Cardiovascular Imaging

Angiography is an x-ray exam of the arteries and veins used to diagnose blood vessel problems and blockages which involves the use of a catheter inserted into an artery. The catheter is inserted through a small nick in the skin that is about the size of a pencil tip, a contrast agent or x-ray dye is then injected to increase the visibility of the blood vessels on the x-ray image.

One of the more common uses of angiogram is to determine if there is a blockage or narrowing in the blood vessels that interferes with the normal flow of blood through the body. Often times, the interventional radiologist can treat the blocked blood vessel with angioplasty and thrombolysis techniques. Other reasons for performing angiograms include aneurysms, cerebral vascular disease such as stroke or bleeding in the brain, blood vessel malformations or to diagnose medical conditions that are not resolved with other tests. Angiograms can also be used by surgeons to assist in planning an operation or choosing the appropriate surgical procedure.

Angioplasty is a technique in which the interventional radiologist inserts a very small balloon attached to a thin catheter into a blood vessel in order to open an artery. A small nick is made in the skin and the catheter is inserted into the blood vessel guided by x-ray imaging which assists in finding the appropriate location in which to inflate the balloon to open the artery.

A stent, or small metal tube, is often inserted to hold the blood vessel open. In some cases where the blockage is caused by a blood clot, thrombolytic drugs that dissolve clots are injected through the catheter to break-up the clot and restore the blood flow.

These blockages can be caused by peripheral artery disease and in some cases renal vascular hypertension or high blood pressure which is caused by blockage to the artery to the kidney.

An aneurysm, or a weakness in the aorta, is an area in the aorta which bulges like a balloon from the pressure of the blood flow and if it grows can burst and hemorrhage or bleed uncontrollably. The aorta is the main blood vessel that carries blood from the heart to the rest of the body. The most common type of aortic aneurysm is an abdominal aortic aneurysm which can often be treated by a non-surgical stent-graft repair procedures.

An incision is made in the groin and a catheter is inserted into the blood vessel that leads to the aorta. A stent-graft which is a Dacron tube inside a metal cylinder is inserted through the catheter. The interventional radiologist watches the progression of the catheter on an x-ray monitor and directs or threads the stent to the location in the aorta where the aneurysm is located. Once the stent-graft is in place, the metal cylinder is expanded like a spring to hold tightly against the wall of the blood vessel. Blood will flow through the stent-graft, avoiding the aneurysm and the aneurysm will typically shrink over time.

Development of blood clots or emboli can be life threatening if they travel to the brain, lungs or heart and effect vital organ function or create an obstruction in the blood supply to that organ. Two interventional procedures are used to reduce the blood clot risks including thrombolysis and filter placement. Thrombolysis involves a process where a catheter is guided to the site of the clot and clot-busting drugs or thromobolytics are infused to break up the clot. Filter placement is a technique used when a blood clot is found in the blood vessels of the leg or deep vein thrombosis. A filter is guided via catheter into the blood vessel, or vena cava, which carries blood to the heart. The filter is used to trap the blood clot before it can reach the heart or lungs.

This test detects the amount of calcification present in the coronary arteries which allows an accurate prediction of the likelihood of narrowing of coronary arteries. Calcium is easily detected by CT scanning. The test provides a Coronary Artery Calcification Score based on the amount of calcification present. The scan is recommended for middle aged adults 35-70, with one or more risk factor including high cholesterol, high blood pressure, family history of heart disease, obesity, smoking and sedentary lifestyle.

MRI of the heart, aorta, coronary arteries and blood vessels is a fast and noninvasive tool for diagnosing coronary artery disease and heart problems. MRI allows an examination of the size and thickness of the chambers of the heart and assessment of heart attack or progressive heart disease damage. Cardiac MRI is completed without an incision and it results in less discomfort and risk than traditional cardiac procedures.

Athersclerosis is hardening of the arteries. This can cause narrowing and blockage of blood vessels. When this occurs, blood flow to part of the brain can be threatened and stroke can occur.

In 2004 a minimally invasive treatment for carotid atherosclerosis called carotid stenting received FDA approval. This procedure is performed by opening the artery with a small tube and then inflating a balloon catheter to press the plaque into the sides of the artery wall. Similar to angioplasty, this procedure is also utilized in the heart. Subsequently, a stent, or supportive tube, is then placed in the artery to cover the plaque and help keep the vessel open.

In deciding between surgery and stenting to treat carotid atherosclerosis, doctors consider the patient's overall health condition. In cases where a patient is symptomatic and at high risk for surgery (experiencing poor health in general, manifesting a heart condition or experiencing a previous stroke), angioplasty and stenting has been proven in a recent trial to be at least as effective as surgery. If the carotid artery is minimally constricted due to blockage, medical treatment may be recommended. However, if significant blockage is present, surgery (endarterectomy) is usually performed. Designed to remove the plaque causing the constriction which in turn allows the blood to flow more freely, endarterectomy is becoming increasingly more common, and is often referred to as "the gold standard" treatment for carotid atherosclerosis. Endarterectomy is especially recommended for patients who have significant blockage.

In cases where a narrowing or stenosis is present in the vertebral artery, angioplasty and stenting are usually performed.

CTA is a method of evaluating the vascular system using reconstructions of CT-acquired data. Angiography is an examination of vessels of the abdomen, brain and extremities and has typically been done through a catheter with x-ray contrast or dye injected into the artery, and then a scan is produced. With CT angiography the procedure is non-invasive, allows for decreased contrast dosage, and is a much shorter procedure that produces an increased amount of information. This procedure is completed in a less invasive manner than traditional angiography which results in less discomfort and risk at a lower cost.

Doppler ultrasound is a study that examines the major blood vessels in order to determine blockages to blood flow caused by clots, build up of plaque or congenital malformations. These studies can also be used to display vascular flow and the relationship to surrounding masses.

Endovascular Embolization of vascular lesions is a relatively new technique. The treatment is performed by injecting minute particles or introducing coils through a catheter to block the flow of blood. This procedure can be used for the following blood vessel abnormalities: AVMs, AVFs, traumatic vascular lesions (holes or tears in the lining of vessels), carotid cavernous fistulas (direct connection between a carotid artery and a vein), spinal vascular malformations (abnormal vessels in connections between the arteries and veins in the spinal cord, the spine or surrounding structures) and extracranial vascular malformations (abnormal vessels forming abnormal connection between the arteries and veins in the head and neck). The procedures can be done prior to surgery to make the surgery safer. Embolization can also be performed before radiation therapy to help shrink the lesion.

MRA is a non-invasive technique using MRI to image blood vessels of any body part, most commonly it is used for vessels of the head and neck and is used for the treatment of heart disorders, stroke and blood vessel disease. It is an alternative to conventional angiography and is used for detection of plaques and stenoses or narrowing in the blood vessel. This procedure is completed in a less invasive manner than traditional angiography which results in less discomfort and risk at a lower cost.

Stroke is the third leading cause of death in this country and the leading cause of adult disability. A stroke occurs when a section of the brain is deprived of blood supply which carries oxygen to the brain.

Symptoms:
The most common symptoms of a stroke are: sudden numbness or weakness in the face, arm and/or leg, particularly on one side of the body; sudden confusion, difficulty speaking or comprehending speech; sudden problems seeing including double or blurred vision, partial blindness; dizziness, difficulty walking, loss of balance and coordination; sudden onset of a severe, unexplained headache. If you experience any of these symptoms, immediately call 911 for emergency medical care.

Diagnosis:
There are a number of types of diagnostic exams that can be performed to determine if a stroke has occurred or someone is at risk for a stroke. A CT scan is typically the first test performed to diagnose a stroke. This exam can confirm a stroke and determine if the cause of the stroke is hemorrhage in the brain. An MRI may be performed to further localize the location of the stroke and determine the source. It may be able to identify the area deprived of blood flow and help determine treatment options. Angiography is an x-ray exam in which a contrast agent or dye is injected into a vein or artery to highlight the blood vessel. This exam allows interventionalists to define the exact location; special catheters can then be directed to the location to administer treatment. Doppler ultrasound may also be used to pinpoint blockage as well as MRA (Magnetic Resonance Angiography).

Treatment:

To Dissolve Clots:
If a stroke has been caused by blood clots, tPA or tissue plasminogen activator (a clot-dissolving drug) is frequently used to break-up or reduce the size of blood clots to the brain immediately following a stroke. The drug is typically administered through a special catheter within three to six hours after a stroke.

To Open Narrowed Carotid Arteries:
If a stroke is a result of narrowed carotid arteries, follow-up treatment involves procedures to open the narrowed arteries to prevent further strokes. A surgical treatment, carotid endarterectomy can be performed to scrape the plaque from the artery wall. Intracranial and Extracrnial Angioplasty is another procedure that interventional radiologists use to treat atherosclerosis ("hardening of the arteries") in the blood vessels of the head and neck. This "balloon" procedure is utilized to open up constricted blood vessels to increase blood flow and minimize blockage which leads to a stroke. The procedure is done with a small balloon catheter inserted, usually through the groin, which can be guided to the narrowing and inflated to open the blockage. In some instances a stent, or a small metal tube, is put in place that assists in holding the vessel open.

To Treat Hemorrhages:
When a stroke is caused by bleeding into the brain (hemorrhagic stroke) the treatment is different than that used for blood clots. Typically, a surgical clip has been the procedure used to treat hemorrhages. The use of coil embolization procedures performed by interventional neuroradiologists is increasing. In an embolization, an embolizing agent is injected via a catheter under x-ray guidance at the site of the ruptured blood vessel. The agent clots or closes off the bleeding blood vessel. Another procedure that may be used to stop bleeding or rupture is GCD coil insertion. The GDC is used to pack the vessel tightly to close off blood flow from the site. The coil is inserted via catheter.

A vascular duplex ultrasound uses sound waves that bounce off blood vessels to create an image.

Carotid Duplex ultrasound is used to look for plaque and blockages within the carotid arteries. The carotid arteries carry blood to the brain and are located within the neck.

Venous Duplex ultrasound is used to detect blood clots in the venous system (veins) of the upper or lower extremities.

Renal Artery Duplex ultrasound examines the arteries that lead to the kidneys. These arteries are located within the abdomen. An 8-hour fasting prep is required for this exam.

Mesenteric Artery Duplex ultrasound examines the arteries that supply blood flow to your large and small intestines. An 8-hour fasting prep is required for this exam.

Abdominal Aorta Duplex ultrasound is used to evaluate or detect the presence of an aneurysm or blockage within the abdominal aorta. An 8-hour fasting prep is required for this exam.

On some occasions it is necessary to permanently or temporarily occlude or close off a major artery in the head. Most people can tolerate having one carotid artery blocked. This may be done in order that a tumor which has grown around the artery might be removed or shrunk or that other malformations in the head might be avoided by the flow of blood. Typically a temporary test occlusion is performed in order to ascertain that it is safe to temporarily or permanently occlude an artery. A catheter is inserted into the artery and material is injected to block off the blood flow.

Vasospasm is the narrowing of the vessels that supply blood to the brain that occurs after bleed from a cerebral aneurysm. The spasm can prevent enough blood from reaching the brain and may lead to stroke. A catheter is placed into an artery and medication is infused to dilate the arteries More than one artery may need to be treated and it is not uncommon that the procedure may need to be repeated over the course of time.