Currently, the direction of development of ultrasound in the medical field is color ultrasound, the following we talk about the characteristics of color ultrasound:
Color ultrasound is simply a high-definition black and white ultrasound plus color Doppler, first of all, ultrasound frequency shift diagnostic method, i.e., D ultrasound, which is an application of the principle of the Doppler effect, when there is a relative motion between the source of the sound and the receiving body (i.e., probe and the reflector). This method applies the principle of the Doppler effect, when there is relative motion between the sound source and the receiver (i.e., the probe and the reflector), the frequency of the echoes changes, and this change in frequency is called frequency shift.
Color Doppler ultrasound generally uses autocorrelation for Doppler signal processing, and the blood flow signals obtained by autocorrelation are color-coded and then superimposed on a two-dimensional image in real time to form a color Doppler ultrasound blood flow image. As a result, color Doppler ultrasound (i.e., color ultrasound) not only has the advantages of two-dimensional ultrasound structural images, but also provides a wealth of information on hemodynamics, and its practical application has been widely valued and welcomed, and it is known as "non-traumatic angiography" in clinical practice. Its main advantages are: ① It can quickly and intuitively display the two-dimensional distribution of blood flow. ②It can show the running direction of blood flow. ③It is good for identifying arteries and veins. ④It is good for recognizing vascular and non-vascular lesions. ⑤ It facilitates the understanding of the nature of blood flow. ⑥ It can facilitate the understanding of the temporal phase and velocity of blood flow. ⑦ It can reliably detect shunts and refluxes. (8) It can quantitatively analyze the origin, width, length, and area of blood flow bundles.
But the color ultrasound using the relevant technology is a pulse wave, the speed of the detector is too high, the color of the color flow color error will occur, in the quantitative analysis is significantly inferior to the spectral Doppler, nowadays color Doppler ultrasound instrument have the function of the spectral Doppler, that is, for the color - dual-function ultrasound.
Color Doppler flow mapping (CDF), also known as color Doppler ultrasound imaging (CDI), which obtains the same source of echo information and spectral Doppler, the distribution and direction of blood flow is shown in two dimensions, and different speeds are distinguished by different colors. Dual-energy Doppler ultrasound systems, that is, B-mode ultrasound images show the location of blood vessels. Doppler measures blood flow, and this combination of B-mode and Doppler systems allows for more precise localization of any given vessel.
1. Direction of blood flow In the spectral Doppler display, the direction of blood flow is distinguished by the zero baseline. Above the zero baseline indicates flow toward the probe, and below the zero baseline indicates flow away from the probe. In CDI, the direction of blood flow is color-coded, with red or yellow chromatograms indicating blood flow toward the probe (hot) and blue or blue-green chromatograms indicating blood flow away from the probe (cold).
2. Vascular distribution CDI shows blood flow within the lumen of a blood vessel and is therefore a flow channel type of display, which does not show the vessel wall or periphery.
3. Identification of the types of blood vessels in cancerous nodules The blood vessels of hepatocellular carcinoma nodules can be categorized with CDI. Distinguish them as perinodal winding vessels, curved vessels to the inner edge of the nodule. The inflow vessels of the nodule, the internal vessels of the nodule and the outflow vessels of the nodule.
Color ultrasound clinical application
(A) vascular disease
Using 10MHz high-frequency probe can find the calcification point in the blood vessel less than 1mm, for the carotid artery atherosclerotic occlusive disease has a better diagnostic value, but also can use the blood flow to probe the local amplification to determine the degree of luminal stenosis, embolus whether there is a possibility of dislodgement, whether it produces an ulcer, to prevent cerebral thrombosis occurs.
Color ultrasound for all kinds of arteriovenous fistula can be said to be the best diagnostic method, when the probe to the colorful mosaic of ring color spectrum can be confirmed.
For carotid artery aneurysm, abdominal main vein aneurysm, vascular occlusive vasculitis, chronic venous disease of the lower extremities (including lower extremity varicose veins, primary deep vein valve insufficiency, deep vein reflux obstruction of the lower extremities, thrombophlebitis and venous thrombosis) using color ultrasound high-definition, local magnification and blood flow spectroscopic investigation can be made a more correct diagnosis.
(2) abdominal organs
Mainly used in the liver and kidneys, but for the abdominal cavity benign and malignant lesions identification, gallbladder cancer and large polyps, chronic inflammation identification, common bile ducts, hepatic arteries, such as the difference between the disease has a certain auxiliary diagnostic value.
Color ultrasound of cirrhosis can make a better judgment from the size of the lumen of various blood vessels in the liver, the speed and direction of the internal flow rate and the establishment of collateral circulation. For nodular cirrhosis and diffuse hepatocellular carcinoma which are difficult to be distinguished by black-and-white ultrasound, high-frequency probing and blood flow spectrum probing can be utilized to make differential diagnosis.
For the differentiation of benign and malignant space-occupying lesions in the liver, cysts and various kinds of arteriovenous tumors, it has a better diagnostic value, and primary liver cancer and secondary liver cancer can be differentiated by internal blood supply.
Color ultrasound used in the kidney is mainly used for renal vascular lesions, such as the aforementioned renal arteriovenous fistula, when the clinical manifestations of intervals, painless hematuria can not find the cause of the strong indications. For renal artery stenosis, one of the common causes of secondary hypertension, ultrasound can basically make a definitive diagnosis, with a diagnostic accuracy of 98.6% and a sensitivity of 100% when the blood flow velocity at the stenosis is detected to be greater than 150 cm/s. On the other hand, it is also the differential diagnosis of renal cancer, renal pelvis migratory cancer and benign tumors.
(3) Small organs
In small organs, color ultrasound has obvious diagnostic accuracy compared with black-and-white ultrasound, mainly for thyroid, breast, and eye, in a way, the 10MHz probe without color flow Doppler has been compared with the ordinary black-and-white ultrasound of 5MHz, the probe is much clearer, and it can diagnose and make differential diagnosis for the thyroid pathology according to the blood supply of the thyroid gland, among which, the image of hyperthyroidism is the most typical, with specificity, and the image of hyperthyroidism is the most typical. The image of hyperthyroidism is the most typical and specific, which is a "sea of fire sign". Simple goiter has no significant change compared to normal thyroid blood flow. Subacute thyroiditis, Hashimoto's thyroiditis between the two, can be distinguished by this, and through the nodules and the surrounding blood flow can be well distinguished nodular goiter, thyroid adenoma and thyroid cancer, so it is recommended that the diagnosis of the thyroid gland is not too clear, the patient has a certain affordability can be done ultrasound to further clarify the diagnosis.
Breast ultrasound is mainly used for breast fibroma and breast cancer differential diagnosis, while the eye is mainly on the eye vascular lesions have better diagnostic value.
(4) Prostate and seminal vesicles
It is because rectal exploration is the best method to diagnose the prostate at present, so it is specially proposed here. This method of exploration of the prostate gland is divided into the migratory zone, the central zone, the peripheral zone, and another part of the prostate fibromuscular stromal zone. The migratory zone includes both sides of the periurethral sphincter and the abdomen, which is the origin of 100% of BPH, while the migratory zone accounts for only 5% of the size of the prostate in normal subjects. The central area is around the ejaculatory ducts and the tip wall points to the seminal mound, while the peripheral area includes the posterior part of the prostate and the tips on both sides, which is the origin of 70-80% of cancers, and the apical peritoneum is bookish or even disappeared, forming an anatomically weak area, which is a common metastatic channel of cancers and a key area of biopsy of the prostate. Rectal examination has good diagnostic value for various prostate and seminal vesicle diseases, and when combined with prostate biopsy, the diagnosis is basically clear, and prostate diseases, especially prostate cancer, are on the rise in China, and the incidence of prostate cancer in Europe and the United States is even ranked behind lung cancer as the second highest incidence of cancer, and abdominal examination of the prostate is basically unable to make a diagnosis, so it is recommended that the clinic use more rectal Therefore, it is recommended to use rectal ultrasound to diagnose prostate diseases without abdominal exploration.
(E) Obstetrics and gynecology
Color ultrasound for obstetrics and gynecology is the main advantage of benign and malignant tumors and umbilical cord disease, fetal heart disease and placental function assessment, trophoblastic diseases have a better auxiliary diagnostic value, infertility, pelvic varicose veins through the observation of the blood flow spectra, but also can be made in black and white ultrasound difficult to diagnose. The use of vaginal probe has certain advantages over abdominal exploration, and its superiority is mainly reflected in ① the sensitivity of uterine arteries, ovarian blood flow, high display rate. ②Shorten the examination time and obtain accurate Doppler spectrum. ③No need to fill the bladder. ④It is not disturbed by obesity, abdominal scars, or bowel insufflation. ⑤The activity of the tip of the probe is used to search for the pelvic organ tenderness site to determine whether there are adhesions in the pelvis.