Daly P F, Zimmerman J B, Gillen J S, Wolf G L
Pittsburgh NMR Institute, Pennsylvania 15213.
Am J Physiol Imaging. 1989;4(4):165-74.
MR contrast agents injected intravenously reach the kidney very rapidly. Modification of a gradient recalled echo sequence allowed acquisition of 32 sequential MR images each 3.9 s apart on a 1.5 T clinical imager. This sequence was then used to observe the renal accumulation of contrast agent following an intravenous bolus of 100 microns/kg GdDTPA, 60 microns/kg albumin-(GdDTPA) or 9.6 and 40 mg/kg of 0.7 mu magnetic latex microspheres in rats or rabbits. Serial changes in image intensity were obtained with 3.9 s temporal and 0.08 ml spatial resolution. The renal cortical response to GdDTPA was similar to changes in blood 1/T1, but the medulla showed first a signal enhancement owing to the initial increased T1 relaxation followed by loss of signal as increased concentrations caused T2 relaxation to become predominant. Changes in intensity caused by magnetite and albumin-(GdDTPA) correlated with the 1/T1 changes observed in blood samples consistent with the predominantly intravascular location of these two agents. We conclude that MRI provides high spatial resolution with sufficient temporal resolution to record tissue response to an intravenous bolus of MR contrast agents.
经静脉注射的磁共振成像（MR）造影剂能很快到达肾脏。对梯度回波序列进行修改后，可在1.5T临床成像仪上每隔3.9秒采集32幅连续的MR图像。然后使用该序列观察大鼠或兔子静脉注射100微克/千克钆喷酸葡胺（GdDTPA）、60微克/千克白蛋白 - 钆喷酸葡胺（albumin-(GdDTPA)）或9.6毫克/千克和40毫克/千克的0.7微米磁性乳胶微球后造影剂在肾脏中的蓄积情况。以3.9秒的时间分辨率和0.08毫升的空间分辨率获取图像强度的系列变化。肾脏皮质对钆喷酸葡胺的反应与血液1/T1的变化相似，但髓质首先因T1弛豫最初增加而出现信号增强，随后随着浓度增加导致T2弛豫占主导地位而信号丧失。由磁铁矿和白蛋白 - 钆喷酸葡胺引起的强度变化与在血液样本中观察到的1/T1变化相关，这与这两种造影剂主要位于血管内的情况一致。我们得出结论，磁共振成像提供了高空间分辨率以及足够的时间分辨率，以记录组织对静脉注射MR造影剂的反应。
