Jung H W, Chang K H, Choi D S, Han M H, Han M C
Department of Diagnostic Radiology, Seoul National University Hospital, College of Medicine, Korea.
AJR Am J Roentgenol. 1995 Nov;165(5):1251-5. doi: 10.2214/ajr.165.5.7572513.
Although contrast-enhanced MR angiography has been shown useful in evaluating intracranial vascular lesions, particularly those with slow flow, the optimal dose of contrast material has not been found. Accordingly, we performed a study to determine the optimal dose of gadopentetate dimeglumine for contrast-enhanced MR angiography of intracranial vascular diseases.
In this prospective study, 152 consecutive adult patients suspected of having intracranial vascular diseases had cerebral MR angiograms. Images were obtained with a three-dimensional time-of-flight sequence with magnetization transfer saturation on a 1.5-T unit. Imaging parameters (43/8 [TR/TE], 20 degrees flip angle, 64 1-mm-thick sections) were identical in each MR angiogram. One hundred twenty-two of 152 patients were randomly assigned to receive one of four doses (0, 5, 10, or 20 ml) of gadopentetate dimeglumine for MR angiography (36, 37, 38, and 11 patients, respectively). In patients who had normal major cerebral arteries on MR angiograms, degree and extent of visualization of the cerebral veins and small intracranial arteries were rated blindly on a three-point scale, and the results were compared among the four groups given different doses of contrast material. In another 30 patients who had unenhanced and enhanced MR angiograms, the presence or absence of artifactual narrowing of the internal carotid artery or major cerebral arteries (caused by signal loss due to slow or turbulent flow seen only on unenhanced images) and the visibility of arteriovenous malformation were determined.
In nearly all patients, regardless of the dose of contrast material, the cerebral veins were well visualized on MR images. Degree and extent of visualization of the cerebral veins appeared to depend on the dose of contrast material. In the 20-ml injection group, venous overlap limited interpretation of the small and large arteries, whereas in the 5- and 10-ml groups, the signal intensity of the veins was much less intense, causing no difficulty in interpretation. However, no significant differences in visibility of the small arteries were apparent between the unenhanced and enhanced MR angiograms, even though the small vessels were better visualized in some patients who received either 5 or 10 ml of contrast material. In six of the 30 patients who had both unenhanced and enhanced MR angiograms, the unenhanced images showed artifactual narrowing of the internal carotid or middle cerebral arteries, which proved to be normal on contrast-enhanced MR angiograms. Venous sinuses or draining veins were better delineated on contrast-enhanced MR angiograms in all six patients with arteriovenous malformation.
Five to 10 milliliters of gadopentetate dimeglumine appears to be an optimal dose range for contrast-enhanced cerebral MR angiography. Use of this dose can help in differentiating true stenosis of large arteries from artifactual narrowing and in depicting small arteriovenous malformation with slow flow.
尽管对比增强磁共振血管造影已被证明在评估颅内血管病变，尤其是血流缓慢的病变方面很有用，但尚未找到造影剂的最佳剂量。因此，我们进行了一项研究，以确定钆喷酸葡胺用于颅内血管疾病对比增强磁共振血管造影的最佳剂量。
在这项前瞻性研究中，152例连续的怀疑患有颅内血管疾病的成年患者接受了脑部磁共振血管造影。使用1.5-T设备，通过带有磁化传递饱和的三维时间飞跃序列获取图像。每次磁共振血管造影的成像参数（43/8 [TR/TE]，20度翻转角，64层1毫米厚的切片）均相同。152例患者中的122例被随机分配接受四种剂量（0、5、10或20毫升）的钆喷酸葡胺进行磁共振血管造影（分别为36、37、38和11例患者）。对于磁共振血管造影显示大脑主要动脉正常的患者，对脑静脉和颅内小动脉的显影程度和范围进行盲法三点评分，并比较给予不同剂量造影剂的四组结果。在另外30例进行了平扫和增强磁共振血管造影的患者中，确定颈内动脉或大脑主要动脉是否存在伪像性狭窄（仅在平扫图像上由于缓慢或湍流导致信号丢失引起）以及动静脉畸形的可见性。
几乎在所有患者中，无论造影剂剂量如何，脑静脉在磁共振图像上均能清晰显影。脑静脉的显影程度和范围似乎取决于造影剂的剂量。在20毫升注射组中，静脉重叠限制了对大小动脉的解读，而在5毫升和10毫升组中，静脉的信号强度要弱得多，对解读没有造成困难。然而，平扫和增强磁共振血管造影之间小动脉的可见性没有明显差异，尽管在一些接受5或10毫升造影剂的患者中，小血管显示得更好。在30例进行了平扫和增强磁共振血管造影的患者中，有6例患者的平扫图像显示颈内动脉或大脑中动脉存在伪像性狭窄，而在对比增强磁共振血管造影上显示正常。在所有6例患有动静脉畸形的患者中，对比增强磁共振血管造影能更好地勾勒出静脉窦或引流静脉。
5至10毫升钆喷酸葡胺似乎是对比增强脑部磁共振血管造影中的最佳剂量范围。使用此剂量有助于区分大动脉的真性狭窄与伪像性狭窄，并有助于显示血流缓慢的小动静脉畸形。
