Runge V M, Wells J W
Magnetic Resonance Imaging and Spectroscopy Center, University of Kentucky, Lexington, USA.
Invest Radiol. 1996 Jul;31(7):395-400. doi: 10.1097/00004424-199607000-00002.
Gadolinium (Gd) and dysprosium (Dy) analogues, chelated with HP-DO3A, were compared at both 0.5- and 1.0-mol/L concentrations for efficacy in first-pass brain studies on magnetic resonance (MR) imaging at 1.5 tesla (T).
Ten healthy cats were examined with a dose of 0.3 mmol/kg, using two concentrations of each agent (0.5 mol/L and 1.0 mol/L, 20 examinations). Gadolinium-HP-DO3A (gadoteridol or ProHance) or Dy-HP-DO3A was injected at 9 mL/second, with acquisition of 64 sequential steady-state free precession (SSFP) images at a rate of one each 0.6 second.
The change in white matter signal intensity, at the peak of the first pass of the contrast agent bolus in the brain, was -231 +/- 68 for the 0.5-mol/L formulation of Gd-HP-DO3A, compared with -267 +/- 57 for the 1.0-mol/L formulation. Using the 0.5-mol/L formulation of Dy-HP-DO3A, the change at peak was -318 +/- 42, a result statistically improved compared with both the 0.5-mol/L (P < 0.02) and 1.0-mol/L (P < 0.04) Gd-HP-DO3A formulations. A further improvement was observed with the 1.0-mol/L Dy-HP-DO3A formulation, with the change being -368 +/- 33.
First-pass brain MR studies at 1.5 T are improved by use of higher concentration Gd chelate formulations (1.0 versus 0.5 mol/L) and by substitution of the Dy ion for the Gd ion in the chelate. Injection of higher-concentration formulations results in higher initial arterial metal ion concentration. Incomplete blood mixing on transit during first pass causes the higher initial concentration, which then results in a greater susceptibility effect on imaging. The superiority of the Dy formulation compared with the Gd formulation is anticipated because of the higher magnetic moment of Dy. The curves for tissue signal intensity versus time during first pass return artifactually to near baseline after Gd chelate injection (when SSFP imaging techniques are used), a differentiating feature from results with the Dy chelate. This difference can be explained by a substantial T1 effect of the Gd chelate, despite acquisition of images that are predominantly susceptibility weighted.
将与HP - DO3A螯合的钆（Gd）和镝（Dy）类似物在0.5摩尔/升和1.0摩尔/升浓度下进行比较，以研究其在1.5特斯拉（T）磁共振（MR）成像的首次通过脑研究中的效能。
对10只健康猫以0.3毫摩尔/千克的剂量进行检查，每种试剂使用两种浓度（0.5摩尔/升和1.0摩尔/升，共20次检查）。钆 - HP - DO3A（钆特醇或普美显）或镝 - HP - DO3A以9毫升/秒的速度注射，以每0.6秒一幅的速率采集64幅连续的稳态自由进动（SSFP）图像。
在造影剂团注首次通过脑的峰值时，0.5摩尔/升的钆 - HP - DO3A制剂的白质信号强度变化为-231±68，而1.0摩尔/升制剂的变化为-267±57。使用0.5摩尔/升的镝 - HP - DO3A制剂时，峰值变化为-318±42，与0.5摩尔/升（P < 0.02）和1.0摩尔/升（P < 0.04）的钆 - HP - DO3A制剂相比，该结果在统计学上有改善。使用1.0摩尔/升的镝 - HP - DO3A制剂观察到进一步改善，变化为-368±33。
在1.5 T下进行首次通过脑MR研究时，使用更高浓度的钆螯合制剂（1.0摩尔/升与0.5摩尔/升相比）以及在螯合物中用镝离子替代钆离子可改善研究效果。注射更高浓度的制剂会导致更高的初始动脉金属离子浓度。首次通过期间血液混合不完全导致初始浓度更高，进而对成像产生更大的磁化率效应。由于镝的磁矩更高，预计镝制剂比钆制剂更具优势。在注射钆螯合物后（使用SSFP成像技术时），首次通过期间组织信号强度与时间的曲线会人为地回到接近基线，这是与镝螯合物结果的一个区别特征。尽管采集的图像主要是磁化率加权的，但这种差异可以用钆螯合物显著的T1效应来解释。
