Iris Eshed MD, Presenter: Nothing to Disclose

Christian E. Althoff MD, Abstract Co-Author: Nothing to Disclose

Alexander K Scheel MD, Abstract Co-Author: Nothing to Disclose

Marina Backhaus MD, Abstract Co-Author: Nothing to Disclose

Bernd K. Hamm MD, Abstract Co-Author: Nothing to Disclose

Kay-Geert A. Hermann MD, Abstract Co-Author: Nothing to Disclose

The purpose of the study was to investigate impact of a double dose compared to a single dose of contrast material in low field MRI on semi-quantitative scoring of synovitis in patients with rheumatoid arthritis (RA).

This prospective study included 38 patients with RA (23 women and 15 men, mean age 52 years). All patients underwent low field MRI of the hand (C-scan, Esaote, Italy). Three-dimensional T1-weighted gradient-recalled echo sequences in coronal section orientation were performed without contrast medium, after intravenous injection of 0.1 mmol/kg Gd-DTPA (Magnevist, Schering AG, Germany) (single dose) and after an additional dose of 0.1 mmol/kg Gd-DTPA (double dose). The 2nd-5th metacarpal joints were evaluated. Images were divided into two sets: single and double dose sets. Two readers (reader A and B) blinded to the patients clinical data and to the dosage, independently scored the sets for synovitis according to the OMERACT-RAMRIS score (Conaghan P, et al. Ann Rheum Dis 2005;64 Suppl 1:i11-i21). Also, for each MCP joint in the two sets a signal to noise ratio (SNR) was calculated.

149 MCP joints of the 38 patients were evaluated. There was a good inter reader agreement for each of the two sets (Interclass correlation coefficient (ICC) of 0.75 for the single dose set and of 0.83 for the double dose) with no statistical significant difference between the two readers (p>0.05, McNemar test). Median SNR of the single dose set was 15.9 and 16.6 for the double dose set (p<0.0001, Wilcoxon’s test). For the single dose set mean RAMRIS scores of 1.7 and 1.6 were recorded for reader A and B, respectively. For the double dose set these values were 1.9 and 2.0, respectively (p<0.005, McNemar’s test).

In low field MRI, when evaluating RA, the dose of contrast material influences synovitis scoring. Double dosage improves the image’s SNR and leads to higher scores of synovitis. We therefore recommend a double dose (0.2 mmol/kg) of contrast material for evaluation and scoring of rheumatoid arthritis in low field MRI.

Eshed, I, Althoff, C, Scheel, A, Backhaus, M, Hamm, B, Hermann, K, Low-Field MRI for Assessing Synovitis in Patients with Rheumatoid Arthritis: Impact of Gd-DTPA Dose on Synovitis Scoring?.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4411205.html