It is not uncommon to receive ambiguous and incorrect imaging reports from radiologists. There are numerous reasons for this, such as poor clinical information, differential experience, imaging protocols, etc. As there is no unified protocol for MRI sequencing reports are limited by these factors. Studies have also shown that there is poor agreement on scan interpretation, with experienced surgeons being more accurate than radiologists, as they can better correlate the imaging with the clinical information. There is a lot of mystique and misunderstanding around MRI imaging and many surgeons find it confusing. In this lecture I will provide some of my tips and experience in understanding MRI scanning for the surgeon and clinician.
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QUESTION A
My IDEAL investigation for cuff pathology
is:
a. Ultrasound
b. MRI
c. MR Arthrogram
d. CT Arthrogram
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QUESTION B
My IDEAL investigation for Instability is:
a. Ultrasound
b. MRI
c. MR Arthrogram
d. CT Arthrogram
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QUESTION 1
Radiologists are better at interpreting MRI
scans than surgeons:
a. True
!
b. False
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QUESTION 2
MRI Sequences:
a. T1 is best for pathology
b. In T2 fat tissue is bright
c. A long TR is shows inflammation
b. STIR is a Fat Suppression sequence
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QUESTION 3
MR Arthrogram:
a. ABER improves accuracy
b. Cannot show Bony lesions
c. Is not ideal for fatty infiltration
d. Is 100% accurate for labral tears
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CONFUSING REPORTS
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There is a partial full tear of the
supraspinatus tendon.
There is a complete partial tear of the
supraspinatus tendon.
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INADEQUATE SCANS
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Grainy Shadows
Movement
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CUFF PATHOLOGY IN ASYMPTOMATIC
• 96 MRI’s viewed by 2 radiologists
• 20% PTT; 15% FTT
– Increased with age:
• >60yrs = 55% PTT; 30% FTT
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Sher et al. JBJS. 1995
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MR ARTHROGRAM V. SCOPE
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Sensitivity Specificity Accuracy
SLAP 0.42 0.92 77%
Rotator Cuff Tear 0.50 0.86 83%
Hill Sachs 0.91 0.78 90%
Bankart 0.85 0.83 86%
N Karlson, J Geoghan, L Funk; 2008
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RADIOLOGIST LOCALITY
• Nine radiologists - regional & secondary care
• MR diagnostic accuracy is better when surgeon and
radiologist work in the same institution.
• Differences between local- and non-local MRA data
suggest that diagnostic accuracy is better in the local
secondary referral centre.
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N Karlson, J Geoghan, L Funk; SECEC 2011
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DO NOT RELY ON THE SCAN REPORT
An experienced Shoulder Surgeon better
Can correlate with clinical context
Experience of reviewing Scopes & Scans
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MRI BASICS
• T1 - Fat Bright - Anatomy
• T2 - Water Bright - Pathology
• Standard 3mm thick slices
• Thick slices = more signal & less grainy, but
lower spatial resolution (due to volume
averaging)
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MRI BASICS
• PD = Long TR & Short TE
• T1 = Short TR & Short TE
• T2 = Long TR & Long TE
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• TE is always < TR
• Short TR < 500ms
• Long TR > 1500ms
• Short TE < 30ms
• Long TE > 90ms
http://www.imaios.com/en/e-Courses/e-MRI/MRI-signal-contrast/Signal-weighting
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MRI SEQUENCES
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• No universal standards
• Each Hospital has different MRI Protocols
• Each Radiologist has different experience
• Each clinical question demands different approach
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MR ARTHROGRAM
• Direct / Indirect
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SUMMARY
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• Beware / Be aware of Reports
• Full 6 series
• T1 FS Axial - Instability
• T2 FS Cor - Rotator Cuff
• T1 Sag to Scapula ‘Y’
• MRA:
– Direct
– T1 FS in 2 planes (axial; sagittal)
– ABER (if able)
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RELATIONSHIPS
• Clinical Imaging is a ‘request for consultation to
clarify a clinical query’
• NOT ‘ordering’ an investigation
!
• Vetting of request should be an MSK Radiologist
• Provide clear clinical info and query
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I can see it now !
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QUESTION 1
Radiologists are better at interpreting MRI
scans than surgeons:
a. True
!
b. False
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51
QUESTION 2
MRI Sequences:
a. T1 is best for pathology
b. In T2 fat tissue is bright
c. A long TR is shows inflammation
b. STIR is a Fat Suppression sequence
52. AMSTERDAM / THE NETHERLANDS
www.esska-congress.org
52
QUESTION 3
MR Arthrogram:
a. ABER improves accuracy
b. Cannot show Bony lesions
c. Is not ideal for fatty infiltration
d. Is 100% accurate for labral tears
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WWW.SHOULDERDOC.CO.UK
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Full Time / Part Time