10:47pm Sunday 24 September 2017

PET plus CT accurately visualizes suspected breast cancer tumors in 3-D, UC Davis researchers report

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.

Project funding for the breast PET/CT came from the Komen Foundation, the California Breast Cancer Research Program, the American Cancer Society and the National Institutes of Health.

About the UC Davis Department of Biomedical Engineering
The Department of Biomedical Engineering at UC Davis is actively contributing to new approaches to visualizing biological tissues. The results of research in medical imaging provide better diagnostic tools in clinical settings and improve the development of drugs and other therapies. Faculty and graduate students are involved in the development and application of new instruments and techniques in magnetic resonance imaging, ultrasound, positron emission tomography, computed tomography and optical imaging.

About UC Davis Cancer Center
UC Davis Cancer Center is the only National Cancer Institute-designated center serving the Central Valley and inland Northern California, a region of more than 6 million people. Its specialists provide compassionate, comprehensive care for more than 9,000 adults and children every year, and offer patients access to more than 150 clinical trials at any given time. Its innovative research program includes more than 280 scientists from UC Davis Health System in Sacramento, Calif.; the UC Davis campus in Davis, Calif.; and Lawrence Livermore National Laboratory in Livermore, Calif. For more information, visit www.ucdmc.ucdavis.edu/cancer.

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