Potential use of a diluted high-relaxivity gadolinium-based intra-articular contrast agent for magnetic resonance arthrography: an in-vitro study

Background Magnetic resonance arthrography (MRA) requires intra-articular injection of gadolinium-based diluted paramagnetic contrast material. To our knowledge, gadobenate dimeglumine (Gd-BOPTA) has never been used for intra-articular applications. Our aim was to test in vitro different concentrations of Gd-BOPTA to be potentially used to perform MRA. Methods Gd-BOPTA was diluted in saline (NaCl 0.9%) to achieve different concentrations (4 mmol/l; 2 mmol/l; 1 mmol/l; 0.67 mmol/l; 0.5 mmol/l). Six sets of five sterile pipes were prepared with 5 ml of each solution, five sets added with 0.5 ml of fresh synovial fluid. Two separate pipes were prepared with 5 ml of gadopentetate dimeglumine (Gd-DTPA) at 2 mmol/l, one pipe added with 0.5 ml of synovial fluid. Pipes were imaged using a T1-weighted sequence at 1.5 T. For each pipe, signal intensity (SI) in arbitrary units (au) was measured. Results SI reproducibility range was 86-99%. Mean Gd-BOPTA SI in pipes containing synovial fluid increased from 1236 +/- 8au (0.5 mmol/l) up to 1610 +/- 44au (1 mmol/l) and down to 1405 +/- 33au (4 mmol/l). Mean Gd-BOPTA SI in pipes without synovial fluid increased from 1184 +/- 29au (0.5 mmol/l) up to 1530 +/- 38au (1 mmol/l), and down to 1347 +/- 39au (4 mmol/l). SI of pipes without synovial fluid was lower than that of pipes with synovial fluid for both Gd-BOPTA and Gd-DTPA (P <= 0.002). Regarding pipes with synovial fluid, mean Gd-DTPA SI at 2 mmol/l was 1246 +/- 27au. Compared with Gd-BOPTA, SI was not different at 0.5 mmol/l (- 0.2%, P = 0.587) while it was higher (P < 0.001) at all other concentrations (range + 13.3%[4 mmol/l] - + 28.3%[1 mmol/l]). Regarding pipes without synovial fluid, mean Gd-DTPA SI at 2 mmol/l was 1275 +/- 56au. Compared with Gd-BOPTA, SI was lower at 0.5 mmol/l (- 6.8%,P < 0.001), while it was higher (P < 0.001) at all other concentrations (range + 6.1%[4 mmol/l] - + 19.6% [1 mmol/l]). Conclusions In vitro, Gd-BOPTA at 1 mmol/ had a + 28% SI increase in comparison to Gd-DTPA 2 mmol/l. SI similar to Gd-DTPA can be obtained using one fourth concentration of Gd-BOPTA.