时间分辨随机轨道MR血管成像对周围动脉闭塞性疾病小腿动脉的成像研究

目的 评价3.0 T时间分辨随机轨道(TWIST)MRA提供的小腿动脉血流动力学指标和形态学诊断的价值.方法 40例临床证实或怀疑周围动脉闭塞性疾病(PAOD)的患者接受小腿段TWIST MRA及全下肢对比增强MRA(CE-MRA)检查.由TWIST MRA确定双侧腘动脉开始显示时间,双侧腘动脉开始显影时间差,小腿动脉通过时间和小腿动脉平均达峰时间.分析小腿动脉平均达峰时间与踝肱指数(ABI)的关系.评价小腿各段动脉在TWIST MRA及CE-MRA的图像显示情况,包括血管显示度、静脉重叠情况和动脉狭窄程度.组间比较采用t检验或校正t检验,动脉平均达峰时间与ABI的关系采用Pearson分析.对16例患者,以DSA为金标准,分别评价TWIST MRA、CE-MRA诊断各级动脉狭窄的敏感性和特异性.结果 (1)纳入评价的79侧下肢腘动脉开始显影时间为(30.7±7.6)s,双侧腘动脉开始显影时间差为(2.1±2.5)s,小腿动脉通过时间为(35.6±16.9)s,小腿动脉平均达峰时间为(52.6±17.6)s.(2)24例接受ABI检查的患者共计得到48个ABI指数(均值为0.62±0.23),与小腿动脉平均达峰时间呈正相关(r＝0.627,P＜0.01).(3)851段参与评价的血管中,TWIST MRA显影动脉节段849段,显示度评分为(2.83±0.48)分;CE-MRA显影动脉节段845段,显示度评分为(2.78±0.43)分(P＞0.05).(4)以DSA共显示的194段动脉节段为金标准,TWIST MRA显示正常及轻度狭窄的敏感性为96.7%(118/122)、特异性为100.0% (72/72),显示明显狭窄的敏感性为94.1%(32/34)、特异性为96.2% (154/160),显示闭塞的敏感性为94.7%(36/38)、特异性为98.7% (154/156);CE-MRA显示正常及轻度狭窄的敏感性为95.9%(117/122)、特异性为100% (72/72),显示明显狭窄的敏感性为91.2%(31/34)、特异性为95.6% (153/160),显示闭塞的敏感性为94.7%(36/38)、特异性为98.1%(153/156).结论 TWIST MRA操作简便,无静脉污染,一次检查不仅能准确显示小腿动脉病变,而且能提供反映疾病程度的功能学信息.

Abstract：

Objective To explore the value of time-resolved angiography with interleaved stochastic trajectories (TWIST)in providing hemodynamic indices and morphological imaging of calf arteries in patients with peripheral arterial occlusive disease(PAOD) with 3.0 T MR scanner. Methods Forty patients with confirmed or suspected PAOD underwent TWIST MRA for the calf arteries and conventional contrast-enhanced MRA(CE-MRA) for the whole lower peripheral arteries. TWIST MRA data were used to determine the bolus arriving time of the popliteal artery, the time difference of the bolus arrival in the popliteal artery between the two legs, calf artery transit time, and the mean peak enhancement time of calf arteries. The mean value of peak enhancement time of calf arteries was correlated with ankle-brachial index(ABI). The calf arteries were divided into 13 segments. The visible score of arterial segment was recorded, and the degree of arterial stenosis was graded too. In 16 patients, DSA was used as the gold standard to evaluate the sensitivity and specificity of TWIST MRA and CE-MRA. Results The bolus arriving time of the popliteal artery was (0.7±7.6) s the time difference of the bolus arrival in the popliteal artery between the two legs was (2.1±2.5) s, the calf artery transit time was (35.6±16.9) s, the mean value of peak enhancement time of calf arteries was (52.6±17.6) s. ABI was acquired from 24 patients and 48 legs, which correlated well with the mean value of peak enhancement time in calf arteries (r＝0.627,P＜0.01). The mean visible score was (2.83±0.48) of TWIST MRA images and (2.78±0.43) of CE-MRA images. There was no significant difference between them (P＞0.05). On CE-MRA, there were 38 legs with varying degrees of early venous enhancement; in contrast, there was no venous contamination on TWIST MRA. The sensitivity and specificity of TWIST MRA were 96.7% (118/122) and 100.0% (72/72) in showing normal artery and mild stenosis, 94.1% (32/34) and 96.2% (154/160) in showing severe stenosis, and 94.7% (36/38) and 98.7% (154/156) in showing occlusion. The sensitivity and specificity of CE-MRA were 95.9% (117/122) and 100.0% (72/72) in showing normal artery and mild stenosis, 91.2% (31/34) and 95.6% (153/160) in showing severe stenosis, and 94.7% (36/38) and 98.1% (153/156) in showing occlusion. Conclusion TWIST MRA is a preferable choice for calf arterial occlusive disease, which provided nice morphological images and useful hemodynamic indices with simple operation.

Imaging evaluation of calf arteries in patients with peripheral arterial occlusive disease by using time-resolved angiography with interleaved stochastic trajectories on MR scanner

Objective To explore the value of time-resolved angiography with interleaved stochastic trajectories (TWIST)in providing hemodynamic indices and morphological imaging of calf arteries in patients with peripheral arterial occlusive disease(PAOD) with 3.0 T MR scanner. Methods Forty patients with confirmed or suspected PAOD underwent TWIST MRA for the calf arteries and conventional contrast-enhanced MRA(CE-MRA) for the whole lower peripheral arteries. TWIST MRA data were used to determine the bolus arriving time of the popliteal artery, the time difference of the bolus arrival in the popliteal artery between the two legs, calf artery transit time, and the mean peak enhancement time of calf arteries. The mean value of peak enhancement time of calf arteries was correlated with ankle-brachial index(ABI). The calf arteries were divided into 13 segments. The visible score of arterial segment was recorded, and the degree of arterial stenosis was graded too. In 16 patients, DSA was used as the gold standard to evaluate the sensitivity and specificity of TWIST MRA and CE-MRA. Results The bolus arriving time of the popliteal artery was (0.7±7.6) s the time difference of the bolus arrival in the popliteal artery between the two legs was (2.1±2.5) s, the calf artery transit time was (35.6±16.9) s, the mean value of peak enhancement time of calf arteries was (52.6±17.6) s. ABI was acquired from 24 patients and 48 legs, which correlated well with the mean value of peak enhancement time in calf arteries (r＝0.627,P＜0.01). The mean visible score was (2.83±0.48) of TWIST MRA images and (2.78±0.43) of CE-MRA images. There was no significant difference between them (P＞0.05). On CE-MRA, there were 38 legs with varying degrees of early venous enhancement; in contrast, there was no venous contamination on TWIST MRA. The sensitivity and specificity of TWIST MRA were 96.7% (118/122) and 100.0% (72/72) in showing normal artery and mild stenosis, 94.1% (32/34) and 96.2% (154/160) in showing severe stenosis, and 94.7% (36/38) and 98.7% (154/156) in showing occlusion. The sensitivity and specificity of CE-MRA were 95.9% (117/122) and 100.0% (72/72) in showing normal artery and mild stenosis, 91.2% (31/34) and 95.6% (153/160) in showing severe stenosis, and 94.7% (36/38) and 98.1% (153/156) in showing occlusion. Conclusion TWIST MRA is a preferable choice for calf arterial occlusive disease, which provided nice morphological images and useful hemodynamic indices with simple operation.