imaging midterm Flashcards
sensitivity
SnNout
negative, out
good for ruling out if test is negative
specificity
SpPin
positive, in
good for ruling in if test is positive
potential errors in imaging
pt mistaken for another
wrong extremity
less obvious injuries missed
areas of referred pain imaged not area of symptoms
misinterpreted by radiologist
poor quality images
ordering images
understand most current standards
evidence base screening
mech of injury and location
brief anatomically correct descriptions
can request priority for routine, serious, life threatening
relevance of pathology
comprehensive history and physical examination
radiologist suggests clinical correlation
interpretation
interpreting rests primarily with radiologist
skilled review
reflective imaging
ultrasound and MRI
energy inserted into system, captured, and converted into and image when returned
ultrasound
form mechanical compression of molecules
MRI
combination of electromagnetic and radio energy to produce signals from body that can be collected and analyzed to produce an image
ionizing radiation
x-rays, CT
require ionizing radiation exposure with attendant risks
CT
IR penetrates matter and creates image through computer
hounsfield units- over 2000 levels between black and white
water point in hounsfields
negative 1000
air point in hounsfields
postive 1000
what is CT good for?
bony pathologies
what is MRI good for?
soft tissue pathologies
emission imaging
bone scan
add radiopharmaceutical agent in blood
shows areas with increased metabolic activity
are bony scans binary
yes, give either yes or no answer.
they demonstrate only increased metabolic activity, not the cause
are bone scans diagnostic?
no, they are also non-specific
what are bone scans used for
injuries to skeleton
degenerative changes
extent of certain metastatic lesions
are bone scans good for fractures?
bone scans are time sensitive and positive in case of fractures, such as overuse or stress syndromes
are bone scans expensive?
bone scans are more expensive than standard films, but significantly less expensive than CT or MRI
standard x-ray films
follows series of analytical steps
requires knowledge of anatomy and spatial relationships
creates bony displacement or reactions such as lesions in surrounding skeletal structures
cost-effective and highly specific for skeletal pathology
ionizing radiation
air density
most radiolucent and absorbs least number of particles
darkest portion
fat density
considered radiolucent
not as dark as air, but darker than others
fluid density
more absorbent than air or fat
intermediate radiolucency
bone densities
most dense
calcium is metal like density
radio-opaque
appear white
is cortical or cancellous bone more dense
cortical
when are shields used?
to protect body parts exposed to radiation that are not of interest in examination
what do you use to select views that limit radiation exposure
diagnostic imaging literature
what view do use use for scoliosis and why?
PA
reduce exposure to breasts and thyroid
what are plain radiographs not sensitive to?
early changes in tumors, infections and some fractures
subtle pathologies - chance of false negative high
where are plain films more specific than bone scans or MRI?
characterizing specific calcification patterns and periosteal reactions
number of exposures required for plain
minimum of two taken at 90 degrees to one another
cervical and lumbar require 5 each
body position relative to source of beam
closer to the plate, the better the resolution will be
further from the light source, the more precise resulting shadow
overuse of imaging
significant economic problem in US
clinical prediction rules
indicate need, help reduce unnecessary imaging
basic radiographic principles
do no harm
request by DPT written clearly in standard terminology
never use x-ray as substitute for taking history and physical
correlate history, physical, labs, x-rays to make PT diagnosis
avoid repetitious exposure and use shields
if fracture indicated, x-ray should be performed
include joint above and below suspected pathology
lack of x-ray evidence of fracture does not rule out fracture
special studies indicated when signs/symptoms do not correlate with x-ray findings
soft tissue films can rule out foreign bodies
look at both sides
frequency of follow up x-rays depends on various factors
suspected fractures not seen on initial x-ray should be x-rayed again in 10-14 days
include all differential diagnoses to be ruled out or accepted
history of neck trauma should have cross-table lateral of c spine to rule out fracture or dislocation before any treatment
post-reduction films to judge adequacy and maintenance
read on view box with hot light
arthrograms have risk of infection or allergic reaction
always view fractures with suspicion of pathological etiology
only accept quality x-rays
orientation of films
check pt name
check dates
orient on view box by date and sequence
check for right and left markers
develop a system
how does bone react to its environment
just like any other tissue, but in slow motion
wolff’s law
stressed bone reacts over time by strengthening areas of increased stress and demineralizing or eliminating areas of lowered stress
ABCS
alignment
bone density and dimension
cartilage
soft tissue
alignment (ABCS)
study size, number, shape, and alignment of bones
bone (ABCS)
health of skeletal system interconnected to overall health of organism
density and dimension
bone density (ABCS)
specific to region and that portion of bone being imaged
cancellous bones should have consistent trabecular patterns throughout
is periosteum swelling or lifting from bone
bone dimensions (ABCS)
specific to anatomic region and bone being evaluated
compare both sides
cartilage (ABCS)
width and symmetry of joint space
cartilage spacer between bony articular surfaces
soft tissue (ABCS)
look for swelling, capsular distension, periosteal elevation
soft tissue affects structure of musculoskeletal system
tomography
slices down to 1mm
relatively higher IR but confined to smaller are and has superior resolution to plain radiographs
two types of tomography
conventional tomography
computed tomography (CT)
film and body part stationary while exposed to radiation
plain radiographs
CT
tube moves
sequential images in parallel planes
adjust thickness of slices
increased details compared to plain
during CT
pt on table moved inside scanning gantry
tube rotated 360 degrees around pt
relative density values in shades of gray
limited differentiation between types of soft tissue
excellent definition of bone
limitations of CT
less complex and expensive than MRI
higher radiation doses and cost to conventional
MRI more useful for disc herniations
indications of CT
combo of CT and MRI to evaluate combo of bone and soft tissue
CT provides additional details of spinal osteophytes and spinal fractures
MRI
ability to image both bone and soft tissue
uses magnetic fields to produce images
MRI physics
magnetic properties of body’s tissues
exposed to strong radio-frequency pulses that produce measurable changes in body’s atoms
depend on intrinsic spin of atoms with odd number of neutrons or protons
atomic nuclei align to direction of magnetic field
RF cause nuclei to absorb energy and produce resonance for type of tissue
upon removal of RF energy absorbed is released as electrical signal
signal intensity
strength of radio wave that tissue emits following removal of RF
bright images
high signal intensity
dark images
low signal images
image quality
movement can decrease image quality
slices too thin or too close produce interference
longitudinal or T1 relaxation
return of protons to equilibrium following application and removal of RF pulse
fat have bright signal
bone bright
proteinaceous material medium to bright
other soft tissues have normal low
T1 weighted clearly delineate soft tissue
transverse or T2 relaxation
describes associated loss of coherence or phase between individual protons immediately following application of RF pulse
fluids are bright - 2 like H2O
overall less details in soft tissue
proton density weighted
combine properties of T1 and T2 weighted images and produce good anatomic detail with little tissue contrast
fat spin echo (FSE)
T2 weighted produce bright fat
fat suppression produces dull fat for contrast to bright fluid
second RF rapidly applied
FSE T2 reveal marrow pathology
inversion recovery (STIR)
reduces signal from fat and increases signal from fluid and edema
MRI contraindications
any ferromagnetic metal implants
claustrophobia
relative high cost
MRI indications
high quality images of large joint components
3 orthogonal planes, one suppresses fat
FSE or gradient echo should be included
intra-articular contrast increases sensitivity to diagnose rotator cuff tears, labral lesions or articular cartilage injuries
useful to diagnose muscle and tendon tears
superior to ultrasound for monitoring stages of healing
scintigraphy (bone scans)
reveal uptake of radiopharmaceutical substance into areas of reactive bone
injected hours prior to bone scan
reveal areas of radionuclide uptake
hot spots
metabolically active areas such as healing have higher uptake
appear dark
bone scan indications
scan for presence and distribution of lesions
help screen for metastasis
sensitive but not specific
sensitive for changes in fractures, infection, tumors
what is the one exceptions to sensitivity of bone scan
multiple myeloma
what is multiple myeloma
diffuse osteopenia and multiple lucent areas of bone that result in painful fractures
lucent areas represent cold lesions that may not be metabolically active enough to cause increased uptake of radiopharmaceutical on bone scan
increased erythrocyte sedimentation rate on plain
DPT applications
bone scans to detect stress fractures
displaced femoral neck fractures and subsequent AVN of femoral head from unrecognized FHSF
stress fracture
MRI with T2 and STIR sequences warranted
radionuclide bone scan reveals
old and well healed fractures
degenerative joint disease
open growth plates
sacroiliac joints
ultrasound
fast and inexpensive
no IR
highly sensitive to identification of fine soft tissue changes
applications of US
real time muscle contractions
tendon gliding
muscle size
US physics
sound waves
differences in signal return provide ability to distinguish structures
better images of superficial structures, more useful on thin pts
bone and metal reflect sound and cannot be imaged
clinical applications of US
excellent for rotator cuff, glenoid labrum hard to see
evaluation of hemarthrosis of knee, cannot see menisci, articular cartilage, ACL/PCL
early changes in RA
acute muscle and tendon injures
DPT applications of US
direct operator interaction with pt
power doppler very detailed, can demonstrate hyperemia in RC and biceps tendon
standard views for glenohumeral joint
ap external rotation
ap internal rotation
CR perpendicular to 1 inch inferior to coracoid process
shoulder distance from glenoid fossa to humeral head
5mm
internal rotation
allows to see lesser tuberosity on medial humeral head
west point view
used for glenoid rim and relationship of humerus to glenoid
pt prone and arm at 90-90 position, beam angled 25 degrees cephalad and 25 degree lateral to medial
used for bankart lesions with history of instability
acromion superior to glenoid
coracoid inferior to glenoid
CR through axilla toward AC joint
AC joint
tearing of ligaments cause it to shift upward
AP view of AC
pt seated beam in ap direction but 15 degrees cephalad
CR perpendicular to midline of body at level of AC
Weighted AC
weights hung from wrists to depress AC joint without causing muscle stabilization
include both affected and unaffected side
Scapula views
AP
lateral or trans-scapluar
AP scapula
CR perpendicular to midscapular area 2 inches inferior to coracoid process
lateral scapula
CR perpendicular to mid-lateral border of scapula
anterior oblique (Y) scapula
pt 60 degrees anterior oblique position and CR through GH perpendicular to image receptor
scapula looks like a Y
bankart lesion
anterioinferior aspect of glenoid labrum
complication of anterior shoulder dislocation
often with hill-sachs lesion
hill-sachs lesion
posterolateral humeral head compression fracture
anterior shoulder dislocations
shoulder osteoarthritis
Loss of joint space
Osteophytes
Subchondral cysts
Subchondral sclerosis
standard views of shoulder
AP with hand supinated
lateral with hand positioned laterally
oblique with hand pronated
AP elbow
CR perpendicular to elbow joint
elbow straight
carrying angle of forearm
longitudinal axes of distal humerus and proximal ulna
lateral right elbow
CR perpendicular to elbow
elbow at 90 degree angle
normal position of capitulum
longitudinal axis of proximal radius passes through center of capitulum
anterior border of humerus normally intersects middle 1/3 of capitulum
oblique view of elbow
CR perpendicular to arm and enters at elbow joint
can see the coronoid process very well
standard wrist views
PA
lateral
semipronated oblique
semipronated oblique
evaluation of scaphoid and distal radius
special views for wrist
radial and ulnar deviation
scaphoid visualization in ulnar deviation
PA wrist
CR passes through mid carpal joint
three arcuate lines
arc 1 - under proximal row
arc 2 - above proximal row
arc 3 - under distal row
ulnar variance
want ulna and radius level
negative when ulna shorter
positive when ulna longer
radial angle
formed by line perpendicular to long axis and line drawn across radial articular surface
should be 15-25 degrees
oblique wrist
CR through midcarpal joint
hand flat
lateral wrist
CR passes through midcarpal joint
through lateral side of wrist
hand views
PA
oblique
lateral
PA hand
CR perpendicular to hand at 3rd MC joint
hand flat
radiographic spatial relationships with PA hand
slant through 3-5 MC
2nd MC through center of radius
4th IP above 5th IP
boxer’s fracture
pinky
sometimes 4th finger
oblique hand
CR through 3rd MC joint
45 degree foam block used
why is a foam block used for oblique hand
elevation of fingers opens MCP and IP
lateral hand
CR through 2nd MCP joint
through lateral hand
terrible triad
dislocation of elbow
fracture of radial head
fracture of coronoid process
radial head fracture classifications
1: non displaced
2: non comminuted, displaced
3: comminuted
coronoid fracture classifications
1: avulsion of tip of bone
2: detached fragment of less than 50%
3: detached fragment of more than 50%
kienbock disease
osteonecrosis of lunate
dominant wrist of young adult men due to repeated loading
middle age women equally between dom and non dom
with negative ulnar variance
scaphoid AVN
~75% arterial supply to scaphoid from branches of radial artery
vascular supply to proximal pole is mainly retrograde
how many vertebrae total and in each section
total: 33
cervical:7
thoracic: 12
lumbar: 5
sacral: 5 fused
coccygeal: 4 fused
C1 or Atlas
no vertebral body
wrapped around dens of C2
held in place by transverse ligament - prevents anterior displacement of C1 and C2
articular facets more horizontal in AP to facilitate rotation, wedge shaped in ML plane
lacks intervertebral disk - decreased shock absorption and stabilization
C2 or Axis
projection through C1
odontoid/dens
no IVD between it and C1
dens fractures
by trauma, congenital malformation, failure to fuse
1: oblique fx through upper 1/3 of odontoid, stable
2: transverse fx through base where it joins to body
3: fx of odontoid down into body
lower C spine
C3-C7
size, components, shape, density, dimensions similar
compare above and below to each other
standard views of c spine
odontoid (open mouth)(APOM)
AP
left oblique
right oblique
lateral
odontoid
beam directed into the open mouth of pt
alignment in APOM
demonstrate odontoid and lateral masses of C1
distance between lateral edges of odontoid and medial edges of lateral masses are symmetrical
articular surfaces of C1 and C2 should be parallel
jefferson’s fracture
lateral overhanging of lateral mass beyond lateral margins of C2
offset in C1 and C2
over 2mm is abnormal
under 1-2mm can be from head rotation or tilt
bone density with APOM
odontoid should have no luncencies
AP c spine
pt supine or sitting
C3-C7
AP c spine alignment
spinous processes make vertical line
each segment assess for rotation and tilting
comparison of vertebra
vertebra above and below each other within C3-C7 can be compared to assess and changes in density
soft tissue AP c spine
dark shadowlike trachea seem in midline
may indicate presence of tumor, pneumothorax, or hemothorax
pancoat’s tumor
white mass in upper lung area
displaces trachea
left and right oblique C spine
compare both for side by side consistency
evaluate IV foramina, pedicles, articular facets
lateral view C spine
usually most informative of standard views
best viewed after other 4
often supports differential established during review of previous routine views
alignment in lateral view of c spine
absence of lordosis, kyphosis, normal lordosis
follow anterior and posterior longitudinal ligament and junctions of lamina and spinous processes
atlantodens interval (ADI)
must not exceed 3mm
any distance above must be evaluated for stability
risk factors: trauma, CT/AI disease, congenital disease
if at risk, flex/ex studies done before any manual therapy
lateral view with flexion (C spine)
pt in full flexion
ADI should not widen
hangman’s fracture
cervical trauma
anterior body of C2 overhangs C3
lucency through pedicles of C2
occurs with rapid deceleration and with hyperextension
most do not survive
anklylosing spondylitis
syndesmophytes bridging anterior vertebral bodies
aka bamboo spine
uncinate joints in column two
rheumatoid arthritis
decreases mineralization of c spine and anterior subluxation
soft tissue in lateral view of c spine
decreased density indicative of hemorrhage
increased distance between spinous processes may indicate ligament tear
what is flattening of the cervical spine an indication of?
cervical spasm
in compromise of soft tissue…
… possible to have dislocation of spine without fractures
compression fracture
anterior body is not the same height as posterior body
variations on normal
absence of space between two bodies may represent HNP or failure of embryonic segmentation
block vertebrae, hemivertebrae, transitional vertebrae
spina bifida occulta of atlas
absence of spinal laminal line in lateral projection
incompletely ossified posterior arch
block segments - congenital and acquired
acquired - from pathology or surgery
columnar shape
congenital - wasp waist, hourglass shaped
also could have a mixed block - combo of the two
variations of block segments
lack of complete segmentation considered in differential in absence of obvious explanation of pain in atraumatic cases
aggressive manual therapy not recommended on non-mobile segment levels
found throughout spine
