Montgomery Douglas D, Morrison William B, Schweitzer Mark E, Weishaupt Dominik, Dougherty Lawrence
Department of Radiology, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania.
J Magn Reson Imaging. 2002 Mar;15(3):334-43. doi: 10.1002/jmri.10065.
To optimize direct magnetic resonance (MR) arthrography by determining the effect of dilution of gadolinium in iodinated contrast, saline, or albumin on T1-weighted, T2-weighted, and gradient-recalled echo (GRE) images, and the effect of scanner field strength.
Gadopentetate dimeglumine was diluted into normal saline, albumin, or iodinated contrast (0.625 mmol/liter to 40 mmol/liter). Samples were scanned at 1.5T and 0.2T. Signal intensity was measured using T1-weighted spin-echo (SE), T2-weighted SE, and two- and three-dimensional GRE (20 degrees-75 degrees flip angle) sequences. Graphical analysis of signal intensity vs. gadolinium concentration was performed.
Albumin had no effect on gadolinium contrast. Dilution of gadolinium in iodinated contrast decreased signal intensity on all sequences compared to samples of identical concentration diluted in saline at both 1.5T and 0.2T: with a 2 mmol/liter gadolinium solution at 1.5T, signal was decreased by 26.1% on T1-weighted images, 31.7% on GRE20 images, and 28.9% on GRE45 images, and the T2 value decreased by 71.1%; at 0.2T, signal was decreased by 23.5% on T1-weighted images. On all sequences, the peak signal shifted to the left (lower gadolinium concentration) when diluted in iodinated contrast. Peak signal was also seen at different gadolinium concentrations on different sequences and field strength: at 1.5T, peak in saline/iodine was 2.5/0.625 mmol/liter on T1-weighted images, and 2.5/1.25 mmol/liter on GRE20 and GRE45 sequences. At 0.2T, peak in saline/iodine was 0.625-2.5/1.25 mmol/liter on T1-weighted images, 0.625-2.5/1.25 on GRE45 images, 2.5-10.0/1.25-5.0 mmol/liter on GRE65 images, and 1.25-5.0/0.625-1.25 mmol/liter on GRE75 images.
Dilution of gadolinium in iodinated contrast results in decreased signal on T1-weighted, T2-weighted, and GRE images compared to dilution in saline or albuminfor both 1.5-T and 0.2-T scanners; if gadolinium is diluted in iodinated contrast for MR arthrography, a lower concentration should be used because the peak is shifted to the left. The use of iodinated contrast should be minimized, as it may diminish enhancement and lower the sensitivity and specificity of MR arthrography. Optimal gadolinium concentration for MR arthrography is dependent on scanner field strength and a broader range of gadolinium concentration can be used to provide maximal signal at low field strength.
通过确定钆在碘化造影剂、生理盐水或白蛋白中的稀释对T1加权、T2加权和梯度回波（GRE）图像的影响以及扫描场强的影响，优化直接磁共振（MR）关节造影。
将钆喷酸葡胺稀释到生理盐水、白蛋白或碘化造影剂中（0.625 mmol/升至40 mmol/升）。样品在1.5T和0.2T下进行扫描。使用T1加权自旋回波（SE）、T2加权SE以及二维和三维GRE（翻转角20度 - 75度）序列测量信号强度。对信号强度与钆浓度进行图形分析。
白蛋白对钆造影剂无影响。在1.5T和0.2T下，与在生理盐水中稀释的相同浓度样品相比，钆在碘化造影剂中的稀释使所有序列上的信号强度降低：在1.5T下，对于2 mmol/升的钆溶液，T1加权图像上信号降低26.1%，GRE20图像上降低31.7%，GRE45图像上降低28.9%，T2值降低71.1%；在0.2T下，T1加权图像上信号降低23.5%。在所有序列上，当在碘化造影剂中稀释时，峰值信号向左移动（钆浓度降低）。在不同序列和场强下，在不同的钆浓度处也可见峰值信号：在1.5T下，生理盐水/碘中的峰值在T1加权图像上为2.5/0.6mmol/升，在GRE20和GRE45序列上为2.5/1.25 mmol/升。在0.2T下，生理盐水/碘中的峰值在T1加权图像上为0.625 - 2.5/1.25 mmol/升，在GRE45图像上为0.625 - 2.5/1.25，在GRE65图像上为2.5 - 10.0/1.25 - 5.0 mmol/升，在GRE75图像上为1.25 - 5.0/0.625 - 1.25 mmol/升。
与在生理盐水或白蛋白中稀释相比，钆在碘化造影剂中的稀释导致1.5T和0·T扫描仪的T1加权、T2加权和GRE图像上的信号降低；如果在MR关节造影中将钆稀释在碘化造影剂中，应使用较低浓度，因为峰值向左移动。应尽量减少碘化造影剂的使用，因为它可能会减少增强并降低MR关节造影的敏感性和特异性。MR关节造影的最佳钆浓度取决于扫描场强，并且在低场强下可以使用更宽范围的钆浓度来提供最大信号。
