Semiconductor-based gamma camera finds subcentimeter breast tumors

CONTEXT: Dr. Deborah J. Rhodes and colleagues at the Mayo Clinic in Rochester, MN, have developed a new molecular breast imaging technique that combines a cadmium-zinc-telluride semiconductor detector with light breast compression to improve image resolution. The detector can be placed very close to the breast, eliminating dead space associated with conventional scintimammography. Earlier trials indicated that when equipped with a long-bore collimator, it was superior to conventional gamma cameras.

RESULTS: The gamma camera, equipped with an array of 2.5 x 2.5-mm solid-state detector elements producing a 20 x 20-cm field-of-view, was mounted on a modified mammography gantry. Forty women scheduled for breast biopsy were imaged after the injection of 20 millicuries of technetium-99m sestamibi. The scanner identified 33 of 36 cancerous lesions for an overall sensitivity rate of 92%. It found 19 of 22 surgery-confirmed lesions smaller than 1 cm for a sensitivity of 86%. The study was published in the January issue of Mayo Clinic Proceedings.

IMAGE: Molecular breast imaging using a modified mammography gantry detects invasive cancer in a patient's right breast. Dimensions of the lesion at surgery were 17 x 13 x 19 mm.

IMPLICATIONS: Breast imaging performed with this new technology will cost less than MRI and is not affected by breast density, as is the case with conventional mammography. The technology potentially fills a gap in the current array of breast imaging options, according to Rhodes.

"It will not replace mammograms, ultrasound, or MRI but will offer an important additional option to subgroups of women who are not served well by traditional imaging techniques," she said.