Download diagnostic imaging

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Plain film radiography : Patient /Soft tissue /Bone /Joint
Patient : age / sex /built
Soft tissue : shape /density
Bone : periosteal /cortex /endosteum /density
Joint : bone /space /congruity
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X-rays using contrast media : Sinography,
Arthrography ,
Myelography
Xerodiography,
Computed Tomography and its USES
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Magnetic resonance imaging
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Diagnostic ultrasound and its USES
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Radionuclide imaging and Bone seeking isotopes , clinical
application
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Plain film X-ray examination is almost 100
years old
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Provides information simultaneously on
the size , shape , tissue density and bone
architecture–which when taken together
will usually suggest a diagnosis
PLAIN FILM RADIOGRAPHY
THE PATIENT
THE JOINT
Stand back from the viewing screen”PROXIMITY BREEDS TUNNEL VISION”
THE SOFT TISSUES
THE BONES
Identification
 Age
 Sex
 Built
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SHAPE
DENSITY
• Muscle planes: wasting
or swelling
• e.g bulging outlines
around the hip---- joint
effusion
• Increased : abscess ,
calcification in tendon
• Decreased : fat , gas
Periosteal surface , periosteal new bone
formation characteristic of infection ,
fractures, malignancy
Cortex evidence of destruction
Endosteum
Density has increased or decreased
Normally in the knee joint : 6-8 mm
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carpal body : 1mm
 Consists of articulating bones and the
space between them
 Orientation of joint
 Congruity of bone ends
 Narrowing or asymmetry of joint space
 Bony outgrowth
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Narrowing of joint space + osteophytes +
subarticular cysts-----------
OSTEOARTHRITIS
SINOGRAPHY
• Inject dye into
an open sinus ,
film shows the
track and
whether or not
it leads to
underlying
bone or joint
ARTHROGRAPHY
• Intra-articular loose bodies
defects will produce filling
defects in opaque
contrast medium
MYELOGRAPHY
• Used in Disc
pathologies
previously
• Complications:
• Headache
• Convulsions
• Arachnoiditis
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Regularly used ionic , water soluble iodide dye
: METRIZAMIDE
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Low neurotoxicity
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At working concentrations more or less isotonic
with cerebrospinal fluid
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Can be used throughout the length of the
spinal canal
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ADV : Detailed imaging
Rapidly absorbed and excreted
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Uses conventional X-ray exposure but the
recording is done on a recording plate
where it registers the activity as an
electric charge density pattern and then
transfers it to a plastic coated paper as a
positive image.
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Cutting images through selected tissue
planes with greater resolution
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Images are transaxial , exposing
anatomical planes that are never
exposed in plain film X-rays
USES :
1. Excellent contrast resolution so is able to display
size and shape of bone and soft tissue masses
in transverse plane
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2. Diagnosis of spinal disorders , joint abnormalities
and pelvic lesions
3. Assessment of complex fractures , fractures in
sites not normally accessible e.g tibial condyle
, carpal bones
4. Intravscular , intra-articular or intrathecal
contrast media can be used to highlight
blood vessels or cavity outlines and show their
relationship to adjacent masses
Radiofrequency emission from atoms
and molecules in tissues exposed to a
static magnetic force
 Hydrogen nucleus within the tissue
 Depends on : Hydrogen nucleus within
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the tissue
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Spin character
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Relaxation rate following
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proton excitation
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Better contrast resolution and refined
differentiation of tissues
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Can be reconstituted to give a 3-D picture
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The phenomenon of relaxation is defined by
two independent time constants T1 and T2,
thus giving rise to two simultaneous signals .
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Tissues containing abundant hydrogen emit
high intensity signals and produce the brightest
images and those containing little hydrogen
like cortical bone , ligament , tendon , air
appear black , grey scale would be cartilage ,
spinal canal and muscle
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T1 weighted images show greater
definition and provide anatomical
pictures
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T2 weighted images tell more about
physiological characteristics of the
tissues
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High frequency sound waves generated
by a transducer can penetrate several
centimetres into soft tissues
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As they pass through the tissue interface
some of these waves are reflected back
to the transducer , where they are
registered as electrical signals and
displayed as images on a screen or plate
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Advantage of this technique equipment is
simple and portable –can be used
everywhere and NO SIDE EFFECTS
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Depending on their structure , different
tissues are referred to as :
Highly echogenic
Mildly echogenic
Echo free
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Fluid filled cysts are echo free , fat is highly
echogenic and semi solid organs
demonstrate varying degrees of
echogenicity
USES
1.Marked echogenic contrast between cystic
and solid masses useful in detecting
haematomas , abscess , arterial aneurysms
2.Capable of detecting intra-articular fluid–
diagnose synovial effusion
3.Screening new born babies for DDH
4. To diagnose ROTATOR CUFF TEARS
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Photon emission by radionuclides taken
up in specific tissues can be recorded by
either a simple rectilinear scanner or a
gamma camera to produce an image
which reflects current activity in that
tissue or organ
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Ideal isotope is Technetium -99m
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It has appropriate energy , short half
life(6 hours ) and is rapidly excreted
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When linked to a bone seeking
phosphate compound is concentrated
in skeletal tissues
Bone seeking isotope –Technetium
diphosphonate is injected intravenously
and activity recorded in two stages:
 1. shortly after injection while it is still in
the blood stream-PERFUSION OR BLOOD
POOL PHASE
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2. Three hours later when the isotope has
been taken up in the bone –BONE PHASE
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In early Bloodpool phase the vascular
soft tissue around the joint produces the
darkest image ; 3 hours later this activity
has faded and the bone outlines are
shown more clearly
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Greatest activity is in the cancellous
tissue at the ends of long bones
INCREASED
ACTIVITY IN
PERFUSION
PHASE
DECREASED
ACTIVITY IN
PERFUSION
PHASE
INCREASED
ACTIVITY IN
BONE
PHASE
DECREASED
ACTIVITY IN
BONE PHASE
CLINICAL APPLICATIONS:
1.Diagnosis of stress fractures
2.Detection of small bone abscess
3.Investigate loosening or infection around
prosthesis
4.Diagnosis of femoral head ischaemia
5.Early detection of bone metastases
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