This page describes the ongoing research performed by our group to develop methods for imaged-guided breast biopsy

 PROJECT Outline

    An estimated 25% of women receiving mammograms have radiographically dense breasts, which make lesion detection difficult or impossible because the tumors are virtually indistinguishable from dense normal breast tissue. This number is certain to rise in light of the recent recommendation by the National Cancer Institute that women over the age of 40 and at average risk for breast cancer start regular mammographic screening; considering dense breasts are most common in women under the age of 50. When mammograms are not definitive, the dense breasts are physically examined, with usually no further evaluation. While physical exam of the breast is a very valuable diagnostic tool, the nodular nature of many dense, fibrous breasts can make detection of lesions challenging in this group.

    Recently, imaging of the radioactive sugar FDG with Positron Emission Tomography (PET) scanners has been successfully applied to the detection of breast cancer. The effectiveness of FDG as a tracer for cancer detection is due to the fact that most cancers use more sugar than normal cells. Therefore, unlike mammography, which relies on differences in density between tumor and normal tissue, breast imaging with FDG is based on the metabolic differences between cancerous and normal tissues. Hence, the similarity of density between tumor and dense breast tissue which complicates the use of mammography does not interfere with lesion detection. One of the drawbacks in the use of FDG and PET to detect and evaluate cancers has been that the resolution of conventional PET scanners limit the minimum size of the detectable tumor and require lengthy acquisition times. Recently new dedicated high-sensitivity breast imagers which produce rapid, high-resolution planar images of FDG concentration in the breast have been developed. These devices called Positron Emission Mammography (PEM) scanners have shown some promise in the ability to detect small FDG-avid lesions in the breast.

    Since increased FDG uptake is often associated with malignant cancer, some have suggested that this method could be used to determine whether a suspicious lesion is cancerous. While this is an attractive proposal, it is unlikely that the information obtained solely from FDG images can replace more definitive pathology results gained from tissue samples acquired through biopsy. Therefore, an effective method for performing needle biopsies of lesions discovered with FDG is necessary; especially to effectively diagnose the population of women with radio-dense breasts. While methods for performing biopsies using PET images as guides have been developed, these techniques were developed for brain biopsy and usually require complex and bulky equipment unsuited for application to breast imaging. Additionally, these methods are designed for use with traditional PET scanners, not for the potentially more valuable dedicated breast scanners. The PEM imaging system was contructed by the Detector Group led by Stan Majewski at Jefferson National Accelerator Facility in Newport News, VA.

INSTRUMENTATION

    We have developed a novel method for performing core biopsy of lesions using a new class of breast imaging devices and a special stereotactic algorithm (United States Patent #5,961,457).  This technique, known as Positron Emission Guided Breast Biopsy, is targeted specifically at women with difficult to image breasts. Factors such as amounts of radioactive sugar injected, timing of the scanning process and data acquisition duration will be investigated. Ultimately, it is envisioned that this method would not be used for screening, instead it would be used to examine the breasts of women with indeterminate mammograms and who have other risk factors associated with breast cancer (ie. familiar or personal history of breast cancer). Development of this novel, simple and rapid method for the radionuclide-guidance of suspicious breast lesions, could potentially improve the detection and effective diagnosis of normally undetected tumors in women with dense breasts; possibly resulting in earlier treatment and increased breast cancer survival rates in this population .

 Detectors Mounted on Biopsy Table                    Biopsy Apparatus User Interface

Example of a PEM image.

  Picture showing image pixel separation for PEM detector.

This image of a phantom was acquired with our PEM imager.  The phantom is a 4cm thick block of gelatin simulating a compressed breast.  Four spheres with different diameters (5, 9, 12 and 15mm) were imbedded in the gelatin block.  The spheres and gelatin contained concentrations of FDG commonly reported for breast carcinoma and normal breast tissue.  The image was filtered and intensity levels adjusted to optimize the image.  Image acquisition time was 5min.

PUBLISHED PAPERS

R.R. Raylman, E.P. Ficaro, R.L. Wahl. Stereotactic Coordinates from ECT Sinograms for Radionuclide-Guided Breast Biopsy. Journal of Nuclear Medicine 1996;37:1562-1567.

R.R. Raylman, S. Majewski, R. Wojcik, A.G. Weisenberger, B. Kross, H.A. Bishop.  The Potential Role of Positron Emission Mammography for Detection of Breast Cancer. A Phantom Study.  Medical Physics 2000;27(8):1943-1954.

R. R. Raylman, S. Majewski, A.G. Weisenberger, V. Popov, R. Wojcik, B. Kross, J.S. Schreiman, H. A. Bishop. Positron Emission Mammography-Guided Breast Biopsy, Journal of Nuclear Medicine, 2001;42:960-966.

R.R. Raylman, S. Majewski, R. Wojcik, A.G. Weisenberger, B. Kross, V. Popov. Corrections for the Effects of Accidental Coincidences, Compton Scatter and Object Size In Positron Emission Mammography (PEM) Imaging. IEEE Transactions on Nuclear Science, 2001;48:913-923.

R.R. Raylman, S. Majewski, M.F. Smith, R. Wojcik, A.G. Weisenberger, B. Kross, V. Popov, J.J. Derakhshan, Comparison of Scintillators for Positron Emission Mammography (PEM) Systems, IEEE Transactions on Nuclear Science, 2003;50:42-49.

M.F. Smith, S. Majewski, A.G. Weisenberger, D.A. Kieper, R.R. Raylman, T.G. Turkington, Analysis of Factors Affecting Positron Emission Mammography (PEM) Image Formation, IEEE Transactions on Nuclear Science, 2003;50:53-59.

ACKNOWLEDGEMENTS

This work was supported by a research grant from the National Cancer Institute (1 R21 CA82752-01).