Imagine having a major surgery in which the surgeon uses beams of ultrasound energy to remove a tumor without a single incision. To some, this might sound like science fiction, but believe it or not, this type of surgery has now become a reality.
With high-intensity focused ultrasound, doctors can reach tissues deep within the body—in the bones, brain, blood vessels, etc.—without making a single cut…and often with minimal discomfort.
Focused ultrasound in action: The FDA has currently approved high-intensity focused ultrasound for treating uterine fibroids, prostate problems (cancer or prostate enlargement) and cancer that has spread to the bones.
Focused ultrasound differs from other scalpel-free technologies, such as Gamma Knife, because no radiation is involved and imaging feedback is in real time.
Many additional uses for focused ultrasound are being studied. Those that show tremendous promise…
• Deep-vein thrombosis (DVT). Many blood clots that form in the deep veins in the legs dissolve on their own, but others keep growing and are often life-threatening when a part of the clot breaks off and travels to the lungs. The standard treatment is a lengthy course of warfarin (Coumadin) or some other blood thinner. A tissue plasminogen activator (tPA) that breaks down the clot is given if the clot is very large and/or life-threatening. Both of these treatments have a high risk for dangerous side effects. Clots can also be removed with a catheter, which is used to guide a balloon or to inject tPA. But this carries risks as well.
Ultrasound breakthrough: Early research suggests that ultrasound vibrations can break up clots and also make them more susceptible to tPA.
• Drug delivery. There are few drugs for Parkinson’s or Alzheimer’s disease—now or in development—that can help these conditions. Reason: It’s very difficult for drugs to pass through the blood-brain barrier, a protective layer of tightly joined cells that line the blood vessels in the brain.
Ultrasound breakthrough: High-intensity focused ultrasound temporarily causes the cell junctions to open, which allows drugs to pass into the brain. This could give Alzheimer’s or Parkinson’s drugs easier access to affected brain regions and help chemotherapy drugs reach hard-to-treat brain tumors.
• Brain tumors. Ultrasound energy can pass through the skull and burn away a tumor without affecting healthy parts of the brain. The focused beam can target an area as small as a grain of rice. This could be an important breakthrough because conventional surgery and/or radiation can cause unintended brain damage, resulting in a loss of mental or physical function.
In 2014, focused ultrasound was used for the first time to successfully treat a recurrent brain tumor. The patient, who was treated in Zurich, was awake during the procedure and experienced no side effects or complications.
Ultrasound for brain tumors still presents technical challenges. Example: Irregularities in skull thickness and the high speed of sound passing through bone can cause overheating in the brain. One possible solution: Circulating chilled water around the scalp.
• Essential tremor. The New England Journal of Medicine recently published the results of a small exploratory study that used focused ultrasound for essential tremor, a neurological disorder that causes involuntary shaking. The study looked at 15 patients who had a poor response to medication. Doctors used ultrasound to perform unilateral thalamotomy, a procedure that destroys cells in the thalamus, an area of the brain involved in sensory and motor signal relay.
Results: After one year, tremors in the dominant hand had improved by 75%, and patients showed an 85% improvement in the ability to perform daily functions. The complications (such as an increase in involuntary movements) were comparable to those caused by conventional surgery—but the patients were spared the usual surgical trauma.
Focused ultrasound is still at an early stage of development. We’re likely to see a rapid expansion of uses beyond those already approved by the FDA within the next five or six years—but a lot of uncertainty remains.
Most procedures are being done only in laboratories or as a part of clinical studies,* and the procedures (and equipment) are very expensive. Even the procedures that have FDA approval may not be covered by insurance. For more information, go to the website of the Focused Ultrasound Foundation.
When you were a kid, did you ever use a magnifying glass to burn a hole through a leaf using the sun’s rays? The principle is the same with focused ultrasound, except that ultrasound waves (ultrafast vibrating sound waves) are used instead of sunbeams.
These are not the same low-intensity sound waves that are used in diagnostic scans. With high-intensity focused ultrasound, multiple beams of high energy pass through an acoustic lens (instead of a magnifying glass) and then converge to focus on a small area. The beams pass harmlessly through the body until they reach the desired location. There, they generate enough energy to destroy tumors, break down blood clots or create openings in the walls of blood vessels—all without affecting nearby tissues, unlike radiation, which impacts everything in its path.
There’s no incision, so recovery times are quicker. And there’s little risk of bleeding (the heat of ultrasound closes bleeding vessels) or infection (no external germs are introduced). Patients might experience burning sensations during the procedure, but the discomfort is usually slight.
*To find a clinical trial in your area, go to ClinicalTrials.gov. In the search box, type in “high-intensity focused ultrasound.”
