60 Abstracts

Imaging in eros ive osteoarthrit is: digital radiology vs convent iona l radiology F. TROTTA*, M. GOVONI*, C. ORZINCOLO'~, G. CIANCIO* AND P. N. SCUTELLARI~

*Division of Rheumatology, tDepartment of Radiology S. Anna Hospital, Ferrara, Italy $Instutute of Radiology, Ferrara University, Italy

Digital radiology represents a recent advance in diag- nosis imaging. It has been proposed for the study of arthropathies. In this study, the authors compare the images obtained by digital and conventional radio- graphy in 18 patients affected by erosive osteoarthritis. Patients (16 F : 2 M, aged 38-72 years) were identified by radiological criteria (Martel, 1980). Both conventional and digital radiograms showed the same sensitivity in pointing out the osteoarticular features of the disease i.e. erosions (distal or proximal interphalangeal joint, metacarpo-phalangeal or trapezio-metacarpal joint);

joint space narrowing; osteophytosis; articula r subluxa- tions. Digital radiography was superior to conventional radiography in demonstrating periarticular soft-tissue alterations (80% vs 20%). Digital radiography is parti- cularly useful in identifying capsular calcifications because this technique uses 'edge contrast enhance- ment'. This is advantageous in obtaining better defini- tion of the calcifications and i n revealing their relationships with articular or periarticular structures. However, their significance remains not well under- stood regarding to the pathogenesis.

Quanti tat ive evaluat ion of hip joint space height with computer ized image analys i s

A. M. TRON, T. CONROZIER, J. C. BALBLANC, P. MATHIEU AND E. VIGNON Claude Bernard University, H6pital Edouard Herriot, Lyon, France

z

Any quantitative study of progression in osteoarthritis (OA) would require a simple and accurate method of measurement of articular cartilage thickness. Both the surface area (SA, mm 2) and the mean joint space height (MISH, mm) of hip joint X-rays have been measured using an image analysis computer (Hologic). The measured part of the joint space was defined by an internal line (OI) joining the centre of the femoral head (O) and the summit of the homolateral sacrum aileron. It would also include an external line (EJ) going from O to the edge of the acetabulum. Three X-rays, obtained by three different radiologists, of 20 normal and OA hips

were measured blind five times by two different observers. The mean coefficient of variation (CV) (vari- ance analysis) was 4.7 and 3.3~/o for SA and MISH, respectively. The mean CV of MISH was 2.9 and 3.5~/o for the first and second observer respectively. The coeffi- cient of correlation is highly significant between SA and MISH (R = 0.87, P = 0.001). A 4.3 and 5.1~/o mean CV was found for the SA measurement of the two observers. The MISH, measured in both hips of 78 normal subjects, did not vary with the right or left side and with age, but was significantly larger in men than women (7.2+ 1 and 6.43 + 1 mm, P = 0.001, respectively).

Digital image analysis , a rapid and reproducible method for joint space m e a s u r e m e n t

J. BYRNE*, G. HEALDt, M. F. JAMESt, M. KAY,, J. H. SHORTER~ AND J. E. DACRE* *St Bartholomews Hospital, London U.K.

tSmithKline Beecham Pharmaceuticals, Harlow, U.K.

In osteoarthritis (OA), joint destruction is conven- tionally assessed radiologically. Current scoring systems are not sensitive enough to detect small changes. We have used digital image analysis to measure radiographic joint space in finger metacarpo- phalangeal (MCP), proximal interphalangeal (PIP) and distal interphalangeal (DIP), knee and hip joints.

A video image of the radiograph is converted to digital form and stored on a 'Photon' framestore card within an IBM PS/2 microcomputer. Joint space is measured automatically by two specially derived mathe- matical algorithms. The proximal joint margin is located by finding regions of rapidly changing radio- graphic density, the distal edge is then located by finding corresponding pixels with maximum brightness.

Results are expressed as mean joint space in mm. The technique is very fast, accurate and easy to use.

Coefficients of variation of repeated measurements (N = 10) of the same radiograph ranged from 1.3-8.3%. Mean

joint spaces are shown:

Mean value Joint mm (S.D.) N

DIP 0.99 (0.21) 32 PIP 1.07 (0.21) 32 MCP 1.64 (0.17) 32 Knee (medial JS) 5.81 (0.97) 60 Hip 4.63 (0.70) 60

O s t e o a r t h r i t i s and Cart i lage Vol. 1 No. 1 61

Results show good inter- and intra-observer correlat ions for all joints (R > 0.90 in all cases). Hip and knee measurements are at present superior to those of finger joints, however, studies are currently underway to improve the methodology.

Thus, digital image analysis of jo int space is fast, accurate and versatile, and' has considerable potent ial for epidemiological and medical studies.

The corre lat ion between i sokinet ic trac ings and m a g n e t i c re sonance im ag ing (MRI) in cart i lage

disorders of the knee G. FELICETTI*, M. FIORIt, A. MARIANO* AND F. AVANZA t

Clinica del Lavaro Foundation, IRCCS *Centro Medico di Riabilitazione di Montescano tCentro Medico di Pavia, Italy

Isokinetic equipment is used as an effective method for both functional evaluat ion and strengthening numerous muscle groups and is par t icular ly useful for those of the knee. MRI is an imaging diagnostic method which does not use radiation, is noninvasive and can provide multi- planar views. We studied 30 male subjects (average age 24.5 years). They all had chondromalacia between grade I and grade III (more exactly; eight with grade I and 22 with grades II and III) diagnosed by artroscopic exam- ination. Each of these patients underwent isokinetic evaluation of flexion extension of the knee at 60°/s and MRI using equipment with medium field intensi ty (0.35 T). Images were taken in sagit tal and axial planes aimed on the re t ropatel lar cart i lage with contiguous sections of variable thickness from 2.5 mm with Spin Echo and

Gradiant Echo technique, differently weighted to obtain images with an ar thrographic effect.

In patients affected by grade I lesions the isokinet ic and MRI examinations always indicated lesions. In more severe lesions the isokinetic examination showed an absence of the normal plateau s tate of the peak torque and the MRI imaging demonstrated morpho- logical changes with signal intensity corresponding to the cart i lage state. This varied from focal changes of signal intensi ty to exposure of the subchondral bone.

In conclusion, these functional imaging methods of evaluat ing cart i lage lesions, can be used in monitor ing the evolution of a lesion and may be useful in following a specific treatment.

Monitoring of gonarthros i s us ing echography V. PATELLA*, B. MORETTI*, V. PESCE*, F. MARTINOt, L. MACARINI t AND L. RESTA$ "

*Istitute of Radiology, t ls t Orthopaedic Department and Patological Anatomy Istitute, University of Bari, Italy

The aim of this study is to define the various stages in the evolution of gonarthrosis by echography. Previously we showed valid measurment of cart i lage thickness of the trochlea and femoral condyles. In order to val idate the echographic examination for ar t icular cart i lage tissue, 10 patients underwent knee echography before and after knee arthroplasty. The average age of the patients was65 years (from 57-81 years) and the degree of thinning and the echostructure of the cart i lage was examined via transverse epipatel lar scans with the knee flexed to 90 °. The echographic parameters were corre- lated with the histology specimens obtained during surgery. The la t ter are indicative of wearing of the cartilage, the cel lular i ty and discontinuity of the cortical and sub-cortical zones. The scans were repeated

three times by two operators and the inter-operator rel iabil i ty was examined. There was a significant corre- lat ion between the echographic and histological results (Spearman's index). The increased echogenicity of the cartilage-bone interface showed a correlat ion with the reduction in the thickness of the carti lage; the correla- t ion between an increase in echogenicity and reduction in thickness of the cart i lage was less marked.

We can conclude that echography is a valid means of evaluating car t i lage composition in the knee and is useful as a monitor of gonarthrosis. The procedure can

.... evaluate reductions in the thickness between 0.3-0.4 mm and the al terat ions in the echostructure of the cart i lage as well as the i r regular carti lage-bone interface.