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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