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Welcome to spa-imaging.org

This website is designed to promote diagnostic imaging of arthritides predominantly affecting the sacroiliac and spinal joints, collectively named axial spondyloarthritis (axSpA).


Magnetic resonance imaging (MRI) is increasingly used in the diagnosis of axSpA being a sensitive method for detecting active inflammatory changes as well as permanent structural damage, and is also suitable for monitoring the disease.

Delay in the diagnosis of axSpA is still considerable with an estimated mean diagnostic delay of 6.7 year, doi:10.1093/RHEUMATOLOGY/KEAA807. It is a hope that an increased and correct use of MRI in the diagnosis of axSpA will reduce the delay and thereby potential contribute to less disability.

It is important for the use of MRI to detect and follow axSpA that the assessment of images is correct and uniform between the departments performing MRI. To ensure this, there is a need for easily accessible images showing typical disease manifestations and normal findings at MRI as well as diseases simulating SpA changes.


The overall purpose of this website is to illustrate and describe the typical imaging findings seen as part of axSpA corresponding to different degrees of disease severity with a focus on MRI findings. Moreover, to show MR changes that may be misinterpreted as arthritis in addition to normal findings to ensure that physicians who use MRI to diagnose and monitor axSpA easily can acquire knowledge promoting optimal use of MRI.
Besides, patients should have the opportunity to acquire knowledge about the diagnostic and monitoring possibilities by MRI and other imaging methods, which contribute to their diagnosis and treatment.

To increase reader-friendliness and applicability for patients this website offers explanation of medical terminology beneath.


Rheumatic inflammation located to the sacroiliac joints (SIJs) is a hallmark of axial SpA (axSpA). Therefore, this website focuses on illustrating changes in these joints corresponding to various degrees of arthritis (sacroiliitis) in addition to normal findings, including normal anatomical variations and diseases that can simulate sacroiliitis.

As spinal changes are also an important part of axSpA, especially in the later stages, this website describes different degrees and types of axSpA changes in the spine in addition to their most important differential diagnoses.
Changes in other joint regions are illustrated briefly.

Other radiological imaging methods than MRI are described and explained for comparison and in situations where they may be advantageous or preferable.

Creator / webmaster

Anne Grethe Jurik, Professor, DMSc.
Department of Radiology,

Aarhus University Hospital,

Palle Juul-Jensen Boulevard 35
8200 Århus N


E-mail: jurik@dadlnet.dk

The website is supported financially by the Danish Ankylosing Spondylitis Society by honouring Anne Grethe Jurik and Berit Schiotzz-Christensen with the Bechterew prize in 2007.
Explanation of medical terms

Anterior = in front

Apophyseal joints = small genuine synovial joints between the vertebrae posteriorly

AxSpA = axial spondyloarthritis

Biopsy = tissue sample

Cervical spine = neck (spine)

CNO = Chronic non-bacterial osteitis

Costo-vertebral joints = joints between the vertebral bodies and the ribs

CT = computer tomography

Differential diagnoses = disease which can simulate sacroiliitis or spinal spondyloarthritis changes

Extremities = limbs

Enteropathic arthritis = arthritis associated with inflammatory bowel disease

Entheses = attachment of capsules and tendons to bone

Erosion = demarcated osseous defect due to tissue destruction as part of the inflammatory disease process

Gadolineum (Gd.) = MRI contrast agent

Contrast enhancement = increased blood flow visualized by contrast agent

Hyperostosis = enlargement of bone/joint region

Lateral view = view form the side

Lumbar spine = lower back

Lumbar region = lower back region

Monitor = watch

MR = magnetic resonance

MR-scanning = magnetic resonance scanning

MRI = magnetic resonance imaging

OMERACT = Outcome Measures in Rheumatoid Arthritis Clinical Trials

Osteoporosis = decreased bone density

Posterior = at the back

PsA = psoriatic arthritis

Psoriatic arthritis = arthritis associated with the skin disease psoriasis

Pustulotic arthro-osteitis = rheumatic disorder associated with skin disease in the palm of the hand and/or sole of the foot (pustulosis palmoplantaris)

Reactive arthritis = arthritis elicited by an infection somewhere else in the body

Sacroiliac joints = joints between the sacrum and the iliac bones

Sacroiliitis = inflammatory changes in the sacroiliac joints

SAPHO = syndrome encompassing synovitis, acne, pustulosis, hyperostosis and osteitis

Sequence = MR recording mode

Seronegative spondyloarthritis = inflammatory disorder predominantly involving the sacroiliac and spinal joints

Sclerosis = increased bone density

Scout view = initial fast MR sequence to be used for planning the slice orientation

SIJ = sacroiliac joint

SpA = spondyloarthritis

Spine = back

Spine deformity = pathological change of the back curves

STIR (Short Tau Inversion Recovery) sequence = MR recording mode

Structural changes = permanent damage

T1FS = MR recording mode

Tl-weighted sequence = MR recording mode

T1-weighted fat-suppressed (T1FS) sequence = MR recording mode

T2-weighted fat-suppressed sequence = MR recording mode

Trabecular bone = osseous structure inside a bone

Vascularized = containing blood vessels

Vertebral column = spine


The website, which has been online since 17. September 2008, is currently undergoing major revision/update.

Visitors since May 1st., 2008:  1803471