摘要目的 探讨不同剂量对比剂磁共振成像(MRI)动态增强扫描对骶前区血管网三维成像的效果,并评价减少对比剂用量的可行性及临床应用价值.方法 选取2012年2月至5月间于本院就诊的40例因盆腔良性病变常规行MRI检查的成年女性患者,数字随机法随机分为两组,A组对比剂剂量为钆浓度0.5 mol/L 20 ml,B组为40 ml.采用ACHIEVA 3.0TX双源磁共振扫描仪对患者行盆腔e-THRIVE 3D等体素动态增强MRI序列扫描,采用最大密度投影(MIP)及容积再现重组(VR)后处理技术进行骶前区血管网重建成像,观察骶前区血管的正常解剖及走行,计算骶正中动脉、骶前区横干静脉显示率和骶正中动脉横径.以骶正中动脉为靶点,分别对两组MIP图像质量采取5分制主观评价方法,通过测定信号强度(SI)、信噪比(SNR)和对比噪声比(CNR)的客观评价指标进行综合比较.结果 两组患者图像中骶正中动脉均显示清晰,成功率为100％;骶前区横干静脉的总显示率为72.5％(29/40),其中A组显示率为75％(15/20),B组显示率为70％ (14/20),差异无统计学意义.在e-THRIVE序列横断位图像上A组骶正中动脉横径与B组差异无统计学意义[(1.42±0.06) mm比(1.38±0.07) mm,P=0.117].A组骶正中动脉MIP图像质量主观评价评分略低于B组,但差异无统计学意义[(2.95±0.69)分比(3.10±0.66)分,P=0.479].A组骶正中动脉MIP图像质量客观评价SI、SNR与B组差异无统计学意义(SI:719.63±124.91比811.66±170.60,SNR:61.71±17.35比74.97±27.91,均P＞0.05),而CNR低于B组(45.68±13.35比62.41±23.37,P＜0.05).结论 采用体素动态增强成像序列扫描及后处理技术可以清晰显示骶前区血管网.0.5 mol/L 20 ml钆双胺的剂量同样能达到双倍剂量的显像效果,均可显示骶正中动脉及横干静脉的形态及分布.

abstractsObjective To explore the effects of dynamic contrast-enhanced MRI scanning with different doses of contrasting agents on three-dimensional imaging of the presacral vascular net,and to evaluate the feasibility and clinical significance of low-dose contrasting agents.Methods Between February and May 2012,40 women who underwent routine MRI examination for benign pelvic disease were recruited.These patients were,by using random numbers,allocated to receive 20 ml (group A) or 40 ml of the 0.5mmol/L gadoliniumin (group B) as the contrasting agent.The ACHIEVA 3.0TX MR was employed to perform the e-THRIVE 3D voxel dynamic contrast-enhanced MRI sequence imaging.The presacral area of the vascular net reconstruction images was displayed by using the maximum intensity projection (MIP) and volume rendering (VR) post-processing techniques.The normal anatomy and traveling of the presacral area artery were observed.The proportions of images with middle sacrm artery,cross vein of anterior sacral area and arterial diameter were calculated.Based on the middle sacral artery as the region of interest,the quality of MIP images derived from both groups was assessed by using fi ve-point subjective likert scales.This entailed a comprehensive comparison with the objective evaluation as accessed by measuring the signal intensity (SI),signal to noise ratio(SNR) and the contrast to r oise ratio (CNR).Results The middle sacral arteries were explicitly displayed in both groups,correspon ding to the successful rate of 100％.The cross vein of anterior sacral area was displayed in 72.5％ (29/40) of all cases,75％ (15/20) in group A and 70％ (14/20) in group B,respectively (P＞0.05).In the e-THRIVE sequence axial image,the diameter of middle sacral artery was not statistically different from that in group B [(1.42±0.06)mm vs (1.38±0.07)mm,P=0.117].In the results of the middle sacral arteries of MIP image quality,average score of subjective evaluation in group A was numerically but not statistically lower than that in group B (2.95±0.69 vs 3.10±0.66,P=0.479).The differences in SI and SNR,the parameters for MIP imaging assessment of the middle sacral artery,did not reach statistical significance between lboth groups (SI:719.63± 124.91 vs 811.66±170.60,SNR:61.71± 17.35 vs 74.97±27.91,both P＞0.05).Group A yielded markedly lower CNR than group B (45.68±13.35 vs 62.41±23.37,P＜0.05).Conclusion The e-THRIVE 3D voxel dynamic contrastenhanced MRI imaging sequence scan and post-processing techniques can be used to display the anterior sacral area vascular net.Gadolinium,when administered at the dose of 20 ml,equivalently displays morphology and distribution of the presacral vessels compared with the doubling doses.