Andreisek Gustav, Froehlich Johannes M, Hodler Juerg, Weishaupt Dominik, Beutler Verena, Pfirrmann Christian W A, Boesch Chris, Nanz Daniel
Institute for Diagnostic Radiology and Department of Medical Radiology, University Hospital Zurich, Raemistrasse 100, 8091 Zurich, Switzerland.
Radiology. 2008 Jun;247(3):706-16. doi: 10.1148/radiol.2473071013. Epub 2008 Apr 10.
To prospectively quantify in vitro the influence of gadopentetate dimeglumine and ioversol on the magnetic resonance (MR) imaging signal observed with a variety of musculoskeletal pulse sequences to predict optimum gadolinium concentrations for direct MR arthrography at 1.5 and 3.0 T.
In an in vitro study, T1 and T2 relaxation times of three dilution series of gadopentetate dimeglumine (concentration, 0-20.0 mmol gadolinium per liter) at ioversol concentrations with iodine concentration of 0, 236.4, and 1182 mmol iodine per liter (corresponding to 0, 30, and 150 mg of iodine per milliliter) were measured at 1.5 and 3.0 T. The relaxation rate dependence on concentrations of gadolinium and iodine was analytically modeled, and continuous profiles of signal versus gadolinium concentration were calculated for 10 pulse sequences used in current musculoskeletal imaging. After fitting to experimental discrete profiles, maximum signal-to-noise ratio (SNR), gadolinium concentration with maximum SNR, and range of gadolinium concentration with 90% of maximum SNR were derived. The overall influence of field strength and iodine concentration on these parameters was assessed by using t tests. The deviation of simulated from experimental signal-response profiles was assessed with the autocorrelation of the residuals.
The model reproduced relaxation rates of 0.37-38.24 sec(-1), with a mean error of 4.5%. Calculated SNR profiles matched the discrete experimental profiles, with autocorrelation of the residuals divided by the mean of less than 5.0. Admixture of ioversol consistently reduced T1 and T2, narrowed optimum gadolinium concentration ranges (P = .004-.006), and reduced maximum SNR (P < .001 to not significant). Optimum gadolinium concentration was 0.7-3.4 mmol/L at both field strengths. At 3.0 T, maximum SNR was up to 75% higher than at 1.5 T.
Admixture of ioversol to gadopentetate dimeglumine solutions results in a consistent additional relaxation enhancement, which can be analytically modeled to allow a near-quantitative a priori optimized match of contrast media concentrations and imaging protocol for a broad variety of pulse sequences.
前瞻性地在体外量化钆喷酸葡胺和碘海醇对多种肌肉骨骼脉冲序列观察到的磁共振（MR）成像信号的影响，以预测1.5和3.0 T场强下直接MR关节造影的最佳钆浓度。
在一项体外研究中，在1.5和3.0 T场强下测量了碘浓度分别为0、236.4和1182 mmol碘/升（分别对应于0、30和150 mg碘/毫升）的碘海醇浓度下，钆喷酸葡胺三个稀释系列（浓度为0 - 20.0 mmol钆/升）的T1和T2弛豫时间。分析模拟了弛豫率对钆和碘浓度的依赖性，并计算了当前肌肉骨骼成像中使用的10种脉冲序列的信号与钆浓度的连续曲线。在拟合实验离散曲线后，得出最大信噪比（SNR）、具有最大SNR的钆浓度以及具有90%最大SNR的钆浓度范围。使用t检验评估场强和碘浓度对这些参数的总体影响。用残差的自相关评估模拟信号响应曲线与实验曲线的偏差。
该模型再现的弛豫率为0.37 - 38.24秒⁻¹，平均误差为4.5%。计算得到的SNR曲线与离散实验曲线匹配，残差的自相关除以均值小于5.0。碘海醇的混合持续降低T1和T2，缩小最佳钆浓度范围（P = 0.004 - 0.006），并降低最大SNR（P < 0.001至不显著）。在两种场强下，最佳钆浓度均为0.7 - 3.4 mmol/L。在3.0 T时，最大SNR比在1.5 T时高75%。
在钆喷酸葡胺溶液中加入碘海醇会导致一致的额外弛豫增强，可通过分析建模实现造影剂浓度与成像方案的近定量先验优化匹配，适用于多种脉冲序列。
