Mammography and Beyond Developing Technologies for the Early Detection of Breast Cancer (2001) / Chapter Skim
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2 Breast Imaging and Related Technologies
2 Breast Imaging and Related Technologies
Pages 55-104
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From page 55... ...
However, conventional film-based mammography may not provide adequate diagnostic information for some women with radiodense breast tissue. It has been estimated that this technology misses about 15 percent of breast cancer lesions (Mushlin et al., 1998~.
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From page 56... ...
Potential longer-term solutions using alternative modalities, such as optical or microwave imaging, are also briefly addressed. In addition, this chapter describes how novel technologies may affect breast cancer detection in ways beyond image acquisition, including image processing, display, management, storage, and transmission.
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From page 57... ...
_/Oa Scintimammography Positron emission tomography (PET) o Optical imaging Optical spectroscopy Thermography Electrical potential measurements o Electrical impedance imaging 0 Electronic palpation Thermoacoustic computed tomography, microwave imaging, Hall effect imaging, magnetomammography o + +++ ++ o +++ o o ++ +/oa 0 + o 0 + o 0 + + 0 NA NA NA Yes Yes Yes Yes No No Yes No Yes Yes No No Yes No Yes No No NOTE: This table is an attempt to classify a very diverse set of technologies in a rapidly changing field and thus is subject to change in the near future.
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From page 58... ...
May cause reduction in display of some masses. Three-dimensional ultrasound imaging: permits display of a volume of tissue rather than a single slice.
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From page 59... ...
, to from definition f some issue Lmor size General Electric's Senographe Ability to manipulate Spatial resolution and 2000 D has FDA approval for contrast and magnification luminance of digital use as both hard-copy and with one exposure. Ease display are lower than soft-copy displays.
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From page 60... ...
Use of magnetic resonance spectra and Studied c "functional" molecular markers to measure mamma biochemical components of cells and tissues. aspirate lesions Scintimammography Image created with radioactive tracers, MIBI apt which concentrate more in cancer tissues Other r than in normal tissues.
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From page 61... ...
s that noetic "Smart" MRI contrast agents: agents "activated" by biochemical processes are then detected by MRI; can correlate cell functions with disease state, and can track cell growth and behavior. Limited by identification of appropriate markers and lack of clinical data.
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From page 62... ...
, "Optical Biopsy" Optical tomography Infrared thermography Electrical potential measurements Uses tracers such as labeled glucose to identify regions in the body with altered metabolic activity, which is common in malignant tumors. Target antigens specific to breast cancer, include carcinoembryonic antigen and certain growth factor receptors.
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From page 63... ...
Early clinical studies on transdermal needle diagnostic. Systems being developed by Imaging Diagnostic Systems Inc., Dynamics Optical Breast Imaging Medical Systems, and Advanced Research Technologies, Inc.
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From page 64... ...
for cancerous tissue decrease impedance of device, tissue. mamma with let Electronic palpation Quantitative palpation of breast using Assuranc pressure sensors.
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From page 65... ...
and starting clinical studies for FDA approval. Development in early stages.
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From page 66... ...
A machine or a person may do the separation step, which depends on image contrast. Breast Properties FIGURE 2-1 Properties of breast tissue exploited by different modes of imaging.
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From page 67... ...
DIGITAL MAMMOGRAPHY Significant advances required in virtual reality technologies, including novel algorithms for breast .
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From page 68... ...
, digital image processing can potentially improve the lesion-to-background contrast and enhance subtle details that might be missed in a standard mammogram film. Fine-tuning of the image has not yet been proved to be beneficial for breast cancer detection, but in
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From page 69... ...
Digital mammography currently faces some fundamental technological problems that may impede its implementation. One current limitation of digital mammography is that the spatial resolution and luminance range of images displayed on a CRT even with the most advanced CRT technology are significantly lower for digital mammography than for conventional FSM.
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From page 70... ...
Army Breast Cancer Research and Materiel Command is comparing FFDM with FSM in a general screening population of nearly 7,000 women over age 40. Results thus far suggest that digital mammography performs no better than standard FSM in detecting malignant lesions but so far has led to fewer recalls of women for further examination than conventional mammography in a screening population (Lewin et al., 2000~.
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From page 71... ...
Contrary to conventional wisdom, only a few of the cancers detected in individuals with discrepant results were in areas of dense tissue (Lewin, 1999~. Given the information currently available, FFDM does not appear to offer significant improvements over FSM with regard to breast cancer detection.
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From page 72... ...
' benign 32 biopsies -- -- - - - - - -1 -- - - - - - - - -20 benign 0 high 12 malignant risk (8 invasive) 14 dismissed at conference FIGURE 2-4 Results from the Department of Defense study for the clinical evaluation of full field digital mammography for breast cancer screening.
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From page 73... ...
was first reported in 1977 to detect both benign and malignant breast disease in fatty and dense breasts. CT may also be capable of diagnosing early cancer in women who have had radiation therapy or surgery (Chang et al., 1977~.
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From page 74... ...
can be visualized on prior mammograms in retrospective reviews (Harvey et al., 1993; van Dijck et al., 1993; Warren-Burhenne et al., 2000~. Double reading of mammograms by two radiologists can improve the cancer detection rate (by 4 to 15 percent)
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From page 75... ...
, to use R2 Technologies' detection algorithms with the FDA-approved General Electric digital mammography machine. To date, only the CAD software package produced by R2 Technologies has FDA approval and is being marketed in the United States.
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From page 76... ...
Traditionally used as an adjunct to mammography in the identification of cysts and in guiding aspiration and biopsy, improvements in ultrasound technology have begun to expand the role of ultrasound in the differentiation of benign and malignant breast lesions and selection of patients for biopsy (Figure 2-5~. X-ray mammograms are frequently followed up with ultrasound imaging to determine whether a lesion that appeared on a mammogram is a cyst or a solid mass.
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From page 77... ...
Researchers have therefore begun to evaluate ultrasound in distinguishing malignant tumors from benign lesions (Ziewacz et al., 1999~. In one study of 750 breast lesions that were subsequently biopsied, ultrasound accurately diagnosed benign conditions 99.5 percent of the time.
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From page 78... ...
Physical breast examination by inspection and palpation enables detection of breast cancer by observing differences in mechanical properties, especially stiffness, since cancerous tissue is usually much more rigid and less easily deformable than normal breast tissue. However, cysts and certain benign lesions may have mechanical properties that can mimic malignant tumors, so finding a rigid mass within the breast does not confirm malignancy.
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From page 79... ...
More study is needed to assess these possibilities. Ongoing technological advances in ultrasound imaging have the potential to increase the use of ultrasound in breast cancer detection even more, but their stage of development is too early to predict their ultimate utility.
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From page 80... ...
In general, malignant tumors showed intense uptake of contrast agents, whereas the surrounding normal tissue did not (Figure 2-6~. Following this discovery, MRI has been studied as an emerging but as yet unproven technology for breast cancer detection.
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From page 81... ...
Although this type of cancer makes up only about 10 percent of all breast malignancies, it is frequently missed in mammograms and the extent of the cancer is difficult to determine by other methods. In one very small study of 20 women, MRI accurately predicted the extent of invasive lobular carcinoma in 85 percent of patients, whereas mammography accurately predicted the extent of invasive lobular carcinoma in only 31 percent of patients (Rodenko et al., 1996~.
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From page 82... ...
MRI scans can also reliably detect tumors in women with breast implants or dense breasts, both of which can interfere with interpretation of X-ray mammograms. Consequently, MRI is being tested as a screening technology for high-risk women, who may begin screening at a younger age and thus are more likely to have dense breast tissue.
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From page 83... ...
The technology uses gadolinium contrast agents within a molecular shell that are activated by specific biochemical processes inside the cell and that are then detected by conventional MRI. If the gadolinium agents were activated selectively in breast cancer cells, it could be detected in the images obtained by MRI.
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From page 84... ...
, preliminary studies that used noninvasive MRS have found that the elevated choline content of breast tumors can be detected in viva as well (Gribbestad et al., 1998; Kvistad et al., 1999; Roebuck et al., 1998~. These results suggest that MRS spectra, which are complementary to the images obtained by MRI, could potentially be used to characterize and diagnose breast lesions in a noninvasive manner.
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From page 85... ...
The tracers concentrate more in breast cancers than in normal breast tissues by a mechanism that is not fully understood but that may be related to the degree of cellular proliferation and vascular permeability. Several radioactive compounds are being investigated, although only one, technetium-99m sestamibi (MIBI)
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From page 86... ...
MIBI imaging is generally more expensive than ultrasound imaging or diagnostic mammography but is less expensive than MRI (Allen et al., 1999~. Unlike mammograms, MIBI scans are not affected by dense breast tissue, breast implants, or scarring (Edell and Eisen, 1999~.
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From page 87... ...
Additional improvements in spatial resolution could further improve the clinical utility of MIBI scans for breast cancer detection. New radiopharmaceuticals may also play a role in the future use of scintimammography.
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From page 88... ...
In theory, scanning by PET could prove useful for the detection of breast cancers in women with dense breasts, implants, or scars. However, the inability to biopsy lesions that are identified by PET but that are not visible on a mammogram is a major impediment to accurate diagnosis (Stuntz et al., 1999~.
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From page 89... ...
Past attempts to image tissues with light were severely restricted by the overwhelming scatter that occurs when optical radiation spreads through tissue; however, recent innovations in optical technologies have renewed interest in potential applications for breast cancer detection and characterization (Bosanko et al., 1990; Hebden and Delpy, 1997~. Currently, the two main areas of interest in this field are optical spectroscopy to characterize the structure and biochemical contents of lesions and optical imaging (or tomography)
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From page 90... ...
Furthermore, the physiology and thus the optical characteristics of normal and neoplastic breast tissues can be quite variable depending on the age, hormone status, and genetic background of the woman (Thomsen and Tatman, 1998~. Optical imaging systems are being commercially developed by Imaging Diagnostic Systems Inc.9 (IMDS; Plantation, Florida)
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From page 91... ...
In summary, optical imaging has long been thought to have potential as a means of breast cancer detection, but to date that potential has not yet been realized. Significant technological improvements in recent years may eventually propel this technology into the clinic, but a conclusion cannot yet be reached about its future utility.
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From page 92... ...
The procedure is noninvasive and does not require compression of the breast or radiation exposure. The first published report of breast cancer detection based on temperature measurement appeared in 1956 (Lawson)
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From page 93... ...
In December 1999, OmniCorder was granted FDA clearance to use BioScan as an adjunctive technology for the diagnosis of breast cancer.l3 The company has just begun to manufacture systems for distribution and is also conducting trials for other uses such as management of cancer therapy. Computerized Thermal Imaging, Inc., is also developing a system that records thermal images of breast tissues to construct a three-dimensional map of the breast; the system is being tested in clinical trials for FDA approval.l4 ELECTRICAL POTENTIAL MEASUREMENTS Studies indicate that rapid proliferation of epithelial tissue in the breast disrupts the normal polarization of the epithelium.
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From page 94... ...
It is noninvasive and not uncomfortable to women, and the procedure can be performed in less than 15 minutes (Faupel et al., 1997~. BBE has been tested primarily as a diagnostic tool for women with palpable breast lesions or nonpalpable lesions identified by mammography or ultrasonography.
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From page 95... ...
ELECTRICAL IMPEDANCE IMAGING Transmission of a low-voltage electrical signal through the breast can be used to measure the electrical impedance of the tissues (Figure 2-8~. Cytological and histological changes in cancerous tissue, including changes in the cellular and extracellular contents, electrolyte balances, and cellular membrane properties, can significantly decrease the impedance of cancerous tissue (by a factor of approximately 40 relative to that of normal tissue)
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From page 96... ...
ELECTRONIC PALPATION Electronic palpation uses pressure sensors to quantitatively measure palpable features of the breast such as the hardness and the size of lesionsl7 (Oncology News, l999~. Manual physical examination of the breast currently contributes significantly to cancer detection, but it is inherently 16Center for Devices and Radiological Health, FDA, Radiological Devices Panel Meeting, August 17, 1998, accessed April 3, 2000(http://www.fda.gov/ohrms/dockets/ac/98/ transept / 3446tl .
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From page 97... ...
The resistance of the breast to the device is measured by the pressure sensors and is used to create a computer-generated image of the hardness of the underlying breast tissue. This image serves as a quantitative, objective measurement of the hardness, discreteness, and size of breast lesions for diagnosis.
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From page 98... ...
No consistent effort was made to detect the 22 lesions by mammography.l8 The company is now preparing for clinical trials in the United States for FDA approval of the device. The device will be tested first with a population of women referred for diagnostic workup for possible breast cancer, who will be examined by mammography, palpagraphy, and clinical breast examination.
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From page 99... ...
Microwave Imaging Confocal microwave imaging is a new technique that uses the differential water content of cancerous tissue versus that of noncancerous tissue to detect tumors. The technique transmits short pulses of focused, low-power microwaves into the breast tissue, collects the back-scattered 19Robert Kruger, Optosonics, Inc., personal communication, March 8, 2000.
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From page 100... ...
In theory it will produce a high-contrast three-dimensional image of the breast and should be equally effective for women with dense breasts. Confocal microwave imaging of the breast is being developed primarily by researchers at the University of Wisconsin-Madison, Dartmouth, and Northwestern University.
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From page 101... ...
In theory, MMG should be equally effective for women with dense breasts and would not require breast .
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From page 102... ...
However, significant improvements in virtual reality technologies are still required, including novel algorithms for breast imaging, before this potential can be realized. SUMMARY At present, mammography is the only technology suitable for screening of the general population for breast cancer.
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From page 103... ...
The technology could potentially facilitate novel techniques such as tomosynthesis and digital subtraction mammography with X-ray-based contrast agents, but the value of these methods has not yet been proven. Digital mammography could also potentially improve the practice of screening and diagnostic mammography in other ways, for example, by facilitating electronic storage, retrieval, and transmission of mammograms.
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From page 104... ...
Ultimately, a new technology for early breast cancer detection will be beneficial only if it can lead to a reduction in the morbidity and mortality associated with the disease. Thus, improved methods for early detection of breast cancer may bring new challenges as well as opportunities for intervention.
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