of the spinal curvature draw
o
Curvatures < 20° require only continued observation
o
Curvatures b/t 20° - 40° should be braced
o
Curvatures >40° require surgical intervention
Risser – Ferguson method of scoliosis measure
o
An angle formed by the intersection of lines from the superior and inferior most vertebra of a spinal curvature
which passes both through the center of the apical vertebra and through the center of both the end vertebra
o
This procedure allows for the monitoring and assessment of scoliosis
Thoracic kyphosis
o
Angle formed by lines perpendicular to those along the superior endplate of the T1 body and the inferior
endplate of the T12 body
o
An increased kyphosis may be seen w/ old age, osteoporosis, Scheuermann's disease, congenital anomalies,
muscular paralysis, or cystic fibrosis
Thoracic cage dimension
o
A measure of the distance b/t the anterior surface of T8 and the posterior sternum
o
Lower than normal values indicates 'straight back syndrome' (which should then prompt evaluation for
auscultation for a cardiac murmur)
Lumbar Spine:
Intervertebral disc height
o
Hurxthal's method
The distance b/t the opposing endplates at the midpoint b/t the Anterior and Posterior vertebral body

margins
o
Farfan's method
The anterior disc height and posterior disc height are

measured and expressed as a ratio to disc diameter.
These ratios are then divided Anterior over Posterior to
give disc height
o
The most common causes of disc degeneration is disc
degeneration, post surgery, postchemonucleolysis, infection,
or congenital hypoplasia.
Lumbar intervertebral disc angles
o
Lines are drawn through the lumbar body end plates and the
lines are extended posteriorly until they form an angle
o
These values will be altered in antalgia, muscular imbalance,
and improper posture
Lumbar lordosis
o
An angle created by the intersection of perpendicular lines
from a line drawn through the superior endplate of L1 and
another drawn through the superior endplate of the first sacral
segment
o
While a wide consensus of the importance of lumbar lordosis
is debated an increase tends to move the nucleus pulposus
anteriorly is evident
Lumbosacral angle
o
The angle created by the intersection of a horizontal line and
a line along the sacral base
o
No consensus of the role of this measurement is present at
this time
Lumbosacral disc angle
o
An angle formed by the intersection of a line along the sacral
base (superior endplate of the 1st sacral segment) and a line
along the inferior endplate of L5
o
An increased angle of 15° in associated w/ LBP due to facet
impaction.
Static vertebral malposition/Houston conference listings/Medicare
listings
o
Flexion, Extension, Lateral Flexion, Rotation, Anterolisthesis,
Retrolisthesis, Laterolisthesis
o
These while used as listings are not confirm a clinically significant finding
Lumbar gravity line
o
A vertical line intersecting the center of the L3 vertebral body (determined by X-ing the body)
o
Should this line pass anterior to the sacrum a shearing stress may exist b/t the lumosacral apophyseal joints.
o
Should this line pass posterior to the sacrum more stress may be placed upon the pars interarticularis
Hadley’s “S” curve
o
A curved line along the inferior margin of the TP and down along the inferior articular process to the apophyseal
joint space, continued along the articulation onto the superior articular process of the inferior vertebra
o
An interruption of the contour of this line indicates facet imbrication (subluxation)
Van Akkerveeken's measurement of lumbar instability
o
A pair of lines drawn through the opposing segmental endplates until they intersect posteriorly. Now measure
the distance b/t the intersection and the posterior body margins
o
Greater than 1.5 mm difference is suggestive if disc or ligamentous problems
Lateral bending sign
o
Transverse lines along the superior articular processes of each lumbar vertebra or the superior border of the
pedicles
o
Failure of a local segment to laterally flex ay indicate a posterolateral disc herniation
Percentage method-Anterolisthesis
o
A measure of the amount of anteriority of the posterior/inferior border of the L5 vertebral body divided by the
length of the superior surface of the 1st sacral segment multiplied by 100
Meyerding rating system
o
A line along the superior surface of the 1st sacral segment is divided into 4 equal lengths and the position of the
posterior/inferior border of the L5 vertebra is compared to these lengths
o
If the body is w/in section 1 it is Grade 1…
o
Should the vertebral body 'slip' beyond the sacral prominatory the condition is called spondyloptosis
Ullmann’s line
o
A line drawn through the superior surface of the 1st sacral segment and a perpendicular line to this at the
anterior margin of the sacral base compared to the L5 vertebral body
o
If the L5 vertebral body crosses the perpendicular line then anterolisthesis may be present
Lower Extremity:
Hip joint space
o
A combination of 3 measurements along the acetabulum (superior, medial, and axial at a 45° medial angle)
Teardrop distance
o
A measure of the distance b/t the medial margin of the femoral head and the white cortical line of the 'pelvic
teardrop'
o
Hip pathology (Legg-Calve-Perthes disease highly likely) is likely if a > 2 mm discrepancy from left to right is
present
Center-edge angle/Wiberg’s
o
An angle formed by a vertical line through the central point of the femoral head and another from the femoral
head center to the outer upper acetabular margin
o
A shallow angle may relate to acetabular dysplasia
Symphysis pubis width
o
A measure of the distance across the two pubic ramus
o
Widening of the symphysis may be due to cleidocranial dysplasia, bladder extrosophy, hyperparathyroidism,
post-traumatic diastasis, or inflammatory resorption
Pre-sacral space
o
Distance b/t the anterior surface of the sacrum and the posterior wall of the rectum
o
Increased measurement indicates presence of an abnormal soft tissue mass (possibly due to sacral destruction,
tumor/infection, sacral fracture and associated hematoma, or inflammatory bowel disease)
Acetabular angle
o
An angle measured by the intersection of a transverse line through the right and left cartilages at the pelvic rim
and an oblique line connecting the lateral and medial acetabular surfaces is then drawn
o
Increased acetabular angle is associated w/ acetabular dysplasia or congenital hip dislocation.
o
Decreased acetabular angle is seen in Down's syndrome
Iliac angle and index
o
An angle measured by the intersection of a transverse line through the right and left cartilages at the pelvic rim
and a second line connecting the 1st w/ the most lateral margin of the iliac wing and iliac body
o
Very useful for determing Down's Syndrome < 60° =Down's Syndrome is likely
Protrusio acetabuli/Kohler’s line
o
A line tangential to the cortical margin of the pelvic inlet and the outer border of the obturator foramen
o
If the acetabular floor crosses the line then Protrusio Acetabuli is present. Related to idiopathic form, RA, and
Paget's disease
Shenton’s line
o
A line along the femoral neck and curving linearly to the inferior border of the superior pubic ramus (top of the
obturator foramen)
o
A discontinuity in this line represents a hip dislocation, femoral neck fracture or slipped femoral capital epiphysis
Iliofemoral line
o
A line along the outer surface of the ilium, across the acetabulum, and onto the femoral neck
o
This line should have little convexity (formed by the head of the femur). Should any asymmetry be present
congenital dysplasia, slipped femoral capital epiphysis, dislocation, or fracture should be suspected
Femoral angle
o
An angle formed by a line following the head of the femur along the neck and a second line along the shaft of
the femur
o
A value <120° is coxa vara and >130° is coxa valga
Skinner’s line
o
A line drawn through the femoral shaft w/ a secondary line perpendicular to it and tangential to the tip of the
greater trochanter is compared w/ the fovea capitis (hole in the head of the femur)
o
When the fovea lies below this line there is superior displacement of the femur relative to the femoral head
(commonly related to fracture and conditions leading to coxa vara)
Klein’s line/Kline’s line
o
A tangential line to the lateral cortical margin of the femoral neck is assessed w/ the amount of overlap w/ the
femoral head
o
If no overlapping occurs, or if asymmetry is present, then slippage of the femoral capital epiphysis should be
suspected
Patellar malalignment
o
Patella apex
Apex of patella is directly above the deepest section of the intercondylar sulcus

o
Sulcus angle
An angle formed by tangential intersecting lines drawn into the intercondylar sulcus

o
Lateral patellofemoral joint index
The narrowest medial joint space divided by the narrowest lateral joint space

>1.0=chondromalacia patellae

o
Lateral patellofemoral angle
An angle formed by a line b/t the femoral condyles and a line from the lateral to posterior portion of the

patella
o
Lateral patellar displacement
A line tangential to the medial and lateral condylar surfaces and a perpendicular line at the medial edge

of the femoral condyle
o
Measurements used to reveal contributing causes to patellofemoral joint pain syndromes and instability
Heel pad measurement
o
Measure the shortest distance b/t the external skin contour and the calcaneus
o
Increased skin thickness is a sign of acromegaly
Boehler’s angle
o
o
A pair of lines connecting the anterosuperior point on the calcaneus to the most superior part of the calcaneus
to the superior most portion of the calcaneal tuberosity
High angle incidence is consistent w/ a calcaneal fracture
Upper Extremity:
Glenohumeral joint space
o
An average measurement of the superior, middle, and inferior aspects of the glenohumeral joint
o
Joint space may be diminished due to degenerative arthritis, calcium pyrophosphate dihydriate (CPPD) crystal.
May also be associated w/ acromegaly and posterior humeral dislocation
Acromiohumeral joint space
o
A measure of the distance b/t the inferior surface of the acromion and the articular cortex of the humeral head
o
< 7 mm = rotator cuff tear or degenerative tendonitis w/ superior subluxation of the humerus.
o
> 11 mm = post-traumatic subluxation/dislocation, joint effusion, stroke, or brachial plexus lesions (drooping
shoulder)
Acromioclavicular joint space
o
Average of the superior and inferior measure of this joint
o
Decreased joint space is seen in DJD
o
Increased joint space is caused by traumatic separation or resorption owing to osteolysis in association w/
hyperparathyroidism or RA following trauma
Radio-capitellar line
o
A line drawn through the shaft of the radius should pass through the capitellum
o
May indicate radial head subluxation or dislocation
Metacarpal sign
o
A tangential line through the articular cortex of the 4th and 5th metacarpal heads should pass distal to or barely
touch the 3rd metacarpal head
o
A line passing through the 3rd metacarpal head is a frequent sign of gonadal dysgenesis (Turner's syndrome)
o
A fracture deformity may also produce a positive sign