Olaf Saborowski MD, Presenter: Nothing to Disclose

Hans-Juergen Raatschen MD, Abstract Co-Author: Nothing to Disclose

Gerhard Helmut Simon MD, Abstract Co-Author: Nothing to Disclose

Michael Frederic Wendland PhD, Abstract Co-Author: Nothing to Disclose

Claire Corot PhD, Abstract Co-Author: Nothing to Disclose

Heike E. Daldrup-Link MD, Abstract Co-Author: Nothing to Disclose

To investigate the enhancement characteristics of the folate-receptor targeted MR contrast agent P866 in an established animal model of autoimmune arthritis.

An immune mediated monoarthritis was induced in the right knee of 12 Sprague Dawley rats. MR imaging of both knees was performed at 2 T before, up to 2h and 24h after injection (p.i.) of P866 (n=3 dose finding study, n=6 0.02 mmol Gd/kg), the non-folate receptor targeted P866 analog P1001 (n=3 from the P866 group, 0.02 mmol Gd/kg) or Gd-DOTA (n=3, 0.1 mmol Gd/kg). Pulse sequences comprised T1-GE 80/50/1.7 (flip angle/TR/TE) and inversion recovery 3000/1500/50-200 (TR/TE/TI) sequences. Delta SI data and T1-relaxation times of arthritic knees and contralateral normal knees were determined. MR data were correlated with histopathology.

The maximal enhancement of arthritic joints, quantified as delta SI data, was equivalent for Gd-DOTA at the standard dose of 0.1 mmol Gd/kg (delta SI 130%) and P866 at a dose of 0.04 mmol Gd/kg (120%). In addition, P866 provided a significantly prolonged residual enhancement, especially at low doses. T1-relaxation times of inflamed synovia were significantly decreased 2 h p.i. of 0.02 mmol Gd/kg P866 (p0.05). Fluorescence microscopy confirmed the presence of folate receptor positive macrophages in the inflamed joints, but not in the contralateral normal joints.

A specific accumulation of the high relaxivity gadolinium chelate P866 coupled to the folate moiety was demonstrated in this arthritis model.

Saborowski, O, Raatschen, H, Simon, G, Wendland, M, Corot, C, Daldrup-Link, H, MR Imaging of Immune Mediated Arthritis with the New, Folate-receptor Targeted Contrast Agent P866.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4418621.html