[2007] [OP0141] COMPARISON OF CONTRAST-ENHANCED ULTRASONOGRAPHY (CE-US) AND MR-IMAGING (CE-MRI) IN MONITORING THE EFFICACY OF A BRADYKININ RECEPTOR-2 ANTAGONIST IN PAINFUL KNEE OSTEOARTHRITIS (OA)

I. Song 1, C. Althoff 2, K. Hermann 2, A. Scheel 3, T. Knetsch 4, G. Burmester 5, M. Backhaus 5 1Med. Clinic I, Rheumatology, Universitaetsmedizin Berlin, Charite Campus Benjamin-Franklin, 2Radiology, Charite Campus Mitte, Berlin, 3Nephrology/Rheumatology, University Hospital Goettingen, Goettingen, 4Esaote, Esaote, Neufahrn, 5Rheumatology, Charite Campus Mitte, Berlin, Germany

Background: Just recently the diagnostic value of CE-US and CE-MRI in knee OA has been evaluated.
Objectives: Evaluation of 41 patients with knee OA in regards of the synovial process by CE-US and CE-MRI before and after intraarticular injection of icatibant (IT), a bradykinin receptor-2 antagonist.
Methods: In a randomised, double-blind, placebo-controlled, 3-armed, parallel-group, multi-centre study 266 patients with knee OA were assessed. Three intraarticular injections of 500 or 2000 micro-gram icatibant or respective placebo were administered in weekly intervals into the affected knee joint within 2 weeks and followed up - without any injection - for further 10 weeks.
Subgroup analysis: Out of these 266 patients 41 patients (mean age 65 years) underwent CE-US (12.5 MHz, 3-8 MHz), and 34 patients MRI (0.2T) at baseline and after the 3rd injection of the study medication (after a mean of 22.2 days). US and MRI were performed at the same day. The synovial process (parameters see below) and separately obtained pain data were assessed at both time points.
Results: 15 patients received placebo, 12 the smaller dosage (500 micro-gram) and 14 the higher dosage (2000 micro-gram) of icatibant. There was no difference between the baseline values. Results after 3 intraarticular injections of the study drug:
VAS: pain data acquired by VAS improved for the whole group (N= 41) from a mean value of 57.37 to 34.59 (pain under rest), and from 68.25 to 46.54 (pain under strain), p< 0.001. There was no statistically relevant difference between the different groups.
Effusion in US and MRI, synovitis and Power Doppler in US: there was no change in these parameters in the superior or lateral recess in US and in MRI between the two time points.
Contrast medium: CE-US for the icatibant 500 micro-gram group showed an improvement of 14.9 (SD 7.8) to 2.9 (SD 1.3) (= 80.7% improvement) vs. 16% worsening for placebo and 9.2% improvement for the icatibant 2000 micro-gram group, however this was not statistically relevant (p= 0.145- 0.604 between the groups). CM enhancement in MRI showed no difference.
Comparison of US and MRI: Spearman correlation was 0.591 (p< 0.001) between US and MRI in regards of effusion in the superior recess, 0.304 (p= 0.076) for effusion in the lateral recess and 0.601 (p= 0.000) for contrast enhancement. Kappa analysis showed values of 0.453 (effusion in the superior recess), 0.440 (effusion in the lateral recess) and 0.242 (contrast enhancement).
Conclusion: For our 41 OA patients who were treated with the intraarticular bradykinin-receptor-2 antagonist icatibant there was no statistical significant difference between the three groups in the parameters assessed. This might be due to limitations in regards of the patient number and time interval of US and MRI assessment. Only CE-US showed a remarkable difference for the icatibant 500 micro-gram group compared to the other groups. It has to be further evaluated whether CE-US is more sensitive to identify early inflammatory changes in knee OA and other rheumatic diseases. US and MRI showed good agreement in assessing inflammatory activity in knee OA and are both suitable for treatment monitoring.

Abstract Session: Imaging modalities applied to rheumatic diseases


Citation: Ann Rheum Dis 2007;66(Suppl II):96