Imaging of seronegative spondyloarthritis

Best Practice & Research Clinical RheumatologyVol. 22, No. 6, pp. 1045–1059, 2008

doi:10.1016/j.berh.2008.09.006
available online at http://www.sciencedirect.com
6

Imaging of seronegative spondyloarthritis

A.L. Tan MD, MRCP

Clinical Lecturer in Rheumatology

Academic Unit of Musculoskeletal Disease, University of Leeds and Chapel Allerton Hospital, Leeds, UK

D. McGonagle* PhD, FRCPI

Professor in Regenerative Medicine

Academic Unit of Musculoskeletal Disease, University of Leeds and Chapel Allerton Hospital, Leeds, UK

Department of Rheumatology, Merlin Park Hospital, Galway and National University of Ireland, Galway,

Republic of Ireland

Magnetic resonance imaging (MRI) and ultrasonography (US) are useful adjuncts in the diagnosisof seronegative spondyloarthritides (SpA); a group of diseases that present early at a stage whenradiographic assessment is invariably normal. This chapter will review how MRI and US can beused in the evaluation of early SpA. The diffuse osteitis/enthesitis on MRI may serve as a diagnos-tic hallmark for SpA spinal disease, but needs confirmatory studies for comparison with otherspinal pathologies. MRI is the modality of choice for monitoring axial disease in anti-tumour ne-crosis factor (TNF) therapy responses in the research environment, but it is not yet certainwhether this will be relevant in clinical practice. Anti-TNF therapy may be associated with re-gression of MRI-determined osteitis, but retardation of associated bony fusion is debatable.MRI and US are still undergoing evaluation for the diagnosis of enthesitis of the appendicularskeleton; US, in particular, shows promise at these sites.

Key words: imaging seronegative spondyloarthritis; MRI; ultrasound; enthesitis.

The spondyloarthritides (SpA) are a heterogeneous group of diseases that comprisesankylosing spondylitis (AS), psoriatic arthritis (PsA), reactive arthritis, enteropathic-re-lated arthritis and undifferentiated SpA. SpA patients are generally negative for rheu-matoid factor, hence the term ‘seronegative’, and collectively, SpA shows an

* Corresponding author. Academic Unit of Musculoskeletal Disease, Chapel Allerton Hospital, Chapeltown

Road, Leeds, LS7 4SA, UK. Tel.: þ44 113 3924884; Fax: þ44 113 3924991.

E-mail address: [email protected] (D. McGonagle).

1521-6942/$ - see front matter ª 2008 Elsevier Ltd. All rights reserved.

mailto:[email protected]

http://www.sciencedirect.com

1046 A. L. Tan and D. McGonagle

association with carriage of the HLA-B27 gene. Enthesitis, which is inflammation of theattachment of tendons, ligaments and joint capsules to bone, is the hallmark of SpA.1

Synovitis and osteitis are the other characteristics of SpA, but these tend to be asso-ciated with immediately adjacent enthesis or enthesis organ disease.1

Peripheral enthesitis such as that of the Achilles tendon can be recognized on clin-ical grounds alone and can be used to establish a bedside diagnosis. However, smalljoint enthesitis, or that at clinically inaccessible sites in large synovial joints or in thespinal column, cannot be evaluated clinically, hence the need for imaging techniques.In modern rheumatology, patients with SpA present early in the course of their diseaseat a stage when the historical gold standard of conventional radiography is unlikely todepict diagnostic changes. Coupled with the slow evolution of characteristic radio-graphic changes including sacroiliitis, and the emergence of anti-tumour necrosis factor(TNF) therapy, a considerable need for alternative imaging modalities has emerged.Furthermore, the prognosis in SpA is extremely variable and the quest for imaging fea-tures that may be prognostically useful is also pressing. This chapter outlines the usesof the different imaging modalities in SpA, focusing mainly on magnetic resonance im-aging (MRI) and ultrasonography (US), and highlights how the imaging findings have im-proved our knowledge of enthesitis and SpA.

RADIOGRAPHIC FEATURES OF SPA

Conventional radiography (CR) remains the main imaging modality in clinical practicefor diagnosing SpA. For chronic SpA, new bone formation at enthesis is a fairly char-acteristic feature, and the polyenthesitis of chronic AS that manifests as spinal fusion isdiagnostic. The hallmark of AS is radiographic sacroiliitis; this varies with the stage ofdisease, with joint widening and erosion in early disease, and sclerosis and joint fusionin late disease. Sacroiliitis forms part of the diagnostic and classification criteria forSpA and AS2,3, but several years may elapse between symptom onset and radiographicchanges.4 Nevertheless, a subgroup of early AS cases have diagnostic changes evidenton radiography.5 The poor sensitivity of CR in picking up sacroiliitis has provided theimpetus for an alternative diagnostic test.6 Similarly, other SpA spinal changes on CRsuch as ‘shiny corners’ of vertebral bodies, syndesmophytes and ankylosis are chronicchanges, and other inflammatory spinal changes associated with SpA such as enthesitisand bone marrow oedema are not demonstrated on CR.

With respect to the appendicular skeleton, a wide array of radiographic abnormal-ities are reported, especially in PsA.7 Like the spine, these include entheseal new boneformation, but osteolysis and periostitis are also well reported (Figure 1). Peri-articu-lar radiographic erosion akin to that noted in rheumatoid arthritis (RA) can also occurin SpA, but erosions at the capsular insertions that are more distant from synovial cav-ity or entheseal erosions are well described in PsA. Given the variable extent of smalljoint erosions in SpA and the overlapping features with RA, radiography has alsoproven to be somewhat inadequate for differentiating between SpA and RA.

Prior to the advent of MRI, both computer tomography (CT) and scintigraphy wereused for the evaluation of axial pathology in SpA. CT represents an extension of CRexcept that its tomographic nature permitted a better appreciation of diagnostic sa-croiliac joint changes. CT can depict the bony changes quite well and at a relativelyearly stage compared with CR.8 However, it still lacks the sensitivity of MRI to locateinflammation.9 Like radiography, CT is likely to be normal near clinical presentation;consequently, it lags behind MRI, not only in terms of diagnostic evaluation but alsobecause it entails radiation. Therefore, it should only be used as an adjunct to other

Figure 1. Conventional radiography of the right hand of a patient with psoriatic arthritis (PsA) demonstrat-

ing periostitis or new bone formation in the extracapsular region (arrow heads). These radiographic changes

can be used to help establish a diagnosis of PsA but are often absent in early disease.

Imaging of seronegative spondyloarthritis 1047

imaging modalities to confirm suspected bony changes. Nevertheless, CT providesuseful information about structural bony changes, and therefore has been used foridentifying erosive and sclerotic changes in the axial skeleton where CR or MRI orboth have been inconclusive.10,11

Scintigraphy has been used in the past for the assessment of SpA and may showcharacteristic changes in early disease. However, in patients with sacroiliitis alone, itcould be difficult to distinguish between normal bony uptake at that site and disease.12

Bone scintigraphy has been used to evaluate appendicular joint involvement in SpA.13

In fact, using the technique, it was found that patients with skin psoriasis in the absenceof arthritis had subclinical pericapsular joint disease.14,15 Scintigraphy is commonlyused to detect inflammation in the spine and sacroiliac joints, but the findings are oftentoo non-specific for diagnosis.16 Furthermore, the anatomical detail obtained on scin-tigraphy is inferior to MRI in differentiating between different pathological processes.

What is the current role of CR, CTand scintigraphy in SpA? It is still wise to undertakeradiographic evaluation because it is quick and inexpensive and can help to exclude otherpathologies. Also, rheumatologists often overlook the fact that it may pick up diagnosticchanges of early AS in a significant subset of patients, which makes it quite useful.5 Giventhe emerging data on MRI and US, which are discussed in the following sections, it appearsthat the role of CTand scintigraphy will diminish progressively in the evaluation of SpA.

EMERGENCE OF MRI AND US FOR SPA DIAGNOSTIC EVALUATION

One major drawback of CR is its inability to show inflammation or soft tissue changeswhich are common in SpA, the most striking example being dactylitis. Both MRI and


US are able to highlight areas of inflammation, and whilst MRI is excellent at depictingthis in both soft tissues and bones, US can only show inflammation in soft tissue struc-tures, and only if they are superficial.

MRI has two major roles: as a diagnostic test and for monitoring of therapy. Thelatter of these, namely the use of MRI to monitor biological therapies, is well devel-oped in academic groups for the assessment of anti-TNF therapy in the axial skeleton.Although MRI is in widespread use in clinical practice for the evaluation of suspectedinflammatory back pain, formal studies to demonstrate its diagnostic utility have notbeen published to date.17,18 MRI is occasionally used for the evaluation of peripheraljoints where the presence of diffuse osteitis/enthesitis is suggestive of SpA. However,unlike the spine, the presence of clinically recognized swelling of peripheral joints ina given clinical context makes clinical recognition of SpA easier than in the spine.

US has various advantages over MRI. In addition to being able to identify inflamma-tion and enthesitis, it is more comfortable for the patient, more easily accessible inclinical practice, and multiple joints can be imaged in one sitting. The use of powerDoppler has also helped to increase its sensitivity in identifying enthesitis and synovitis.Indeed, US has a wide variety of roles in SpA, particularly in the area of enthesitis.19

The disadvantage of US is its inability to image very deep structures well, such asthe spine and the sacroiliac joints commonly involved in SpA. Scoring systems forUS are still under development. An erosion on US is defined as a discontinuation ofthe bone cortex in two perpendicular planes20, but further work is needed to defineabnormalities such as spurs.

IMAGING OF THE ENTHESIS-APPLIED ANATOMY CONSIDERATIONS

It is now understood that the entheses are not merely focal insertions, but are actually‘enthesis organs’ that comprise virtually all the adjacent bone and soft tissues.21 Theenthesis organ includes the insertion proper, adjacent periosteal and sesamoid fibro-cartilages, and the underlying bone. These fibrocartilages, in addition to the fibrocar-tilage present at the insertion proper, act as stress shields and afford the underlyingbone some protection. The role of the underlying trabecular bone in normal enthesisfunction has only recently become appreciated.22 A hallmark of enthesitis is bone mar-row oedema on MRI which has histologically been shown to represent an osteitis.23

This osteitis reaction is not seen at all sites of enthesitis, so its absence does not ex-clude an enthesitis-associated pathology. It has also been discovered that some struc-tures that are not, in fact, an enthesis behave as such due to shared anatomical,histological, biomechanical and pathological features.24 Such structures have beentermed ‘functional entheses’, and include synovial joints lined by fibrocartilages includ-ing the sacroiliac joints and the acromioclavicular joints.24,25 They also include wrap-around tendons such as those present adjacent to the malleoli in the ankles. OnMRI, disease of all of these structures may exhibit the same perifibracartilagenous pat-tern of diffuse bone oedema.

A second observation that has been made recently is that the fibrocartilages asso-ciated with the enthesis organ need nutrition and lubrication in a manner akin to nor-mal articular cartilage.26 This brings with it the requirement for immediately adjacentsynovium to fulfil these physiological requirements. The enthesis forms a functionalunit termed a ‘synovio-entheseal complex’ such as the synovium in the retrocalcanealbursa. This implies that the enthesitis-associated pathology may be intimately linkedwith synovitis without the insertion proper per se necessarily exhibiting pathologicalchanges. Given the degree of soft tissue involvement, it is clear that CR is not suitable


for the assessment of early enthesitis. Both MRI and US are comparatively good atdepicting enthesitis, and have been used for diagnosis and understanding of thepathology.27–30

Enthesitis can occur in multiple areas in the body, and MRI is the imaging modality ofchoice to demonstrate these, providing adequate resolution and the ability to accessall areas prone to enthesitis.31,32 Distinctive MRI appearance of enthesitis has been re-ported as soft tissue inflammatory changes outside the capsule of the joint and peri-entheseal bone marrow oedema.29,30 The common joints evaluated by MRI forenthesitic changes are the heel or Achilles tendon, the knee and the finger joints.

The usefulness of both MRI and US in enthesitis is that they have been shown to bemore sensitive at identifying enthesitis than clinical examination.33 In fact, US can de-tect preclinical enthesitis in patients with skin psoriasis alone, suggesting the increasedsensitivity of the technique.34 As a clinical tool, US has been shown to be capable ofmonitoring the changes in enthesitis.35,36 As most enthesitis detected by US are in thelower limbs37,38, a sonographic entheseal index has been developed for the lowerlimbs in AS39, and can be used to aid diagnostic and therapeutic decisions in these pa-tients. SpA often has a similar clinical presentation to RA, but US has been shown to beable to differentiate between the two arthritides based on entheseal findings.38,40 Inaddition, US has been able to differentiate between early RA manifesting as oligoarthri-tis and oligoarthritis proper, based on the presence of extensive subclinical synovitis inthe former.41 Therefore, US may have considerable diagnostic utility for the classifica-tion of arthritis as primarily synovial based or primarily entheseal based.1

US has an even greater role in the research setting in helping to improve our un-derstanding of enthesitis. Recently, US has shown that, at the Achilles tendon enthe-sis, spur or new bone formation tends to develop distally, whilst erosions tend tooccur more proximally.22 The mechanism for this topographic distribution was ex-plained by histology of normal specimens. Where there is greater tension, such asat the distal site of the Achilles tendon enthesis, there tends to be greater densityof bone trabeculae and new bone formation. The converse is true in the proximalpart of the enthesis, where bone trabeculae are sparser and erosive changes areobserved (Figure 2).

Figure 2. Ultrasound of the Achilles tendon (AT) of a patient with ankylosing spondylitis, demonstrating

erosion at the proximal part of the enthesis (arrow). Evidence of hypo-echoic areas within the Achilles

tendon is observed with irregular fibrillar pattern. C, calcaneum.


IMAGING OF THE AXIAL SKELETON

Due to the relatively deep position of the axial skeleton in the body, US is unable toshow these structures well. Nevertheless, it has been shown that colour and duplexDoppler US can detect inflammation in the sacroiliac joints, and can be used to mon-itor the response of sacroiliitis to therapy.42–44 Therefore, in imaging the spine and sa-croiliac joints in SpA, MRI is the preferred imaging modality.

MRI of the axial skeleton

When compared with other imaging modalities, MRI proved to be the most accuratein diagnosing inflammation in the axial skeleton.45 Characteristic changes of the axialskeleton of SpA can be seen on MRI, along with multiple other pathologies of the axialskeleton.32 In SpA, areas of spinal inflammation can be located at the corners of ver-tebrae known as ‘Romanus lesions’, at the vertebral end plates, spinous processes andfacet joints.46 Inflammation of the spine and sacroiliac joints appears as low signal onT1-weighted MRI, and high signal on fat-suppressed or short-tau inversion recovery(STIR) sequences. When the STIR sequence was compared with contrast enhancedT1-weighted spinal MRI, there was a slight increase in sensitivity using the contrast en-hanced T1-weighted sequence47, but this was not sufficient to warrant the recommen-dation of its use over the STIR sequence in studying spinal inflammation.48 These MRIchanges have been correlated with histology, but also suggest that MRI is unable todetect very minor inflammatory changes.49,50 MRI also lacks sensitivity in detectingsmall syndesmophytes.51

SAPHO (synovitis, acne, pustulosis, hyperostosis, and osteitis) syndrome, a relatedsyndrome to SpA sharing various features, commonly affects the axial skeleton, mostfrequently the sternoclavicular joints, but also the spine (Figure 3).52,53 In the spine ofSAPHO subjects, vertebral corner erosions on MRI appear to be a common feature.This is thought to be due to enthesitis akin to Romanus lesions in SpA.52

Figure 3. Magnetic resonance imaging (MRI) of a 59-year-old female with SAPHO (synovitis, acne, pustulo-

sis, hyperostosis, and osteitis) syndrome demonstrating prominent manibriosternal joint involvement. The

patient also had axial spondyloarthritis (SpA) symptomatology. (A) Coronal fat-suppressed MRI of the ster-

num showing bone oedema or osteitis (asterisks), (B) sagittal T1-weighted and (C) fat-suppressed MRI of the

lumbar spine indicating bone oedema in the vertebrae (arrows). Note the lesion on the second lumbar spine

has appearances of end plate enthesitis/osteitis.


Various scoring methods using MRI have been used to diagnose and monitor spinalchanges with therapy.54–56 MRI-determined spinal inflammation has been shown to im-prove with anti-TNF agents.57–59 The diffuse osteitis/enthesitis lesion is often so clearand so extensive that all available scoring systems perform equally well.60,61

More recently, dynamic contrast enhanced MRI and diffusion-weighted MRI have beenshown to be more precise in monitoring spinal disease in AS compared with traditionalMRI sequences such as T1-spin echo and STIR sequences62, partly because they allow ad-ditional quantitative and functional information about the area of inflammation. This tech-nique may be useful in the research setting, but its need in clinical practice is still in doubt.

IMAGING OF APPENDICULAR JOINTS

Both MRI and US are more sensitive than clinical examination and CR in imaging pe-ripheral joints in inflammatory arthritis, and are able to distinguish between PsA andRA.33 Synovitis, enthesitis and erosive changes are the most common imaging findingsin the peripheral joints in SpA, particularly in PsA. Unlike RA, extracapsular changesare often seen in peripheral joints of SpA.63

MRI of appendicular joints

MRI has been shown to be a reliable imaging tool to assess peripheral joint involve-ment in SpA64, and can detect very early changes.65 The main changes observed aresoft tissue oedema, joint effusion, bone erosion, bone marrow oedema and tendonsheath effusion (Figure 4).66 However, these changes are not universal and cannotyet be used as a diagnostic test in individual cases.

A common presentation of SpA affecting the appendicular joints is dactylitis. This‘sausage digit’ appearance were thought to be mainly due to flexor tenosynovitis onMRI.67,68 However, as imaging has improved, it has become clear that synovitis and dif-fuse tissue oedema are also present. In fact, the pathogenesis of dactylitis could be ex-plained by the consequence of polyenthesitis on high-resolution MRI.25,31

At the population level, MRI can also be used to differentiate SpA from other ar-thritis, not just based on enthesitis but based on differing synovial vascular patterns.This has been shown in the knee joint where there was a slight increase in vascularityof the synovitis in SpA as measured by dynamic contrast enhanced MRI when com-pared with RA.69 On high-resolution MRI, distal interphalangeal (DIP) joint involve-ment in PsA had diffuse inflammation of both the soft tissue and bone related topolyenthesitis.70,71 When compared with osteoarthritis, although similar structureswere affected, there was a greater degree of inflammation in the PsA joints. Thishas led to the paradoxical position that with improved resolution of MRI, apparentlydisparate arthropathies have some shared micro-anatomical features; consequently,the clinical diagnosis is going to remain the most important.

MRI of peripheral joint involvement in SpA can also monitor change with ther-apy.61,72,73 Regression of synovitis and enthesitis is well reported. The latter appearsto be particularly responsive to anti-TNF therapy.74 Plans are afoot to develop anMRI system for peripheral joints in PsA.75

US of appendicular joints

US is effective at demonstrating peripheral joint changes in SpA such as synovial pro-liferation, tenosynovitis and joint effusion on grey scale, and increased vascularity

Figure 4. Sagittal fat-suppressed magnetic resonance imaging of the knee in a patient with early spondyloar-

thritis (SpA). There is patellar tendon origin enthesitis manifesting as diffuse adjacent osteitis (arrow). In

knee joint involvement in SpA, this lesion is evident in approximately 30–40% of early SpA cases.


reflecting inflammation on power Doppler.76 SpA and RA can have similar clinical find-ings, but distinguishing features are found between them on US. In SpA, US showsmore frequent enthesitis and new bone formation40, and erosive changes affectingDIP joints are only present in PsA.63

Dactylitis commonly affects the fingers and toes in PsA patients. The most prom-inent feature of dactylitis on US is flexor tenosynovitis.67,77,78 In fact, flexor tendoninvolvement is also seen in non-dactylitic digits in PsA.79 Diffuse thickening of thesoft tissues of the digits in PsA termed ‘pseudotenosynovitis’ has also been observedon US63, which could explain the diffuse swelling as observed in a dactylitic joint. Inaddition to tendon changes, other features seen on US include synovial proliferationand joint effusion.76

US serves as a good imaging tool for monitoring disease progression and therapydue to its relative ease of accessibility.80,81 For the same reason, US can help with di-agnosis and can identify abnormalities in patients with asymptomatic joints.82

NEW DEVELOPMENTS

The goal of imaging in SpA is to be able to diagnose the condition with some confi-dence as early as possible in the disease course. This is clinically relevant as medicaltherapy for SpA has improved significantly in the past few years. The rationale behindimaging as a diagnostic test is based on the concept that RA joint pathology is primarilya synovitis, whilst that in SpA is intimately associated with enthesitis/osteitis.1,83 How-ever, it has not been proven that every joint in every subject with SpA actually has an


enthesitis-associated pathology, but the drive behind new imaging developments re-lates to the concept that higher resolution imaging, new sequences or both will permitthe anatomical differences to be delineated.

Whole-body MRI

More recently, whole-body MRI has been utilized for screening and identifying subclinicaljoint inflammation or enthesitis.84 Whole-body MRI can reveal if the subclinical activejoint is indeed within the synovial joint or whether it is entheseal based, thereby narrow-ing the possible diagnosis. Furthermore, whole-body MRI does not involve any radiation,and can potentially be safer if used repeatedly if patients are to be monitored serially.

High-resolution MRI

Understanding the pathology of small joint involvement such as DIP joint disease char-acteristic of PsA could help with understanding entheseal disease. An imaging modalityallowing adequate resolution of such small joint structures is necessary, and high-resolution MRI using microscopy MRI coils has been used in this respect.70,71 Usingthis technique, the extensive inflammation involving the DIP joints could be seen tobe emanating from the enthesis organ, and that the nail is closely related to the enthe-sis, which could explain the link between skin and nail psoriasis, and arthritis.

Lower- and higher-field strength MRI

Generally, most clinical MRI scanners have a field strength of 1–1.5 Tesla, which is con-sidered adequate for clinical diagnosis. Some difficulties with such scanners are accessi-bility and the problem of claustrophobia for patients. Peripheral or extremity-dedicatedMRI scanners can overcome such issues, are more patient-friendly, less expensive, anddo not necessarily require a radiographer to operate the scanner.85 These tend to be oflower-field strength, ranging from 0.2 to 1 Tesla. As expected, these low-field MRI im-ages have lower resolution, but have been shown to be comparable with a ‘conventional’field strength of 1.5 Tesla in diagnosing inflammation in SpA.86 However, these systemscannot evaluate the axial skeleton which is characteristically involved in SpA. Further-more, the evaluation of SpA is quite reliant on high-quality fat suppression that is ableto depict osteitis. In the authors’ experience, the low-field systems have not been shownto perform especially well in this regard, which remains a concern.87

Higher-field MRI (3 Tesla) is being used more frequently in musculoskeletal imaging. Thisallows improved signal- and contrast-to-noise ratios, resulting in improved image resolu-tion. Studies have confirmed that this approach is valuable for imaging articular cartilage,but as far as the authors are aware, no study on the evaluation of enthesitis has been pub-lished to date.88 Even higher field strengths and ultra-high-field MRI (7–8 Tesla) have beenexplored in vivo, and have been shown to produce better resolution and contrast.89,90 Thiswill help improve the study and understanding of anatomical pathogenesis in arthritis, butwhether such high-field strength is necessary for clinical evaluation is debatable.

Ultrashort echo time MRI sequence

The structures affected in enthesitis such as the ligaments and tendons have short T2and tend to appear dark on conventional MRI, thereby making any pathology of these


structures difficult to appreciate. In order to better visualize enthesitis, newer MRI se-quences have been developed including ultrashort echo time pulse sequences and magicangle imaging which can differentiate the different structures involved in enthesitis.91,92

US

The recent development of three-dimensional US has allowed the extra dimension ofmeasuring the volume of an erosion and shapes of synovium.19,93 Other developmentsin US include high-frequency US that allows detailed evaluation of cartilage and sub-chondral bone.94

SUMMARY

The advent of MRI has transformed our understanding of SpA and has pointed to-wards a unifying biomechanical basis for these arthropathies that is based on the en-thesis organ concept.95 MRI has also proven to be extremely useful for the diagnosis ofearly axial SpA including sacroiliitis, and has proven to be extremely reliable for mon-itoring biological therapy. Both US and MRI also show considerable promise for thediagnostic evaluation of appendicular joint involvement in early SpA. However, the clin-ical use of these tests in early SpA needs further research to define actual indications.Further improvement in imaging technology for these sites could also greatly improveour understanding of disease.

Practice points

� MRI of the axial skeleton is the main imaging modality for diagnosing, assessingand monitoring SpA patients� The position of imaging of the appendicular joints in SpA in clinical practice

requires further confirmation

Research agenda

� More sensitive and specific imaging techniques using MRI and US need to bedeveloped to help with further understanding of SpA pathology� Evaluation of existing modalities in the clinical setting as diagnostic and prog-

nostic tests

REFERENCES

*1. McGonagle D, Gibbon W & Emery P. Classification of inflammatory arthritis by enthesitis. Lancet 1998;

352: 1137–1140.

2. Dougados M, van der Linden S, Juhlin R et al. The European spondylarthropathy study group prelimi-

nary criteria for the classification of spondylarthropathy. Arthritis and Rheumatism 1991; 34: 1218–1227.


3. van der Linden S, Valkenburg HA & Cats A. Evaluation of diagnostic criteria for ankylosing spondylitis. A

proposal for modification of the New York criteria. Arthritis and Rheumatism 1984; 27: 361–368.

4. Mau W, Zeidler H, Mau R et al. Clinical features and prognosis of patients with possible ankylosing

spondylitis. Results of a 10-year followup. The Journal of Rheumatology 1988; 15: 1109–1114.

5. Eastmond CJ & Robertson EM. A prospective study of early diagnostic investigations in the diagnosis of

ankylosing spondylitis. Scottish Medical Journal 2003; 48: 21–23.

6. Rudwaleit M, van der Heijde D, Khan MA et al. How to diagnose axial spondyloarthritis early. Annals of

the Rheumatic Diseases 2004; 63: 535–543.

7. Tan AL & McGonagle D. Imaging. In Mease PJ & Helliwell PS (eds.). Atlas of Psoriatic Arthritis. London:

Springer, 2008.

8. Fam AG, Rubenstein JD, Chin-Sang H & Leung FY. Computed tomography in the diagnosis of early an-

kylosing spondylitis. Arthritis and Rheumatism 1985; 28: 930–937.

*9. Yu W, Feng F, Dion E et al. Comparison of radiography, computed tomography and magnetic resonance im-

aging in the detection of sacroiliitis accompanying ankylosing spondylitis. Skeletal Radiology 1998; 27: 311–320.

10. Puhakka KB, Jurik AG, Egund N et al. Imaging of sacroiliitis in early seronegative spondylarthropathy.

Assessment of abnormalities by MR in comparison with radiography and CT. Acta Radiologica 2003;

44: 218–229.

11. Kenny JB, Hughes PL & Whitehouse GH. Discovertebral destruction in ankylosing spondylitis: the role

of computed tomography and magnetic resonance imaging. The British Journal of Radiology 1990; 63:

448–455.

12. Spencer DG, Adams FG, Horton PW & Buchanan WW. Scintiscanning in ankylosing spondylitis: a clin-

ical, radiological and quantitative radioisotopic study. The Journal of Rheumatology 1979; 6: 426–431.

13. Stoeger A, Mur E, Penz-Schneeweiss D et al. Technetium-99m human immunoglobulin scintigraphy in

psoriatic arthropathy: first results. European Journal of Nuclear Medicine 1994; 21: 342–344.

14. Namey TC & Rosenthall L. Periarticular uptake of 99mtechnetium diphosphonate in psoriatics: corre-

lation with cutaneous activity. Arthritis and Rheumatism 1976; 19: 607–612.

15. Raza N, Hameed A & Ali MK. Detection of subclinical joint involvement in psoriasis with bone scintig-

raphy and its response to oral methotrexate. Clinical and Experimental Dermatology 2008; 33: 70–73.

*16. Blum U, Buitrago-Tellez C, Mundinger A et al. Magnetic resonance imaging (MRI) for detection of active

sacroiliitis – a prospective study comparing conventional radiography, scintigraphy, and contrast en-

hanced MRI. The Journal of Rheumatology 1996; 23: 2107–2115.

17. Rahme R & Moussa R. The modic vertebral endplate and marrow changes: pathologic significance and

relation to low back pain and segmental instability of the lumbar spine. American Journal of Neuroradiology

2008; 29: 838–842.

18. Malfair D & Beall DP. Imaging the degenerative diseases of the lumbar spine. Magnetic Resonance Imaging

Clinics of North America 2007; 15: 221–238. vi.

19. Kelly S, Taylor P & Pitzalis C. Ultrasound imaging in spondyloathropathies: from imaging to diagnostic

intervention. Current Opinion in Rheumatology 2008; 20: 408–415.

20. Wakefield RJ, Gibbon WW, Conaghan PG et al. The value of sonography in the detection of bone ero-

sions in patients with rheumatoid arthritis: a comparison with conventional radiography. Arthritis and

Rheumatism 2000; 43: 2762–2770.

*21. Benjamin M, Moriggl B, Brenner E et al. The ‘‘enthesis organ’’ concept: why enthesopathies may not

present as focal insertional disorders. Arthritis and Rheumatism 2004; 50: 3306–3313.

22. McGonagle D, Wakefield RJ, Tan AL et al. Distinct topography of erosion and new bone formation in

achilles tendon enthesitis: implications for understanding the link between inflammation and bone

formation in spondylarthritis. Arthritis and Rheumatism 2008 Sep; 58(9): 2694–2699.

23. McGonagle D, Marzo-Ortega H, O’Connor P et al. Histological assessment of the early enthesitis lesion

in spondyloarthropathy. Annals of the Rheumatic Diseases 2002; 61: 534–537.

*24. Benjamin M & McGonagle D. The anatomical basis for disease localisation in seronegative

spondyloarthropathy at entheses and related sites. Journal of Anatomy 2001; 199: 503–526.

*25. McGonagle D, Marzo-Ortega H, Benjamin M & Emery P. Report on the Second International Enthesitis

Workshop. Arthritis and Rheumatism 2003; 48: 896–905.

*26. McGonagle D, Lories RJ, Tan AL & Benjamin M. The concept of a ‘‘synovio-entheseal complex’’ and its

implications for understanding joint inflammation and damage in psoriatic arthritis and beyond. Arthritis

and Rheumatism 2007; 56: 2482–2491.


27. Kamel M, Eid H & Mansour R. Ultrasound detection of heel enthesitis: a comparison with magnetic

resonance imaging. The Journal of Rheumatology 2003; 30: 774–778.

28. Kamel M, Eid H & Mansour R. Ultrasound detection of knee patellar enthesitis: a comparison with mag-

netic resonance imaging. Annals of the Rheumatic Diseases 2004; 63: 213–214.

29. McGonagle D, Gibbon W, O’Connor P et al. Characteristic magnetic resonance imaging entheseal

changes of knee synovitis in spondylarthropathy. Arthritis and Rheumatism 1998; 41: 694–700.

30. McGonagle D, Marzo-Ortega H, O’Connor P et al. The role of biomechanical factors and HLA-B27 in

magnetic resonance imaging-determined bone changes in plantar fascia enthesopathy. Arthritis and Rheu-

matism 2002; 46: 489–493.

31. Eshed I, Bollow M, McGonagle DG et al. MRI of enthesitis of the appendicular skeleton in spondyloar-

thritis. Annals of the Rheumatic Diseases 2007; 66: 1553–1559.

32. Hermann KG, Althoff CE, Schneider U et al. Spinal changes in patients with spondyloarthritis: compar-

ison of MR imaging and radiographic appearances. Radiographics 2005; 25: 559–569 [discussion 569–

570].

33. Wiell C, Szkudlarek M, Hasselquist M et al. Ultrasonography, magnetic resonance imaging, radiography,

and clinical assessment of inflammatory and destructive changes in fingers and toes of patients with

psoriatic arthritis. Arthritis Research & Therapy 2007; 9: R119.

34. Gisondi P, Tinazzi I, El-Dalati G et al. Lower limb enthesopathy in patients with psoriasis without clinical

signs of arthropathy: a hospital-based case-control study. Annals of the Rheumatic Diseases 2008; 67:

26–30.

35. Ozgocmen S, Kiris A, Ardicoglu O et al. Glucocorticoid iontophoresis for Achilles tendon enthesitis in

ankylosing spondylitis: significant response documented by power Doppler ultrasound. Rheumatology

International 2005; 25: 158–160.

36. Genc H, Duyur Cakit B, Nacir B et al. The effects of sulfasalazine treatment on enthesal abnormalities

of inflammatory rheumatic diseases. Clinical Rheumatology 2007; 26: 1104–1110.

37. Kiris A, Kaya A, Ozgocmen S & Kocakoc E. Assessment of enthesitis in ankylosing spondylitis by power

Doppler ultrasonography. Skeletal Radiology 2006; 35: 522–528.

38. D’Agostino MA, Said-Nahal R, Hacquard-Bouder C et al. Assessment of peripheral enthesitis in the

spondylarthropathies by ultrasonography combined with power Doppler: a cross-sectional study.

Arthritis and Rheumatism 2003; 48: 523–533.

39. Alcalde M, Acebes JC, Cruz M et al. A sonographic enthesitic index of lower limbs is a valuable tool in

the assessment of ankylosing spondylitis. Annals of the Rheumatic Diseases 2007; 66: 1015–1019.

40. Frediani B, Falsetti P, Storri L et al. Ultrasound and clinical evaluation of quadricipital tendon enthe-

sitis in patients with psoriatic arthritis and rheumatoid arthritis. Clinical Rheumatology 2002; 21:

294–298.

41. Wakefield RJ, Green MJ, Marzo-Ortega H et al. Should oligoarthritis be reclassified? Ultrasound reveals

a high prevalence of subclinical disease. Annals of the Rheumatic Diseases 2004; 63: 382–385.

42. Arslan H, Sakarya ME, Adak B et al. Duplex and color Doppler sonographic findings in active sacroiliitis.

American Journal of Roentgenology 1999; 173: 677–680.

43. Unlu E, Pamuk ON & Cakir N. Color and duplex Doppler sonography to detect sacroiliitis and spinal

inflammation in ankylosing spondylitis. Can this method reveal response to anti-tumor necrosis factor

therapy? The Journal of Rheumatology 2007; 34: 110–116.

44. Klauser A, Halpern EJ, Frauscher F et al. Inflammatory low back pain: high negative predictive value of

contrast-enhanced color Doppler ultrasound in the detection of inflamed sacroiliac joints. Arthritis and

Rheumatism 2005; 53: 440–444.

45. Battafarano DF, West SG, Rak KM et al. Comparison of bone scan, computed tomography, and mag-

netic resonance imaging in the diagnosis of active sacroiliitis. Seminars in Arthritis and Rheumatism

1993; 23: 161–176.

46. McGonagle D, Tan AL, Wakefield R & Emery P. Imaging in ankylosing spondylitis. In Van Royen BJ &

Dijkmans BAC (eds.). Ankylosing Spondylitis: Diagnosis and Management. New York: Taylor & Francis,

2006, pp. 71–82.

47. Baraliakos X, Hermann KG, Landewe R et al. Assessment of acute spinal inflammation in patients with

ankylosing spondylitis by magnetic resonance imaging: a comparison between contrast enhanced T1

and short tau inversion recovery (STIR) sequences. Annals of the Rheumatic Diseases 2005; 64:

1141–1144.


48. Hermann KG, Landewe RB, Braun J et al. Magnetic resonance imaging of inflammatory lesions in the

spine in ankylosing spondylitis clinical trials: is paramagnetic contrast medium necessary? The Journal

of Rheumatology 2005; 32: 2056–2060.

49. Appel H, Loddenkemper C, Grozdanovic Z et al. Correlation of histopathological findings and magnetic

resonance imaging in the spine of patients with ankylosing spondylitis. Arthritis Research & Therapy 2006;

8: R143.

50. Marzo-Ortega H, O’Connor P, Emery P & McGonagle D. Sacroiliac joint biopsies in early sacroiliitis.

Rheumatology (Oxford) 2007; 46: 1210–1211.

51. Braun J, Baraliakos X, Golder W et al. Magnetic resonance imaging examinations of the spine in patients

with ankylosing spondylitis, before and after successful therapy with infliximab: evaluation of a new

scoring system. Arthritis and Rheumatism 2003; 48: 1126–1136.

52. Laredo JD, Vuillemin-Bodaghi V, Boutry N et al. SAPHO syndrome: MR appearance of vertebral involve-

ment. Radiology 2007; 242: 825–831.

53. Cotten A, Flipo RM, Mentre A et al. SAPHO syndrome. Radiographics 1995; 15: 1147–1154.

54. Treitl M, Korner M, Becker-Gaab C et al. Magnetic resonance imaging assessment of spinal inflammation

in patients treated for ankylosing spondylitis. The Journal of Rheumatology 2008; 35: 126–136.

55. Lambert RG, Salonen D, Rahman P et al. Adalimumab significantly reduces both spinal and sacroiliac

joint inflammation in patients with ankylosing spondylitis: a multicenter, randomized, double-blind, pla-

cebo-controlled study. Arthritis and Rheumatism 2007; 56: 4005–4014.

56. Shankaranarayana S, Tan AL, Madden J & McGonagle D. Fat-suppression magnetic resonance imaging in

the diagnosis of late-onset axial spondyloarthropathy. Annals of the Rheumatic Diseases 2007; 66:

1405–1406.

57. Braun J, Landewe R, Hermann KG et al. Major reduction in spinal inflammation in patients with an-

kylosing spondylitis after treatment with infliximab: results of a multicenter, randomized, double-

blind, placebo-controlled magnetic resonance imaging study. Arthritis and Rheumatism 2006; 54:

1646–1652.

58. Haibel H, Rudwaleit M, Brandt HC et al. Adalimumab reduces spinal symptoms in active ankylosing

spondylitis: clinical and magnetic resonance imaging results of a fifty-two-week open-label trial. Arthritis

and Rheumatism 2006; 54: 678–681.

59. Marzo-Ortega H, McGonagle D, Jarrett S et al. Infliximab in combination with methotrexate in active

ankylosing spondylitis: a clinical and imaging study. Annals of the Rheumatic Diseases 2005; 64:

1568–1575.

60. van der Heijde D, Landewe R, Hermann KG et al. Is there a preferred method for scoring activity of the

spine by magnetic resonance imaging in ankylosing spondylitis? The Journal of Rheumatology 2007; 34:

871–873.

61. Marzo-Ortega H, McGonagle D, O’Connor P & Emery P. Efficacy of etanercept in the treatment of the

entheseal pathology in resistant spondylarthropathy: a clinical and magnetic resonance imaging study.


62. Gaspersic N, Sersa I, Jevtic V et al. Monitoring ankylosing spondylitis therapy by dynamic contrast-en-

hanced and diffusion-weighted magnetic resonance imaging. Skeletal Radiology 2008; 37: 123–131.

63. Fournie B, Margarit-Coll N, Champetier de Ribes TL et al. Extrasynovial ultrasound abnormalities in the

psoriatic finger. Prospective comparative power-Doppler study versus rheumatoid arthritis. Joint Bone

Spine 2006; 73: 527–531.

64. Hoenen-Clavert V, Rat AC, Loeuille D et al. Inflammatory and structural evaluation in spondyloarthritis:

magnetic resonance imaging analysis of axial and peripheral involvement. The Journal of Rheumatology

2007; 34: 762–768.

65. Erdem CZ, Sarikaya S, Erdem LO et al. MR imaging features of foot involvement in ankylosing spondy-

litis. European Journal of Radiology 2005; 53: 110–119.

66. Ghanem N, Uhl M, Pache G et al. MRI in psoriatic arthritis with hand and foot involvement. Rheuma-

tology International 2007; 27: 387–393.

67. Olivieri I, Barozzi L, Favaro L et al. Dactylitis in patients with seronegative spondylarthropathy. Assess-

ment by ultrasonography and magnetic resonance imaging. Arthritis and Rheumatism 1996; 39:

1524–1528.

68. Olivieri I, Barozzi L, Pierro A et al. Toe dactylitis in patients with spondyloarthropathy: assessment by

magnetic resonance imaging. The Journal of Rheumatology 1997; 24: 926–930.


69. Rhodes LA, Tan AL, Tanner SF et al. Regional variation and differential response to therapy for knee

synovitis adjacent to the cartilage-pannus junction and suprapatellar pouch in inflammatory arthritis:

implications for pathogenesis and treatment. Arthritis and Rheumatism 2004; 50: 2428–2432.

*70. Tan AL, Benjamin M, Toumi H et al. The relationship between the extensor tendon enthesis and the nail

in distal interphalangeal joint disease in psoriatic arthritis – a high-resolution MRI and histological study.

Rheumatology (Oxford) 2007; 46: 253–256.

71. Tan AL, Grainger AJ, Tanner SF et al. A high-resolution magnetic resonance imaging study of distal in-

terphalangeal joint arthropathy in psoriatic arthritis and osteoarthritis: are they the same? Arthritis and

Rheumatism 2006; 54: 1328–1333.

72. Antoni C, Dechant C, Hanns-Martin Lorenz PD et al. Open-label study of infliximab treatment for pso-

riatic arthritis: clinical and magnetic resonance imaging measurements of reduction of inflammation. Ar-

thritis and Rheumatism 2002; 47: 506–512.

73. Maksymowych WP, Jhangri GS, Lambert RG et al. Infliximab in ankylosing spondylitis: a prospective ob-

servational inception cohort analysis of efficacy and safety. The Journal of Rheumatology 2002; 29:

959–965.

74. Marzo-Ortega H, McGonagle D, Rhodes LA et al. Efficacy of infliximab on MRI-determined bone

oedema in psoriatic arthritis. Annals of the Rheumatic Diseases 2007; 66: 778–781.

75. McQueen F, Lassere M, Bird P et al. Developing a magnetic resonance imaging scoring system for

peripheral psoriatic arthritis. The Journal of Rheumatology 2007; 34: 859–861.

76. Milosavljevic J, Lindqvist U & Elvin A. Ultrasound and power Doppler evaluation of the hand and wrist in

patients with psoriatic arthritis. Acta Radiologica 2005; 46: 374–385.

77. Kane D, Greaney T, Bresnihan B et al. Ultrasonography in the diagnosis and management of psoriatic

dactylitis. The Journal of Rheumatology 1999; 26: 1746–1751.

78. Wakefield RJ, Emery P & Veale D. Ultrasonography and psoriatic arthritis. The Journal of Rheumatology

2000; 27: 1564–1565.

79. Grassi W, Filippucci E, Farina A & Cervini C. Sonographic imaging of the distal phalanx. Seminars in


80. Iagnocco A, Cerioni A, Coari G et al. Intra-articular methotrexate in the treatment of rheumatoid

arthritis and psoriatic arthritis: a clinical and sonographic study. Clinical Rheumatology 2006; 25:

159–163.

81. Fiocco U, Ferro F, Vezzu M et al. Rheumatoid and psoriatic knee synovitis: clinical, grey scale, and power

Doppler ultrasound assessment of the response to etanercept. Annals of the Rheumatic Diseases 2005;

64: 899–905.

82. Galluzzo E, Lischi DM, Taglione E et al. Sonographic analysis of the ankle in patients with psoriatic ar-

thritis. Scandinavian Journal of Rheumatology 2000; 29: 52–55.

*83. McGonagle D, Conaghan PG & Emery P. Psoriatic arthritis: a unified concept twenty years on. Arthritis

and Rheumatism 1999; 42: 1080–1086.

84. Weber U, Pfirrmann CW, Kissling RO et al. Whole body MR imaging in ankylosing spondylitis: a descrip-

tive pilot study in patients with suspected early and active confirmed ankylosing spondylitis. BMC Mus-

culoskeletal Disorders 2007; 8: 20.

85. Savnik A, Malmskov H, Thomsen HS et al. MRI of the arthritic small joints: comparison of extremity

MRI (0.2 T) vs high-field MRI (1.5 T). European Journal of Radiology 2001; 11: 1030–1038.

86. Eshed I, Althoff CE, Feist E et al. Magnetic resonance imaging of hindfoot involvement in patients with

spondyloarthritides: comparison of low-field and high-field strength units. European Journal of Radiology

2008; 65: 140–147.

87. Ejbjerg BJ, Narvestad E, Jacobsen S et al. Optimised, low cost, low field dedicated extremity MRI is

highly specific and sensitive for synovitis and bone erosions in rheumatoid arthritis wrist and finger

joints: comparison with conventional high field MRI and radiography. Annals of the Rheumatic Diseases

2005; 64: 1280–1287.

88. von Engelhardt LV, Kraft CN, Pennekamp PH et al. The evaluation of articular cartilage lesions of the

knee with a 3-Tesla magnet. Arthroscopy 2007; 23: 496–502.

89. Regatte RR & Schweitzer ME. Ultra-high-field MRI of the musculoskeletal system at 7.0T. Journal of Mag-

netic Resonance Imaging 2007; 25: 262–269.

90. Ashman CJ, Farooki S, Abduljalil AM & Chakeres DW. In vivo high resolution coronal MRI of the wrist

at 8.0 tesla. Journal of Computer Assisted Tomography 2002; 26: 387–391.


91. Benjamin M, Milz S & Bydder GM. Magnetic resonance imaging of entheses. Part 2. Clinical Radiology

2008; 63: 704–711.

92. Benjamin M, Milz S & Bydder GM. Magnetic resonance imaging of entheses. Part 1. Clinical Radiology

2008; 63: 691–703.

93. Ju JH, Kang KY, Kim IJ et al. Three-dimensional ultrasonographic application for analyzing synovial hy-

pertrophy of the knee in patients with osteoarthritis. Journal of Ultrasound in Medicine 2008; 27:

729–736.

94. Laasanen MS, Toyras J, Vasara A et al. Quantitative ultrasound imaging of spontaneous repair of porcine

cartilage. Osteoarthritis and Cartilage 2006; 14: 258–263.

*95. McGonagle D, Tan AL & Benjamin M. The biomechanical link between skin and joint disease in psoriasis

and psoriatic arthritis: what every dermatologist needs to know. Annals of the Rheumatic Diseases 2008;

67: 1–4.

Documents

Imaging of seronegative spondyloarthritis