Diagnostic Imaging
April 2004

SPECIAL SECTION: WOMEN'S HEALTH

High-intensity focused ultrasound zaps solid tumors

Ablation treatment provides quick noninvasive solution for uterine fibroids and other masses

High-intensity focused ultrasound is proving to be a highly versatile treatment technique that can safely and accurately ablate solid tumors of various types, according to studies presented at the 2003 RSNA meeting. And in the case of uterine fibroids, the technique provides an additional treatment option that does not require hospitalization for recovery or postoperative medication.

Dr. Feng Wu, director of the clinical center for tumor therapy at Chongqing Medical University, and colleagues collected clinical data from 1038 patients at 10 Chinese hospitals. All the patients had been treated with focused ultrasound ablation for solid tumors ranging from malignant bone tumors to breast cancer, kidney cancer, and uterine fibroids.

The investigators exposed the lesions, the majority of which were greater than 5 cm in diameter, to acoustic focal peak intensities of 5000 to 15,000 W/cm2 in one session.

Wu and colleagues reported that follow-up showed either no or reduced blood supply to the treated tumors, and imaging at six to 12 months showed obvious regression of the lesions. Wu said that his colleagues are also using focused ultrasound to treat uterine fibroids and are reporting satisfactory results.

A pair of studies presented at the RSNA meeting provided additional evidence for the viability of the technique in treating uterine fibroids.

In a study led by Dr. Miriam Sklair-Levy, a radiologist at Hadassah University Hospital in Jerusalem, researchers used MR-guided focused ultrasound to treat 22 women presenting with symptomatic uterine fibroids. They reported successful treatment with no complications. The mean volume of the fibroid treated was 109.3 mL3 and the average reduction in fibroid tissue was 30.2%.

In a similar study, researchers at Johns Hopkins Medical Institutions used T2-weighted MR imaging to identify and target fibroids in 16 patients. They ablated the tissue using sonication from high-intensity ultrasound. Using MR, the researchers monitored both tissue temperature and targeting throughout the ultrasound treatment. Patients received an MR follow-up six months later.

The average volume of the 22 fibroids treated was 114.1 cc, and the average volume reduction was 57%. In quality-of-life surveys conducted after the procedure, 88% of the patients had improved symptom severity scores. They reported no significant pain during the treatment, and the researchers reported no instances of unintended ablation or MR evidence of adjacent tissue damage.

"We've described in this paper and others the efficacy of the patients' improved symptoms, and they are equivalent, if not more so, to patients treated with uterine artery embolization or other surgical procedures, both in complication rate and efficacy," said lead author Dr. Hyun Kim, an assistant professor of radiology and surgery at Johns Hopkins.

The technique is not appropriate for every patient. The researchers avoided using the technique for patients with fibroids located at the back of the uterus, which would have placed the sonication too close to sensitive nerves near the spine. And in those same patients, the distance to the lesion would have dissipated the ultrasound energy as it passed through the layers of tissue.

More studies and clear guidelines are needed to help determine which treatments are appropriate for which patients, Kim said. But the technique's noninvasiveness may be the major deciding factor for some patients.

"The focused ultrasound technique is a wonderful triumph for people looking for treatment. In the past, patients had only the options of a hysterectomy or the less invasive UAE. But a lot of people are afraid of any type of surgery, and focused ultrasound is a viable, noninvasive method of treating fibroids with good efficacy," Kim said.