What is the difference between B-mode ultrasound and four-dimensional ultrasound?

System B ultrasound is a two-dimensional planar image, four-dimensional color Doppler ultrasound is a real-time dynamic stereoscopic image, which can observe the size, shape and surrounding tissue relationship of the lesion in three-dimensional space, see the internal structure, shape size and blood flow inside the tissue, and observe whether there are rich blood vessels inside and around the lesion. Four-dimensional color Doppler ultrasound can observe the blood supply of pathological changes. Color Doppler ultrasound can examine abdominal vessels, limb vessels, neck vessels and vertebral arteries and veins. In addition to observing whether there are plaques, it can also measure blood flow velocity through color Doppler ultrasound, so judge the degree of stenosis of blood vessels.