Introduction
Interventional radiology - a minimally invasive alternative to surgery - is helping thousands of patients with heart disease, osteoporosis, tumors and many other conditions who are not able to undergo surgery. For these patients, an interventional radiology procedure may provide the same benefits as surgery without the stress of a surgical operation.

Interventional radiologists differ from conventional surgeons by using digital technology to make repairs in the body and by making tiny or no incisions. The radiologist does not need to look directly at the area in which he is working. Instead, he inserts a tiny endoscope (a tube with flexible glass that allows the viewer to see inside the body) through a catheter placed in the patient's vein or artery. These flexible endoscopes use state of the art lenses to transmit images to a monitor (screen) placed near the patient. The radiologist watches the monitor and manipulates his instruments outside the body.

Many procedures can be done in one day and can be performed with the patient sedated but conscious.

Interventional radiology has five main benefits:

• It results in less trauma to the body than does surgery
• It requires less anesthesia
• It shortens the hospital stay
• It shortens the recovery period
• It results in less pain

How is interventional radiology performed?
Patients should discuss the possibility of undergoing an interventional radiology procedure with their primary physician. Their physician will then determine whether he/she will benefit from a procedure, and refer the patient to a radiologist.

At the initial visit, the radiologist reviews the patient's medical records, and discusses the procedure, its risks and its benefits. Patients usually can be admitted on the same day. Most of the procedures described in this article begin with an intravenous catheter placed in the hand or arm that delivers medication to help the patient relax, and to minimize any discomfort. Patients are conscious, and can talk with their health-care team.

In most cases, a specially trained nurse monitors vital signs such as heartbeat and blood pressure throughout the procedure. For children and patients with serious medical problems, an anesthesiologist will be on hand to provide anesthesia, if necessary.

Once the patient is comfortable, the radiologist paints an antibacterial solution on the skin where the catheter will be placed. This decreases the possibility of infection. Sterile surgical drapes are placed around the area to prevent any contamination with germs.

The radiologist then injects the skin with a small amount of local anesthesia such as lidocaine. This rarely causes any significant discomfort. When the skin is numb, a hollow needle or plastic sheath is placed directly into a large blood vessel. Catheters can then be passed through the sheath or needle.

Case Study
Dr. Jeffrey Pollak, associate professor of radiology at Yale University School of Medicine and co-director of the Center for Interventional Radiology describes a unique case where interventional radiology was used to both diagnose and treat a difficult problem.

"The patient had already been through two operations to remove gallstones from the channel (duct) between the gall bladder and intestine through which bile drains. Nevertheless, classic x-ray images continued to show something the size and shape of a gallstone still present in the duct, causing a build up of bile and pain.

"However," adds Dr. Pollak "catheters placed in the duct showed no evidence of a stone. We were able to pass a tiny endoscope directly into the duct and were surprised to see a tiny polyp obstructing bile flow. Previous attempts at catheter placement flattened the polyp against the wall of the channel so it seemed to disappear. We were able to definitively find the problem and remove the polyp without the patient undergoing further surgery."

What health problems can be diagnosed and /or treated by interventional radiology?
Interventional radiologists have developed procedures that can help a number of medical conditions including opening clogged arteries, shrinking fibroid tumors and reducing or eliminating the pain of osteoporosis.

Some of the most common interventional radiology procedures are angioplasty, stent grafting, embolization, tumor embolization, fibroid embolization and vertebralplasty.

Descriptions of Interventional Radiology Procedures Angioplasty: Opening narrowed arteries
One of the most common interventional radiology procedures is called angioplasty, used in patients at risk for heart attack or stroke. Balloons passed through catheters are inflated in dangerously narrowed arteries to restore blood flow to many parts of the body, most commonly the brain, kidneys and legs.

Blood flow can also be restored to arteries that have been completely obstructed by clots by placing chemicals to dissolve the clots in specific locations or by mechanically removing clots from larger vessels.

In some cases the radiologist will also place a stent- a small mesh cylinder- in the artery using the same technique as in the angioplasty, to help keep the artery open after angioplasty.

Stent grafting
Stent grafting places a synthetic tube or stent into large blood vessels, usually the abdominal aorta, when an aneurysm (a bulging weakness in the vessel wall) is at risk of rupturing and causing fatal bleeding.

Most patients with abdominal aortic aneurysms are elderly and have additional serious diseases that may prevent them from undergoing surgery. The stent graft procedure offers a highly successful alternative to surgery and minimizes the risk of aneurysm rupture.

Embolization: Plugging blood vessels
Embolization is a commonly performed procedure. The radiologist places tiny metal coils, plastic plugs, or gelatin sponges directly in open blood vessels or in aneurysms before rupture and serious bleeding occur. When patients are acutely bleeding, emergency embolization can be life saving, especially if the blood vessels are difficult to see during surgery or are located in an area not easy to access surgically. Severe nosebleeds, postpartum (after childbirth) hemorrhage, ruptured blood vessels in the brain and traumatic bleeding may all be successfully isolated and treated using embolization.

Tumor embolization
Tumors throughout the body can also be treated with embolization. By cutting off the arterial blood supply to the tumor with coils or plugs, the oxygen and nutrients that the tumor needs to grow are also cut off. This process, called tumor devascularization, may shrink the tumor enough so that it can be treated with surgery, chemotherapy or both.

Uterine fibroid embolization
Recently, interventional radiologists at Yale University School of Medicine have used embolization to successfully shrink uterine fibroid tumors in 85-90% of patients. Shrinking fibroid tumors is beneficial for women whose tumors are large enough to give the appearance of an advanced pregnancy or that cause pain and bleeding.

"Patients usually have some discomfort for 7-10 days after the embolization while the tumor is shrinking, although less than the pain anticipated from a surgical incision. Most patients can return to work a week after embolization, compared to a 4-6 week recovery from surgery," says Dr. Melvin Rosenblatt, associate professor of radiology and co-director of the Center for Interventional Radiology at Yale University School of Medicine.

Not all centers offer fibroid embolization and not all women are candidates for the procedure. Approximately 1-2% of women will have complications from the procedure including infection and premature menopause.

Blood Clots and Varicose Veins
Embolization can be used to remove or dissolve blood clots in the legs. When patients have recurrent blood clots, pieces (emboli) may float through the heart lodging in the lungs. This potentially fatal problem can be treated by placing a filter into the vena cava, the large vein that carries blood directly into the heart. Patients who receive blood thinners to prevent recurrent clots and emboli have a 5-8% recurrence rate. This rate is decreased to approximately 3% when filters are placed.

Another technique, radio frequency ablation, uses energy waves to reduce or eliminate varicose veins. Although varicose veins are not a life-threatening problem, many patients find that they significantly interfere with their activity level and daily functioning.

Vertebralplasty
For elderly patients with severe osteoporosis, collapse of the vertebral bodies in the spine causes debilitating pain and immobility. In vertebralplasty, a needle is placed directly into the spine. The radiologist then injects methylmethacrylate, or synthetic bone cement, to replace the lost bone strength and prevent future small fractures.

"If treated in the first few weeks after onset of symptoms, vertebralplasty can greatly decrease pain for over 80% of osteoporosis patients," said Dr. Michele Johnson, associate professor of radiology at Yale University School of Medicine and director of Interventional Neuroradiology. "Patients usually report less pain and improved mobility within 24 hours," she adds.

Help for Cancer Patients
Some interventional radiology procedures have been developed especially to improve the quality of life for patients with severe illnesses, such as cancer. Patients with end-stage cancers, for example, often experience symptoms, such as an accumulation of fluid in the chest cavity, that do not respond to treatment.

A radiologist can insert a small catheter into the chest cavity that can be left in place, allowing the fluid to drain. Chemicals can then be inserted through the catheter to minimize or prevent the fluid from building up again. With the catheter, patients no longer need to undergo a painful daily procedure at the hospital to have the fluid drained.

What the future holds
Rapid strides are being made in this area of medicine. Interventional radiologists are able to take advantage of the increased use of digital technology in several ways:

• Improved 3-D reconstruction that gives better perspectives of the human body will help radiologists increase the scope and range of their procedures.
• Advances in magnetic resonance imaging (MRI ) will help radiologists see parts of the body that are too small to be seen on contemporary imaging equipment.
• Nanotechnology (tiny computer technology) is producing microscopic electronic devices that can be placed through catheters. Once placed, their function can be controlled externally or programmed.
• And improved devices made of more durable materials will keep blood vessels open more reliably and prevent the recurrence of narrowed arteries.