Clinical PET system for early stage breast cancer diagnosis

May 18 2011

European researchers have developed a clinical PET system with the highest resolution and sensitivity in the market, specifically dedicated to breast cancer detection in early stages. The MAMMI (MAMmography with Molecular Imaging) device will allow doctors to start treatments one or even two years earlier than usual and also evaluate the patient's response to chemotherapy.

Coordinated by José María Benlloch, researcher of the Spanish National Research Council (CSIC) and co-director of the Institute for Molecular Imaging Instrumentation (I3M), 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 electronics circuit design.

The device is currently installed in the National Cancer Institute in Amsterdam (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 fifty patients. The new system will shortly be installed in the Provincial Hospital of Castellón (Spain) and other international hospitals have shown their interest in purchasing it.

The most striking novelty 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 picture is taken without compressing the breast thanks to the ring shape of the detector that surrounds the pendant breast. According to Dr Benlloch: "This significantly improves the visualisation and diagnosis because sometimes there are tumours 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) assessed the company ONCOVISION 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 PET system

The other major innovation is the technique used. The traditional mammogram is an x-ray of mammary glands. MAMMI, however, is based on the PET technique (Positron Emission Tomography) for the diagnosis of breast cancer, which offers numerous advantages.

In the first stages of a cancer, the malignant cells replicate in an uncontrolled way and, after one to two years, cause 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 morphological images and does not recognize the cancer until there is a lesion, the MAMMI PET measures the metabolic activity of the tumour 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 people with a high risk of suffering the disease. However, the result is a low resolution image and therefore does not detect small tumours. "Our device, however, is devoted exclusively to breasts so the detectors are very close to this part of the body and show tumours in early stages," explains 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 generally improves the diagnosis of all patients, but it is especially effective for women with breast implants or young women whose breast density has always made obtaining a clear image difficult.

Assessment in later stages

The mammography device marketed by the Valencian company 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 tumour tissue from the scar left by the operation."

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