肺动脉非对比剂增强MR血管成像应用的扫描技术探讨

Non-contrast-enhanced MR angiography of pulmonary artery using spatial labeling with multiple inversion pulses sequence:investigation of scanning technique

目的:观察不同翻转带放置方法时多翻转空间标记脉冲技术(SLEEK)非对比剂增强肺动脉血管成像的效果,探讨肺动脉SLEEK-MRA最佳翻转带放置方法。方法:将40例无肺动脉及肺部疾病的健康志愿者作为研究对象,利用1.5T MRI扫描仪对所有志愿者行肺动脉SLEEK-MRA扫描,每例志愿者分别采用"+"字交叉法和肺野平行放置法放置翻转带,扫描完成后将原始图像传至工作站进行图像后处理,由2位影像学诊断医师采用4分法对肺动脉4级分支的图像质量进行主观评分,并测量肺动脉主干及左、右肺动脉干的对比信噪比(CNR)及信号信噪比(SNR)。利用单因素方差分析对计量资料进行统计学分析;利用Cohen's Kappa检验评估2位医师之间判断结果的一致性。结果:40例志愿者均顺利完成扫描。两位读片医师对肺动脉4级分支(主干、左右肺动脉干、叶间动脉和段间动脉)图像质量评分的一致性非常好(Kappa值分别为0.931、0.880、0.778和0.778)。在肺野平行放置法MRA图像上,两位医师对肺动脉4级分支的图像质量评分的均值分别为2.71±0.52、2.67±0.34、2.48±0.29和2.44±0.21,均高于"十字"交叉法(分别为2.17±0.41、1.79±0.34、1.43±0.15和0.72±0.31),两组间差异均有统计学意义(P<0.05)。肺动脉主干及左、右肺动脉干的CNR及SNR,在肺野平行放置法图像上(CNR:524.81、470.65、428.71;SNR:539.31、486.14、436.12)均优于"十字"交叉法(CNR:289.58、302.81、285.71;SNR:310.14、314.01、311.61),差异有统计学意义(P<0.05)。结论:使用肺野平行放置法设置翻转带进行SLEEK-MRA肺动脉成像,可清晰显示肺动脉主干及其外周小分支动脉,成像效果较佳,可作为临床上SLEEK-MRA检查时的常规翻转带放置方法。

Objective：To compare the image quality of unenhanced magnetic resonance pulmonary artery （PA） angi- ography using spatial labeling with multiple inversion pulses （SLEEK） technique with two different methods to set presatu- ration band. Methods：40 healthy volunteers who had no contraindications to MRI and no recent health problems or surgeries were recruited in the study. All subjects underwent SLEEK-MRA on a 1.5T MRI system for assessing pulmonary artery by using two different methods to place presaturation band. The presaturation band was put in the lung field either parallel （group A） or crossed （group B） to each other. All original data from SLEEK scan were transmitted to an imaging worksta- tion for post-processing. The images were assessed by two radiologists, the image quality of pulmonary artery （4 main seg- ments including main trunk,left and right PA,segmental PA） was evaluated on the basis of a four-point scale,and the con- trast-to-noise ratio （CNR） and signal-to-noise ratio （SNR） of the 4 main segments of PA were measured and calculated. The ability of SLEEK MRA to evaluate PA was analyzed by using the one-ANOVA test,and the Cohen＇s Kappa was used to examine the concordance between the two readers. Results： A total of 40 patients were successfully examined with SLEEK MRA,image quality of all patients was acceptable. The scores of the image quality of the 4 main segments of PA evaluated by the two radiologists showed excellent concordance （Kappa= 0. 931,0. 880,0. 778 and 0. 778, respectively）. On SLEEK MRA using method A,the image quality of the 4 segments of PA was 2.71±0.52,2.67±0.34,2.48±0.29 and 2.44±0.21,which was higher than that （2.17±0.41,1.79±0.34,1.43±0.15 and 0.72±0.31） on SLEEK MRA using method B with statistical difference （P〈0.05）. The CNRs and SNRs of main trunk,left and right PA in method A group were 524. 81,470.65,428.71 and 539.31,486.14,436.12,which were higher than those in method B group （289.58,302.81,285.71 and 310.14,314.01 and 311.61） ,with statistic difference （P〈0.05）. Conclusion：SLEEK MRA with parallel presaturation bands in the lung field could clearly show pulmonary artery,it could be a reliable method in SLEEK MRA.