Transcript What Imaging Study Should I Order for …? Ordering the Appropriate

What Imaging Study Should I
Order for …?
Approach to Imaging for
Optimal Clinical Diagnosis:
Musculoskeletal Disorders
Darius Biskup M.D.
Disclosures
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No financial disclosures
Objectives:
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Review common musculoskeletal imaging
modalities
Discuss advantages and disadvantages of
imaging tests
Discuss use of contrast agents
Discuss imaging test approach to optimize
clinical diagnosis of musculoskeletal disorders
Common Musculoskeletal Imaging
Modalities
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Plain film
Fluoroscopy
CT
MRI
Nuclear Medicine
Ultrasound
Advantages and Disadvantages
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Knowing what a test can and can not assess will
help optimize test ordering
Plain film
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Advantages
Best initial test in most
clinical settings
Quick/available
Excellent boney detail
Broad assessment
Can offer clues to
narrow next diagnostic
step
Plain film
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Disadvantages
Poor assessment of soft
tissues
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tendons, ligaments
muscles
organs
Frequently negative for
acute findings
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more likely positive in
acute trauma
Fluoroscopy
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Advantages
Offers dynamic
assessment
Needle guidance for
arthrograms, joint
injections, aspirations
Fluoroscopy
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Disadvantages
Limited assessment of
soft tissue
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Compliment with CT or
MRI
invasive – arthrogram,
injection
CT
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Advantages
Noninvasive, quick,
convenient
Excellent detail of
osseous anatomy
Surgical planning
CT
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Disadvantages
Radiation
Allergic reaction
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IV contrast
Limitations in
assessment of small soft
tissue detail
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tendons, ligaments,
effusions, bursitis
MRI
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Advantages
No radiation
Excellent soft tissue
detail
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Tendons, ligaments
Cartilage
Soft tissue, Muscles
Marrow
MRI
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Disadvantages
Pt claustrophobic
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sedation
Limited assessment of
osseous detail
Weight limits
Metal susceptibility artifact
Motion sensitive
Takes time
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Most scans 30 minutes
Ultrasound
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Advantages
No radiation
Good targeted assessment
Best initial test for vascular
assessment
DVT/ PVD
Great test for pediatric
patients
Biopsy/aspiration
guidance in soft tissues
Ultrasound
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Disadvantages
Operator
dependent
Limited
assessment
Time dependant
Nuclear Medicine
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Advantages
Targeted exam
Functional/metabolic
exam
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Bone scan
WBC Indium/gallium
Nuclear Medicine
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Disadvantages
Targeted exam
Limited spatial resolution
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May require additional
imaging correlate
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abnormal activity on bone
scan
IV contrast for CT or MRI
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Renal function important!
CT creatine < 1.5
MRI GFR > 45mL/min
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Allergic reactions
Mild – hives
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nephrogenic systemic fibrosis
(NSF)
No contrast for Dialysis
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If renal function is poor can
always start with noncontrast study
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pre-medicate
Moderate bronchospasm,
respiratory compromise
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consider another modality; do
exam without contrast
Severe- anaphylaxis –
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NO contrast
IV contrast not needed
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MRI/CT imaging of
joints
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Most MSK studies for
joint assessment do NOT
need contrast
Fractures – occult,
nonunion
Pre op planning
When to order IV contrast
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Any study assessing
tumor/mass
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Allows better
characterization
Assess for “itis”
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Cellulitis/abscess
osteomyelitis
Post op lumbar spine
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MRA
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Lower extremity runoff contrast
When in doubt, let the
radiologist figure it out
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Order MRI of … ,
contrast as needed.
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Consider authorization
issues
Talk to radiologist
Choosing the right imaging test to
optimize clinical diagnosis
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Xray – most utilized
modality and most
commonly order in initial
evaluation
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MRI
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CT – multiplanar bony
detail- complex fractures,
osseous lesions
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Nuclear medicine
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Tendons, ligaments,
marrow edema
contusions
Internal derangement
Bone scan
Indium/sulfur colloid
US
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Targeted assessment
Plain film
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Excellent osseous detail
Key in initial evaluation of joints
 Assess for
fractures/dislocations
 Arthritis
 Osseous disorders/
mineralization
 Hardware evaluation
CT
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Excellent osseous detail
Good soft tissue detail
Useful for postoperative
evaluation, complex
fractures, occult fx, intraarticular loose bodies,fluid
collections, soft tissue gas
Limited assessment of
menisci, labra, ligaments,
tendons, marrow assessment
MRI
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Superior soft tissue detail
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tendons, ligaments
Superior marrow evaluation
 Edema, contusions, occult
fx, osseous lesions
Limited osseous detail
evaluation
Ferromagnetic susceptibility
artifact
Motion
Claustrophobic pt – can
sedate patients
 Optimizing
clinical diagnosis of
MSK disorders with imaging
Joint pain w/ negative findings/xray
does not correlate
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hx decreased ROM/
weakness/ impingement
Plain film best initial test
MRI to assess soft tissue
Tear vs Tendinosis
Full thickness tear
Partial articular surface tear
Rotator cuff teas
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Patient has
pacemaker – can we
still evaluate rotator
cuff ?
YES
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Arthrogram
CT arthrogram adds
anatomy
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Knee pain, negative
xray
Next step –MRI
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Menisci
Ligaments
Tendons
My patient has metal hardware, can I
still order an MRI
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Is it useful?
Metal Artifact Reduction Sequences
(MARS)
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Assess soft tissue,
effusions, fluid
collections
Tendons, ligaments
Osteolysis adjacent to
hardware
Assessment of internal
derangement if not joint
replacement
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How do I order it?
eg – MRI right hip
MARS protocol
Tumor/mass
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Mass/lump felt by
clinician or patient
What to order
first?
Xray – best initial
step
Extremity soft tissue tumor/mass
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Abnormal xray/ normal xray
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If it can be normal, why order it?
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Can aid in assessment of mass – calcifications, bone involvement
What to order next?
MRI
How to order it?
MRI w/ & w/o contrast tumor/mass protocol
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e.g. MRI right lower extremity tumor/mass protocol w &
w/o contrast
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Capsule marker
placed around mass
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If mass not initially
found by patient,
show exact location
so the can reproduce
site for exam
Identifies target mass
vs. additional not
clinically detected
lesions
Fall, back pain, age indeterminate
compression fracture on xray
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What if patient has pacemaker and there is a
compression fracture deformity?
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Bone scan
Imaging of spine
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Back pain
Xray
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initial best test
Imaging of spine
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CT spine– no IV contast
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MRI spine w/o
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Limited in assessment of
spinal stenosis
most routine work for
LBP, radiculopathy
MRI spine w/ & w/o
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Post op follow up
Oncology
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Can’t do MRI, but I
suspect central canal
stenosis
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CT myelogram
Low back pain, radiculopathy
CT myelogram
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Good option when
can’t do MRI
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Pacemaker
Post op metal
Invasive
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Contrast injected
into thecal sac
Nuclear Isotope Studies
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Bone scan – infections, osteomyeltits,
stress/insufficiency fx “ diffuse bone pain”
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Limited spatial resolution – compliment with
plain films
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Indium/sulfur colloid – infections
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esp with hardware
Gallium- infections
I want to assess for osteomyeltis but
my patient has a pacemaker
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No hardware
Plain film
3 phase bone scan
Indium scan
(gallium in spine)
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Hardware
Plain film
3 phase bone
Induim/sulfur colloid
scan
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Marrow displacement
I want to assess for hardware
loosening vs infection
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Plain film
3 phase bone scan
Induim/sulfur colloid
scan
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Marrow displacement
Objectives:




Review common musculoskeletal imaging
modalities
Discuss advantages and disadvantages of
imaging tests
Discuss use of contrast agents
Discuss imaging test approach to optimize
clinical diagnosis of musculoskeletal disorders
Take away pearls
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
Knowing what a test can
and can not assess will
help in optimal test
ordering

Xray most useful initial
imaging modality
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MRI’s best done if
targeted – soft tissue
mass, joint, limb
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Protocols differ
Many exams can be
substituted to get a
diagnosis if a condition
prevents a desired exam
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Talk to your radiologist
Do I Need Contrast?
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Optimal for
Mass/oncology
“Itis” –infection, abscess
Post op Lumbar spine
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Not needed
MRI/CT of joints (not
suspecting infection or
mass)
When in doubt, let the
radiologist figure it out
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Talk to your radiologist
Questions?