Earls J P, Patel N H, Smith P A, DeSena S, Meissner M H
Department of Radiology, Harborview Medical Center, University of Washington School of Medicine, Seattle 98104, USA.
AJR Am J Roentgenol. 1998 Sep;171(3):599-604. doi: 10.2214/ajr.171.3.9725281.
Three-dimensional gadolinium-enhanced MR angiography is a rapid and accurate method that can at times image only a limited amount of anatomy during an examination. We evaluated a technique that doubled the anatomy imaged by obtaining two separate gadolinium-enhanced MR angiograms during a single examination.
Twenty-three patients referred for MR evaluation of aortic or peripheral vascular disease underwent two successive gadolinium-enhanced three-dimensional MR angiographic examinations during a single MR examination. An injection of 15 ml of gadopentetate dimeglumine was used for the first MR angiogram, and 25 ml was used for the second MR angiogram. The angiograms were quantitatively and qualitatively evaluated to determine the effect of residual gadolinium from the initial MR angiogram on the second angiogram.
The two studies depicted either the entire aorta to the femoral arteries (n = 10) or the distal aorta to the popliteal arteries (n = 13). The total mean gadolinium dose was 0.245 mmol/kg per patient. An average of 15 min elapsed between injections. The value of arterial signal-to-noise ratio (mean, 48.8 versus 56.4) and artery-to-vein contrast-to-noise ratio (mean, 45.5 versus 49.0) increased between the first and second angiograms, respectively. Residual gadolinium elevated the values for venous signal-to-noise ratio (mean, 2.3 versus 7.2) and background-to-muscle signal-to-noise ratio (mean, 5.5 versus 10.1) on the second MR angiogram. Qualitative evaluation by three observers showed no significant differences in diagnostic usefulness or overall image quality between the first and second MR angiograms.
The use of two low-dose gadolinium-enhanced three-dimensional MR angiograms during a single examination is a feasible approach to increase anatomic coverage when performing gadolinium-enhanced three-dimensional MR angiography of the aorta and peripheral vessels. Although background enhancement is slightly elevated on the second angiogram, such enhancement does not significantly change diagnostic usefulness or overall image quality.
三维钆增强磁共振血管造影是一种快速准确的方法，但有时在检查过程中只能对有限的解剖结构进行成像。我们评估了一种技术，即在单次检查中通过获取两次单独的钆增强磁共振血管造影来使成像的解剖结构增加一倍。
23例因主动脉或外周血管疾病而接受磁共振评估的患者在单次磁共振检查期间接受了连续两次钆增强三维磁共振血管造影检查。第一次磁共振血管造影注射15 ml钆喷酸葡胺，第二次注射25 ml。对血管造影进行定量和定性评估，以确定初次磁共振血管造影中残留的钆对第二次血管造影的影响。
两项研究分别显示了从主动脉到股动脉的整个范围（n = 10）或从主动脉远端到腘动脉的范围（n = 13）。每位患者钆的总平均剂量为0.245 mmol/kg。两次注射之间平均间隔15分钟。第一次和第二次血管造影之间，动脉信噪比（平均值分别为48.8和56.4）以及动脉与静脉的对比噪声比（平均值分别为45.5和49.0）的值分别增加。残留的钆提高了第二次磁共振血管造影中静脉信噪比（平均值分别为2.3和7.2）以及背景与肌肉的信噪比（平均值分别为5.5和10.1）的值。三位观察者的定性评估显示，第一次和第二次磁共振血管造影在诊断效用或整体图像质量方面无显著差异。
在单次检查中使用两次低剂量钆增强三维磁共振血管造影是在对主动脉和外周血管进行钆增强三维磁共振血管造影时增加解剖覆盖范围的一种可行方法。尽管第二次血管造影时背景增强略有升高，但这种增强并未显著改变诊断效用或整体图像质量。
