Pearls and Pitfalls of Imaging

Pearls and Pitfalls of Diagnostic Imaging Modalities Monica Khanna Division of Musculoskeletal Radiology Department of Medical Imaging University Health Network, Mount Sinai Hospital, Women’s College Hospital

Modalities
plain film
computed tomography
ultrasound
nuclear medicine
interventional
magnetic resonance imaging

Patient Assessment
History
Clinical Examination
Basic Investigations
Special Investigations

Plain Film
mainstay of bone and joint imaging, particularly in trauma
advantages
fast
inexpensive
readily available
good for assessing bones and joints

Plain Film
disadvantages
uses ionising radiation (x rays)
limited information regarding soft tissues

Treat the patient not the radiograph

Fracture dislocation

2. Take a history and examine the patient before requesting a radiograph

Pain in arm –nerve root entrapment in the neck

Maisonneuve fracture

2. Take a history and examine the patient before requesting a radiograph 3. Request a radiograph only when necessary 4. Never look at a radiograph without seeing the patient, and never see the patient without looking at the radiograph

5. Look at every radiograph, the whole radiograph, and the radiograph as a whole.

Rule of twos
Two views
Two joints
Two sides
Two occasions
Two radiographs
5 . Re-examine the patient when there is an incongruity between the radiograph and the expected findings

Orthogonal views (at 90° to each other) i.e. AP and lateral

Ideally include joint above and below, particularly when there are paired bones i.e. tibia and fibula / radius and ulna

ER day 14 day 21

8. Take radiographs before and after procedures 9. If a radiograph does not look quite right ask and listen: there is probably something wrong 10. Ensure you are protected by fail safe mechanisms

Plain Film
advantages
fast
inexpensive
readily available
good for assessing bones and joints
disadvantages
uses ionising radiation (x rays)
limited information regarding soft tissues

Computed Tomography (CT)
x ray tube rotated around the patient
cross sectional imaging capability
reformatting in other planes and 3D
best for bony cortex and calcification
good at evaluation of comminuted fractures to complex structures
pelvis
calcaneus
wrist

calcaneal fracture

coronal and sagittal reformatting

Computed Tomography (CT)
disadvantages
radiation dose to patient
metal artefact
poor soft tissue characterization
Use of contrast agent

CT MRI

Intravenous Contrast Media
Relatively good safety record
Adverse effects are generally mild and self limited
Adverse Reactions ~ 15%
Mild ~ Urticaria, pruritus, vomiting, dizziness
Moderate ~ Headache, oedema, bradycardia, HT
Severe ~ arrhythmias, hypotension, pulmonary oedema, seizures, syncope
Nephropathy

Contrast Media Induced Nephropathy
Risk factors:
Prior renal insufficiency ~ diabetic nephropathy
Raised serum Creatinine
Congestive cardiac failure
Dehydration
Hyperuricaemia
Nephrotoxic drugs: NSAIDs, aminoglycoside antibiotics
Advanced age
Large doses of ICM at a single study

Treatment of contrast reactions
Most occur within 20mins of injection
Urticaria ~ diphenhydramine
Bronchospasm ~ O2, +/-adrenaline
Hypotension with tachycardia ~ O2, iv fluids +/- dopamine
Vasovagal reaction ~ O2, iv fluids, +/- atropine
Unrepsonsive patient ~ call a code, defibrillation

Ultrasound

Ultrasound
increased demand and growth of MSK ultrasonography
becoming more frequently utilized
continual improvement in technology
wide availability
relatively lower cost

Advances in technology
higher frequency transducers (7-15 MHz)
smaller footprint probes
power doppler
extended field of view
3D imaging
tissue harmonics

Advances in technology

Haematoma between medial head of Gastrocnemius and Soleus

Musculoskeletal Ultrasound
Advantages
ready accessibility
portability
relatively quick scan time
better patient tolerability
contralateral comparison

Advantages (continued)
personal interaction with the patient
directed / targeted examination specific for each individual
clinical history
dynamic imaging
compression of structures
movement of a joint

Disadvantages
highly operator dependant
long learning curve
physician time-intensive examination
proper training and experience required (most N. American training programs do not perform a significant number of MSK ultrasound)
artifact

Main MSK applications
infants for DDH
tendon injuries especially rotator cuff
foreign body
soft tissue masses
US guided biopsy

Achilles tendon

Achilles tendinopathy

Achilles tendon tear undectable tendon at site of injury

Achilles tendon tear undetectable tendon at site of injury

solid vs cystic masses
cystic
no doppler flow
anechoic

Popliteal / Baker’s cyst

Popliteal / Baker’s cyst ‘ speech bubble’

Nerve sheath tumor

normal supraspinatus tendon longitudinal transverse

normal supraspinatus tendon longitudinal transverse full thickness supraspinatus tear

Foreign Bodies
hyperechoic
acoustic shadowing
“ comet tail” or “ring down” artifact
hypoechoic halo

Nuclear Medicine
entire skeleton at once
bone scan is an indicator of bone turn over
very sensitive, not specific
fracture
tumour
arthritis
infection
metabolic bone disease

‘ Non-specific uptake xiphoid process region of the sternum. Correlation with clinical examination suggested.’
‘ Unless there has been trauma to these sites I cannot exclude metastatic disease and further radiologic correlation is recommended.’
‘ This likely represents a normal variant, however, correlation with x-ray is recommended to rule out loosening or other pathology.’
‘ Clinical correlation and further investigation with a left shoulder radiograph is recommended.’
‘ Suspected degenerative change midcervical spine, radiograph would be confirmatory.’
‘ Possible traumatic injury to the sternoclavicular joints bilaterally. Radiographic correlation is recommended.’
‘ Mild focal activity within the left acetabulum anteriorly which is non-specific and could be related to either degenerative changes or a metastatic deposit.’
Nuclear Medicine

‘ Non-specific uptake xiphoid process region of the sternum. Correlation with clinical examination suggested.’
‘ Unless there has been trauma to these sites I cannot exclude metastatic disease and further radiologic correlation is recommended.’
‘ This likely represents a normal variant, however, correlation with x-ray is recommended to rule out loosening or other pathology.’
‘ Clinical correlation and further investigation with a left shoulder radiograph is recommended.’
‘ Suspected degenerative change midcervical spine, radiograph would be confirmatory .’
‘ Possible traumatic injury to the sternoclavicular joints bilaterally. Radiographic correlation is recommended.’
‘ Mild focal activity within the left acetabulum anteriorly which is non-specific and could be related to either degenerative changes or a metastatic deposit .’
Nuclear Medicine

bone scan normal multiple metastases

normal plain film bone scan – multiple bony metastases

Interventional
arthrography
injections and aspiration
joints
bursae
tendon sheaths / paratenon
biopsy
ultrasound guided
CT guided
spinal interventional
facet joint injections
nerve root blocks
discograms
vertebroplasty

Modalities
Fluoroscopy – arthrography, joint injections
Ultrasound – soft tissues
Soft tissue biopsy
Peri tendon injections
Cyst aspirations
CT
deep soft tissue biopsies
bone intervention

Arthrography

Injections and Aspirations
Aspirations
Bakers cyst
Ganglia (wrist, shoulder)
? Infection (hip, shoulder)
Injections
Joints
Tendon sheaths
Ankle (peroneal, achilles)

Therapeutic joint injections
Studies show up to 50% of “blind” joint injections are not in the joint
Usually following failed bedside injection
Injectate
Depomedrol (methyl prednisolone)
Kenalog (triamcinolone)
Celestone (betamethazone)
Sensorcaine (bupivicaine)

CT guided biopsy More deep, complex bony lesions and spinal lesions May give premed with fentanyl and midazolam

Radiofrequency ablation

Press Release: The 2003 Nobel Prize in Physiology or Medicine 6 October 2003 The Nobel Assembly at Karolinska Institutet has today decided to award The Nobel Prize in Physiology or Medicine for 2003 jointly to Paul C Lauterbur and Peter Mansfield “ for their discoveries concerning magnetic resonance imaging" Magnetic Resonance Imaging (MRI)

patient in a strong magnetic field
multiplanar imaging
excellent soft tissue contrast
ideally suited for MSK
Magnetic Resonance Imaging (MRI)

coronal sagittal axial soft tissue contrast and multiplanar imaging help pre-operative assessment of MSK tumours

soft tissue contrast CT MRI T1 MRI T2 fat sat

soft tissue contrast CT MRI T1 MRI T2 fat sat tumour proximal humerus rim of calcification best seen on CT soft tissue anatomy best on MR tumour best seen on T2 MR image

disadvantages
contraindications
orbital metallic foreign bodies
pacemakers
neurostimulatory devices
claustrophobia
1 st trimester theoretical risk
artefacts from ferromagnetic objects
imaging of osseous anatomy, fractures and calcification lacking
Magnetic Resonance Imaging (MRI)

interlocking intramedullary nail distal femur

complex hip surgery causing artefact on MRI

Claustrophobia and MRI
3-5% compromise scan quality in closed magnet
Open systems (94% of failed exams in a closed system were successful in an open scanner)
Patient satisfaction US>MRI

Gadolinium use in MR
Rarely used in our practice
T1 fat sat post Gd T2 fat sat Cyst Myxoma T2 fat sat T1 fat sat post Gd

Gadolinium
Allergic reactions much less common than Iodine
Most are mild reactions
0.1% frequency of reactions
Treated in a similar manner to iodine reactions
Nephrogenic systemic fibrosis

Ultrasound vs. MRI

Strengths of US MR response
Cheap, available
No radiation
Dynamic
Fast
Better tolerated
Higher spatial resolution
Guides intervention

Cheap, available OK, fine
No radiation
Dynamic
Fast
Better tolerated
Guides intervention

No radiation No radiation
Dynamic
Fast
Better tolerated
Guides intervention

Dynamic You win
Fast
Better tolerated
Guides intervention

Dynamic You win
Fast Getting better – watch out
Better tolerated
Guides intervention

Dynamic You win
Better tolerated Open / extremity systems
Guides intervention

Dynamic You win
Higher spatial resolution Improving
Guides intervention

Dynamic You win
Higher spatial resolution Improving
Guides intervention Major advantage

Strengths of MR US response
Less operator dependant
More graphic display
Global assessment

Less operator dependant Get better training
More graphic display
Global assessment

More graphic display Use extended field of view and label
Global assessment

More graphic display Use extended field of view and label
Global assessment Get a plain film

US vs. MRI scorecard
Cheap, available US
No radiation US = MRI
Dynamic US
Fast US > MRI
Better tolerated US = MRI
Higher spatial resolution US = MRI
Guides intervention US
Operator dependant MR
Graphic display MR
Global assessment MR

US vs. MRI conclusion
Complementary

US vs. MRI conclusion
Complementary
US operator dependant (esp RCT)
US clearly indicated if c/i to mri
US faster and cheaper
US is great for dynamic and intervention

MSK MRI at Mount Sinai Hospital and the University Health Network

the future 44s 1min26s

Metallic Hardware

Cartilage T2 mapping* FSE multi-echo* T2 mapping with Functool*

Cartilage T2 mapping*

Summary
Initial patient assessment
Imaging Modalities

Thank you

Pearls and Pitfalls of Imaging

by Nurse Practitioners' Association of Ontario on Aug 02, 2011

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