Test 3: Imaging Flashcards
what are the routine radiographs of the hip
lateral frog leg
AP
what can you visualize with a hip AP radiograph
hip joint and proximal femur
looking at iliofemoral line, shenton’s hip line, and femoral neck angle
what are the iliofemoral line and shenton’s hip line
iliofemoral = smooth curve alone outer ilium that extends into neck
shenton’s = smooth curve around obturator foramen
important obervations when viewing the hip xray (ABCDS)
well preserved joint space
smooth margins of acetabulum/femoral head
obvious ball and socket
cortex margins on shaft
cancellous markings on head and neck
what is the purpose of the lateral frog view
visualizes head, neck, and proximal femur
lesser trochanter is more anterior
routine radiographs of the knee
AP
lateral
PA axial “tunnel” view
tangential
what can you see with a knee AP view
distal femur
proximal tibia (and respective joint)
fibular head
important things to obeserve with AP knee
patella superimposed and not typically visible unless baja
well defined/equal joint spaces
tibia/femur alignment
distinct cortical margins and cancellous markings
advantage of the knee lateral view
visualize profile of PF joint
can determine alta/baja positioning of patella
how similar should the length of the patella and the patellar tendon be?
within 20% variance
what can you view with the knee PA axial tunnel view
intercondylar fossa and eminence
posterior femur and tibia
tibial plateaus
used to detect loose bodies, osteochondral defexts, or narrowing of joint space
performed in standing for ARJC
tunnel should be round and open
what can you see with the knee tangential view
PF joint space and surfaces
can see sulcus angle; obs depth; if shallow may be more prone to dislocation
can see congruence angle; helps determine patellar position within sulcus (>16 deg associated with hyper)
ottawa knee rules
over 55
fibular head tenderness
isolated patellar tenderness
inability to flex knee to 90
inability to walk 4 steps after injury
routine ankle radiographs
AP
AP oblique
lateral
what can you see with the ankle AP view
distal tib/fib and talar dome
lateral malleolus should me more distal than medial
can see upper and medial talus; medial or lateral shift is abnormal
cam see distal tib/fib joint space
what can you see with the ankle AP oblique view
mortise is visible with 15-20 deg hip IR
can see entire talocrural joint space
mortise is typically 3-4 mm or < 1/2 cm all the way around
> 6mm measure used for syndesmotic injury
what can you see with ankle lateral view
tibiotalar and subtalar
talonavicular and calcaneocuboid joints
bony members
what is the ankle anterior drawer stress view used for
xray while performing ligament test
measure from tibia to posterior talus
normal = 5mm or 1/2 cm
abnormal = > 10 mm or 1 cm
5-10 mm of separation requires comparison between sides
what is the ankle EV/IV stress view used for
measure angle between the bottom of the tibia and the talar dome
abnormal = mortise widens, >15 deg for IV or >10 deg for EV
also abnormal if >5 deg difference between sides
routine radiographs for foot
AP
lateral
oblique
what can you see with foot AP view
mid and fore foot
can note individual bones
look at 1st intermetatarsal angle; intersection of lines bisecting 1st and 2nd MT shafts (normal is < 5-10 deg)
what can you see with the lateral view of the foot
subtalar, talonavicular, and calcaneocuboid joints and members
different from ankle because less tibiofibular imaged
what can you see with the foot oblique view
foot and leg medially rotated
visualizes forefoot primarily but also all tarsals except cuneiform and a portion of the talus
important observations with foot oblique view
MTs image with sharp clearly defined cortical borders
sesamoids
2nd-4th distal phalanges DIFFICULT TO SEE
joint spaces and midtarsal joints
what are the ottawa ankle rules
tender at posterior aspect or tip of lateral malleolus OR
at posterior aspect or tip of medial malleolus OR
inability to bear weight immedialtely and at ER
what are the ottawa foot rules
tender at base of 5th MT
tender at navicular bone
inability to bear weight immediately after or in ER
major advantages of US
real time info for superficial soft tissue
higher resolution for superficial tendon, ligament, and muscle than MRI
major disadvantage of US
inability to scan deeper joint structures
image quality is dependent on operator
things to understand about a sonograph
brighter signal from reflextion of smoother and denser structures = swelling, tendinosis; akak hyperechoic appearance
irregular borders or lack of structure = tear
wider structure = swelling/thickening
how to choose imaging options
radiograph = initial
CT and MRI recommended for complex fxs and osteochondral lesions
MRI recommended for stress fxs and tendon abnormalities
MRi arthrography (+contrast) for ligament and cartilage issues
US appropriate for superficial soft tissue abnormalities
who should get imaging with LBP
over 55 and hx on cancer
saddle paraesthesias
bowel/bladder dysfunction
specific neuro deficits
progressive/disabling symptoms
no improvement in 6 wks
what structures are what colors with radiographs
black = air
gray = soft tissue
white = bone
bright white = dye
solid white = metal
how many markers should you identify with imaging
at least 2
ABCS of radiographs
alignment = misalignment indicates fx/dislocation (with possible cord compromise)
bone density = outer cortical bone is brighter white than inner cancellous
cartilage space = narrowing, sclerosis, growth plates
soft tissues = muscle wasting/capsular distention/periosteal disruption
routine radiographs for L/S
AP
lateral
R and L oblique
lateral L5,S1
what are you looking for with a AP view of spine
vertically aligned vertebral bodies
preserved intervertebral spaces
midline spinous processes (larger in upper/smaller spacing in lower segments)
what do the articular processes look like in AP view of spine
casts a butterfly shaped shadow on vertebral bodies
joints not specifically visible but alignment is noted
what do pedicles look like on AP view of spine
oval densities
equidistance from SPs
level of iliac crest indicates what
clinically = L3/4
imaging = L4/L5
what are you looking for with lateral imaging of the spine
3 parallel lines
-anterior vertebral borders
-posterior vertebral borders
-spinolaminar line (junction of SP and lamina)
should remain constant regardless of position of spine
what is Barge’s angle
angle between sacral base and vertical line
53 deg average
what is ferguson’s angle
angle between sacral base and horizontal line
41 average
what does a smaller barge’s and a larger ferguson’s angle indicate
more lordosis
greater facet compression
anterior shear forces
lateral foramen narrowing
what does a larger barge’s and a smaller ferguson’s angle indicate
less lordosis
greater vertebral body and discal compression
oblique view is best for picking up what
spondylolysis or spondylolisthesis
major advantages of CT
less overlap
can locate subtle bone changes
major disadvantages of CT
greater radiation exposure
limited with soft tissue abnormalities
what should you understand about a transverse plane slice of CT
patient is supine so anterior surface is at the top of each image slice
look upward at tha anatomic structures from below so your right is the pts left
how are sagittal plane CT slices viewed
from L to R
major advantages of MRI
excellent for soft tissue abnormalities, cancellous/bone marrow conditions, or staging metastasis
no radiation like with CT or xray
high resolution
major disadvantages of MRI
contraindications with magnetic implants except for stable joint implants
precaution with claustrophobia
difference between T1 and T2 MRI
T2 image = bright fluid; shows inflammation
T1 image = dark fluid; better anatomically
what is indicated on T1 imaging
brigth signals from fat and bone marrow
dark signals form cortical bone and fluid
best at demonstrating anatomical definition of structure
what is indicated on T2 images
bright signals from fluid and water
best for demonstrating swelling and neoplasms; particularly in cancellous bone
why would persistent IDD not have bright white on imaging
persistent becomes fibrotic
