Ultrasound News From RSNA 2019

Minimally Invasive Procedure Relieves Parkinson’s Tremors

A procedure that applies pulses of focused ultrasound to the brain is safe and effective for reducing tremors and improving quality of life in people with essential tremor or Parkinson’s disease tremor, according to a study presented at RSNA 2019. Tremors are rhythmic, involuntary muscle movements that cause shaking in one or more parts of the body, usually in the hands. They are characteristic of movement disorders such as essential tremor and Parkinson’s, two progressive conditions that affect millions of people worldwide. Previous treatment options for reducing tremors in patients who have not responded to medical therapy include deep brain stimulation, a surgical procedure that involves implanting a small electrode in the brain connected to a pulse generator that is implanted in the chest like a pacemaker.

A more recently available option is MR-guided focused ultrasound (MRgFUS) thalamotomy, an incisionless IR procedure in which focused beams of sound energy are used to heat and destroy a small part of a structure in the brain called the thalamus. The procedure gives relief to the opposite side of the body, meaning that treatment to the right side of the brain would relieve tremors on the left side of the body and vice versa. As a minimally invasive approach, focused ultrasound has advantages over deep brain stimulation, including a reduced risk of complications from bleeding and infections, according to study lead author Federico Bruno, MD, a radiologist in the department of biotechnological and applied clinical sciences at the University of L’Aquila in Italy.

“Another advantage is the immediate effect this treatment provides, unlike deep brain stimulation which requires a break-in period for the electrostimulation,” Bruno said. “Additionally, treatment with MRgFUS requires shorter hospitalization and is a fairly well-tolerated procedure, even by more fragile patients.”

For the study, Bruno and colleagues enrolled 39 patients, average age 64.5 years, with disabling tremors that had not responded to treatment. The people in the study group, including 18 with essential tremor and 21 with Parkinson’s, had experienced symptoms for an average of more than 10 years.

The researchers evaluated the patients for tremor severity and quality of life before MRgFUS thalamotomy, immediately after treatment, and over the course of the ensuing year. They found that 37 of 39 patients, or 95%, had substantial and immediate reduction of tremor. These reductions in tremor were sustained in follow-up evaluations. Quality of life evaluation showed substantial improvement in both the essential tremor and Parkinson’s groups.

“The study we present reports our experience of over a year in the treatment of tremor by thalamotomy with focused ultrasound,” Bruno said. “It is worth noting that we had a high number of patients with Parkinson’s disease in our series, compared to previously published data, where the procedure was used mainly in the treatment of essential tremor patients.”

Currently, MRgFUS thalamotomy is only available at a limited number of sites worldwide, Bruno said, but may become more widespread as research findings supporting its use are published. Improvements in neuroimaging techniques that allow for greater precision and detail in planning, implementation, and monitoring over time of the treatment should also expand its availability.

“The clinical application of this technique for neurological diseases is an absolute novelty—the clinical use was approved by the FDA less than three years ago,” Bruno said. “Few patients know of this treatment option so far, and there are not many specialized centers equipped with the required technology.”

Future research in this area includes the possibility of treating both sides of the thalamus. MRgFUS is also being explored in areas beyond movement disorders, Bruno noted. Several preclinical studies and clinical trials are looking at the technique for the treatment of neurological conditions such as neuropathic pain, epilepsy, and obsessive-compulsive disorders, as well as for treatment of brain tumors.

— Source: RSNA

Focused Ultrasound May Open Door to Alzheimer’s Treatment

Focused ultrasound is a safe and effective way to target and open areas of the blood-brain barrier, potentially allowing for new treatment approaches to Alzheimer’s disease, according to initial study results presented at RSNA 2019. There currently is no effective treatment for Alzheimer’s disease, the most common cause of dementia. The blood-brain barrier, a network of blood vessels and tissues that keeps foreign substances from entering the brain, presents a challenge to scientists researching treatments, as it also blocks potentially therapeutic medications from reaching targets inside the brain. Studies on animals have shown that pulses of low-intensity focused ultrasound (LIFU) delivered under MRI guidance can reversibly open this barrier and allow for targeted drug and stem cell delivery.

Researchers at three sites have been studying LIFU in humans for more than a year in a clinical trial led by Ali Rezai, MD, director of the West Virginia University (WVU) Rockefeller Neuroscience Institute in Morgantown, West Virginia. For the study, researchers delivered LIFU to specific sites in the brain critical to memory in three women, ages 61, 72, and 73, with early-stage Alzheimer’s disease and evidence of amyloid plaques—abnormal clumps of protein in the brain that are linked with Alzheimer’s disease. The patients received three successive treatments at two-week intervals. Researchers tracked them for bleeding, infection, and edema. Posttreatment brain MRI confirmed that the blood-brain barrier opened within the target areas immediately after treatment. Closure of the barrier was observed at each target within 24 hours.

“The results are promising,” said study coauthor Rashi Mehta, MD, an associate professor at WVU and research scholar at West Virginia Clinical and Translational Science Institute. “We were able to open the blood-brain barrier in a very precise manner and document closure of the barrier within 24 hours. The technique was reproduced successfully in the patients, with no adverse effects.”

MRI-guided LIFU involves placement of a helmet over the patient’s head after they are positioned in the MRI scanner. The helmet is equipped with more than 1,000 separate ultrasound transducers angled in different orientations. Each transducer delivers sound waves targeted to a specific area of the brain. Patients also receive an injection of contrast agent made up of microscopic bubbles. Once ultrasound is applied to the target area, the bubbles oscillate.

“The helmet transducer delivers focal energy to specified locations in the brain,” Mehta said. “Oscillation of the microbubbles causes mechanical effects on the capillaries in the target area, resulting in a transient loosening of the blood-brain barrier.” 

LIFU could help deliver therapeutic drugs into the brain to improve their effectiveness. Even without drugs, opening of the brain-blood barrier in animals has shown positive effects, Mehta said. These effects may be due to increased flow of the fluid that cleans the brain of toxic substances, an immune response triggered by the opening, or some combination of the two. While the research so far has focused on the technique’s safety, in the future, the researchers intend to study LIFU’s therapeutic effects.

“We’d like to treat more patients and study the long-term effects to see if there are improvements in memory and symptoms associated with Alzheimer’s disease,” Mehta said. “As safety is further clarified, the next step would be to use this approach to help deliver clinical drugs.”

— Source: RSNA