When compared with scintimammographic images taken on a standard gamma camera, the new camera, called a high-resolution breast-specific gamma camera (HRBGC), was able to detect more (78%) malignancies than a standard gamma camera (68%). The sensitivity of breast cancer detected in lesions <1cm increased from 46.7% to 66.7% using the new camera. It also detected 3 lesions that were not visible with mammography; one of which did not appear on the standard camera. All three were in areas of dense breast tissue.
Scintimammography is a technique in which women are injected with the radiotracer 99mTc-sestamibi that is absorbed more by malignant tissue than normal tissue, resulting in an image that can be used to locate cancerous areas. Scintimammography has been shown in studies to detect breast cancer better than traditional mammography. Standard gamma cameras have some significant drawbacks, including registration and resolution issues, and the fact that they cannot acquire multiple views, making it difficult detect lesions <1cm. This preliminary study utilized a prototype breast-specific gamma camera that was designed to address these problems.
Fifty women with a total of 58 lesions that were either palpable, or which had shown up on a mammogram or sonogram even though they couldn't be felt, were included in the study. After injection with the radiopharmaceutical, the women received consecutive scans; one with the conventional gamma camera, and then one with the prototype camera. All the lesions were ultimately either surgically or needle biopsied, so that findings were pathologically confirmed. Of the lesions, 30 (52%) were benign, and 28 (48%) were malignant. The study authors suggested that since the second, high-resolution scan was undertaken outside the limits of the tracer's activity, future studies with proper dose-to-scan time-scanning might show even better results.
"This new type of camera ultimately may offer physicians a practical way to include scintimammography, with its superior ability to detect cancer, in their clinical practice as an adjunct to mammography," stated study author Rachel Brem, MD.
A commentary that accompanied the article noted that while current mammography is very good at detecting breast abnormalities it only predicts 50% of the time whether the abnormality is actually breast cancer. Scintimammography and the breast-specific camera may overcome the problem of differentiating benign from malignant abnormalities in addition to locating otherwise undetected cancers.
High-Resolution Scintimammography: A Pilot Study was written by Rachel F. Brem, MD of the Breast Imaging and Intervention Center, George Washington University Medical Center, Washington, DC; Joelle M. Schoonjans, MD, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Institutions, Baltimore, MD; Douglas A. Kieper, BS and Stan Majewski, PhD, Thomas Jefferson National Accelerator Facility, Newport News, Virginia; Steven Goodman, MD, PhD, Department of Oncology, Johns Hopkins Institutions, Baltimore, MD; and Cahid Civelek, MD, Department of Radiology and Radiological Science, Johns Hopkins Institutions. This article was supported by a grant from Dilon Technologies, Inc., and by DuPont Pharma, Inc. Dr. Brem is a consultant to and has stock options in Dilon Technologies, Inc.
Copies of the article and images related to the study are available to media upon request to Karen Lubieniecki at Karenlub@aol.com; (703) 683-0357. Copies of this and past issues of The Journal of Nuclear Medicine are available online at jnm.snmjournals.org. Print copies can be obtained at $15 per copy by contacting the SNM Service Center, Society of Nuclear Medicine, 1850 Samuel Morse Drive, Reston, VA 20190-5315; phone: (703) 326-1186; fax: (703) 708-9015; e-mail: servicecenter@snm.org. A yearly subscription to the journal is $170. A journal subscription is a member benefit of the Society of Nuclear Medicine.
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