Ganguly Arundhuti, Gold Garry E, Butts Pauly Kim, Mayer Dirk, Moseley Michael M, Pelc Norbert J, Fahrig Rebecca
Lucas MRS Center, Department of Radiology, Stanford University, 1201 Welch Road, Stanford, CA 94305, USA.
J Magn Reson Imaging. 2007 Jun;25(6):1219-25. doi: 10.1002/jmri.20934.
To quantify the effect of iodine on the gadolinium (Gd) contrast-enhanced signal in MR arthrography.
Saline solutions of Gd contrast agent (0-1 mmol/liter) were mixed with iodinated contrast agent (0-185 mmol/liter). The T1 and T2 relaxation constants of these solutions were measured at 1.5T. Different types of commonly used iodinated contrast agents as well as sodium iodide (NaI) solutions were also analyzed.
Iodine caused significant T2 shortening and some T1 shortening in Gd contrast solutions. Both contrast agents independently obeyed the standard relaxation relation, and their mixture obeyed a modified version of this relation. The side chains in various iodine molecules and their viscosities affected the relaxation properties differently. For various spin-echo (SE) sequences, the signal from synovial fluid containing different concentrations of the two contrast agents was calculated. The T2-weighted signal appeared to be most affected by the increase in iodine concentrations. In the absence of Gd contrast, all SE sequences showed an initial increase in signal from iodine contrast.
A generalized relation for the relaxivities of Gd contrast in the presence of iodine was established. The side chains of iodine contrast were found to alter the relaxivities of Gd contrast. Imaging with proton density (PD)-weighted SE with only iodine contrast agent was found to be feasible.
量化碘对磁共振关节造影中钆（Gd）对比增强信号的影响。
将钆对比剂的盐溶液（0 - 1 mmol/升）与碘化对比剂（0 - 185 mmol/升）混合。在1.5T下测量这些溶液的T1和T2弛豫常数。还分析了不同类型常用的碘化对比剂以及碘化钠（NaI）溶液。
碘导致钆对比溶液中T2显著缩短以及一些T1缩短。两种对比剂各自都符合标准弛豫关系，且它们的混合物符合该关系的修正版本。各种碘分子中的侧链及其粘度对弛豫特性的影响不同。对于各种自旋回波（SE）序列，计算了含有不同浓度两种对比剂的滑液的信号。T2加权信号似乎受碘浓度增加的影响最大。在没有钆对比剂的情况下，所有SE序列显示碘对比剂的信号最初增加。
建立了碘存在时钆对比剂弛豫率的广义关系。发现碘对比剂的侧链会改变钆对比剂的弛豫率。发现仅使用碘对比剂进行质子密度（PD）加权SE成像可行。
