Mayo Clinic reports that a new radiological modality called Molecular Breast Imaging “uses a new dual-head gamma camera system and is sensitive enough to detect tumors less than 10 millimeters (about two-fifths of an inch) in diameter in 88 percent of cases where it is used. Early findings from an ongoing comparison of the device with mammography show that it can detect small cancers that were not found with mammography, say the investigators. Mayo Clinic physicist Michael O’Connor, Ph.D., will present these results Saturday, Dec. 16, at the 2006 meeting of the San Antonio Breast Cancer Symposium.”
From the Mayo statement:
Conventional gamma cameras cannot be easily adapted for breast imaging. Instead, the investigators used new, small semiconductor-based gamma cameras and incorporated them into a new breast imaging system. Images obtained with these gamma cameras are not affected by dense or fatty tissue. In the procedure, women are injected with a small amount of the radioactive drug sestamibi that preferentially travels to tumors, which absorb the substance. These women then are seated in front of the device, which looks like “a strange mammography unit,” Dr. O’Connor says. Each breast is lightly compressed between the gamma cameras with just enough pressure to keep it from moving for 5 to 10 minutes while several images are taken. “It is much more comfortable for women, because a force of only 15 pounds is used, compared to the 45-pound force compression needed to take a mammogram,” he says.
The image usually shows low, but some, absorption of the sestamibi throughout the breast. In areas of cancer, the amount of drug absorption is significantly increased by the cancer. Although some benign conditions such as fibroadenomas will occasionally absorb the drug, creating a false-positive result, the researchers believe that the error rate is less than the approximately 10 percent rate found with traditional mammography.
The system used in the study was the LumaGEM® by Gamma Medica, a Northridge, California company.
The latest version of the device is explained by the company:
LumaGEM® 3200S is a high-performance, solid-state gamma camera, featuring a unique compact imaging head. LumaGEM® 3200S provides unparalleled resolution for use with Sestamibi and similar agents that localize in neovascular structures for breast cancer detection.
LumaGEM® 3200S is the latest advance in compact gamma cameras, having at its core, an array of fully solid state Cadmium Zinc Telluride (CZT) pixels. The field of view is larger and the energy resolution is the best in the industry at <6% for 99mTc providing significantly improved scatter rejection. LumaGEM® 3200S attaches to existing upright mammography systems for scintimammography of breast lesions. The camera mounts directly onto the system in place of the film bucky, and its compact size, and small "dead-edge" means it can image all the way up to the chest wall. This unique mounting mechanism, as well as the use of breast compression, allows the radiologist to obtain images using any standard mammography view (e.g. CC, ML). Correlation with the mammogram is excellent!