Artery stenosis and occlusive lesions of the lower extremities can be caused by a variety of diseases. The more common ones are atherosclerosis, multiple aorticitis, thrombotic occlusive vasculitis, trauma, etc. Cause narrowing of the arterial lumen, and even occlusion.When the stenosis rate of the artery diameter of the lower extremity reaches more than 50%, the intravascular pressure and blood flow at the far end of the stenosis will decrease, and the patient may experience intermittent lameness.The surgical decision on whether treatment is required is mainly based on the clinical symptoms, and the treatment method used should refer to the degree of stenosis and the scope of the lesion.At present, the main imaging examination methods for lower limb artery stenosis and occlusive diseases are: color Doppler ultrasound (CDU), digital subtractive angiography (DSA), CT vascular imaging (CTA), magnetic resonance angiography (MRA) and so on.The advantages and limitations of various inspection methods are now summarized.

one.Color Doppler ultrasound (CDU)

CDU is currently widely used in clinical practice as an ideal method for diagnosing artery stenosis and occlusive diseases of the lower extremities.Using color Doppler ultrasound, the two-dimensional structure of blood vessels, the filling of color blood flow, the flow rate and direction of blood flow in the blood vessel cavity, and the spectral Doppler waveform can be clearly displayed.

Two.Percutaneous artery digital subtraction angiography (DSA)

DSA is by inserting a contrast catheter into a pre-selected blood vessel and injecting a contrast agent to make the lumen of the artery develop under the X-ray line, which can directly reflect the inner diameter of the blood vessels and the characteristics of plaques.

For many years, DSA has been the “gold standard” for diagnosing artery stenosis.DSA examination can clarify the site, scope, branch and lateral branch circulation of vascular lesions, understand the inflow and outflow channels of diseased blood vessels, and provide clinicians with an important basis for choosing reasonable treatment methods and evaluating the prognosis. For some cases, interventional treatment can also be performed at the same time as the examination.

Three.CT Vascular imaging (CTA)

In recent years, with the development and continuous improvement of CT equipment, especially the continuous improvement of scanning speed, CT vascular imaging (CTA) has become more and more mature, and it is increasingly widely used in the detection of artery stenosis or occlusive diseases of the lower extremities.The main principle is that after intravenous injection of the contrast agent, a large range of volumetric data collection is completed by holding your breath at a time during the peak period of filling of the target intravascular contrast agent, and then the computer performs a three-dimensional reconstruction of the vascular structure at an independent workstation to produce an image similar to an angiogram.

Four.Magnetic resonance angiography (MRA)

Magnetic resonance angiography is an imaging technique obtained by the difference between the MR signal of flowing blood and the MR signal of the surrounding resting tissue.It is a non-invasive magnetic resonance imaging technique that does not introduce any contrast agents.This technique can be used to measure blood flow velocity and observe the characteristics of blood vessels and blood flow status.

In recent years, the widespread application of three-dimensional contrast enhanced MRA (3D-CE-MRA) in vascular examination of the lower extremities has provided a new method for the diagnosis of arterial diseases of the lower extremities.

In summary, DSA has the advantages of high resolution of small blood vessels, intuitive development of the lesion site, and interventional treatment at the same time during examination. As the gold standard for the diagnosis of vascular lesions, it has always occupied a dominant position in the diagnosis of arterial lesions of the lower extremities.However, the scope of application of CTA is also becoming more and more extensive. Almost all lesions of the middle and large arteries in the body can be checked for CTA and valuable information can be obtained.There are reports that CE-MRA has become a first-line examination method for comprehensive evaluation of arterial lesions of the lower extremities, and it is even the preferred examination method in many foreign medical centers [18]. It is expected to replace invasive DSA examination in diagnosis in the future.Because of its low price, safety and noninvasive, color Doppler ultrasound can be used as a means to roughly judge the site and degree of vascular stenosis, and can be used as the preferred method for judging the efficacy and long-term follow-up of patients and monitoring of disease changes. It is most widely used in the diagnosis of early lesions of the lower limb arteries.

Department of Ultrasound Liu Hao

2018.2.22