Imaging Mimics of SacroiliitisPhysician / Mohammad Abdelbaky

M.Sc. Physical Medicine, Rheumatology & RehabilitationAss. Lecturer – Al Azhar University

(Assiute)Egypt

mohammadbaky@gmail.com

J. Scott Bainbridge, MD, www.DenverBackPainSpecialists.com

J. Scott Bainbridge, MD, www.DenverBackPainSpecialists.com

Normal X-ray

CT scan

Maxime DOUGADOS, MD Paris Descartes University

Normal MRICoronal T1

Ultrasonography

Maxime DOUGADOS, MD Paris Descartes University

Grade 0 Grade 1

Grade 2

Grade 3

Grade 4

1984 Modified New York Criteria for AS

Clinical Criteria•Low back pain ≥ 3 months, improved by exercise and not relieved by rest•Limitation of lumbar spine in sagittal and frontal planes•Limitation of chest expansion (relative to normal values corrected for age and sex)

Radiological criteria•Bilateral grade 2-4 sacroiliitis OR•Unilateral 3-4 sacroiliitis

Requirements: bilateral grade 2-4 or unilateral grade 3-4 sacroiliitis AND any clinical criteria (see XRay Grading of SI joints).

Reference: Van der Linden et al.  Arthritis Rheum 1984;27:361.

MRI

MRI Protocol

SIJ Protocol:According to the ASAS classification criteria, active inflammatory lesions are best visualized on with whole-body of 1.0 or 1.5 Tesla MRI:

Sequences• STIR or fat-suppressed (fs.) T2.

(512 pixel matrix, 3 – 4 mm slice thickness).• T1: Structural damage and chronic lesions, such as fatty degeneration and erosions.• fs. gadolinium-enhanced T1: in cases of doubt and high suspicion.

Orientation• Semicoronal sections at least 10 – 12 slices.• - + axial oblique. van den Berg R, van der Heijde DM. 2010: How should we diagnose spondyloarthritis according to the ASAS classification criteria: a guide for practicing physicians. Pol Arch Med Wewn; 120:452???457Clarissa Canella, Bruno Schau, Elisio Ribeiro, Bruna Sbaffi and Edson Marchiori 2013: MRI in Seronegative Spondyloarthritis: Imaging Features and Differential Diagnosis in the Spine and Sacroiliac Joints, American Journal of Roentgenology, Volume 200, Issue 1.

Spinal Protocol:• Sagittal T1 & STIR or fs T2 sequences• If gadolinium administration is performed, T1-weighted sequences

with fs. should be obtained in the sagittal plane.• - + Axial slices: for assessment of the posterior spinal elements.• - + Coronal slices: for assessment of the costovertebral,

costotransverse, and facet joints.

Clarissa Canella, Bruno Schau, Elisio Ribeiro, Bruna Sbaffi and Edson Marchiori 2013: MRI in Seronegative Spondyloarthritis: Imaging Features and Differential Diagnosis in the Spine and Sacroiliac Joints, American Journal of Roentgenology, Volume 200, Issue 1.

Simple MRI Request for SpAwhole-body of 1.0 or 1.5 Tesla MRI:

• SIJ: • Semi-coronal at least 10–12 slices & axial oblique T1 & STIR or fs.T2 (+ gadolinium

with doubt or high suspicion)• - + axial oblique.

• Spine:• Sagittal T1 & STIR or fs T2 (+ gadolinium with doubt or high suspicion)• - + Axial T1 & STIR or fs T2• - + Coronal T1 & STIR or fs T2

Typical MRI LesionsActive inflammation (fs T2 ,STIR or post-gadolinium T1):

• bone marrow oedema (osteitis) • Capsulitis• Synovitis • Enthesitis

Chronic inflammatory lesions (T1):• Sclerosis • erosions • fat deposition • bony bridges or ankyloses

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Simultaneous radiography shows definite chronic changes in the form of erosion and joint space widening (arrow) with some subchondral sclerosis in the iliac bone.

Chronic changes

Semi-coronal T1 FS image clearly shows erosion corresponding to the right sacroiliac joint (arrow). The semi-axial STIR image demonstrates accompanying inflammation in the surrounding bone (arrow).

Mixture of joint space and osseous inflammation

Semi-coronal and semi-axial T1 FS after intravenous Gd. contrast showing enhancement in the joint space (black arrow) as well as in the adjacent bone (white arrow).

Mixture of joint space and osseous inflammation

Semi-coronal and semi-axial T1 FS after intravenous Gd. contrast showing enhancement in the joint space (black arrow) as well as in the adjacent bone (white arrow).

Psoriatic arthropathy

Reactive arthritis

Early MR changes of the SIJs are usually confined to the distal part of the joint containing synovia. In transient arthritis the MR abnormalities consist of uni- or bilateral BMO. Chronic changes such as erosion and fatty deposition are usually lacking. The changes may therefore heal without sequels. There is always a risk of recurrent episodes of inflammation and the disease may transform into a chronic stage. The imaging features can then be AS-like except that chronic spinal changes often present more voluminous new bone formation than seen in AS.

Semi-coronal T1-weighted image shows erosion of the joint facts (arrows).

Enteropathic arthropathy

Often presents more pronounced changes in the ligamentous part of the joint than seen in other forms of SpA.often heals with new bone formation.New bone formation can therefore be seen later in the disease. It is best visualised by CT.

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blurred joint facets of lt SIJ 

Septic sacroiliitis

www.spa-imaging.org

40-year-old woman with infectious sacroiliitis. Axial fat-suppressed gadolinium-enhanced T1-weighted MR image of sacroiliac joints shows bone marrow enhancement of sacrum (white solid arrows), irregularity of articular space of left sacroiliac joint (asterisks), abscess (open arrows), and enhancement of adjacent soft tissue (black solid arrows).

Clarissa Canella, Bruno Schau, Elisio Ribeiro, Bruna Sbaffi and Edson Marchiori 2013: MRI in Seronegative Spondyloarthritis: Imaging Features and Differential Diagnosis in the Spine and Sacroiliac Joints, American Journal of Roentgenology, Volume 200, Issue 1.

27-year-old man, showing erosions of the right sacroiliac joint and demarcation of the cortex of the right ischial tuberosity

Tuberculous sacroiliitis

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3489219/

Osteitis condensans ilii

•Brown tumours

Hyperparathyroidism

http://radiopaedia.org/articles/hyperparathyroidismHenry Knipe, Frank Gaillard., et al.

37 years old male patient with 2 years history of inflammatory & mechanical LBP

37 years old male patient with 2 years history of inflammatory & mechanical LBP

Referred to Oncology

Unilateral Sacroiliitis• TB• Brucella• Other septic arthritis

Bilateral and symmetric• Ankylosing spondylitis• Inflammatory bowel disease

Bilateral and asymmetric• Rheumatoid arthritis• Psoriasis• Reiter’s • Gout (rare cause)

http://learningradiology.com/notes/bonenotes/sacroiliitispage.htm#sthash.QoltKFBb.dpuf

ConclusionApply ASAS definition of MRI sacroiliitis

Follow criteria in diagnosis not only clinical sense

In doubt of infective sacroiliitis DONOT forget axial oblique sections with gadolinium enhancement

Questions