Pitfalls of MRI in Spondyloarthritis

Pitfalls of MRI in Spondyloarthritis
Dr Alex Bennett
FRCP PhD
Consultant Rheumatologist Headley Court
Visiting Senior Lecturer University of Leeds
ASAS classification criteria for axial SpA
(chronic back pain >3 months, age at onset <45 years)
Sacroiliitis*
plus
≥ 1 clinical parameter**
HLA-B27
or
Plus
≥ 2 other clinical parameters**
*Sacroiliitis (x-rays or MRI):
—Definite radiographic sacroiliitis (grade 2
bilaterally or grade 3-4 unilaterally; according to
modified New York criteria 1984)
or
— Active (acute) inflammation of sacroiliac joints
on MRI, highly suggestive of sacroiliitis
associated with SpA (22)
•
•
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•
•
•
•
•
•
•
•
Inflammatory back pain
Arthritis
Enthesitis (heel)
Uveitis
Dactylitis
Psoriases
Crohn’s disease/ ulcerative colitis
Good response to NSAIDs
Family history for SpA
HLA-B27
Elevated CRP
Sensitivity 82.9%, specificity 84.4%; n=649 patients with chronic back pain and age at onset ,45 years. Imaging arm (sacroiliitis) alone has
a sensitivity of 66.2% and a specificity
of 97.3%.
Elevated
CRP 2009;68(6):777-783
is considered a SpA feature in the context of chronic back pain.
1. Rudwaleit
M et al.**Note:
Ann Rheum
Disease
Rudwaleit M et al. Ann Rheum Disease 2009;68(6):777-783
Pitfalls
Conforming with widely held but often incorrect beliefs
Requesting the Wrong Scans
Mis-Diagnosis
Technical Errors
MRI inadequacies & Disease idiosyncrasies
Conforming with Widely Held but
often incorrect Beliefs
The Radiologist is Always Right!
What the **** is
this?!
This is an obvious
case of
degenerative
disease
The request
mentioned
something called
Spondyloarthitis!?!
Don’t be a Lemming
Assume Nothing
Make friends with your radiologist!
Requesting the Wrong Scan!
Protocol & Sequences
• Whole Spine
•4 sequences
• cervico-thoracic – T1 and STIR
• thoraco-lumbar – T1 and STIR
•Sagittal only (to include pedicles and facets)
• SIJs
• 2 sequences
• coronal oblique T1 and STIR
• Contrast Not Required
35% AS
38% axial-SpA
NO ACTIVE MRI SACROILIITIS
25% AS patients
SPINAL
BUT NO
ACTIVE SIJ LESIONS
Images courtesy of Dr Alexander Bennett
Thoracic spine
most
spinal lesions
Scan planning
Posterior Element Lesions
STIR
STIR
Inflammatory Lesions
T1w
STIR
Fatty Lesions
T1w
T1w
Mis-diagnosis
Sacroiliac Joints
ASAS definition of “positive MRI”
1. Sieper J et al. Ann Rheum Dis 2009;68:ii1-ii44
“Positive MRI”
STIR
One slice sufficient
Image from ASAS handbook
STIR
2 slices required
Differential Diagnosis: Septic Sacroiliitis
T1SE
STIR
Differential Diagnosis: Insufficiency Fracture
STIR
T1SE
Spine
ASAS Definition of a Positive Spinal MRI
• Inflammatory Romanus/corner lesions:
≥2
• Fatty Romanus/corner lesions:
≥3
• Posterior element lesions?
ASAS Definition of a positive Spinal MRI-In press
Differential Diagnoses
A
B
Degenerative Disease
Images courtesy of Dr Alexander Bennett
C
SpA
Metastases
Septic Discitis v Spondylodiscitis
T1
STIR
Septic Discitis v Spondylodiscitis
T1
STIR
Degenerative Disease v Spondylodiscitis
T1
STIR
Artefact mimicking spinal lesions in SpA:
haemangioma
T1SE
STIR
Technical Glitches
Artefacts
• Coil effect
– Spurious high signal at the lower SIJs
• Anatomical artefact
– Phase encoding artefact – adjacent structures
– Mimics – subchondral blood vessels
Phase-encoding artefact : blood flowing through great vessels
T1SE
STIR
MRI Inadequacies
HISTOPATHOLOGY v MRI
V
8
3
Appel H et al. Arthritis Res Ther 2006
Disease Idiosyncrasies
Fluctuating Disease
21%
Baseline
12 months
46%
Marzo-Ortega, ARD 2009
Baseline
7%
26%
Images Courtesy of Prof J Sieper
Stone et al, Rheumatology 2008
12 weeks
“Negative” MRI
NOT necessarily
“Normal” MRI
Summary
Conforming with widely held but often incorrect beliefs
Requesting the Wrong Scans
Mis-Diagnosis
Technical Errors
MRI inadequacies & Disease idiosyncrasies
Thank You