MRI offers an unparalleled picture of joint in osteoarthritis

[Guest guest]

Rheumawire

Feb 6, 2004

MRI offers " an unparalleled picture of joint in osteoarthritis "

Cambridge, UK - Taken together, a new study and an accompanying

editorial portend a growing and significant role for magnetic resonance

imaging (MRI) in the understanding of osteoarthritis (OA). The reports

appear in the January 2004 issue of Arthritis & Rheumatism [1,2].

" Although much further work is needed before widespread clinical

application of MRI can be achieved, the future of this technology

appears to be very bright, given its potential to provide an

unparalleled picture of the joint in OA, " the editorial concludes.

" Hopefully this picture, which will be richer and more detailed than

anything before, will lead to both new understanding of the disease and

new approaches to treatment. "

The new study explores use of MRI to measure loss of cartilage in knee

OA, and finds " it is possible to simplify the measures used, which may

make cartilage volume measurement more feasible, especially in

large-scale epidemiologic studies " [1].

The researchers, led by Dr Flavia M Cicuttini (Monash University Medical

School, Prahran, , Australia), followed 117 patients with knee

OA for about 2 years.

Femoral and tibial cartilage volumes were determined from T1-weighted

fat-saturated MRIs of the knee from coronal views. In the medial

tibiofemoral joint, the mean loss of cartilage was 0.15 +/- 0.30 mL/year

for femoral cartilage and 0.10 +/- 0.25 mL/year for tibial cartilage. In

the lateral tibiofemoral joint, the average loss was 0.15 +/- 0.22

mL/year for femoral cartilage and 0.12 +/- 0.16 mL/year for tibial

cartilage.

Since there was a significant correlation between the degree of loss of

tibial cartilage and the degree of loss of femoral cartilage in both

tibiofemoral joints, measuring tibial cartilage alone may be sufficient,

the researchers comment. Measurements of the total femoral cartilage are

less reproducible, and there are difficulties in identifying what

components of the femoral cartilage to measure, they add.

This study " is an important demonstration of the progress researchers

have made in developing MRI methods for measuring the dimensions of

human articular cartilage especially in the knee, " comments Dr Laurie D

Hall (University of Cambridge School of Clinical Medicine, UK) in the

accompanying editorial [2].

However, this is just the tip of the iceberg since the implications of

MRI in OA are much broader, Hall tells rheumawire. In the next 10 years,

" there will be huge changes, " Hall predicts. " Most importantly, more

rheumatologists will be able to use MRI to help them to evaluate joint

damage and hence to optimize their patient management, " she says.

The cost of MRI scanners will decrease and the unique power of MRI will

become more widely understood than it is at present, she forecasts.

" However, the biggest potential benefit is that MRI will make it

possible to measure clinical effects during the development of new OA

treatments, " she says.

" Those new methods will come partly from university-based researchers,

partly from hospital-based clinicians (rheumatologists, orthopedic

surgeons and physiotherapists), and importantly from both the

pharmaceutical industry, which is already investing in huge programmes

to develop new drugs, and from the tissue-culture industry, which is

already growing 'plugs' of replacement cartilage for clinical use by

orthopedic surgeons, " she tells rheumawire. " Clearly all of the above

research will require long lead times, but the progress to date is very

encouraging, " she says.

That said, " the benefit to individual OA patients will depend on whether

or not the improved diagnosis will lead to a more effective treatment, "

Hall says. " The problem is that at present there is no pharmaceutical

drug that can slow down, let alone reverse the progression of OA damage.

So the rheumatologist can only prescribe pain killers for early stages

of OA, and then pass the patient to an orthopedic surgeon for possible

joint replacement when the cartilage has been lost, " she says.

The US National Institutes of Health is embarking on trials of 4 new MRI

scanners to be used in identical protocols over a period of 5 years to

develop a huge database of knee MRI scans. In these studies, each

patient will be assessed clinically and by standard radiographic

measurement. " It is hoped that MRI will provide a more sensitive index

of both disease onset and progression, " says Dr Gayle E Lester, PhD

(National Institutes of Health, Bethesda, MD). " We will also be

collecting biological specimens that will serve, in conjunction with the

clinical and imaging data, as a resource for validation of biochemical

markers and identification of new molecular targets of OA. "

" We anticipate that the baseline recruitment, which is just beginning,

will take 12-15 months, " she says. Clinical data and images should be

available for analysis within 1-1.5 years, ie by June 2005. " Because

data collection will be ongoing, the database will be updated at 6 month

intervals for the rest of the study period through 2008, " she says.

" It is hoped that the data generated from the OA images will enable us

to determine the sensitivity and specificity of MRI for the onset and

progression of OA in the knee, " Lester tells rheumawire. Since the

trials will be following individuals who don't have OA but are

identified to be at " high risk " for development of OA, " we hope to

determine whether or not MRI will enable us to find early markers of

disease that might enable treatment of individuals early on in the

disease process. " " Such a diagnostic tool would help with the

development of therapeutic agents to prevent and treat early OA, " she

adds. A smaller component of the study cohort will comprise individuals

with obvious OA: " these subjects will be followed for progression of

disease with an intent to determine the usefulness of MRI for monitoring

disease progression, " Lester says.

Mann

Sources

1. Cicuttini FM, Wluka, AE, Wang Y and Stuckey SL. Longitudinal study of

changes in tibial and femoral cartilage in knee osteoarthritis.

Arthritis Rheum 2004; 50:94-97.

2. Hall LD. Magnetic resonance imaging as noninvasive means for

quantitating the dimensions of articular cartilage in the human knee.

Arthritis Rheum 2004; 50:5-9.

I'll tell you where to go!

Mayo Clinic in Rochester

http://www.mayoclinic.org/rochester

s Hopkins Medicine

http://www.hopkinsmedicine.org