Image: PRE: Pretreatment transverse MR image obtained with perfusion technique shows an enhancing lesion of 1.2 cm (circled) in the upper quadrants of the right breast; the lesion shows with irregular margin and appears color-coded in red due to the washout pattern (malignancy). POST: Same MR image technique obtained post-treatment (10 days): Absence of enhancement was seen at perfusion color-coded image after noninvasive thermal ablation with MR-guided high-intensity focused ultrasound; the black hole stands for necrosis nicely demonstrating also the absence of residual tumor (Photo courtesy of RSNA).
A technique that utilizes focused ultrasound under magnetic resonance imaging (MRI) guidance to heat and destroy tumors may offer a safe and effective treatment for breast cancer.
The new findings were presented according to research being presented today at the annual meeting of the Radiological Society of North America (RSNA), held in December 1-6, 2013, in Chicago (IL, USA). MR-guided focused ultrasound (MRgFUS) ablation is a noninvasive technique that requires no incision or puncture to perform. Instead, it uses the acoustic energy from high-intensity focused ultrasound to ablate diseased tissue. Continuous MRI scanning is employed to locate the lesions and monitor the temperature change during the ablation process.
The primary advantages of MRgFUS over other breast cancer treatments are that it is a noninvasive, outpatient procedure offering a quick recovery time, and that it provides precise measurement of temperature alterations during the procedure. “In the treatment stage, we are able to precisely visualize where the energy is having an effect and to measure exactly the rise in temperature,” said Alessandro Napoli, MD, PhD, assistant professor of radiology at Sapienza University (Rome, Italy). “Temperature monitoring is particularly important since too low a temperature is ineffective and too high a temperature may be dangerous.”
Dr. Napoli and colleagues evaluated the safety and efficacy of MRgFUS in 12 patients with invasive ductal breast cancer before surgical removal of the cancer and biopsy of the lymph nodes. They used 3T MRI to validate the presence and treatable location of cancerous lesions. The patients then underwent single-session MRgFUS treatment. Researchers evaluated treatment efficacy through postsurgery pathology.
None of the patients experienced significant complications during or immediately after the procedure. In 10 of the 12 patients, MRI scans revealed no enhancement in the treatment area after the procedure. Postsurgery histological evaluation confirmed the absence of residual disease in the treatment area in those 10 patients. “This procedure allows for safe ablation of breast cancer,” Dr. Napoli said. “At pathology, no significant viable tumor was found in the specimens from these 10 patients.”
In the other two instances, treatment failed due to transducer malfunction, and the pathologist observed residual tumor in the samples.
According to Dr. Napoli, MRI guidance is crucial for correct identification of lesions, treatment planning and real-time control during the procedure. Specifically, tracking with MRI allows for efficient deposit of energy into the region of treatment at the correct range of between 60 °C and 70 °C. “This is carried out by a special sequence that is called MR thermometry,” Dr. Napoli said. “Only MRI presently has the ability to determine, in real time, fine temperature quantification.”
Even though these preliminary findings are promising, Dr. Napoli noted that more studies would be needed before the approach can be adopted as a stand-alone treatment for breast cancer.