Winalski CS et al. - Dendrimer-linked nitroxides, a new family of MR contrast agents targeted to glycosaminoglycan strongly enhance cartilage and are promising as articular cartilage-specific MR contrast agents. Methods
Ability of dendrimer-linked nitroxides to enhance articular cartilage was determined and the intra-articular life-time of these agents was measured
Cartilage T1 was evaluated in solutions of five different dendrimer-linked nitroxides, saline or Gd–DTPA at 1.5 T
The “relaxivity per dose” was calculated
The half-life of joint fluid enhancement was measured at 2 T after solutions were injected into rabbit stifle joints
24h after injection, the joints were examined grossly and by histology for toxicity
Results
All but the largest dendrimer-linked nitroxide were able to intensely enhance articular cartilage on MR
Relaxivity per dose measurements were between 3.5 and 68 times greater than Gd–DTPA
The largest nitroxide appeared to be excluded from articular cartilage
Intra-articular half-lives of the dendrimer-linked nitroxides were sufficiently long for in vivo MR imaging
Histological assessments of joints showed minimal synovial inflammatory and necrosis scores 1 day post-injection
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