Genovese Eugenio, Callegari Leonardo, Magenta Biasina Alberto, Angeretti Maria Gloria, Sosto Pasquale, Faletti Carlo, Fugazzola Carlo
Cattedra di Radiologia dell'Università dell'Insubria, Ospedale di Circolo, Fondazione Macchi, Varese, Italy.
Radiol Med. 2003 Nov-Dec;106(5-6):489-96.
Pain on capsule distension in painful joints may affect feasibility of the MR Arthrography. We tried to overcome this limitation by adding a local anesthetic (lidocaine) to the paramagnetic contrast agent solution. We aimed at: a) investigating which contrast agent dilution provides the best signal-to-noise ratio in the SE T1 sequences; b) evaluating the effects of lidocaine on the signal intensity and on the viscosity of the solutions; assessing the viscosity of solutions containing iodinated contrast agent.
The paramagnetic contrast agent was diluted with saline and lidocaine at various concentrations. Signal intensity was measured with a 1.5 Tesla superconductive MR unit with a dedicated head coil; we used T1-weighted spin-echo sequence. The viscosity coefficient of the solutions was analyzed and compared with that of solutions containing iodinated contrast agents (but not lidocaine).
Signal intensity is also unaffected by variations in the concentration of lidocaine, which does not interfere with the biphasic behavior of Gadolinium. Viscosity is scarcely affected by changes in lidocaine concentration when the paramagnetic contrast agent concentration is not changed.
The optimal signal-to-noise ratio in T1-weighted sequences is provided by 0.4%, contrast agent dilution but contrast agent-saline solutions, with(out) lidocaine, cannot be considered steady and signal intensity values change over time. The addition of lidocaine does not significantly influence the signal-to-noise ratio and the viscosity of the solutions. The low viscosity of the paramagnetic contrast agent appears to favor quicker spread of the solution, even in tiny defects; thanks to its anesthetic effect, lidocaine could facilitates execution of the examination in painful joints without affecting the diagnostic result.
疼痛关节的关节囊扩张时的疼痛可能会影响磁共振关节造影的可行性。我们试图通过在顺磁性造影剂溶液中添加局部麻醉剂（利多卡因）来克服这一限制。我们的目标是：a）研究哪种造影剂稀释度在SE T1序列中提供最佳信噪比；b）评估利多卡因对溶液信号强度和粘度的影响；评估含碘造影剂溶液的粘度。
将顺磁性造影剂用不同浓度的盐水和利多卡因稀释。使用配备专用头部线圈的1.5特斯拉超导磁共振单元测量信号强度；我们使用T1加权自旋回波序列。分析溶液的粘度系数，并与含碘造影剂（但不含利多卡因）的溶液进行比较。
信号强度也不受利多卡因浓度变化的影响，利多卡因不会干扰钆的双相行为。当顺磁性造影剂浓度不变时，利多卡因浓度的变化对粘度几乎没有影响。
T1加权序列中的最佳信噪比由0.4%的造影剂稀释度提供，但含（或不含）利多卡因的造影剂-盐水溶液不稳定，信号强度值会随时间变化。添加利多卡因不会显著影响溶液的信噪比和粘度。顺磁性造影剂的低粘度似乎有利于溶液更快扩散，即使在微小缺损处也是如此；由于其麻醉作用，利多卡因可便于在疼痛关节中进行检查，而不影响诊断结果。
