一种降低肾动脉MR检查造影剂剂量方法的研究

Study on a Computation Method of Reducing the Contrast Agent for Renal Artery MR Angiography

目的探索通过改变K空间填充方式来降低肾动脉MR扫描顺磁性造影剂剂量的可行性。方法随机选取因怀疑肾动脉病变而行肾动脉CEMRA检查的病人20例。检查分两组进行,其中双倍剂量组采用中心填充方式,单倍剂量组采用椭圆中心填充方式。在冠状位图像上分别测量双肾动脉信噪比(SNR),肾动脉与周围脂肪的对比噪声比(CNR),然后进行三维MIP重建。由两位观察者单独评价两组的三维图像质量,肾动脉分支及肾静脉伪影情况。对测量结果和图像质量评分进行统计学处理。结果两组肾动脉SNR分别为139.29±11.12和145.48±10.39;CNR分别为118.38±10.16和124.08±10.29,两组间肾动脉SNR及CNR的差异均无统计学意义(P>0.05)。两组三维重建图像均100%达到诊断要求,肾动脉分支及肾静脉伪影方面两组间无显著差异。结论在磁共振造影剂注射速度相同的情况下,通过改变K空间填充方式可有效降低磁共振造影剂剂量。

Objective To evaluate the feasibility of reducing the contrast agent dose for renal artery MR angiography through changing K-space filling approach. Methods Twenty patients who had performed CEMRA scan for suspected renal artery disease were randomly selected in this study. Patients were equally divided into two groups. The first group was for double dose and was scanned with centric filling K-space approach to acquire renal artery angiography. The second group was for single dose and was scanned with elliptical centric filling K-space approach to obtain the image. Bilateral SNR and CNR of renal artery were measured and 3D MIP images of angiography were reconstructed. Two observers separately evaluated the image qualities, grades of artery branch and renal venous artifact for both groups. The results of measurement and image quality scores were statistically analyzed. Results SNR of two groups were 139.29 ± 11.12 and 145.48 ± 10.39, respectively. CNR of two groups were 118.38 ± 10.16 and 124.08 ± 10.29, respectively. Both groups＇ renal artery angiography satisfied the standard of diagnosing. There was no significant difference between the grades of artery branch and scores of renal venous artifact for two groups. Conclusion With the same injection speed of MR contrast agent, changed K-spaee filling approach can effectively reduce the dose for required MR contrast agent.