Drive carefully, life is precious
Diagnostic Imaging for Rehab Doctors
Learning outcome and objectives1. Become familiar with various medical imaging modalities2. Understanding the advantages and disadvantages of different imaging
modalities3. Be able to recommend the correct modality given a case study4. Integrate diagnostic imaging information into physical therapy practice
Why do rehab doctors need to understand medical imaging?
1. Clinical Reasons?• How will it effect treatment?• How will it effect prognosis?• What about direct access?
2. Research Implications?
Clinical reasons: 1.not responding as expected, 2.possible undiagnosed fracture, 3.deg changes (joint space), 4.-assess status of hardware, 5.-make clinical decisions whether surgery vs. no surgical treatmentResearch reasons: 1.-biomechanical studies, 2.-correlate clinical tests with imaging findings, 3.-look at reliability and validity of imaging tools,
Imaging modalities
Ionizing modalities Non-ionizing modalities
Radiography/Plain x-ray MRI CAT Scan or CT scan US & Doppler
Isotope bone scan Flouroscopy
Radiography
Basic Concepts
What is an X-Ray?Electromagnetic
Radiation - short wavelength
An X-ray machine is essentially a camera. Instead of visible light it uses X-rays to expose the
film. X-rays are like light in that they are electromagnetic
waves, but they are more energetic so they can penetrate many materials to varying degrees.
When the X-rays hit the film, they expose it just as light would.
Since bone, fat, muscle, tumors and other masses all absorb X-rays at different levels, the image on the film lets you see different (distinct) structures inside the body because of the different levels of exposure on the film.
Professor RoentgenDiscovered accidentally in 1895
Experimenting with a machine that, unknown to him, was producing x-rays
Saw the bones of his hand in the shadow cast on a piece of cardboard in his lab
What Roentgen saw Today's ImageToday's Image
RadiodensityX-rays not absorbed,
screen produces photons when struck, and exposes the film, turning it dark
When an object absorbs the X-rays - fewer photons produced, film stays light
Radiopaque Radiolucent
Principle components of x-ray tube:Source of electrons Target Evacuated envelope High-voltage source
The X-ray tube parts:
Cathode (-)Filament made of
tungstenAnode (+) target
Tungsten disc that turns on a rotor
Statormotor that turns
the rotorPort
Exit for the x-rays
X-ray ProductionX-rays are produced when high velocity
electrons are decelerated during interactions with a high atomic number material, such as the tungsten target in an X-ray tube.
An electrically heated filament within the X-ray tube generates electrons that are then accelerated from the filament to hit the tungsten target by the application of a high voltage to the tube.
The electron speed can exceed half the speed of light before being rapidly decelerated in the target.
X-ray productionPush the “rotor” or
“prep” buttonCharges the filament
– causes thermionic emission (e- cloud)
Begins rotating the anode.
Push the “exposure” or “x-ray” buttone-’s move toward
anode target to produce x-rays
X-rays characteristicsHighly penetrating, invisible raysElectrically neutralTravel in straight lines.Travel with the speed of light in vaccum: 300, 000 km/sec or 186, 400 miles/sec.Ionize matter by removing orbital electronsInduce fluorescense in some substances.
Fluorescent screen glow after being stricken with photons.
Can't be focused by lenses nor by collimators.
CONCONVENTIONAL CONcCCORADIOGRAPHY
PRODUCES STATIC IMAGES
Shielding
Therapeutic x-ray production, where mega electron volts (MeV) are used, has a higher conversion of electrons into photons.
In the diagnostic range (KeV), there is more conversion of the electrons to heat.
Total number of electrons converted to heat is 99%.
Only 1% of the electrons are converted to photons
Attenuation
Attenuation – reduction in the number of photons as they pass through matter
Attenuation occurs in several different ways:Some photons are absorbed by matter
they pass through
Other’s change course in matter, called “scatter
A-B-C-D
A- Alignment- is the bone in good general alignment
B- Bone- general bone densityC- Cartilage- sufficient cartilage space
D- Dee other stuff??Muscles, fat pads and lines, joint capsules, miscellaneous soft-tissue findings, bullets
Alignment
Alignment
Bone
Bone
Cartilage
Dang
The role of imaging is to confirm the infection and show extent. Radiography will show the infection, however usually late. Radiography has a high specificity but low sensitivity.
Blood test are more useful for the diagnosis of osteomyletis
Viewing ImagesX-ray study named for the direction the
beam travels1. AP 2. PA3. Lateral
Orient film as if you were facing the patient, his/her Left will be on your Right
Views
Lateral
Oblique
Views
AP Open Mouth
Dens
Superior articulating facetSuperior articulating facetTransverse processTransverse processPediclePedicleLaminaLaminaInferior articulating facetInferior articulating facet
Lumbar Spine, Oblique View
Lumbar Spine, Oblique View
“SCOTTY DOG”
Lumbar Spondylolysis
The defect‘lysis’ involves
the parsinarticularis
and can allowthe vertebra
above tosubluxforward
Still Alive?
…That was close
Bullet can be in any of these places (anterior to posterior at same level)1 - spinal cord2 - trachea3 – Superior Vena Cava
4 - aorta
Viewing ImagesA radiograph is a two dimensional representation
Therefore, “One View is No View”Two views are needed, ideally at 90 degress to one another for proper 3-D like interpretation
Radiograph revealed horizontal fracture of the lower patalla
To sum it upIt is relatively much more
important for a physical therapist to recognize the
indications for diagnostic imaging,
to select the most appropriate imaging study, and
to image the appropriate area(s) than it is to interpret the image
Computed Tomography (CT)1. Also called CAT scanning or “CT”2. X-Ray beam moves 360 around the patient3. Consecutive x-ray “slices” around the patient4. Computer can recreate 3D image of the body or Image “slices” reconstructed by computation5. Best for evaluating bone and soft tissue tumors, fractures, intra-articular abnormalities, and
bone mineral analysis
Computed Tomography
6. The image formed is related to the subjects density
7. Image display on computer or multiple films
8. New technology is multislice helical scanner
CT (by Picker)
Computed Tomography (CT)
LV
VERTEBRAL BODY
SPINALCANAL
TRANSVERSEPROCESS
RIB
LUNGRA
LA
RV
AORTA
Magnetic Resonance Imaging (MRI)
What is a MRI?• The use of a High Power Magnet (.3 -2.0 Teslas) To align hydrogen atoms in the body to which a radio wave frequency is applied to produce an image
Higher Tesla level= increased resolutionNo standardization among imaging centers
Magnetic Resonance Imaging
1. Also called “MRI” 2. Image formed by transmitting and receiving
radio waves inside a high magnetic field3. Image “slices” reconstructed by computation4. The image formed is related to:
1. Scanner settings2. Patient hydrogen density3. Patient hydrogen chemical/physical
environment5. Image display on computer or multiple films
MRI by Picker
Indications for MRI
Diagnosing multiple sclerosis (MS) Diagnosing tumors of the pituitary gland and
brain Diagnosing infections in the brain, spine or
joints Visualizing torn ligaments in the wrist, knee
and ankle Visualizing shoulder injuries Diagnosing tendonitis Evaluating masses in the soft tissues of the
body Evaluating bone tumors, cysts and bulging or
herniated discs in the spine Diagnosing strokes in their earliest stages
T1 Vs T2T1Tissue with high
water content will apear dark (grey)Fat, edema, infection
Tissue with low water content will appear white/ brighterBone
T2Tissue with high
water content will appear white/ brighter
Tissue with low water content will appear darker (grey)
World War IIWater is white on T2
T1 vs. T2T1 image of knee T2 image of knee
Gastrocnemius
Semimembranosus
Popliteal vein
Quad Tendon Semimembrano
sus
ACL
Semitendonosus
Knee - MRI Sagittal
ANTERIORCRUCIATE LIGAMENT
POSTERIORCRUCIATE LIGAMENT
PATHOLOGY
ACL Tear
Knee - MRI Sagittal
TORN POSTERIOR MEDIAL MENISCUS
Meniscus
Torn Meniscus
MRI shoulder
humerus
infrasp
inat
us
Scapula
Tere
s
min
or
supraspinatus
Deltoid
Clavicle
Glenoid labrum
Long Head of Triceps
Shoulder - MRI – Axial Plane
SupS
D
D
IS
Shoulder - MRI – Axial Plane
Shoulder - MRI – Coronal Plane
Supraspinatus
Rotator CuffSS Tendon
Fluid inJoint
Glenoid
Acr -- Clav
Shoulder
Supraspinatus Tear
Subdeltoid Bursa
Lumbar Spine - MRI
Coronal T1 Sagittal T1 Sagittal T2
Axial T1 body
Axial T1 disc
Axial T2 body
Axial T2 disc
Lumbar Spine – MRI Axial
Body
Psoas
Spinal Canal
Herniated disc
Lumbar Spine – MRI Sagittal T2
DEXA SCAN
Looks at bone mineral densities
Nuclear ScintigraphyUses gamma rays to produce an
image, emitted from the patientRadioactive nuclide given IV, per os,
per rectum etc.Abnormal function, metabolic activity,
abnormal amount of uptakePoor for anatomical information
www.upei.ca/~vetrad
Nuclear camera
Skeletal Scintigraphy(Bone Scan)
Indication: Cancer, stress or hidden fractures
Ultrasound1. Also called “sono” or “echo” or “US”2. Image formed by transmitting and
receiving high frequency sound waves3. Image “slices” reconstructed by
computation4. The image formed is related to
interfaces between tissue areas of differing sound transmission characteristics
5. Image display on computer or multiple films
Convex 3.5 MHzFor abdominal and OB/GYN studies
Micro-convex: 6.5MHzFor transvaginal andtransrectal studies
Ultrasoundmachine
Ultrasound examination
Text BooksDavid Sutton’s
Radiology
THANK YOU
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