Jacquier Alexis, Wendland Michael, Do Loi, Robert Philippe, Corot Claire, Higgins Charles B, Saeed Maythem
Department of Radiology, University of California San Francisco, CA 94134-0628, USA.
Contrast Media Mol Imaging. 2008 May-Jun;3(3):112-9. doi: 10.1002/cmmi.237.
The objectives of the study were: (1) to compare the kinetics of a new gadolinium-based low-diffusibility magnetic resonance (MR) contrast medium, P846 and Gd-DOTA in left ventricular (LV) blood and in normal and ischemically injured myocardium using inversion recovery echo-planar imaging (IR-EPI) and (2) to compare the enhancement pattern after injection of P846 with Gd-DOTA, using T1-weighted spin-echo imaging (T1-SE). Sixteen rats were subjected to left descending artery (LAD) occlusion for 30 min, followed by 2.5 h reperfusion. MR imaging was performed before and after administration of the contrast medium in two different groups of animals: one group (n = 8) received 0.05 mmol kg(-1) P846 and the other (n = 8) 0.1 mmol kg(-1) Gd-DOTA. A blipped IR-EPI and a multislice T1-SE were performed before injection and for 90 min after injection. T1-values were derived by fitting regional signal intensity on the IR-EPI images, the R1, DeltaR1 (R(1postcontrast) - R(1precontrast)) and DeltaR1 ratios were calculated in LV blood, normal and injured myocardium. On SE-T(1), the signal intensity ratio (SI) and extent of injury were measured. True infarct size was measured using histochemical staining. Changes in DeltaR(1) were 4.8 times greater with 0.05 mmol kg(-1) P846 than with 0.1 mmol kg(-1) Gd-DOTA in LV blood (6.3 +/- 0.9 vs 0.9 +/- 0.1 s(-1), p < 0.0001), normal (1.7 +/- 0.2 vs 0.34 +/- 0.03 s(-1), p < 0.0001) and ischemically injured myocardium (5.4 +/- 0.4 vs 1.6 +/- 0.1 s(-1), p < 0.0001). MR imaging experiments showed that the signal enhancement with P846 is longer (90 min), which might be explained by a lower diffusion of P846 compared with Gd-DOTA (30 min). P846 differentiates viable and nonviable myocardium. Despite lower gadolinium dose, P846 permits differentiation of viable and nonviable myocardium owing to a high contrast and a long imaging window with conventional t1-weighted SE sequence.
（1）使用反转恢复回波平面成像（IR-EPI）比较一种新型钆基低扩散性磁共振（MR）造影剂P846和钆喷酸葡胺（Gd-DOTA）在左心室（LV）血液以及正常和缺血损伤心肌中的动力学；（2）使用T1加权自旋回波成像（T1-SE）比较注射P846和Gd-DOTA后的增强模式。16只大鼠左冠状动脉前降支（LAD）闭塞30分钟，随后再灌注2.5小时。在两组不同的动物中于给予造影剂前后进行MR成像：一组（n = 8）接受0.05 mmol kg⁻¹ P846，另一组（n = 8）接受0.1 mmol kg⁻¹ Gd-DOTA。在注射前以及注射后90分钟进行快速小角度激发IR-EPI和多层T1-SE检查。通过拟合IR-EPI图像上的局部信号强度得出T1值，计算LV血液、正常和损伤心肌中的R1、ΔR1（造影剂注射后R1 - 造影剂注射前R1）和ΔR1比率。在SE-T1上，测量信号强度比（SI）和损伤范围。使用组织化学染色测量实际梗死面积。在LV血液中，0.05 mmol kg⁻¹ P846引起的ΔR1变化比0.1 mmol kg⁻¹ Gd-DOTA大4.8倍（6.3 ± 0.9对0.9 ± 0.1 s⁻¹，p < 0.0001），在正常心肌中（1.7 ± 0.2对0.34 ± 0.03 s⁻¹，p < 0.0001）以及缺血损伤心肌中（5.4 ± 0.4对1.6 ± 0.1 s⁻¹，p < 0.0001）。MR成像实验表明，P846引起的信号增强持续时间更长（90分钟），这可能是因为与Gd-DOTA（30分钟）相比，P846的扩散性较低。P846能够区分存活心肌和坏死心肌。尽管钆剂量较低，但由于对比度高且使用传统T1加权SE序列时有较长的成像窗口，P846仍能区分存活心肌和坏死心肌。
