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Assessment o the rheumAtologicAl pAtient

meDicine 34:9 350 2006 ev ld. A vd.

Ivestiatios irheumatoloyrb B

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Keywords aabd; ccp; An; enA; AncA; ay; v-

a; ad; mri; ada; ctInvestigations are o great value in rheumatology, but a single

test is rarely diagnostic because o the limited specicity o most

tests.1 Investigations should be selected and results interpreted in

the light o the clinical history and examination: simply sendingo a battery o investigations without assessing the clinical prob-

lem will oten result in conusion rather than enlightenment.

Blood tests

Acute phase reactats

The acute phase response can be measured by erythrocyte

sedimentation rate (ESR), plasma viscosity or C-reactive protein

(CRP). ESR is less specic than the other two and is increased by

Robin ButlerFRCP is Consultant Rheumatologist at the Robert Jones

and Agnes Hunt Orthopaedic Hospital, Oswestry, UK. He qualied

rom Charing Cross Hospital Medical School, London, and trained

in rheumatology at Charing Cross Hospital and Westminster

Hospital, London. His research interests include the management o

complicated rheumatoid arthritis, vasculitis and corticosteroid-induced

osteoporosis. Conficts o interest: none declared.

Victor N Cassar-Pullicino MRCS FRCR DMRD is Consultant Radiologist at the

Robert Jones and Agnes Hunt Orthopaedic Hospital, Oswestry, UK. He

qualied rom the University o Malta, and trained in radiology at the

University o Birmingham, UK. His research interests are spinal and

articular disorders, including sports injuries. Conficts o interest: none

declared.

anaemia and hyperglobulinaemia and it rises with age. All can be

used to assess the activity o infammatory rheumatic disorders,

although systemic lupus erythematosus (SLE) is unusual in that

CRP is typically normal or only slightly raised unless there isconcurrent inection. A high ESR or CRP at onset is a poor prog-

nostic actor in rheumatoid arthritis.

Uric acid

Uric acid is o limited solubility in blood and tissue fuids and

so the higher the serum uric acid level the greater the risk o

crystal precipitation in and around joints and hence o gout.

With increasing obesity and alcohol consumption in the general

population the mean serum urate is rising and so is the requency

o gout. It is important to remember that the gold standard or

the diagnosis o gout is identication o urate crystals in synovial

fuid or other tissue. Because hyperuricaemia (>0.42mmol/l in

men and >0.36mmol/l in women) is much more common thangout, hyperuricaemia can be at most consistent with gout but not

diagnostic. Furthermore, the serum uric acid can all during an

acute attack, so that a normal value during an attack does not

exclude the diagnosis. Adequacy o allopurinol or other treat-

ment can be assessed by measurement o serum uric acid.

Autoatibodies (Table 1)

Rheumatoid actor (RF) and cyclic citrullinated protein (CCP)

antibodies: RF is ound in about 75% o people with rheumatoid

arthritis (RA) but it is also ound in about 5% o the general

population and an even higher proportion o the elderly, as well

as in various rheumatic and other disorders including inection,

chronic liver disease and lymphoprolierative disorders. As atest, it thereore lacks sensitivity and is o very low specicity.

Nonetheless, high titre RF has been consistently shown to be a

marker or severe disease and hence o some use as a prognostic

marker.

Recently, antibodies to CCP have attracted much interest. Both

RF and anti-CCP antibodies can be ound in the sera o people

many years beore the development o overt disease, but anti-

CCP appear sooner and are more predictive o severe disease.2 As

with RF, about 75% o people with RA have antibodies to CCP

but these have a specicity o more than 95% or a diagnosis o

RA, although they are occasionally ound in people with Sjgrens

syndrome, psoriatic arthritis and rarely in other conditions.

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Antinuclear actor (ANF), DNA and extractable nuclear antigen(ENA) antibodies: ANF is ound in about 95% o people with SLE,

the remainder typically having antibodies to Ro. ANF is also airly

common in other rheumatic and general medical disorders (e.g.

inections, chronic infammatory disorders and malignancy) and

this limited specicity restricts its diagnostic value. By contrast

antibodies to ds-DNA and Sm have high specicity or SLE, and

the titre o ds-DNA antibodies is helpul or monitoring disease

activity. Antibodies to ENA are ound in various connective tissue

disorders with some degree o overlap, but some are airly specic

or certain disorders, or example, Scl-70 (anti-topoisomerase 1)

or scleroderma and Jo-1 (anti-histidyl tRNA synthetase) or myo-

sitis associated with interstitial pulmonary disease. RNA binding

protein (RNP) is present in undierentiated connective disorderassociated with severe Raynauds phenomenon, but is also seen

in about 30% o people with SLE. A centromere pattern o ANF is

strongly associated with the CREST variant o scleroderma.

Phospholipid antibodies: this group o antibodies comprises the

lupus anticoagulant and antibodies to cardiolipin and2-glycoprotein

I. They are associated with the anti-phospholipid syndrome (APS)

which is characterized by recurrent venous and arterial thrombosis

and, in women, recurrent etal loss. They are also ound in about

one-third o people with SLE who are similarly at risk o clotting.

IgG class antibodies are generally associated with a higher risk o

clotting than those o IgM class, and the higher the titre o antibod-

ies the greater the risk. Phospholipid antibodies are also sometimesound in people with rheumatoid arthritis and other infammatory

disorders without apparent clotting problems.

Although generally concordant, some people with APS have

low titre or negative tests or cardiolipin antibodies but lupus

anticoagulant can be detected by prolonged kaolin clotting

time (KCT) or by the Russell viper venom test, or antibodies to

2-glycoprotein I are present. In cases with a high index o suspi-

cion, it is thereore appropriate to do more than one test.

Anti-neutrophil cytoplasmic antibodies (ANCA) are ound in

dierent types o vasculitis and some other conditions. There

are two main types: cytoplasmic (c-ANCA) and peri-nuclear

(p- ANCA) based on their staining pattern on immunofuores-cence. A c-ANCA pattern is typically produced by antibodies

reacting with serine proteinase 3 (PR3) and p-ANCA by those

which react with myeloperoxidase (MPO).

PR3 antibodies are present in most cases o Wegeners granulo-

matosis (WG), although they are also seen in about 45% o those

with microscopic polyangiitis and sometimes in acute inections

and infammatory bowel disease. The titre o antibodies tends

to vary according to the activity o the disease in WG and some

reports suggest that the titre can be used to monitor this. p-ANCA

antibodies are seen in about 65% o cases o Churg-Strauss syn-

drome and about 50% o those with microscopic polyangiitis,

but are sometimes seen in rheumatoid arthritis, infammatory

bowel disease and other infammatory disorders.

Complemet

Inherited deciency o complement components, especially C4,

is a risk actor or the development o SLE. During active disease

levels o C4 and less oten C3 will all and serial measurements

can be helpul to monitor disease activity. Hypocomplementae-

mia is also seen in mixed cryoglobulinaemia and other disorders

associated with circulating immune complexes.

HLA typi

HLA-B27 is ound in approximately 95% o people with isolated

ankylosing spondylitis (AS), 70% o people with AS who have

psoriasis, 50% o people with AS who have either Crohns diseaseor ulcerative colitis, and 70% o people with reactive arthritis.

However, it is also ound in about 8% o the healthy Caucasian

population, only a small proportion o whom develop these dis-

eases, and so it is o very limited value as a diagnostic test. In

people in whom a spondyloarthropathy is suspected it is more

appropriate to make the diagnosis by clinical assessment and X- ray

or MR imaging o the sacro-iliac joints or spine (see below).

RA is associated with the tissue type HLA-DRB1*04 but again

this is common in the healthy population and so tissue typing

is unhelpul or diagnosis. HLA-DRB1 alleles which encode a

common structural element known as the shared epitope are

markers or severe disease, but testing or this is currently a

Approximate requecy (%) o autoatibodies*

Atibody RA Sjores SLE APS Scleroderma PM/DM Cotrols

r 80 70 25 20 5 5

An 25 65 95 60 25 5

DnA 5 - 65 - - -

s - - 20 - - -

r 5 70 35 30 - -

la - 40 15 5 - -

cad 20 30 30 85 20 10 5

s-70 - - - - 20 - -

J-1 - - - - - 20 -

*qy va x ad aay d ad a dd .. d a ay a . Aps: a-d

yd; pm/Dm: yy/day.qy a w a ad a xd 25% x d a. (-) < 5%.

Table 1


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research tool. It appears that people who possess the shared epi-

tope and smoke are at signicantly increased risk o developing

both CCP antibodies and RA.

Syovial fuid

Synovial fuid aspiration can be o diagnostic value in septic and

crystal arthritis and can help to distinguish infammatory romnon-infammatory disorders (Table 2). Fluid should be sent or

Gram stain and culture, as well as examination or urate or cal-

cium pyrophosphate dihydrate crystals which are ound in gout

and pseudogout, respectively.

Imai

A combined clinical and radiological approach is essential in the

diagnosis and management o rheumatological disorders and their

complications. There is signicant overlap between the radiological

eatures o several rheumatic disorders; thereore, close collabora-

tion is required between clinician and radiologist when selecting

the appropriate imaging modality and interpreting the result.

Basic joit structure

In a typical synovial joint, the bone ends are covered by hyaline

cartilage and there is a synovial lining; the joint can move reely.

In cartilaginous joints (e.g. the intervertebral and manubrioster-

nal joints, the pubic symphysis), the bone ends are covered with

hyaline cartilage but the bones are linked by brocartilage and

strong ligaments; movement depends on compression o the rela-

tively sot intervening brocartilage. Dierent disease processes

occur in the two types o joint. Diseases o cartilaginous joints

are oten associated with disorders o the enthesis (the site o

attachment o a tendon or ligament to bone). Dierent imaging

modalities are appropriate or bone, cartilage and synovium, all owhich may show abnormalities in dierent rheumatic disorders.

Imai modalities

Plain radiography is the mainstay o musculoskeletal imag-

ing and has a central role in rheumatological diagnosis. It is

increasingly being complemented by other techniques, notably

ultrasound, CT and MRI. Each o these modalities has strengths

and weaknesses in dierent situations (Table 3). Routine views

can be supplemented by special projections (e.g. the hands, sac-

roiliac joints). Dynamic views can also give urther inormation;

or example, to demonstrate spinal instability. The limitation o

plain radiography is that radiographic changes can take months

to appear in rheumatoid arthritis (RA); only septic arthritis is

likely to show abnormalities within days o disease onset. Early

radiographic signs o disease usually indicate a well-establisheddisease process and the changes are usually irreversible.

Tomography has been largely superseded by CT and MRI o the

spine, but can still be helpul in the temporomandibular, costo-

vertebral and sternoclavicular joints.

Contrast arthrography is perormed by injecting contrast

medium or air into a joint beore radiography or CT. It is par-

ticularly helpul in the knee and shoulder to identiy meniscal or

rotator cu tears, intra-articular loose bodies and transchondral

ractures. Contrast studies with MRI are gaining popularity.

Ultrasonography can be used to assess joint eusions, synovialprolieration, erosions, intra-articular loose bodies (Figure 1),

tendon thickening or rupture and to detect para-articular cysts. It

is more accurate than clinical assessment in shoulder pain.3 Per-

usion within synovial prolieration can be assessed with power

Doppler ultrasonography.

Ultrasound or early detection o RA. Compared with clinical

assessment, high resolution ultrasonography will detect synovial

prolieration more accurately and can distinguish it rom eusion,

peri-articular infammation and at.4 Erosions can be detected

long beore they become visible with plain radiographs which

aids diagnosis. The sensitivity o ultrasound in detection o new

erosions and persistent synovial prolieration makes it a valuabletool in the serial assessment o the adequacy o treatment.

Isotope scanning using technetium-99m is widely used to seek

bone metastases. It also demonstrates bone or joint inection

and infammation, because it shows increased blood fow to, or

increased metabolic activity in, bones, joints or entheses. Isotope

scanning is sensitive but not specic, and increased uptake is

seen in osteoarthritic joints and ailed prostheses. This modality

is perhaps most useul in excluding signicant infammatory,

inective or neoplastic musculoskeletal disease.

CT is particularly useul or complex anatomy. It demonstrates

bone well and can be used or peripheral joints and the spine.Recent developments enable three-dimensional reconstruction o

images, which can be useul in the spine (e.g. to diagnose spinal

stenosis). CT can be combined with conventional myelography

or arthrography to provide more inormation.

MRI is superior to CT in imaging sot tissues, including liga-

ments, cartilage, intervertebral disc and muscle; it is thus par-

ticularly helpul in the diagnosis o musculoskeletal disorders.

The most commonly used magnetic resonance sequences are T1-

weighted, T2-weighted and STIR. The contrast resolution o these

sequences is superior to that o plain radiography and CT, but

T1-weighted images are better or delineating anatomical detail,

Typical characteristics o syovial fuid idieret codtios

Type o fuid Special eatures Leucocytes per mm3

na V, < 200 (< 25%

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ifaay

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ay b w

200075,000

(> 50% )

s a oaq .

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Table 2


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T2-weighted images are best or identiying the presence o fuid

e.g. CSF, eusions, and STIR or identiying bone and sot tis-sue oedema (Figure 2). Gadolinium-DTPA intravenous injection

aids in the dierentiation o synovitis rom eusion and deter-

mines vascularity in osteonecrosis. MRI is the best method or

demonstration o intervertebral disc pathology and prolapse, and

pressure on the spinal cord or nerve roots rom disc herniation,

rheumatoid subluxation or spinal stenosis. It has revolutionized

detection o sot tissue lesions in the knee and shoulder (e.g.

meniscal, rotator cu). It can be used to assess muscle involve-

ment in polymyositis and is invaluable in sot tissue, articular

and bone tumours. Because the method shows bone marrow

well, it is used to diagnose and stage osteonecrosis. Progress in

sotware and magnetic resonance sequences has increased the

role o MRI in the assessment o articular cartilage; the thicknesso cartilage, the volume o loss and the extent o surace area

involvement can be calculated. The status o subchondral bone,

the extent o synovial prolieration and the results o treatment o

cartilage deects can also be delineated by MRI.

Radioloical sis o syovial disease

Joint eusion may be evident on a plain radiograph as an area

o increased sot tissue density or displacement o periarticular

at pads, but is more reliably demonstrated by ultrasonography

or MRI. The characteristics o the fuid may aid diagnosis; or

example, the presence o blood on MRI suggests trauma, haemo-

philia or pigmented villonodular synovitis.

Synovial hypertrophy is the hallmark o infammatory arthritis.

It cannot be distinguished rom an eusion on plain radiography

and is better shown by ultrasonography or MRI. It is impossible

to determine the type o infammatory arthropathy using MRI.

Bursal enlargement and cysts can be readily demonstrated by

ultrasonography or MRI. Contrast CT can be useul in the identi-

cation o intra-articular loose bodies.

Calcium deposition occurs most commonly in calcium pyro-

phosphate dihydrate deposition (CPPD) disease and can be seen

on plain radiography or CT. It may aect both synovium andcartilage. Synovial chondromatosis may be associated with intra-

articular loose bodies in addition to calcied lesions in synovium.

Small periarticular deposits o calcium near the interphalangeal

joints oten represent hydroxyapatite crystals.

Haemosiderin deposition: iron can be recognized by its charac-

teristics on MRI. Large iron deposits are seen in haemochromato-

sis and ollowing repeated intra-articular bleeding in haemophilia

and pigmented villonodular synovitis. Some iron may accumu-

late in the synovium in RA.

Changes in adjacent bone can oten be seen on plain radio-

graphs, but may be better demonstrated by CT and MRI. Periarticular osteopeniais typically seen in RA and other

chronic infammatory arthropathies, though it typically does not

occur in psoriatic arthritis. It is a characteristic eature o acute

and chronic inection, and thereore occurs in septic arthritis,

osteomyelitis and tuberculosis and is a prominent eature o

refex dystrophy syndrome (Sudecks atrophy).

Erosion marginal erosion o bone is the radiological hall-

mark o RA (Figure 3), but also occurs in other infammatory

arthropathies. Erosions typically begin in the bare areas at the

margins o joints, where intra-articular bone is not covered by

cartilage. In psoriatic arthritis, joint involvement is typically

asymmetrical, unlike in RA, and erosions are less prominent. In

Relative merits o imai modalities

Plai radioraphy Arthroraphy Plai CT Ultrasooraphy MRI Isotopes

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caa +++ ++++ ++++ +

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e + + + +++ ++++

nw b a ++ ++++ + ++

pa a ++++ ++++ + ++ +

Avaa b + ++ ++++ ++++

, day ; +, ; ++, ava; +++, d; ++++, x; , ad/ (- d).

Table 3

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severe cases, however, there may be marked erosion with whit-

tling o bone and progression to pencil-in-cup deormities. In

gout, large punched-out erosions may be seen, but these are

typically extra-articular and in the metaphyseal region, and have

a prominent overhanging lip (Figure 4).

New bone formation psoriatic arthritis and Reiters syn-

drome oten show new bone ormation in relation to marginal

erosions that gives a whiskered appearance. Periosteal reaction

is also prominent in these conditions and in osteomyelitis, and

may be seen in juvenile chronic arthritis.

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Radioloical sis o cartilae damae

Joint space reduction: it is dicult to judge articular loss on

plain radiography because a fexion deormity may lead to anapparent reduction in joint space. In the lower limbs, cartilage

thickness can be estimated on weight-bearing views. Cartilage

thickness can be better assessed using MRI or contrast arthrogra-

phy with CT. In RA and inection, cartilage loss aects the whole

cartilage surace, whereas in osteoarthritis the cartilage loss

tends to be irregular in distribution. Most arthropathies are asso-

ciated with cartilage damage and narrowing o the joint space,

but there are exceptions notably systemic lupus erythematosus,

gout (except in advanced stages) and relatively uncommon dis-

orders such as pigmented villonodular synovitis and multicentric

reticulocytosis, in which the preservation o joint space is useul

in diagnosis.

Cartilage calcifcation (chondrocalcinosis) is a characteristic

eature o CPPD. It is also seen in hyperparathyroidism, gout,

haemochromatosis and, less commonly, Wilsons disease.

Changes in subchondral bone: subchondral bone cysts occur

only where there is loss o integrity o the overlying cartilage. In

RA, they can be dicult to distinguish rom erosions when the

plane o the lm does not include the area o cortical destruction.

They are not disease-specic, and occur in osteoarthritis and

infammatory arthropathies. Particularly large subchondral cysts

(geodes) are seen in the robustus orm o RA, CPPD and haemo-

philia. Subchondral bony sclerosis is a hallmark o osteoarthritis,

but is nonspecic because reactive sclerosis is also a maniesta-

tion o seronegative arthropathies.

Osteophytosis with cortical buttressing is a characteristic eature

o osteoarthritis (Figure 5). An osteophyte is a cartilage-covered

bony projection at the margin o the joint; it seems to represent

a hypertrophic response to joint damage, in contrast to the atro-

phic process represented by cartilage loss and joint space narrow-ing. Buttressing o bone results rom thickening o the adjacent

bony cortex and is oten seen in the hip; it probably represents a

response to altered biomechanics o the joint.

Joint migration represents loss o the normal congruity o the

joint. It may result rom severe damage to periarticular structures

(e.g. ligaments and tendons in RA) or rom severe joint damage

in septic arthritis, osteomyelitis or a Charcots joint. Collapse o

the acetabulum results in protrusio acetabulae; the emoral head

migrates centrally in RA and superolaterally in osteoarthritis.

Radioloical sis o ethesopathy

The enthesis is particularly aected in seronegative spondylo-arthropathies; pathological changes in the enthesis are analogous

to those that occur in the spine (see below). Plain radiographs

are unremarkable during the initial infammatory reaction,

but an isotope bone scan oten demonstrates increased uptake

(Figure 6a). This is ollowed by erosion o bone, reactive sclero-

sis and bony prolieration to orm a bone spur (Figure 6b); these

changes are visible on radiography. MRI is increasingly used to

demonstrate enthesopathy in both the axial and the appendicular

skeleton.

Imai o spial disease

Conventional radiographs are o limited use in spinal imaging

because they provide no inormation on sot tissue structuresincluding the intervertebral discs, spinal cord and nerve roots;

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these can be demonstrated by MRI. CT illustrates spinal stenosis,

acet joint abnormalities and spinal deormity.

Degenerative disease: degenerative disc disease may result in

disc prolapse and compression o nerve roots. Narrowing and

disorganization o the disc oten leads to spondylosis (horizontal

outgrowths o bone around the circumerence o the vertebral

rim, analogous to the osteophytes that occur in osteoarthritis

o peripheral joints). The apophyseal (acet) joints are synovial

joints, which may be aected by osteoarthritis.

MRI is the method o choice in detecting spinal cord or

nerve root compression. Diuse idiopathic skeletal hyperostosis(Forestiers disease) is a severe orm o degeneration in which

forid osteophytes and fowing ossication between adjacent verte-

bral bodies occur, with thick prominent ossication o the anterior

longitudinal ligament (Figure 7). The osseous outgrowths begin at

the enthesis where the anterior longitudinal ligament inserts on

the vertebral body, and not at the intervertebral disc attachments.

These changes are usually apparent on radiography (best seen in

lateral views), but can oten be demonstrated better by CT.

RA aects the synovial joints o the spine (the apophyseal joints)

and the uncovertebral (neurocentral) joints o the cervical spine.

In addition, rheumatoid synovial prolieration (pannus) can lead

to spinal cord compression in the neck as a result o direct pressureor subluxation secondary to ligamentous rupture. Such instabil-

ity can be demonstrated by obtaining lateral radiographs in both

fexion and extension. MRI is now the investigation o choice or

imaging the rheumatoid cervical spine because it shows pannus

and the spinal cord in addition to the bony structure (Figure 8).

Ankylosing spondylitis: sacroiliitis is usually the rst radio-

logical maniestation o ankylosing spondylitis. Erosion o the

margins o the sacroiliac joint is associated with sclerosis in the

subchondral bone; ultimately, the joint may use (ankylosis).

Changes may be apparent on radiography, but special views may

be required because the appearance o the lumbar spine and

pelvis on lms can be misleading. In the early stages, the joint

appearance can be dicult to interpret, particularly in adoles-

cents, in whom widening is common and normal, though sclero-

sis is usually absent. In dicult cases, MRI or CT can be used to

detect early changes (Figure 9). MRI shows the bone outline less

well but has the advantage that it does not involve exposure o

the gonads to radiation, and demonstrates subchondral infam-

mation within the marrow. Isotope scanning is no longer used.

Spinal disease in ankylosing spondylitis ollows a similar pat-

tern. The rst lesions (Romanus lesions) typically appear at theanterosuperior or antero-inerior margins o the vertebral bodies

adjacent to the insertion o the annulus brosus (Figure 10). There

is erosion o the bone with subjacent sclerosis and the bony deect

is gradually lled in; this leads to squaring o the vertebral bodies

(loss o their normal anterior concavity) and production o syn-

desmophytes (projections o new bone that grow vertically and

eventually bridge adjacent vertebrae). A similar process aects the

acet joints. Severe cases may lead to a bamboo spine, in which

bony bridging o vertebrae anteriorly and o the posterior elements

is complete. These changes are generally shown adequately by

radiography, but CT is useul in showing changes in the apophy-

seal joints. MRI is much more sensitive than plain x-rays in the

identication o early changes, spondylodiscitis and lesions at theinsertion o the annulus brosus (Figure 11). MRI can also be

used to evaluate response to treatment with TNF- inhibitors,5

although it is not yet clear that such improvement in MRI ndings

will be associated with the prevention o classical syndesmophyte

ormation and bony bridging seen on radiographs.

Reiters syndrome and psoriatic spondylitis: the spinal changes

in Reiters syndrome and psoriatic spondylitis are similar to those

seen in idiopathic ankylosing spondylitis. However, the sacroili-

itis is less likely to be symmetrical and skip lesions (in which

some intervertebral levels show marked changes whereas oth-

ers are completely spared) are common. In addition, pronounced

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paravertebral ossication may be seen; this is thicker and denser,

asymmetrical and irregular compared with the thin, regular and

symmetrical appearance typical o ankylosing spondylitis.

Inection: pyogenic inection can aect the disc space or verte-

bral body. Tuberculous inection o the spine is similar, but tendsto be more insidious in onset and associated with larger para-

spinal abscesses. Metastatic disease is oten the main diagnostic

alternative to spinal inection, but in this case the disc space is

spared even when adjacent vertebrae have secondary deposits.

Thus, a preserved disc space between two eroded vertebrae is

an ominous nding because it suggests malignancy, whereas a

damaged disc suggests inection.

Advanced changes are visible on radiography, but in the early

stages isotope scanning is helpul and either CT or MRI shows

vertebral damage. MRI is particularly useul in demonstrating the

extent o sot tissue involvement.

Malignancy: with the exception o multiple myeloma, primarybone tumours are seldom encountered in rheumatological prac-

tice. However, metastatic disease can present with myalgia and

bone pain. Skeletal areas o residual red marrow (spine, pelvis,

proximal emora and proximal humeri) are the most common

sites o metastatic disease. The radiographic appearances can be

lytic or sclerotic, and vertebral body collapse is a not uncom-

mon presentation. Destruction o one or both pedicles with

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preservation o the adjacent intervertebral disc space suggests

the possibility o malignant disease. Scintigraphy and MRI are

helpul in the assessment o metastatic disease in the spine. MRI

has been shown to be more sensitive than plain radiography and

radionuclide bone scintigraphy in the detection o metastatic

disease (breast, renal, prostate cancer) and multiple myeloma.

Although bone scintigraphy assesses the whole skeleton, it

should be noted that isolated peripheral skeletal metastases were

seen in only 2% o patients in a study comparing whole body

scintigraphy with MRI o the spine, pelvis and proximal emorain 200 patients with breast or prostate cancer. MRI o the spine

is more sensitive and specic or metastatic disease than bone

scintigraphy6 because the mechanism o detection relies on the

presence o tumour within the bone marrow, whereas scintigra-

phy relies on a bone response to the presence o disease.

Assessi disease proressio

RA: serial assessment o joint damage in RA is more complicated

than it appears. Several scoring systems have been devised,

most o which ocus on the progression o erosive disease and

cartilage loss. MRI and ultrasonography are more sensitive than

plain radiographs in the detection o erosions. Both are more

sensitive than clinical examination in the detection o synovitis

and may be useul or assessing response to treatment, although

X-ray changes remain the gold standard in clinical trials or the

time being.

Osteoarthritis: standard sets o radiographs have been produced

against which osteoarthritic changes in a given joint can be scored.

Cartilage thickness can be judged to some extent by measuring

the joint space on radiography with or without magnication.

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Fiure 11 Aky

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t a

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However, it is dicult to position the joint such that the X-ray

beam is perpendicular to the axis o the joint and hence to take

ollow-up lms in precisely the same position. CT can be helpul,

particularly when combined with contrast arthrography, but MRI

demonstrates cartilage most satisactorily and may be useul in

the assessment o the degree o cartilage loss.

REFEREnCES

1 sd J. labay a a da.

Best Pract Res Clin Rheumatol 2004; 18: 24969.

2 Zda A J W, va Vj W J, pj g J m. u ad a

a-ccp aabd ad a. Rheumatol 2006;

45: 205.

3 nad e, Aad p, D m e et al. pa sd:

ca ya xaa ad aa d.

Ann Rheum Dis 2002; 61: 1326.

4 szkdak m, navad e, Kad m, c-pay m, t h s,

oaad m. uaay aaaaa j

ad a: a w a a a,va aday ad a a.Arthritis Rheum

2004; 50: 210312.

5 s J, Baaak X, l J et al. p d a

faa a ad by a a a

a w aky dy a 2 ya a w

a- a a fxab. Rheumatology

2005; 44: 152530.

6 ta Z c, tab D, gd s, g V. mri v add

b ay b aa. Clin Radiol

1999; 54: 44851.

FURTHER READIng

Aa adad ada. Rheumatology2005; 44(s. 4):

v4372.

(Classic set o radiographs which show varying degrees o OA, RA

and ankylosing spondylitis.)

rk D. Bone and joint imaging. pada: sad, 2004.

(Authoritative textbook o musculoskeletal radiology and

imaging.)

Wakd r J, K K o, caa p g, Bw A K, oc p J,

ey p. t aay ad a a

a ay ad a. Clin Exp Rheumatol 2003;21(s. 31): s429.

(Useul review o the clinical value o these methods.)

intx rheum

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