MR arthrography: impact of steroids, local anesthetics, and iodinated contrast material on gadolinium signal intensity in phantoms at 1.5 and 3.0 T.

PURPOSE: To determine if gadolinium signal intensity at direct magnetic resonance (MR) arthrography is affected by the addition of steroids, anesthetics, or iodinated contrast material. MATERIALS AND METHODS: This study did not require approval by the institutional review board because no patients or patient data were involved. An in vitro study was performed to evaluate various concentrations of three gadolinium contrast agents (gadopentetate dimeglumine, gadobenate dimeglumine, and gadofosveset trisodium) diluted in either saline or iodinated contrast material (50% and full-strength iohexol 300). Three steroids (betamethasone, triamcinolone, and methylprednisolone) and three local anesthetics (lidocaine, ropivacaine, and bupivacaine) were added to solutions in clinical doses. T1-weighted fat-suppressed MR imaging sequences were performed in phantoms at 1.5 and 3.0 T. Signal intensities were measured. All experiments were repeated in full for a total of three replications each. The data were analyzed by using two-way factorial analysis of variance. RESULTS: Dilution of gadolinium into iohexol reduced the signal intensity in all samples compared with dilution in saline alone. Peak signal intensities were at 0.625 and 1.25 mmol/L of gadolinium in iohexol at both magnet strengths. At 1.5 T, the addition of steroids and anesthetics to the saline solutions had no impact on the signal intensity curves, with the peak signal intensity at gadolinium concentrations of 2.5 and 1.25 mmol/L. At 3.0 T, the addition of steroids and anesthetics had minimal effect on signal intensity curves, with the peak signal intensity at 1.25 mmol/L of gadolinium. CONCLUSION: The addition of steroids and/or anesthetics to gadolinium solutions for MR arthrography does not substantially impact signal intensity. When gadolinium is diluted into a 50% or greater strength of iohexol, the signal intensity curve shifts so that the maximum signal intensity is obtained with lower gadolinium concentrations (0.625-1.25 mmol/L).

Shoulder MR arthrography: intraarticular anesthetic reduces periprocedural pain and major motion artifacts but does not decrease imaging time.

PURPOSE: To prospectively determine whether the addition of an intraarticular anesthetic to the magnetic resonance (MR) arthrography solution has an effect on periprocedural pain, motion artifacts, and imaging time. MATERIALS AND METHODS: This study was approved by the institutional review board, and written informed consent was obtained from all patients. From September 2009 to March 2010, 127 patients, most imaged for shoulder pain, were randomized into two groups. The first group (group A, 63 patients) received intraarticular injection of gadopentetate dimeglumine, ropivacaine 0.5%, and normal saline in a ratio of 1:100:100. The second group (group B, 64 patients) received intraarticular injection of gadopentetate dimeglumine and normal saline in a ratio of 1:200. Pain was assessed before and after injection and immediately after 1.5-T MR imaging and rated on a scale of 0 to 10. Motion artifact was assessed by two musculoskeletal radiologists and two fellows by using a scale of 0 to 3 (0=no artifact, 1=artifact present but not affecting diagnostic image quality, 2=artifact present and diminishing diagnostic image quality, and 3=artifact present and rendering image nondiagnostic). MR imaging time and examinations with repeated sequences were recorded. Wilcoxon rank sum, analysis of covariance, and permutation data analyses were performed. RESULTS: The mean pain levels before injection, after injection, and after MR imaging were 3.5, 2.3, and 2.5, respectively, for group A and 3.6, 3.1, and 3.2 for group B. After adjusting for age, sex, and preinjection pain level, the mean differences in pre- and postinjection pain and preinjection pain and post-MR imaging pain between the two groups were -0.9 (P=.017) and -0.8 (P=.056), respectively. No significant difference in mean total MR imaging time or number of patients with repeat sequences was noted. Radiologists 1 and 2 recorded grade 2 or 3 motion in six and five patients, respectively, in group A and 15 and 14 patients, respectively, in group B (P=.047 and .048, respectively). Radiologists 3 and 4 recorded grade 2 or 3 motion in 13 and 23 patients, respectively, in group A and 23 and 33 patients, respectively, in group B (P=.093 and .110, respectively). CONCLUSION: The use of an intraarticular anesthetic significantly reduces periprocedural pain and major motion artifacts associated with MR shoulder arthrography; however, total MR imaging time is not reduced.