Color coded blood flow and blood perfusion techniques are applied to the endovascular treatment of infrapopliteal arterial occlusion,to establish a method of quantitative evaluation of blood flow and tissue perfusion,to improve the level of calculation of condition and curative effect. So as to establish a new complete evaluation system of infrapopliteal arterial occlusive disease, to guide clinical further. At the same time establish a digital information platform for clinical, lay the foundation for the large research.

Inclusion Criteria:

1. Patients are diagnosed as lower limb atherosclerosis occlusion from June 2016 to June 2018 in our centre;
2. All participating patients provided written informed consent and willing to participate;
3. aged 40 years and more;
4. the class of lower ischemia is upon 4;
5. below-the-knee arteries stenosis or occlusion is indicated by duplex or computed tomographic angiography;
6. there is no heavy stenosis in superficial femoral artery (stenosis<30%), or short length lesion(length≤5cm, stenosis≥30%);
7. infection or ulceration don't happen in the area of surgery;
8. below the inguinal ligament arteries don't have the history of bypass or interventional surgery.

Exclusion Criteria:

1. disagree and refuse to the free therapy;
2. lesion length of superior artery is more than 5cm;
3. history of heart dysfunction: congestive heart failure,, myocardial infarction, severe arrhythmia;
4. With severe metabolic disease, renal impairment(serum creatinine>1.4mg/dL, glomerular filtration rate<60) affect the excretion of contrast agents;
5. have the diseases or agents which will reduce the viable of data;
6. allergy to iodinated contrast medium.

These new technologies are performed in the treatment of patients older than 40 years. They present with rest pain, intermittent claudication, ulceration or gangrenous. Some of them have the risk factors of CLI, as hypertension, diabetes, hyperlipidemia or smoking. They are referred to our vascular service for CLI-infrapopliteal artery occlusion. Computed tomographic angiography discloses the occlusive lesion in anteriortibial, posterior tibial or peroneal arteries.