Breast-Specific Gamma Imaging is giving surgeons a much better way to detect breast cancer, according to the findings of a group of doctors from Legacy Good Samaritan Hospital (Portland, Oregon) perhaps an even better method than MRI.
The findings were presented during the Society of Black Academic Surgeons' annual meeting in Cleveland.
BSGI is a molecular breast-imaging technique used for the early detection of breast cancer and in the differentiation of malignant and benign tumors. It relies on advanced gamma imaging technology and mammographic positioning to optimize result.
The surgeons used Dilon Technologies' (Newport News, Virginia) high-resolution gamma camera, the Dilon 6800, which was given FDA approval in 1999. The device was marketed much later beginning only three years ago and received CE-mark status just this May.
The Dilon 6800 is a high-resolution, small-field-of-view gamma camera, optimized to perform BSGI, a molecular breast-imaging procedure that images the metabolic activity of breast lesions through radiotracer uptake.
Many medical centers around the country are now offering BSGI to their patients, including Cornell University Medical Center (New York); George Washington University Medical Center (Washington) and Northwestern Memorial Hospital (Chicago).
The device has been used on more than 25,000 patients in hospitals and private imaging centers nationwide, according to the company.
"This device looks at how the tissue observed behaves and is a more physiological approach than standard MRIs," Nancy Morter, director of marketing and corporate communications for Dilon, told Diagnostics & Imaging Week.
"It's about the size of an ultrasound and it's mobile," she added.
The study, which used the device, evaluated 138 patients with a cancer diagnosis. In this group, additional disease was found in a total of 11% of patients. Some 6% were in the same breast and 5% were in the opposite breast. This finding is very similar to that of an MRI study conducted by Northwestern University; however, BSGI provided a significantly lower false positive rate of 7% compared to 78% with the MRI study.
"Cancer tests have two values," Morter said. "First is the sensitivity, and that tells you when there is an abnormality. Second is the specificity, and that tells you when there is no abnormality. Well, MRIs have about the same sensitivity as [BGSI, but also] has a higher rate of false positives or sensitivity than BGSI. The result is too many people are having biopsises which is an expensive process."
In a separate study published in Breast Journal last year, 33 indeterminate lesions were evaluated using the Dilon 6800. There were a total of nine pathologically confirmed cancers in eight patients. Breast MRI resulted in 18 false positive cases while BSGI demonstrated only seven. There was no statistically significant difference in sensitivity of cancer detection between BSGI and MRI. BSGI demonstrated a greater specificity than MRI, 71% and 25%, respectively.
The study authors concluded that BSGI has comparable sensitivity and greater specificity than MRI for the detection of breast cancer in patients with equivocal mammograms. The smallest cancer detected by BSGI was 3 mm.
For difficult-to-diagnose patients, BSGI serves as a complementary diagnostic adjunctive procedure to mammography and ultrasound. With BSGI, the patient receives a radioactive tracing agent that is absorbed by all the cells in the body. Cancerous cells in the breast, due to their increased rate of metabolic activity, absorb a greater amount of the tracing agent than normal, healthy cells and generally appear as "hot spots" on BSGI images.
BSGI is ideal for patients with mammograms that are difficult to interpret. The interpretation challenges include dense breast tissue; suspicious areas on a mammogram; lumps that can be felt but not seen with mammography or ultrasound; implants and breast augmentation; scarring from previous surgeries and for women with notable family history of breast cancer.
"It's a more reliable method than MRIs and it's less expensive," Morter said.
Dilon was started 10 years ago and is a private company. The Dilon 6800 remains as the company's cornerstone device, but it isn't limited just toward monitoring for breast cancer.
Other uses include monitoring thyroids and spot bone scans.