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Use of mammography in asymptomatic women does discover breast cancer at an earlier point in development, as measured by size, invasiveness, and nodal involvement. The integration of mammography into routine periodic evaluation of asymptomatic women over 35 years of age should diminish the threat of breast cancer.
PURPOSE: To evaluate a new wavelet-based computer-assisted detection (CAD) system for detecting and enhancing microcalcifications. MATERIAL AND METHODS: A total of 280 mammograms acquired by full-field digital mammography (Senographe 2000D; G.E. Medical Systems Milwaukee, Wisc., USA) were analyzed with and without a new wavelet-based CAD system for detecting and enhancing microcalcifications. The mammograms comprised roughly equal numbers of cases from each of the BIRADS (Breast Imaging, Reporting and Data System, according to the American College of Roentgenology) categories 1-5. Histologic confirmation was available for all of the 180 cases assigned BIRADS categories 3-5. Four readers interpreted all 280 images for suspicious microcalcifications using a scale of 1-5. The readers alternately assessed 5 images with and 5 without CAD. In a second reading immediately following the first, the readers had to reassess the 280 mammograms. The images that had already been interpreted without CAD were now presented with CAD and vice versa. The images were interpreted as soft copies on a diagnostic mammography workstation (Image Diagnost GmbH, Neufahrn/Munich, Germany). All images interpreted with CAD were presented with enhancement of microcalcifications by wavelet algorithms and prompting of microcalcifications. ROC (receiver operating characteristic) analyses were performed, and image interpretation time with and without CAD was measured. RESULTS: The overall time for interpretation required by all 4 readers together was 483 min with CAD compared to 580 min without CAD. ROC analysis revealed no significant advantage of CAD for the individual readers. Readers 3 (0.811/0.817) and 4 (0.799/0.843) had a slightly improved AUC (area under the curve) with CAD. Readers 1 and 2 had a slightly lower AUC with CAD (0.832 versus 0.861 and 0.818 versus 0.849). CONCLUSION: The CAD system significantly (P<0.05, t test) speeded up image interpretation with respect to the identification of microcalcifications, while the diagnostic quality remained almost identical under the study conditions.
PURPOSE: To evaluate whether relevant diagnostic information can be achieved when using magnetic resonance mammography (MRM) on mid-field as a supplement to conventional imaging and clinical examination in women with primary breast cancer. MATERIAL AND METHODS: 30 women (55 breasts containing 49 malignant tumors) planned for uni- or bilateral mastectomy were examined with dynamic MRM on mid-field, 0.6T. The women were examined with mammography (M) and ultrasonography (US) prior to MRM. The descriptions of the conventional examinations were evaluated retrospectively, whereas the MRM was evaluated prospectively, with knowledge of the M+US findings. Imaging findings suggesting malignancy were registered and correlated with pathology after mastectomy. A home-made rating system for evaluation of the detected lesions was tested. RESULTS: MRM detected seven additional malignant tumors, failed to detect three lesions and characterized four as gray-zone lesions according to the rating system. Sensitivity of finding the tumors with M+US was 79.0%, with a PPV for malignant tumors of 84.4%. One breast in which MRM found a malignant tumor had not initially been examined with US. Sensitivity with MRM was 91.6%, with a positive predictive value of malignant tumors of 97.7%. CONCLUSION: MRM on mid-field seems to improve the detection of cancers when used as a supplement to M+US in women with primary breast cancer. We believe that the results are fair compared to MRM on high-field, although further research and refinement are needed.
PURPOSE: To develop a method for receiver operating characteristics (ROC) studies in mammography. MATERIAL AND METHODS: We developed a phantom based on excised breast tissue and overlay tiles that could be arranged in an arbitrary pattern across the surface of the breast tissue. Some of the tiles contained structures simulating calcifications or masses that produced image contrast near the experimentally determined detection threshold. Based on this phantom, a methodology for performing ROC studies in mammography was developed. The ROC curves were constructed from reporting schemes filled in by radiologists at five different laboratories. The curves were determined by a novel method: a non-linear least-squares fit of a mathematical model to the data. RESULTS: There were large differences among the areas under the ROC curves obtained from the five laboratories.
PURPOSE: To assess the image quality at different mammography laboratories. MATERIAL AND METHODS: Two commercial mammographic test phantoms and one phantom based on excised mammary tissue were used in an assessment of the imaging chain and total performance at 45 Norwegian mammography laboratories. The breast-tissue phantom was used for a receiver operating characteristics (ROC) analysis. This was carried out by putting overlays with identifiable regions (some of which contained a cluster of simulated calcifications) on top of the mammary tissue, and then having a radiologist report the confidence of a finding for each region. RESULTS AND CONCLUSION: The areas under the ROC curves were in general high. In nearly all the laboratories, performance was improved when a magnification technique was applied. There were wide variations among the laboratories in total performance as measured by the area under the ROC curve, and also in the physical parameters derived by means of the commercial phantoms. In general, a good ROC performance was associated with a good physical performance in the imaging chain.
Inadequate use of mammography screening for early detection of breast cancer is an important factor associated with the disproportionate breast cancer death rates in African American women. To improve understanding of the mammography screening experience and health for African Americans, focus groups were held with 30 African American women. Seven categories emerged: (a) the mind, body, and spirit connection: (b) living your life; (c) looking good; (d) good health-bad health; (e) prevention-detection confusion; (f) being afraid of cancer; and (g) what gets in the way. Implications for developing tailored messages and for addressing system barriers are discussed.
BACKGROUND: Women at risk for inherited breast cancer have been identified for intervention studies through newly diagnosed relatives or from volunteers with a family history. This pilot study tested the use of a mammography registry to identify women at risk. METHOD: Fifty women with first-degree relatives diagnosed as having breast cancer before age 45 were randomly selected from the Vermont Breast Cancer Surveillance System. Thirty-three women (66%) completed a phone interview that included a three-generation family pedigree of breast and ovarian cancers. RESULTS: Fifty-one percent of the women were at higher risk for inherited breast cancer based on the family history. Eighteen percent of the first-degree relatives' breast cancers were pathologically confirmed. CONCLUSION: Mammography registries that collect similar family history data may be used to identify women at risk for inherited breast cancer. Many intervention studies would require improved methods to obtain pathologic confirmation.
BACKGROUND: The five-year survival rate for African American women with breast cancer is notably lower than the rate for white women; thus, appropriate cancer education and screening efforts are needed to increase mammography and breast self-examination practices by African American women. METHODS: The Witness Project is a theory-based intervention designed to provide culturally sensitive messages, from African American breast cancer survivors, in churches and community organizations. These messages emphasize the importance of early detection to improve survival. RESULTS: Intervention research in eastern Arkansas with 204 African American women demonstrated a significant increase in the practice of breast self-examination (p < 0.001) and mammography (p < 0.001) after participation in the Witness Project. There was no significant difference between the pre- and postintervention scores for scaled items for the health-belief model and locus of control. CONCLUSIONS: Results demonstrate that culturally appropriate cancer education programs are able to change behavior by meeting the beliefs of participants rather than attempting to change their beliefs.
To determine the effect of the 1994 controversy about mammography screening guidelines on physicians' practices, the authors surveyed primary care physicians at a university medical center in 1995. The 44-item survey elicited information about screening practices for women in four age groups, at the time of the study and five years earlier. High screening rates were maintained for the noncontroversial 50+ age group, but baseline mammography was still being ordered for 30-39-year-olds. Women 40-49 years old as well as older women were being screened less often in 1995.
The ratio (R) of prevalence of screening-detected breast cancer in the first screening round (P) was compared with the expected incidence rate (I) for different age groups in several screening programs. Published data on the first screening round from three Swedish randomized trials and six counties with service screening were used. The women invited to take part in the screening were aged 40-74 years. Not only P and I but also R increased with increasing age. With the youngest age group as reference, the increase was statistically significant for both invasive cancer and invasive cancer and carcinoma in situ together. The studied ratio (R) can be thought of as a measure of efficiency in detecting breast cancer cases in mammography screening. The reasons for the increase are probably that the breast tissue of younger women is denser, which makes the cancer more difficult to detect by mammography, and that slow-growing cancers tend to appear more frequently in older women.
Little is published about step-by-step implementation of telephone counseling interventions to promote community-based health activities. This article describes the authors' experience of implementing a church-based telephone mammography counseling intervention with peer counselors representing three principal racial or ethnic groups: African American, Latino, and Anglo (White). Twenty-six women from 12 churches in the Los Angeles area were recruited and trained to deliver the counseling annually over a two-year period to 570 women participants who were recruited from participating churches (n = 15). The counseling sessions were conducted from church-based telephone centers in key geographic locations in our program area. Training and supervision proved challenging: most of the Latino counselors had fewer than seven years of education and spoke only Spanish, while most of the other counselors had at least some college and spoke only English. Culturally specific and small group interactions, role plays, and a more modular approach to training were the most effective ways to enhance counselors' skills. Latina participants' mammography adherence rates were lowest, and their barriers reflected their low socioeconomic status; as Latina counselors shared basic information about mammograms and where to obtain them at little or no cost, the counseling exchanges tended to be nonconflictive and supportive. Black and White participants were generally more knowledgeable and adherent with screening guidelines than Latinas. We found that it was possible to implement this intervention with diverse groups and conclude with lessons learned that may inform others considering such a strategy.
OBJECTIVE: This study examined racial differences in knowledge, attitudes and practices related to breast cancer screening of black and white women health maintenance organization members over age 40 who are employed at 75 worksites in Pennsylvania and New Jersey in the US. DESIGN: Data are from telephone interviews of 1677 women (20% black). The interviews queried background factors and concepts from the Health Belief Model. RESULTS: Compared to whites blacks were younger and less likely to be married or to have family history of breast cancer. They were also more likely to underestimate their cancer risk and to fear radiation, and less likely to have a doctor advise them to get mammograms. Black and white women did not differ in terms of self-reported mammography use. The results of multivariate modeling suggest that different set of knowledge and belief variables may explain mammography adherence among black and white women. CONCLUSION: These findings have implications for clinical prevention and for patient and community health education in minority populations.
A number of authors have calculated x-ray energies for mammography using, as a criterion, the maximum signal-to-noise ratio (SNR) obtainable per unit dose to the breast or conversely the minimum exposure for constant SNR. The predicted optimum energy increases with increasing breast thickness. Tungsten anode x-ray spectra have been measured with and without various added filter materials to determine how close the resultant spectra can be brought to the predicted optimum energies without reducing the x-ray output to unacceptable levels. The proportion of the total number of x-rays in a measured spectrum lying within a narrow energy band centred on the predicted optimum has been used as an optimum energy index. The effect of various filter materials on the measured x-ray spectra has been investigated both experimentally and theoretically. The resulting spectra have been compared with molybdenum anode, molybdenum filtered x-ray spectra normally used for mammography. It is shown that filters with K-absorption edges close to the predicted optimum energies are the most effective at producing the desired spectral shape. The choices of filter thickness and Vp are also explored in relationship to their effect on the resultant x-ray spectral shape and intensity.
Displacement corrections for in-phantom measurements with ionisation chambers for the purpose of mammography are large and represent a major correction to consider for dose determinations. Experimental data on displacement corrections depend to a large degree on the model used to extrapolate to zero cavity radius. Calculations of displacement correction factors using a Monte Carlo code are presented for different cavity shapes, i.e. spherical, cylindrical and disc-like, in various phantom materials simulating the average breast and breast composing tissues. In addition, the influence of wall material and depth in-phantom are studied. Exponential extrapolation to zero cavity radius should be performed to obtain the dose in homogeneous phantoms. Displacement corrections for photons as used in mammography seem compatible with geometrical considerations made previously. A discrepancy is found between depth-dose data derived from calculations and those found in experiments.
Multiparameter optimizations have been carried out for a wide range of digital mammography system configurations and requirements, with the aim of optimizing the image quality for a given patient dose. These conditions include a range of slot widths for scanning mammography systems, exposure times from 1 to 10 s, focal spot sizes from 80 to 800 microns, a range of detector resolutions and noise levels, dose restrictions, patient thicknesses and targets, and x-ray tube targets. The influences of these on the optimum system configuration in terms of tube potential, filtration, source to patient distance and target magnification are discussed. It is demonstrated that x-ray tube power constraints can significantly restrict the optimum magnification for slot scanning systems, with the result that poor-resolution detectors are not suited for use in a scanning configuration, and that large-focal-spot-good-detector resolution combinations are more suitable. The use of a detector with increased width, raised tube potential and reduced amount of added filtration is shown to be helpful in reducing x-ray tube power limitations. It is shown that, in many cases, correct optimization can bring the detail SNR for an examination using a given detector-x-ray tube configuration to within 10-15% of the SNR achieved with the optimum combination. This gives the designer some scope to consider other factors such as cost and the implications of image size on storage space.
Due to the clinically and technically demanding nature of breast x-ray imaging, mammography still remains one of the few essentially film-based radiological imaging techniques in modern medical imaging. There are a range of possible benefits available if a practical and economical direct digital imaging technique can be introduced to routine clinical practice. There has been much debate regarding the minimum specification required for direct digital acquisition. One such direct digital system available is computed radiography (CR), which has a modest specification when compared with modern screen-film mammography (SFM) systems. This paper details two psychophysical studies in which the detection of simulated microcalcifications with CR has been directly compared to that with SFM. The first study found that under scatter-free conditions the minimum detectable size of microcalcification was approximately 130 microns for both SFM and CR. The second study found that SFM had a 4.6% higher probability of observers being able to correctly identify the shape of 350 microns diameter test details; there was no significant difference for-either larger or smaller test details. From the results of these studies it has been demonstrated that the modest specification of CR, in terms of limiting resolution, does not translate into a dramatic difference in the perception of details at the limit of detectability. When judging the imaging performance of a system it is more important to compare the signal-to-noise ratio transfer spectrum characteristics, rather than simply the modulation transfer function.
The objective of this study is to establish a comprehensive set of backscatter factors for mammography based on the exposure model proposed by the European Protocol on Dosimetry in Mammography. The Monte Carlo calculated backscatter factors (BSFs) presented in this study are for various exposure conditions encountered in mammographic practice as well as in calibration procedures. The data demonstrate the variation of the BSF as a function of the exposure parameters, hence enabling a better match with calibration conditions and, at the same time, reviewing the BSF data already recommended by the European Protocol. Furthermore, earlier data for BSF for general diagnostic radiology are validated.
Laser interstitial thermotherapy (LITT) is a minimally-invasive laser hyperthermia procedure for the treatment of localized tumours. Real-time monitoring of LITT is essential to control the extent of tumour destruction and ensure safe and effective treatments. The feasibility of using high-resolution digital x-ray mammography to monitor LITT of breast cancer was evaluated. Tissue phantoms including polyacrylamide hydrogel and cadaver porcine tissue were heated using a 980 nm diode laser delivered through optical fibres with diffusing tips. Digital images of the tissue phantoms were recorded with a high-resolution digital stereotactic breast biopsy system during heating. The recorded images were processed and analysed to detect heat-induced changes. No changes were detected during heating of the hydrogel. Pixel-by-pixel subtraction of the initial image from images taken during laser heating shows observable thermally-induced changes around the fibre during laser irradiation that correlate with the thermal denaturation zone observed by gross anatomy. These experiments demonstrate that high-resolution digital x-ray mammography can be used to detect heat-induced tissue changes during experimental LITT in fibro-fatty tissue.