Imaging evaluation of calf arteries in patients with peripheral arterial occlusive disease by using time-resolved angiography with interleaved stochastic trajectories on MR scanner / 中华放射学杂志

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.