Carotid Doppler Ultrasound Imaging
Posted by: admin on: November 24, 2010
The carotid Doppler ultrasound imaging is most frequently performed to find stenosis or narrowing of the carotid artery, a condition which gradually increases the risk of a heart attack. In other words the main purpose of carotid ultrasound is to scan patients for narrowing or blockage of their carotid arteries that in case present can increase their risk of having a heart attack. These arteries supply the human brain with oxygen-rich blood.
When the scan is done a thorough healing procedure can be started. It can be done in case a patient has a carotid bruit (an abnormal sound in the neck which is heard with the stethoscope) or high blood pressure. Some other risk factors asking for this type of ultrasound scan are:
- a family history of stroke or heart disease
- advanced age
- elevated blood cholesterol
- diabetes
It is done to:
- check the position of a metal stent placed to keep carotid blood circulation
- detect a hematoma, a collection of clotted blood which can slow and eventually stop blood circulation
- detect the state of the carotid artery right after surgery in order to restore normal blood circulation
- check dissection of the carotid artery, a split between layers of the artery wall which can lead to a weakening of the wall of the artery or obstruction of blood circulation
Doppler ultrasound pictures will help the doctor to analyze
- narrowing of blood canals vessels that can be caused by plaque (plaque is made up of calcium, cholesterol, fat and other substances found in the blood)
- blockages to blood circulation like clots
- congenital malformation and tumors
In kids, it’s used to:
- predict a higher risk of heart attack in kids with sickle cell disease
- find abnormalities in the lymphatic canals, lymph nodes and blood canals
- check blood circulation
Ultrasound scanners consist of a console with electronics and computer, transducer which is used to examine the patient’s body and blood canals and a video display. The transducer’s a tiny hand-held instrument which looks like a microphone, connected to the scanner by a long cord. It sends out high frequency sound waves into the patient’s body and next listens for the returning echoes from the tissues in the body. The principles are quite similar to sonar used by submarines and boats. The ultrasound picture is instantly visible on a video display screen which resembles a lap top or flat TV screen. The picture is created based on the type of body structure the sound travels through, amplitude, frequency and time it takes for the signal to return from the tissue to the transducer.
Color Doppler Ultrasound: Medical Imaging Technique
Posted by: admin on: November 23, 2010
Color Doppler ultrasound is a sophisticated medical imaging procedure that is used to provide visualization of the blood circulation, using color processing to add color to the picture therefore that a health care provider or physician can find out what is happening inside the patient’s body. This procedure requires the use of an ultrasound instrument that is capable of color Doppler ultrasound, and can be performed in a clinic or hospital as an outpatient method. Having this imaging study performed isn’t generally painful, and the patient doesn’t need anesthetics.
Doppler ultrasound takes advantage of the Doppler Effect in order to create a moving picture of the inside of the patient’s body. In this procedure, an ultrasound transducer is used to beam sound into the area of interest, and it reads the returning sound. Basically, when the sound bounces off a moving target such as veins and arteries, the pitch alters as a result of the Doppler Effect. The transducer will detect very subtle pitch alterations and record them visually, creating a picture that shows where blood is circulating and in what direction.
Observed in gray-scale, the photo can be a bit difficult to read. This is where color Doppler ultrasound steps in, with the ultrasound instrument assigning color values that depend on whether blood is moving away from the transducer or towards. In addition to showing the direction of movement, the colors vary in intensity depending on the flow velocity, allowing healthcare providers or physicians to find out just how fast the blood is flowing.
A frequent application of this instrument is in scanning a patient with a suspected occlusion or aneurysm. It’ll reveal places where the velocity of the blood circulation is altering, acting much like a red flag to show a problem. This method can be used to detect blood clots as well, that’ll be quite clearly visible within the color display as well.
In venous malformation or tumor scans, physicians can use it to map out the blood supply and find out how far the growth has spread. This can and will have a big impact on the course of action the physician advises, and exactly how the physician plans to approach surgery and other treatments.
Color Doppler ultrasound generally involves using a transducer on the outside of the patient’s body; on the other hand, it can be used for transvaginal and transrectal scans as well, in which the probe is inserted to get a better view. In these instances, patients can be given muscle relaxers so that the scan will be less unpleasant.
How Doppler Ultrasound Test Is Done
Posted by: admin on: November 22, 2010
A patient will be asked to not use products which contain nicotine (chewing tobacco, cigarettes) for thirty minutes to two hours prior to the Doppler ultrasound. Nicotine causes blood vessels all around the body to constrict. This can lead to false conclusions.
The scan is done by a physician (radiologist) who specializes in interpreting and performing imaging tests or by a sonographer (ultrasound technologist) who is supervised by a radiologist. It’s done in an ultrasound room in a physician’s or hospital office.
One will have to remove any jewelry which can interfere with the Doppler ultrasound. One will have to take off most or even all of clothes; depending on what area is being scanned (one will be allowed to keep on his or her underwear in case it doesn’t interfere with the scan). One may be given a paper or cloth covering to use throughout the scan.
- For stomach tests, one must lie on his or her back.
- For thorax test, one must lie on his or her back with the neck slightly extended.
- For neck and head scans, the head will be turned to one side.
- For a leg or arm test, the exposed leg or arm will be turned slightly outward and the head must be slightly raised. Oftentimes for a leg scan, one will be asked to lie on his or her abdomen.
- Throughout gestation period, a pregnant woman may lie on her left side or on her back with the stomach exposed.
Gel is applied to the skin in order to promote the passage of the sound waves. Next, the transducer is placed in the gel and moved along the skin. One has to lie quite still throughout the entire test. One will hear sounds which represent the circulation of blood through veins and arteries.
The procedure generally lasts thirty minutes to one hour.
Arteries in the Legs and Arms
Doppler ultrasound is generally done on either legs or arms. Even in case the suspected blood circulation problem is in just 1 arm or one leg, both will be scanned for comparison. In case the arms are being tested, they will be scanned first while one is lying down and next again while one is sitting.
Based on what blood canals are being scanned, a blood pressure cuff will be wrapped around both or one limb therefore that the blood pressure will be taken at a number of different spots. While scanning the legs, a blood pressure cuff will be wrapped first around the calf and next around the thigh. The procedure will be done at a number of places on the leg. While scanning the arms, the pressure cuff will be wrapped first around the forearm and next around the upper arm.
Doppler ultrasound procedure can be performed prior and after workouts, in case one is in good health.
Why Doppler Ultrasound Test Is Done
Posted by: admin on: November 13, 2010
Doppler ultrasound test is done to:
1. Evaluate leg pain which can be caused by intermittent claudication. This is a condition caused by atherosclerosis (also known as arteriosclerotic vascular disease or ASVD) of the lower extremities.
2. Find narrowed blocked blood canals as well as blood clots in almost any part of the human body, particularly in the arms, legs and neck. Blood clots in the deep veins of the leg can lead to leg pain as well as swelling and can significantly increase patient’s risk of pulmonary embolism. Narrowed or blocked neck arteries can lead to lost of vision, paralysis, numbness, weakness, or other key symptoms of a stroke.
3. Evaluate abnormal veins causing varicose veins or some other problems.
4. Evaluate blood circulation after a stroke or other condition which could be caused by a problem with blood circulation. Evaluation of a stroke can be done through a method called the TCD (transcranial Doppler ultrasound).
5. Map veins which can be used for blood canal grafts. Furthermore, it can evaluate the condition of grafts used to bypass blockage in a leg or arm.
6. Estimate the amount of blood flow to a transplanted liver or kidney.
7. Check the blood flow after veins and/or arteries surgery.
8. Check for the presence, location and the amount arterial plaque. Plaque in the carotid arteries can sometimes reduce blood circulation to the brain and can increase the risk of stroke.
9. Guide treatment like radiofrequency or laser ablation of abnormal veins.
10. Monitor the health of an unborn child. Blood circulation in the heart and brain, through the placenta or in the umbilical cord of an unborn child can be monitored. This simple yet great test can show weather the unborn child is getting the sufficient amount of nutrients and oxygen. This medical instrument can be used to guide decisions during gestation period if:
- The unborn child is smaller when compared to normal for her or his gestational age. Blood flow through the big blood canal in the umbilical cord can be monitored.
- Rh sensitization has happened. Blood circulation through a blood canal in the brain can be used to check unborn child’s health.
- The mother-to-be has some other problems like sickle cell disease or preeclampsia (a medical condition in which hypertension arises in pregnancy).
TCD or transcranial Doppler ultrasound can be used in kids with sickle cell disease in order to check their risk of stroke. In adults, transcranial Doppler ultrasound can be used to evaluate blood circulation and canal spasms in the brain.
Basic Types of Doppler Ultrasound
Posted by: admin on: November 12, 2010
What Doppler Ultrasound Actually Does?
It uses reflected sound waves in order to evaluate blood while it runs through veins and arteries. It helps physicians evaluate blood circulation through the main blood vessels of the legs, neck and arms. The instrument will reveal any reduced or blocked blood circulation through narrowing in the main arteries of the neck which can cause a stroke. Furthermore, the instrument will show blood clots in leg veins (DVT or deep vein thrombosis) which can break loose and block blood circulation to the lungs (pulmonary embolism). Throughout gestation period, it can be used to look at blood circulation in an fetus, i.e. unborn child in order to check the overall condition of the baby.
During Doppler ultrasound test, a portable instrument (which is called the transducer) is passed over the skin above veins and arteries. This instrument sends and receives sound waves which are amplified via microphone. The sound waves bounce off solid objects, i.e. vein and arteries’ cells. The movement of blood cells, i.e. blood flow causes an alteration in pitch of the reflected sound waves (this is known as the Doppler Effect). In case there’s no blood circulation, the pitch doesn’t alter. Data from the reflected sound waves will be processed by a computer in order to give images or graphs which show the flow of blood through the veins and arteries. These images or graphs will be saved for future analysis.
Types of Doppler Ultrasound
Carotid Duplex Doppler; it uses traditional ultrasound methods to create an image of a veins, arteries as well as surrounding organs. Furthermore, a computer converts the ultrasounds into a graph which provides info concerning the direction as well as speed of blood circulation through the veins and arteries being checked.
Continuous wave or bedside Doppler; it uses the alteration in pitch of the sound waves in order to give info concerning blood circulation through veins and arteries. The physician monitors the sounds produced by the transducer in order to check the blood circulation through an area which is potentially narrowed or blocked. This particular test can be done at the bedside (thus the name) in the medical center with a portable instrument in order to give a quick check of the extent of veins and arteries disease or damage.
Power Doppler; this is a newer generation technique that is up to five times more sensitive in detecting blood circulation when compared to color Doppler. This instrument will create pictures which are difficult or even impossible to get using traditional color Doppler. On the other hand, it is most frequently used to check blood circulation through veins and arteries within solid organs. Blood circulation in individual veins and arteries is most frequently checked by combining duplex with color. These two techniques give much better info on both the speed and direction of blood circulation than when they’re not used together.
Color Doppler; it uses traditional ultrasound methods in order to create an image of veins and arteries. Furthermore, a computer converts the ultrasounds into colors which are overlaid on the picture of the veins and arteries. This shows the direction as well as speed of blood circulation through the veins and arteries.