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What is Vascular Imaging in Ultrasound and why is it done



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Mention the word "ultrasound" and many people picture a scan done during pregnancy. Gel is applied to the skin and a probe slid non-invasively over the abdomen transmitting data, which is translated into images seen on a monitor. With the adjunct of Doppler and color, an expectant mother can hear fetal heart sounds. What she may not know is that her sonographer specialized in obstetric ultrasound. Today, ultrasound is greatly diversified. Techs registered by the American Registry of Diagnostic Sonographers (ARDMS) can specialize in one or more of seven areas of ultrasonography. The most involved and technical specialty is vascular ultrasound.

Doctors order vascular ultrasounds to find blockages, blood clots, bad valves and aneurysms in blood vessels. Vascular scans are much more involved than just taking pictures. Dopplers not only make it possible to actually hear blood flowing, but are key to determining the percentage of blockage and other abnormalities. Abdominal ultrasounds typically take around 20 minutes to perform, whereas some vascular ultrasound exams can take an hour or more depending on the individual case or what the doctor ordered.

Vascular sonographers, more precisely called Registered Vascular Technologists (RVT's), are licensed to use high-pitched sound waves to measure blood flow velocities and evaluate spectral wave forms in the brain, neck, arms, legs, penis and abdominal organs.. Images alone can be deceptive as some blood clots may appear invisible, blending into the surrounding tissue. Understanding and using Doppler to evaluate blood flow is essential in vascular ultrasound examinations.

Blood fats such as cholesterol and triglycerides contribute to plaque accumulation in arteries. These plaques are typically seen on ultrasound and when they block 50% or more of the artery, they affect blood flow. Tobacco use, diabetes and high blood pressure also take their toll on arteries, increasing the risk of vascular disease.

Compromised blood flow in the carotid arteries in the neck, as well as arteries in the brain, can lead to a stroke. As a result of identifying these abnormally high velocity flows in the carotids, many strokes are prevented with surgical removal of plaque called an endarterectomy.

Blocked arteries in the legs cause pain when walking or, with more advanced disease, pain at rest. Severe cases can result in gangrene and amputations. Diagnosing these arteries with ultrasound aids vascular surgeons in bypassing clogged arteries or using other surgical procedures to save limbs by improving blood flow.

Blood clots in the veins of the arms and legs cause pain and swelling. Pieces of clots in the larger veins can break loose and travel to the heart or lungs and cause serious problems and even death. Blood clots can be a result of inactivity for a prolonged period of time, trauma, birth control pills, cancer, pregnancy, varicose veins or certain blood diseases. The risk increases with tobacco use and diabetes.

Vascular ultrasound exams are also done on the blood vessels of abdominal organs. The same plaque that can form blockages in neck arteries can also clog arteries anywhere in the body.

Diabetics are more prone to small vessel disease such as those in the kidneys, toes and brain arteries. Blocked arteries to the kidneys can result in high blood pressure that responds poorly to multiple medications and can eventually result in kidney failure.

Blocked arteries to the intestines causing abdominal pain after eating can be life threatening. Cirrhosis of the liver and tumors affect blood flow as well.

A weakened arterial wall can become enlarged and continue to grow larger. Left alone, an aneurysm can eventually spring a leak in the bulging artery wall and cause death within a few minutes. The RVT not only looks for blockages, but the general size and health of the arteries. Many aneurysms can be corrected surgically if caught in time. Unfortunately, some are inoperable, depending on their location.

Low arterial blood flow to the penis can result in erectile dysfunction (ED). The sonographer can assess the health of arteries feeding the penis. Penile flow can also be tested by taking a blood pressure of it using a specialized blood pressure cuff and a sensor to detect blood flow called a photopulseplethysmography cell (PPG's). Its blood pressure aids doctors in determining the source of the ED.

Small blood pressure cuffs and PPG's are also used to check blood flow in the fingers and toes. Double-sided tape is applied to the tiny PPG cell and stuck on the end of toes or fingers. The tech watches a waveform of the blood flow and takes a blood pressure. Ultrasound is not used for this particular test because these blood vessels are so small. RVT's are trained to use a variety of instruments, nevertheless, ultrasound and its adjunct, Doppler, are the primary tools of the trade.

Bulging varicose veins can be painful, cause swelling, ulcerations, are more prone to clots and are cosmetically unsightly. Surgeons use vascular ultrasound to map a complete picture of which veins are appropriate for stripping. The veins of the extremities can vary quite a bit from person to person, so vein mapping eliminates any guess work.

Vein mapping of the arms and legs is also utilized for veins that will be harvested for heart, leg or arm bypasses. The vein is located with ultrasound. Its path is drawn on the arm or leg with a marker and it is assessed as to its size and general health. Small veins are not useful in bypass grafts so it's important to know their caliber before surgery.

Vascular ultrasound is also used in surgery. Surgeons performing bypass surgery or removing plaque and clots can scan the surgical site with the help of an RVT before closing the patient up, to ensure success.

Today, a shortage of RVT's plagues America. Because of the serious nature of vascular disease, the job often burdens the techs with the responsibility of periodically being on call 24 hours a day. Experienced RVT's are in high demand, jacking some salaries into six-figure incomes. Techs write and record detailed technical reports and are often given a lot of autonomy in comparison to other types of ultrasound. They are not simple technicians who run an ultrasound machine. They understand the physiology of vascular disease.

Vascular ultrasound, however, is not without its caveat. Ultrasound and Doppler are inhibited by hard-as-rock, calcified plaque impenetrable by ultrasound. Abdominal gas blocks images of abdominal vessels. Ultrasound is hampered by the increased depth of the blood vessels in the morbidly obese. When ultrasound is limited by gas or mass, doctors can inject dye (contrast material) into blood vessels and take x-rays. This kind of test is very reliable, but avoided as it is not only unpleasant for the patient, it is not cost-effective. Furthermore, some patients are allergic to the to the contrast material.

Although many tests last under 30 minutes, patients should be prepared to lie still for a prolonged period of time. Patients are required to avoid eating fatty foods and foods that cause gas when scheduled for an abdominal scan. Remember, a little inconvenience is worth obtaining a wealth of information.

Ultrasound exams are recorded and reviewed by a radiologist or vascular surgeon. He or she will dictate the test results and a report will be mailed to the doctor that ordered the test.

While policies may vary from hospital to hospital, typically RVT's are not allowed to give test results to the patient, but be assured, if there is something life-threatening, the tech will ensure that your doctor is notified before you leave. I should know: I'm an RVT.

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