First breast PET/CT scanner to visualize suspected cancerous lesions in 3-D.
Sep 4, 2009 - 11:35:47 PM

An innovative collaboration among UC Davis engineers, physicists and radiologists has resulted in the first-ever fully 3-D breast imaging technique that uses both high-resolution PET and CT scanning.

After years of work to build the dedicated breast PET/CT scanner, the team of scientists has shown that use of the technology on an uncompressed breast can accurately visualize suspected cancerous lesions in three dimensions.

Researchers say their findings, published in the September issue of the Journal of Nuclear Medicine, boost efforts to personalize breast cancer treatment for patients.

“People have been talking about individualized chemotherapy for breast cancer, and this could be the technology that makes such a paradigm fly,” said Ramsey Badawi, a UC Davis physicist and co-author of the study.

Badawi said breast PET/CT would not replace mammography for regular breast cancer screening, but could be used, for example, to determine whether and which chemotherapy would be beneficial before surgical removal of the tumor. It also could be used to locate small tumors to improve staging and aid in surgery planning.

In developing the system, Badawi recognized the potential benefits of PET (positron emission tomography) combined with CT (computed tomography). PET scans measure physiological functions, help monitor how well drugs are working and distinguish benign from malignant tumors. CT scans provide information about the body’s structure. The combined technologies can result in much better images to help doctors make treatment decisions.

The problem was that the combined technologies are only available on full-body PET/CT scanners, which can’t easily pinpoint breast tumors smaller than one-half inch. A new approach would be needed to image small, early-stage tumors.

Badawi joined forces with UC Davis radiology physicist John Boone, who built the first dedicated breast CT scanner, and with Simon Cherry, director of the UC Davis Center for Molecular and Genomic Imaging, who built the first PET machine with enough resolution to accurately image tumors in mice. Badawi mounted a PET scanner onto Boone’s breast CT scanner to capture the dual data. The team was also assisted by UC Davis biomedical engineer Jinyi Qi, who developed advanced techniques for reconstructing the images.

A breast PET/CT scan takes about 10 minutes per breast. The patient lies on a padded table while the breast hangs down through a circular opening, an approach patients have said is far more comfortable than standard compression-based imaging. The CT images are generated using an X-ray source and detector that are rotated around the breast to produce a 3-D map of the breast structure. The PET scan is done next, using a pair of gamma ray detectors that rotate around the breast to produce a second, 3-D map of breast metabolism.

The combination of the two maps shows the precise location of cancer as “hot spots.” In their study of four patients, Badawi and his colleagues found that the scans produced high-resolution 3-D images that accurately showed the size, extent and location of biopsy-confirmed breast cancer.

Badawi said more clinical trials on the device are needed before it can be moved into commercial development. One trial will use the system to monitor women who will undergo chemotherapy prior to surgery to determine if PET/CT can accurately predict tumor response.

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