MR-Guided Focused Ultrasound Ablation Using ExAblate:
The Latest in Uterine Fibroid Treatment

With MR-guided focused ultrasound ablation (MRgFUS) using ExAblate technology, uterine fibroid tumors are destroyed through the power of ultrasound energy. The method is becoming increasingly popular because it

• is noninvasive;
• is an outpatient procedure;
• requires little recovery time;
• does not require constant medication;
• has none of the side effects involved in hormone therapy; and
• does not expose the patient to radiation.

And, because it does not involve surgery, MRgFUS does not pose a risk of infection, blood loss, or adverse reaction to anesthesia.

MRgFUS patients can typically resume normal activities within one day and do not usually require medication to control postprocedure pain.

How MR-Guided Focused Ultrasound Ablation Works

Ultrasound is a type of energy. Like any type of energy, such as light or wind, ultrasound moves in the form of invisible waves that contain power. In MRgFUS, these waves move through your skin, muscle, and fat and their energy is focused on your uterine fibroids.

If the ultrasound waves destroy the fibroids, why do they not hurt my skin or muscle?

Think of focusing ultrasound waves like focusing sunshine through a magnifying glass. If you focus the sun through the magnifying glass at a point on a piece of paper for a period of time, that point on the paper will burn. However, the air between the magnifying glass and the paper is not hot enough to burn anything and neither is the paper surrounding that point, even though it was exposed to the sun. That is because the waves of sunshine travel and collect in that particular place. The collective energy of the waves is enough to burn the paper.

The same is true of the ultrasound waves SightLine uses to destroy fibroids. The collective energy of these waves once they reach the site of the tumor is enough to destroy it. However, at points between the focused ultrasound machine and the tumor, the waves lack the intensity to cause damage since they have not yet converged.

What part does MRI play in the procedure?

The key to destroying uterine fibroids with ultrasound energy is to ensure that enough of the energy has been applied to the tumors. Like the collective waves of sunshine through a magnifying glass, the collective energy of the ultrasound waves increases the temperature of the cells within the tumor. When the temperature of the tumor reaches a certain point, the cells of the tumor are destroyed.

A doctor performing MRgFUS can only ensure that the uterine fibroids are destroyed by keeping track of the temperature of the cells within the tumors. By placing the patient in a magnetic resonance imaging (MRI) machine during the ultrasound ablation, the doctor can detect changes in the tumors’ temperatures. The constant images provided by the MRI allow the physician to continue to apply the ultrasound energy as long as necessary and to determine when no more ultrasound energy is needed. Also, because these images provide your doctor with a constant view of your tumors, they allow her to guide the focused ultrasound to the next portion of the uterus to be treated.