Exam 1 Flashcards
Why Xray
diagnostic procedure
relates an understanding of patient anatomy and physiology communicates data
dictates management (chiropractic, medical, both, other)
Criteria for Ordering Xrays
unexplained weight loss
personal history of cancer
unexplained fever
age more than 50 years
intravnous drug use
prolonged corticosteroid use
severe, unremitting pain at night
trauma sufficient to sauce fracture or injury
pain that worsens when the patient is lying down features of cauda equina syndrome
urinary retention
blateral neurologic signs or symptoms saddle anesthesia (p. 207)
Never Xray without
history and physical exam findings
Purpose of Imaging Studies
assist clinical impression (diagnosis) and management
contribute to clinical picture
evaluation of suspected pathology, biomechanics (scoliosis, components
of subluxation)
Defensive Radiology
(to rule out pathology) doesn’t work because:
- image needs interpreting
- insensitive to eary disease
- correlation with clinical symptoms is poor (e.g., osteophyte that
doesn’t cause pain)
Plain Film Radiography
x-ray exam without contrast media show osseous pathology
shows mal-alignment
inexpensive
has poor sensitivity to early disease
Xray principles
- high energy short-wave electromagnetic radiation
- penetrates various materials
- variable attenuation of the xray beam – influenced by the atomic
number of the structure (denser the structure, greater the
attenuation, less blackening of the film) - ionizes atoms (removes electrons)
Radiodense
= dense, white, opaque, radiopaque
Lucent
= black/dark, radiolucent
Materials of Different Densities
(darkest to lightest) air
fat (oil)
water
bone metal
Magnification
related to divergence of xray beam from xray tube
Radiographic Distortion
unequal magnificaiton secondary to:
- position from the central ray
- position from the image receptor
Anatomical Distortion
radiographic: unequal magnification
anatomic:
Stress Radiography
used in cervical and lumbar spine, AC joint, ankle, knee, show gamekeepers thumb
Fluoroscopy
looking at fluoroscent plate itself, rather than film for evaluation of motion – gi, musculoskeletal image is intensified to reduce radiation dose time-dependent
loss of resolution (using fewer photons due to long patient exposure time)
Linear Tomography
blurs anatomy above and below the object plane (fulcrum) by moving tube and film during exposure to give appearance of an image slice
replaced by CT
Aging a Patient by X-ray
40 signs of degeneration
Computerized Tomography
x-rays combined with computers
Godrey Housfield, 1972 prototype, 1979 Nobel Prize with Allan Cormack tube rotates around patient
very thin fan-shaped beam of x-ray gives thin slices
measures tissue density – calculates amount of x-ray that gets through;
does 1000s of calculations to assign each area a grayscale tone data collected by sensors (no film)
Advantages:
- enhances soft tissue contrast
- removes overlaying anatome may require contrast enhancement for
- CT myelography
- abdomen
- evaluation of aneurysm
bone cortex is white
can be done in bone window or soft tissue window
Housfield Unit
unit of attenuation (ability to stop x-ray) CT # of water=0; bone=+1000; fat=-50
Plan Scan
for correlation with subsequent axial images each slice is collimated to 3-10 mm
Contrast Media in Radiography
high atomic weight compounds:
1. Iodine – used more frequently, intravenous or orally; can cause
allergic reaction; check first for renal function for clearance (BUN,
creatinine); used for
- vascular contrasts
- myelographic contrast
- gi contrasts
2. Barium – gi examinations only, mild reactions (colong cancer, diverticulitis, polyps)
Myelography
(myelo=nerve)
contrast media injected in the subarachnoid space under fluoroscopy largely replaced by MR and CT
Arthrography
injection of iodinated contrast media into a joint
Discography
contrast examination of disc contents
a diagnostic challenge – done to see if patient responds (says ouch)
Intravenous Pyelogram
IVU (urogram)
contrast examination of urinary tract
Radionuclide Imaging
technetium (Tc) infected, oral, inhaled; tagged to other substances to accentuate end-organ uptake
the radioisotope decays, emitting gamma radiation (to stabilize the nucleus)
gamma camera detects the radiation emitted from the body
Bone Scans
radionuclide
technetium (Tc 99) bound to a phosphate compound
hot spots appear darker
evaluates bone pathophysiology and blood supply good for metastatic disease, infection, Paget’s disease sensitive to early disease but not specific
If it looks normal, you can believe it is.
Lung Scans
radionuclide
perfusion (infected)
ventilation (inhaled)
SPECT
Single Photon Emission Computed Tomography
rotation of a photon detector array around body to acquire data from
multiple angles
used for brain, cardiac, bone (spondylolisthesis)
DEXA
Dual Energy X-ray Absorptimetry
beams of xrays at 2 energy levels to determine bone density
best way to quantify osteoporosis
gives T-score: number of standard deviations from young adults normals;
decreases –1 for every 10% of bone lost T –1 or higher, normal
-2.5 to –1 = osteopenia
PET
Positron Emission Tomography
injection of FDG (fluorodeoxyglucose) – molecule of glucose attached to
an atom of radioactive fluor (tumors use lots of glucose)
fluor emits positron which collides with an electron, liberating burst of
energy, gamma rays detected by PET scanner
Ultrasound
images soft tissue structures (not bone or air)
common: galbladder, aneurysm, kidney, liver, obstetrics
uses piezoelectric effect from transducer (crystal and electric current) nonionizing
reflection of beam from interfaces between tissues produces image
MRI
nonionizing
excellent soft tissue contrast
analyzes magnetic spin properties of hydrogen nuclei
Magnet - .2-1.5 Tesla (20,000X magnetic field of earth: magnetic field of
earth is .5 Gauss; 1T=10,000G); superconducting, permanent or resistive (supercooled)
How MR works
H proton has charge and spin, therefore has magnetic field and behaves as a dipole magnet
magnet creates net magnetic moment of H with tissues; H protons rotate or precess at a certain frequency
with correct RF, protons resonate (spin) together (42.58 MHz/T)
RF pulse is manipulated to tils H magnetic field a set amount (90 or 180o) RF pulse removed, magnetic fields realign with magnetic field
weak RF signal produced and detected by scanner
MR Terminology
area of high-intensity signal = white/light
areas area of low signal intensity = dark/black area
T1 v. T2 weighted
manipualtion of RF pulse and time of signal detection results in images of differing contrast
TR = repetition time (time spent pulsing in)
TE = echo time (listening time, with RF turned off)
T1: short TR (800), short TE (30 msec); black CSF T2: long TR (2,000), long TE (90); white CSF
Spin Density: long TR, short TE
Contraindications to MR
cerebral clips (but gi staples ok) [mascara, tattos show up as metal artifact]
Contrast Agents in MR
gadolinium intravenously, inert
increases signal intensity with pathological tissue on T1 images
doesn’t cross intact BBB (shows breakdown of BBB)
enhances tumors
enhances scar tissue
makes pathological fluid bright (white)
used to evaluate post-surgical fibrosis of lumbar spine; fibrosis brightens,
disc does not
Routine Cervical View
lateral
AP open mouth
AP lower
[other: swimmers, obliques, fl/ext, pillars, Fuchs, base posterior]
Lateral Cervical
must include bottom of occiput to top of T1 do first in trauma? points of interest (look for): - alignment - pre-cervical soft tissue space - osteophytes - sella turcica
Harris’s Ring
superior facet of C2 and transverse of C2?
AP Lower Cervical
must include C3-T1 points of interest:
- facets
- uncinates
- spinouses
- lung apices
- trachea (narrows at rima glottidis)
- carotids (not vertebrals)
AP Open Mouth
Oc/C1, C1/C2, dens
points of interest: odontoid fracture, Jefferson fracture (post and ant arches)
Cervical Obliques
taken to look at IVFs
IVFs named for vert above (C4/C5 IVF = C4 IVF)
named for part of body against the film
draw a line through the bodies to divide left and right (same/opposite side
as IVF)
CAOS – cervical anterior obliques same side: IVFs shown are the same
side as first letter of film name (eg RAO) and everything else is opposite, including lumbars CLAP
CL
AP
RAO cervical - shows Right IVFs
LAO cervical - RPO cervical LPO cervical
Left IVFs Left IVFs Right IVFs
anatomy to look at: IVF, uncinates, facets, odontoid
Cervical Flexion Extension
normal flexion:
- front of disc gets smaller, back should open up (sagittal rotation)
- anterior translation of vert normal extension: opposite above
Thoracic Views
AP and Lateral
T1-T12
posterior gutter = lowest point in lung field (fluid collects); look for normally deep angle
Lumbar Spine
T12-S1
Required views: AP and Lateral
other: obliques, spots AP/lateral LS, kinematic
AP Lumbar/APLP
T12-Pelvis – need L1 to ischial tuberosities
points of interest: aorta, abdominal/pelvic viscera
Kohler’s teardrop
where pectineal line meets acetabulum
Inverted Napoleon Hat Sign
indicates spondylolisthesis, do lateral, obliques to check?
Lateral Lumbar
(can see IVFs)
L1-S1
points of interest: retrolisthesis, aorta
Lumbar Obliques
anterior recumbent (better) or posterior upright shows pars and facets (not IVFs) Scotty Dog: - nose = transverse process - ear = superior articular process - body = lamina - front leg = inferior articular process - neck = pars interarticularis CLAP: RAO shows left pars LAO show right pars RPO shows right pars LPO shows left pars
CT vs. MR
CT: bone cortex is white MR: bone cortex is black
Shoulder
see AC/GH joints
views: AP internal and external, Grashey, Stress Views
AP External – taken with epicondyles perpendicular to buckey; see
greater tuberosity
AP Internal – greater tuberosity not prominent
Elbow
Routine: AP and lateral
other: external rotation
AP – elbow is extended; looking at radial head and tuberosities Lateral – positioning is important; looking at radial head, fat pads
Wrist/Hand
Routine: PA, Lateral, Oblique
other: ulna deviated
PA – looking at carpals with joint space of 2-3 mm
Lateral – positioning critical, looking at scaphoid alignment Oblique – looking joint space between trapezium and trapezoid
Knee
Routine: AP, Lateral, open joint
other: Merchant, Tangential
AP – tibial/femoral joint, CPPD, tibial spines
Lateral – 60o flexion; Patellar/femoral joint, patella position
Open joing – to see in intercondylar fossa, groove for popliteus tendon?
Ankle
Routine: AP, Lateral, Oblique
other: stress views
AP – talotibial joint; looking for subchondral fracture, alignment, swelling Oblique – tibio-fibular space
Lateral – taken lateral side down; see talotib joint, midtalar joints, calcaneus; looking for AVN, stress fractures
sustentaculum tali – top area of calcaneus, articulates with talus
Foot
Routine: AP/DP, lateral, oblique other: tangential
tuberosity of 5th metatarsal
Chest
views: PA, lateral
PA – puts heart close to film to look at size of heart review p. 48 notes
gastric air bubble = megenblas? anterior/retrosternal clear space posterior/retrocardial clear space – fills first costophrenic and costocardiac angles
normal: 10 ribs above right diaphragm
don’t see bronchi, bronchioles unless filled (bad)
ROENTGENOMETRICS
Measurements need to be performed accurately and correlated clinically
Major Errors of Mensuration
image unsharpness projectional geometric distortion patient positioning anatomic variations locating standard reference points observer error
Enlarged Sella Turcica
normal max: 16 x 22 mm (width by depth) at focal film distance (FFD) or 40” roof measured from anterior to posterior clinoids If enlarged, could be: - empty sell syndrome - tumor - normal variant - aneurysm Consider: - history - old xrays to rule out normal variant - MR to show tumor vs. empty space
Empty Sella Syndrome
hole in diaphragma sells lets CSF flow in, erodes pituitary
Clivus
= opposing part of sphenoid, from foramen magnum to dorsum sellae
Martins Basilar Angle
drawn from nasion (junction of frontal and nasal bones) to center of sella to basion (anterior margin of foramen magnum; follow ADI up)
normal 137-152 degrees
>152 = platybasia caused by:
- congenital maldevelopment of sphenoid and/or occipital bones
- bone-softening diseases such as Paget’s and osteomalacia
Chamberlain’s Line
hard palate to opisthion (posterior margin of foramen magnum; where internal and external lamina of skull meet; in line with spinolaminar junction)
odontoid should not extend more than 7mm above this line detects basilar invagination or basilar impression
McGregor’s Line
hard palate to inferior occiput
more accurate and easier to reproduce than Chamberlain’s odontoid should not extend above this line by 8-10mm
Basilar Impression
congenital
can be occipitalization
Basilar Invagination
patological can be caused by: - Paget’s disease - osteomalacia - fibrous dysplasia - arthritide such as rhematoid arthritis
George’s Lines
to detect alignment in sagittal plane (anterior or posterior displacement) along posterior vertebral bodies
Spinolaminar Line
to detect alignment in sagittal plane connecting spinolaminar lines
Anterolisthesis/Retrolisthesis
must be due to one of these:
- fracture
- dislocation
- ligamentous laxity (seen on fl/ext)
- degenerative disease
- anatomic reason
- physiologic reason
Retrolisthesis
posterior subluxation/displacement/dislocation/translation
consider drawing George’s lines and compare vert above to vert below—
upper one posterior to one below possibilities:
- trauma
- anatomic such as pedicogenic retrolisthesis (eg, short pedicle)
- physiologic
- degenerative disc disease
[If not due to any other cause, then always degenerative disc.]
Anterolisthesis
anterior subluxation/displacement/translation/dislocation = spondylolisthesis in lumbars due to: - pars defects (anatomic) - short posterior arch (anatomic) - trauma - physiologic - degenerative: posterior joint arthrosis
Atlantodental Interval
measured at smallest point between posterior surfaceof the anterior tubercle and anterior surface of the odontoid (usually inferior aspect)
checks integrity of transverse ligament Normal upper limit:
- Adult 3mm or 2.5mm
- Child 5mm or 4.5mm Etiologies of large ADI:
- trauma (rare, more likely to break odontoid than damage transverse ligament)
- inflammatory arthropathies
- Down Syndrome – 20% born with weird transverse ligament
- upper cervical anomalies such as occipitalization, agenesis of
posterior arch of C1
take flexion/extension – if moving, need neuro consult (may fixate) Rheumatoid arthritis is most common reason for big ADI
Antlantoaxial “Overhang” Sign
lateral margin of lateral masses of atlas extend lateral to superior articular processes of axis
bilateral displacement suggests fracture of atlas or odontoid process [Jefferson’s fracture = bilateral atlas fx]
unilateral offset can mean head tilt
mild overhand is a normal variant especially in children because of
different growth rates of the bones
Cervical Lordosis
- measure angle between C1 plane line and inferior C7 normal: 35-45
hard palate should be level with floor when taking xray >45 = hyperlordosis