PET Imaging Advance Significant for Early Detection of Breast Cancer

European researchers have developed a clinical positron emission tomography (PET) system with very high resolution and sensitivity, specifically designed for breast cancer detection in early stages. The MAMMI (mammography with molecular imaging) device will allow clinicians to begin treatments one or even two years earlier than usual and also evaluate the patient's response to chemotherapy.

Coordinated by José María Benlloch, a researcher from the Spanish National Research Council (CSIC; Madrid, Spain), the MAMMI Project was created by a multidisciplinary team of eight European research institutions and companies, ranging from medical oncology and pharmacokinetics research to molecular imaging instrumentation, advanced image processing software, and integrated electronic circuit design.

The device is currently installed in the National Cancer Institute in Amsterdam (The Netherlands) and was previously set up at the clinic of the Technical University of Munich (Germany), where they have completed the clinical research and examined over 50 patients. The new system will soon be installed in the Provincial Hospital of Castellón (Spain) and other international hospitals have shown their interest in purchasing it.

The most remarkable innovation of the mammogram is the way it captures the image. The patient lies face down on a special table, and enters a breast in one of the openings. Beside the stretcher, the specialist positions a trolley that incorporates the detection system based on a gamma ray sensor. The image is taken without compressing the breast due to the ring shape of the detector that surrounds the pendant breast. According to Dr. Benlloch, "This significantly improves the visualization and diagnosis because sometimes there are tumors that are very close to the base of the pectoral muscle."

This new mammogram also provides greater patient comfort. In this sense, the Biomechanics Institute of Valencia (IBV; Spain) assessed the company Oncovision (Valencia, Spain) in the design, manufacturing, and mechanical tests of the stretcher, and applied user-friendly design methodologies and ergonomic criteria. For example, lifting columns were added to the table to facilitate its use by the elderly and disabled.

The other major development is the technique used. The traditional mammogram is an X-ray of the breast. MAMMI, however, is based on the positron emission tomography (PET) technique for the diagnosis of breast cancer, which offers numerous advantages. In the first stages of a cancer, the malignant cells replicate in an uncontrolled manner, and after one to two years, become a lesion that is visible with the current techniques. After that, the lesion extends and takes about another year until it can be felt.

While current diagnostic equipment is based on morphologic images and does not recognize the cancer until there is a lesion, the MAMMI PET measures the metabolic activity of the tumor by locating the high glucose uptake of the cancer cells. This allows the specialist to detect the disease much earlier and numerous studies have confirmed that early detection reduces mortality by 29%.

Until now, whole-body PET scans were indicated for breast cancer patients or for individuals with a high risk of suffering the disease. However, the result is a low-resolution image and therefore does not detect small tumors. "Our device, however, is devoted exclusively to breasts so the detectors are very close to this part of the body and show tumors in early stages," explained Luis Caballero, head of the project in Oncovision.

In comparison, MAMMI can see lesions as little as 1.5 mm, while the best of the systems that currently exist offers a resolution of 5 mm. The system typically improves the diagnosis of all patients, but it is particularly effective for women with breast implants or young women whose breast density has always made obtaining a clear image difficult.

The mammography device can also monitor whether the treatment the patient with breast cancer is following actually works. According to Dr. Caballero, "By showing the uptake of glucose, the PET technique is the only one able to reveal whether there are still cancer tissues after an operation, since with the other techniques it is impossible to distinguish tumor tissue from the scar left by the operation."

Moreover, according to the researchers, PET reveals whether the therapies of radiation and chemotherapy are effective or need to be modified. Because MAMMI is a more precise PET instrument, it ensures a better assessment of tumor activity and its response to therapy.

Related Links:
Spanish National Research Council
National Cancer Institute, Amsterdam
Oncovision