Randomized trial of screen-film versus full-field digital mammography with soft-copy reading in population-based screening program: follow-up and final results of Oslo II study

[Impact of mammographic breast density on computer-assisted detection (CAD) in a breast imaging department]

OBJECTIVE

To evaluate whether breast density influences the sensitivity of a computer-assisted detection (CAD) system for the detection of breast cancer.

MATERIAL AND METHODS

We prospectively studied 8750 digital mammograms with an associated CAD system. We used BI-RADS criteria to classify breast density. We calculated the overall sensitivity of the radiologist and of the CAD system, as well as the sensitivity for each projection and type of finding in relation to the mammographic density of the breast. Finally, we analyzed the interval carcinomas. We used SPSS 11 for all statistical analyses.

RESULTS

The overall sensitivity of the CAD system was 88.5% (95% CI: 83.2-92.7%), and the overall sensitivity of the radiologist was 93.5% (95% CI: 84.4%-95.5%). The sensitivity of the craniocaudal view was 81.6% (95% CI: 76.5-90.7%) vs 76.5% (95% CI: 69.3-89.3%) for the mediolateral oblique view. The sensitivity for microcalcifications was 98.6% (95% CI: 96.5-99.7%), and the sensitivity for masses 83.4% (95% CI: 81.2-91.7%). We detected discrepancies smaller than 20% both for microcalcifications present in the four types of densities and for masses with densities 1 and 2. In masses with density 3 the discrepancy was 20.8% and in those with density 4 it was 55%. The CAD system failed to mark only 9.1% (9/94) of the cancers presenting as masses. Half of the interval carcinomas were found in type 4 density and 75% manifested as masses, asymmetries, and distortions. The CAD system had marked 35.7% of the carcinomas.

CONCLUSIONS

The craniocaudal view was more sensitive, although this difference was not statistically significant. The sensitivity of CAD was high for microcalcifications in all four density types; however, CAD's sensitivity for masses was low in density types 3 and 4. The CAD system only failed to mark 9.1% of the cancers presenting as masses but was not sensitive for the other two radiological findings included in this marking. Half of the interval carcinomas occurred in type 4 densities and 35.7% had been marked by the CAD system.

Contrast detail phantom comparison on a commercially available unit. Digital breast tomosynthesis (DBT) versus full-field digital mammography (FFDM)

The performance of a commercial digital mammographic system working in 2D planar versus tomosynthesis mode was evaluated in terms of the image signal difference to noise ratio (SDNR). A contrast detail phantom was obtained embedding 1 cm Plexiglas, including 49 holes of different diameter and depth, between two layers containing a breast-simulating material. The phantom was exposed with the details plane perpendicular to the X-ray beam using the manufacturer's standard clinical breast acquisition parameters. SDNR in the digital breast tomosynthesis (DBT) images was higher than that of the full-field digital mammography (FFDM) for 38 out of 49 details in complex background conditions. These differences (p < 0.05) are statistically significant for 19 details out of 38. The relative SDNR results for DBT and FFDM images showed a dependence on the diameter of the details considered. This paper proposes an initial framework for a global image quality evaluation for commercial systems that can operate with different image acquisition modality using the same detector.

[Physical aspects of different tomosynthesis systems]

Digital breast tomosynthesis (DBT) is a new image processing technique based on digital mammography technology. Image slices of the stationary compressed breast are reconstructed from multiple images taken at different angles of the X-ray tube at the same time. The main goal is to achieve a similar radiation dose exposure as common encountered in traditional digital mammography. One of the key advantages of DBT is that lesions are less likely to be hidden amongst normal tissues as they are in traditional digital mammography. This way the quality of diagnosis can be improved, especially for dense breasts. Current DBT implementations from several manufacturers differ in certain features such as scanning angle, number of projections, scanning time, pixel size, reconstruction methods and type of tube movement. A comparison and description of these different characteristics as well as a discussion on the proposed number of imaging planes and related radiation dose requirements are given.

Bias in estimating accuracy of a binary screening test with differential disease verification

Sensitivity, specificity, positive and negative predictive value are typically used to quantify the accuracy of a binary screening test. In some studies, it may not be ethical or feasible to obtain definitive disease ascertainment for all subjects using a gold standard test. When a gold standard test cannot be used, an imperfect reference test that is less than 100 per cent sensitive and specific may be used instead. In breast cancer screening, for example, follow-up for cancer diagnosis is used as an imperfect reference test for women where it is not possible to obtain gold standard results. This incomplete ascertainment of true disease, or differential disease verification, can result in biased estimates of accuracy. In this paper, we derive the apparent accuracy values for studies subject to differential verification. We determine how the bias is affected by the accuracy of the imperfect reference test, the percent who receive the imperfect reference standard test not receiving the gold standard, the prevalence of the disease, and the correlation between the results for the screening test and the imperfect reference test. It is shown that designs with differential disease verification can yield biased estimates of accuracy. Estimates of sensitivity in cancer screening trials may be substantially biased. However, careful design decisions, including selection of the imperfect reference test, can help to minimize bias. A hypothetical breast cancer screening study is used to illustrate the problem.

Contemporary breast imaging and concordance assessment: a surgical perspective

Disease conditions of the breast are very common. Patients with such conditions often present to surgeons for both diagnostic evaluation and treatment. Nearly all of them will require breast imaging. This article summarizes the use, applicability, and concordance assessment of mammography, ultrasonography, and magnetic resonance imaging in patients who have breast complaints or abnormalities on clinical examination or imaging.

Comparative evaluation of digital mammography and film mammography: systematic review and meta-analysis

CONTEXT AND OBJECTIVE

Mammography is the best method for breast-cancer screening and is capable of reducing mortality rates. Studies that have assessed the clinical impact of mammography have been carried out using film mammography. Digital mammography has been proposed as a substitute for film mammography given the benefits inherent to digital technology. The aim of this study was to compare the performance of digital and film mammography.

DESIGN

Systematic review and meta-analysis.

METHOD

The Medline, Scopus, Embase and Lilacs databases were searched looking for paired studies, cohorts and randomized controlled trials published up to 2009 that compared the performance of digital and film mammography, with regard to cancer detection, recall rates and tumor characteristics. The reference lists of included studies were checked for any relevant citations.

RESULTS

A total of 11 studies involving 190,322 digital and 638,348 film mammography images were included. The cancer detection rates were significantly higher for digital mammography than for film mammography (risk relative, RR = 1.17; 95% confidence interval, CI = 1.06-1.29; I² = 19%). The advantage of digital mammography seemed greatest among patients between 50 and 60 years of age. There were no significant differences between the two methods regarding patient recall rates or the characteristics of the tumors detected.

CONCLUSION

The cancer detection rates using digital mammography are slightly higher than the rates using film mammography. There are no significant differences in recall rates between film and digital mammography. The characteristics of the tumors are similar in patients undergoing the two methods.

Digital mammography in a screening programme and its implications for pathology: a comparative study

Aims

Most studies comparing full-field digital mammography (FFDM) with conventional screen-film mammography (SFM) have been radiology-based. The pathological implications of FFDM have received little attention in the literature, especially in the context of screening programmes. The primary objective of this retrospective study is to compare FFDM with SFM in a population-based screening programme with regard to a number of pathological parameters.

Methods

During the study period, 107 818 women underwent screening mammograms with almost equal numbers obtained with each technique (49.9% with SFM vs 50.1% with FFDM). We compared SFM with FFDM using the following parameters: recall rate, diagnostic core biopsy rate, cancer detection rates, B3 rate, B4 rate, preoperative diagnostic rate for malignancy, positive predictive values and tumour characteristics.

Results

The recall rate was significantly higher with FFDM (4.21% vs 3.52%, p<0.0001). The overall cancer detection rate of 7.2 per 1000 women screened with FFDM was also significantly higher than the rate of 6.2 per 1000 women screened with SFM (p=0.04). The B3 rate in the SFM group was 1.3 per 1000 women screened versus 2.5 per 1000 women screened in the FFDM group (p<0.001). The recall rate and cancer detection rates (overall, invasive and pure ductal carcinoma in situ) were all significantly higher with FFDM for lesions presenting as microcalcifications.

Conclusions

The higher cancer detection rate with FFDM in this study was due to improved detection of microcalcifications. However, this was achieved at the cost of a higher recall rate and a higher B3 rate, indicating that overtreatment may be problematic with digital mammography.

[Comparison between electronic zoom and geometric magnification of clusters of microcalcifications on digital mammography]

PURPOSE

With the advent of digital mammography with electronic zoom capabilities, we have sought to determine the need for geometric magnification for the evaluation of clusters of microcalcifications.

PATIENTS AND METHODS

Eighty-eight clusters of microcalcifications were reviewed by two experienced radiologists using electronic zoom (ZOOM) and geometric magnification (MAG). The following criteria were evaluated: image quality, shape and number of microcalcifications, size and shape of the clusters. The clusters were classified based on malignancy risk using the BI-RADS criteria. Histological results from macrobiopsy or surgery as well as 2 year follow-up were used as reference for statistical analysis.

RESULTS

Sensitivity (100% for MAG and 90% for ZOOM), specificity (52% versus 39%), positive predictive value (51% versus 44%) and negative predictive value (100% versus 88%) were superior for geometric magnification compared to electronic zoom irrespective of the reviewer but without reaching statistical significance. However, image quality was significantly superior with geometric magnification (p<<0.05). In addition, reviewers were more confident in their interpretation of geometric magnification images.

CONCLUSION

Geometric magnification remains necessary in routine clinical practice for the characterization of microcalcifications and BI-RADS classification.

[Screening digital mammography: one year result for the Alpes-Maritimes region]

PURPOSE

After one year of experience with screening digital mammography, the results of this technique (n=9640) are compared to screen-film mammography (n=240 376) with double reading.

METHODS

Evaluation for each technique of the rate of call-back, positive results before and after work-up by the first reader and distribution based on the BI-RADS classification by the ACR, rate of complementary US, detected abnormalities (microcalcifications) and detected cancers.

RESULTS

The rate of positive mammograms was significantly higher for the digital technique (17.3% versus 15.1%) because of the first reader (16.3% versus 13.9%) whereas it was significantly lower after complementary work-up (3% versus 3.7%). The rate of BI-RADS 0 was significantly higher with digital imaging irrespective of patient age. The rate of US was higher for type 1 and 2 breasts at digital imaging (46% versus 36%, p<0.0001) while the reverse was true for denser breasts (49% versus 54%; p:0.0005). More microcalcifications were detected on digital imaging (24.4% versus 21.8%) without impact on the rate of DCIS and invasive carcinomas. The rate of cancers detected with both technique were identical.

CONCLUSION

The increased number of positive results at first reading and increased number of US for digital mammography may relate to a learning curve and difficulties in comparing with prior examinations. These results should continuously be monitored and compared to national averages.

Breast cancer screening with imaging: recommendations from the Society of Breast Imaging and the ACR on the use of mammography, breast MRI, breast ultrasound, and other technologies for the detection of clinically occult breast cancer

Screening for breast cancer with mammography has been shown to decrease mortality from breast cancer, and mammography is the mainstay of screening for clinically occult disease. Mammography, however, has well-recognized limitations, and recently, other imaging including ultrasound and magnetic resonance imaging have been used as adjunctive screening tools, mainly for women who may be at increased risk for the development of breast cancer. The Society of Breast Imaging and the Breast Imaging Commission of the ACR are issuing these recommendations to provide guidance to patients and clinicians on the use of imaging to screen for breast cancer. Wherever possible, the recommendations are based on available evidence. Where evidence is lacking, the recommendations are based on consensus opinions of the fellows and executive committee of the Society of Breast Imaging and the members of the Breast Imaging Commission of the ACR.

Predictors of interobserver agreement in breast imaging using the Breast Imaging Reporting and Data System

The Breast Imaging Reporting and Data System (BI-RADS) was introduced in 1993 to standardize the interpretation of mammograms. Though many studies have assessed the validity of the system, fewer have examined its reliability. Our objective is to identify predictors of reliability as measured by the kappa statistic. We identified studies conducted between 1993 and 2009 which reported kappa values for interpreting mammograms using any edition of BI-RADS. Bivariate and multivariate multilevel analyses were used to examine associations between potential predictors and kappa values. We identified ten eligible studies, which yielded 88 kappa values for the analysis. Potential predictors of kappa included: whether or not the study included negative cases, whether single- or two-view mammograms were used, whether or not mammograms were digital versus screen-film, whether or not the fourth edition of BI-RADS was utilized, the BI-RADS category being evaluated, whether or not readers were trained, whether or not there was an overlap in readers' professional activities, the number of cases in the study and the country in which the study was conducted. Our best multivariate model identified training, use of two-view mammograms and BI-RADS categories (masses, calcifications, and final assessments) as predictors of kappa. Training, use of two-view mammograms and focusing on mass description may be useful in increasing reliability in mammogram interpretation. Calcification and final assessment descriptors are areas for potential improvement. These findings are important for implementing policies in BI-RADS use before introducing the system in different settings and improving current implementations.

Conspicuity of microcalcifications on digital screening mammograms using varying degrees of monitor zooming

RATIONALE AND OBJECTIVES

American College of Radiology guidelines suggest that digital screening mammographic images should be viewed at the full resolution at which they were acquired. This slows interpretation speed. The aim of this study was to examine the effect of various levels of zooming on the detection and conspicuity of microcalcifications.

MATERIALS AND METHODS

Six radiologists viewed 40 mammographic images five times in different random orders using five different levels of zooming: full resolution (100%) and 30%, 61%, 88%, and 126% of that size. Thirty-three images contained microcalcifications varying in subtlety, all associated with breast cancer. The clusters were circled. Seven images contained no malignant calcifications but also had randomly placed circles. The radiologists graded the presence or absence and visual conspicuity of any calcifications compared to calcifications in a reference image. They also counted the microcalcifications.

RESULTS

The radiologists saw the microcalcifications in 94% of the images at 30% size and in either 99% or 100% of the other tested levels of zooming. Conspicuity ratings were worst for the 30% size and fairly similar for the others. Using the 30% size, two radiologists failed to see the microcalcifications on either the craniocaudal or mediolateral oblique view taken from one patient. Interobserver agreement regarding the number of calcifications was lowest for the 30% images and second lowest for the 100% images.

CONCLUSIONS

Images at 30% size should not be relied on alone for systematic scanning for microcalcifications. The other four levels of magnification all performed well enough to warrant further testing.

Differentiation of benign and malignant breast lesions by mechanical imaging

Mechanical imaging yields tissue elasticity map and provides quantitative characterization of a detected pathology. The changes in the surface stress patterns as a function of applied load provide information about the elastic composition and geometry of the underlying tissue structures. The objective of this study is the clinical evaluation of breast mechanical imager for breast lesion characterization and differentiation between benign and malignant lesions. The breast mechanical imager includes a probe with pressure sensor array, an electronic unit providing data acquisition from the pressure sensors and communication with a touch-screen laptop computer. We have developed an examination procedure and algorithms to provide assessment of breast lesion features such as hardness related parameters, mobility, and shape. A statistical Bayesian classifier was constructed to distinguish between benign and malignant lesions by utilizing all the listed features as the input. Clinical results for 179 cases, collected at four different clinical sites, have demonstrated that the breast mechanical imager provides a reliable image formation of breast tissue abnormalities and calculation of lesion features. Malignant breast lesions (histologically confirmed) demonstrated increased hardness and strain hardening as well as decreased mobility and longer boundary length in comparison with benign lesions. Statistical analysis of differentiation capability for 147 benign and 32 malignant lesions revealed an average sensitivity of 91.4% and specificity of 86.8% with a standard deviation of +/-6.1%. The area under the receiver operating characteristic curve characterizing benign and malignant lesion discrimination is 86.1% with the confidence interval ranging from 80.3 to 90.9%, with a significance level of P = 0.0001 (area = 50%). The multisite clinical study demonstrated the capability of mechanical imaging for characterization and differentiation of benign and malignant breast lesions. We hypothesize that the breast mechanical imager has the potential to be used as a cost effective device for cancer diagnostics that could reduce the benign biopsy rate, serve as an adjunct to mammography and to be utilized as a screening device for breast cancer detection.

Internal validation of procedure codes on Medicare claims for digital mammograms and computer-aided detection

BACKGROUND

Billing data, such as Medicare claims, are a potential data source for evaluative studies of new digital mammography technologies, such as digital mammography and computer-aided detection (CAD).

OBJECTIVE

To assess the internal validity of procedure codes on Medicare claims for screening mammography interpreted with either digital mammography or CAD.

STUDY DESIGN

We assessed agreement of procedure coding for digital versus film mammography and CAD use versus nonuse for mammograms with claims appearing in two independent Medicare claims files (the Carrier Claims and Outpatient files).

SUBJECTS AND SETTING

Women enrolled in fee-for-service Medicare who received screening mammography in 2001 to 2003 within Surveillance, Epidemiology, and End Results regions, representing 25% of the U.S. population (n = 35,642 women who received 57,632 total mammograms).

MEASURES

Coding agreement beyond chance (kappa), overall, and by year.

RESULTS

Overall coding agreement was excellent for both digital versus film mammography [kappa = 0.81 (95% confidence interval, 0.80-0.83)] and for CAD use versus nonuse [kappa = 0.82 (95% confidence interval, 0.81-0.83)]. However, in 2001, agreement was only moderate (kappa = 0.51 for digital versus film and kappa = 0.50 for CAD use versus nonuse) but increased to higher levels in 2002 and 2003 (kappa > 0.80 for both technologies).

CONCLUSIONS

High internal agreement in procedure codes for digital mammography technologies is consistent with accurate coding on Medicare claims after 2001, although external validation remains desirable.

Screening-detected breast cancers: discordant independent double reading in a population-based screening program

PURPOSE

To analyze discordant and concordant screening-detected breast cancers in a nationwide population-based screening program by using independent double reading with consensus.

MATERIALS AND METHODS

The study is a part of the evaluation of the Norwegian Breast Cancer Screening Program and is covered by the Cancer Registry regulation. Analyses were based on prospective initial interpretation scores of 1 033 870 screenings that included 5611 breast cancers. A five-point scale for probability of cancer was used in the initial interpretation. Screening mammograms with a score of 2 or higher by either radiologist were discussed at consensus meetings where the decision whether to recall was made. A score of 1 by one reader and 2 or higher by the other was defined as a discordant interpretation and discordant cancer, whereas a score of 2 or higher by both readers was defined as a concordant recall and cancer.

RESULTS

Discordant interpretation was present in 5.3% (54 447 of 1 033 870) of the screenings, whereas 2.1% (21 928 of 1 033 870) were concordant positive interpretations. Of the screening-detected cancers, 23.6% (1326 of 5611) were diagnosed in women who were recalled because of screenings with discordant interpretation. One hundred seventeen interval breast cancers were diagnosed among the 40 312 screenings that were dismissed at consensus; these were 6.5% of all interval cancers. A significantly higher proportion of microcalcifications alone was present in discordant cancers (24.9% [304 of 1219]) compared with concordant cancers (17.7% [704 of 3972]) (P < .001).

CONCLUSION

Independent double reading with consensus at mammography screening has the potential to increase the cancer detection rate compared with single reading. Mammograms with microcalcifications alone are significantly more common among discordant cancers.

Screening and prevention of breast cancer in primary care

Mammography remains the mainstay of breast cancer screening. There is little controversy that mammography reduces the risk of dying from breast cancer by about 23% among women between the ages of 50 and 69 years, although the harms associated with false-positive results and overdiagnosis limit the net benefit of mammography. Women in their 70s may have a small benefit from screening mammography, but overdiagnosis increases in this age group as do competing causes of death. While new data support a 16% reduction in breast cancer mortality for 40- to 49-year-old women after 10 years of screening, the net benefit is less compelling in part because of the lower incidence of breast cancer in this age group and because mammography is less sensitive and specific in women younger than 50 years. Digital mammography is more sensitive than film mammography in young women with similar specificity, but no improvements in breast cancer outcomes have been demonstrated. Magnetic resonance imaging may benefit the highest risk women. Randomized trials suggest that self-breast examination does more harm than good. Primary prevention with currently approved medications will have a negligible effect on breast cancer incidence. Public health efforts aimed at increasing mammography screening rates, promoting regular exercise in all women, maintaining a healthy weight, limiting alcohol intake, and limiting postmenopausal hormone therapy may help to continue the recent trend of lower breast cancer incidence and mortality among American women.

Breast cancer screening results 5 years after introduction of digital mammography in a population-based screening program

PURPOSE

To compare full-field digital mammography (FFDM) using computer-aided diagnosis (CAD) with screen-film mammography (SFM) in a population-based breast cancer screening program for initial and subsequent screening examinations.

MATERIALS AND METHODS

The study was approved by the regional medical ethics review board. Informed consent was not required. In a breast cancer screening facility, two of seven conventional mammography units were replaced with FFDM units. Digital mammograms were interpreted by using soft-copy reading with CAD. The same team of radiologists was involved in the double reading of FFDM and SFM images, with differences of opinion resolved in consensus. After 5 years, screening outcomes obtained with both modalities were compared for initial and subsequent screening examination findings.

RESULTS

A total of 367,600 screening examinations were performed, of which 56,518 were digital. Breast cancer was detected in 1927 women (317 with FFDM). At initial screenings, the cancer detection rate was .77% with FFDM and .62% with SFM. At subsequent screenings, detection rates were .55% and .49%, respectively. Differences were not statistically significant. Recalls based on microcalcifications alone doubled with FFDM. A significant increase in the detection of ductal carcinoma in situ was found with FFDM (P < .01). The fraction of invasive cancers with microcalcifications as the only sign of malignancy increased significantly, from 8.1% to 15.8% (P < .001). Recall rates were significantly higher with FFDM in the initial round (4.4% vs 2.3%, P < .001) and in the subsequent round (1.7% vs 1.2%, P < .001).

CONCLUSION

With the FFDM-CAD combination, detection performance is at least as good as that with SFM. The detection of ductal carcinoma in situ and microcalcification clusters improved with FFDM using CAD, while the recall rate increased.

Implementation of digital mammography in a population-based breast cancer screening program: effect of screening round on recall rate and cancer detection

PURPOSE

To compare the effect of the introduction of digital mammography on the recall rate, detection rate, false-positive rate, and rates of invasive procedures performed in the first and successive rounds of a population-based breast cancer screening program with double reading in Barcelona, Spain.

MATERIALS AND METHODS

The study was approved by the ethics committee; informed consent was not required. Data were compared from 12,958 women aged 50-69 years old who participated in a screening round before the introduction of digital mammography (screen-film mammography group) with data from 6074 women who participated in another screening round after the introduction of digital mammography (digital mammography group). Groups were compared for recall rate and detection rate stratified according to first or successive screening rounds, and logistic regression analysis was performed.

RESULTS

Overall recall rates for screen-film and digital mammography groups were 5.5% and 4.2%, respectively (P < .001). The recall rate was higher in the first screening round (11.5% and 11.1% in the screen-film mammography and digital mammography groups, respectively; P = .68) than in successive screening rounds (3.6% and 2.4% in the screen-film mammography and digital mammography groups, respectively; P < .001). The main factors related to the risk of recall were screen-film mammography group (odds ratio = 1.28), first screening round (odds ratio = 3.53), menopausal status (odds ratio = 0.62), and history of personal benign breast disease (odds ratio = 2.26). No significant differences were found in the cancer detection rate between groups. In the first screening round, this rate was higher in the digital than in the screen-film mammography group (1.1% and 0.4%, respectively; P = .009). The invasive test rate was 2.6% and 1.3% in the screen-film and digital mammography groups, respectively (P < .001) and was lower with digital mammography than with screen-film mammography in both the first and successive screening rounds.

CONCLUSION

Digital mammography may reduce the adverse effects of screening programs if this technique is confirmed to have the same diagnostic accuracy as screen-film mammography.

Why does it take longer to read digital than film-screen screening mammograms? A partial explanation

Digital screening mammograms (DM) take longer to interpret than film-screen screening mammograms (FSM). We evaluated what part of the process takes long in our reading environment. We selected cases from those for which timed readings had been performed as part of a previous study. Readers were timed as they performed various computer manipulations on groups of DM cases and as they moved the alternator and adjusted lighting and manual shutters for FSM cases. Subtracting manipulation time from the original interpretation times yielded estimated times to reach a decision. Manipulation times for DM ranged from a low of 11 s when four-view DM were simply opened and closed in a 4-on-1 hanging protocol before moving on to the next study to 113.8 s when each view of six-view DM were brought up 1-on-1, enlarged to 100% resolution, and panned through. Manipulation times for groups of FSM ranged from 8.3 to 12.1 s. Estimated decision-making times for DM ranged from 128.0 to 202.2 s, while estimated decision-making time for FSM ranged from 60.9 to 146.3 s. Computer manipulation time partially explains the discrepancy in interaction times between DM and FSM. Radiologists also appear to spend more time looking at DM than at FSM before making a decision.

Tailored supplemental screening for breast cancer: what now and what next?

OBJECTIVE

This article reviews breast cancer risk assessment and the rationale for current screening guidelines, including when to consider using supplemental screening with MRI or sonography in addition to mammography, and discusses other emerging technologies. Radiologists can help identify women who may benefit from supplemental screening and can help to recommend when and which techniques to perform for this additional screening.

CONCLUSION

Mammography remains the mainstay of breast cancer screening. Mammography should be performed as digital imaging when possible in women with dense breasts. In women at high risk, particularly if they also have dense breasts, annual MRI is recommended, although further validation of outcomes is needed. In intermediate-risk women with dense breasts, especially those with other risk factors, and in high-risk women with dense breasts who are unable to tolerate MRI, supplemental sonography screening is an option at facilities with availability of qualified personnel. Developing technologies are not appropriate for screening at this time, although further study is encouraged.

Timed efficiency of interpretation of digital and film-screen screening mammograms

OBJECTIVE

Our objective was to compare interpretation speeds for digital and film-screen screening mammograms to test whether other variables might affect interpretation times and thus contribute to the apparent difference in interpretation speed between digital mammograms and film-screen mammograms, and to test whether the use of digital rather than film comparison studies might result in significant time savings.

MATERIALS AND METHODS

Four readers were timed in the course of actual clinical interpretation of digital mammograms and film-screen mammograms. Interpretation times were compared for subgroups of studies based on the interpretation of the study by BI-RADS code, the number of images, the presence or absence of comparison studies and the type of comparison study, and whether the radiologist personally selected and hung additional films; the same comparisons were made among individual readers.

RESULTS

For all four readers, mean interpretation times were longer for digital mammograms than for film-screen mammograms, with differences ranging from 76 to 202 seconds. The difference in interpretation speed between digital and film-screen mammograms was independent of other variables. Digital mammogram interpretation times were significantly longer than film-screen mammogram interpretation times regardless of whether the digital mammograms were matched with film or digital comparison studies.

CONCLUSION

In screening mammography interpretation, digital mammograms take longer to read than film-screen mammograms, independent of other variables. Exclusive use of digital comparison studies may not cause interpretation times to drop enough to approach the interpretation time required for film-screen mammograms.

Breast cancer imaging: a perspective for the next decade

Breast imaging is largely indicated for detection, diagnosis, and clinical management of breast cancer and for evaluation of the integrity of breast implants. In this work, a prospective view of techniques for breast cancer detection and diagnosis is provided based on an assessment of current trends. The potential role of emerging techniques that are under various stages of research and development is also addressed. It appears that the primary imaging tool for breast cancer screening in the next decade will be high-resolution, high-contrast, anatomical x-ray imaging with or without depth information. MRI and ultrasonography will have an increasingly important adjunctive role for imaging high-risk patients and women with dense breasts. Pilot studies with dedicated breast CT have demonstrated high-resolution three-dimensional imaging capabilities, but several technological barriers must be overcome before clinical adoption. Radionuclide based imaging techniques and x-ray imaging with intravenously injected contrast offer substantial potential as a diagnostic tools and for evaluation of suspicious lesions. Developing optical and electromagnetic imaging techniques hold significant potential for physiologic information and they are likely to be of most value when integrated with or adjunctively used with techniques that provide anatomic information. Experimental studies with breast specimens suggest that phase-sensitive x-ray imaging techniques can provide edge enhancement and contrast improvement but more research is needed to evaluate their potential role in clinical breast imaging. From the technological perspective, in addition to improvements within each modality, there is likely to be a trend towards multi-modality systems that combine anatomic with physiologic information. We are also likely to transition from a standardized screening, where all women undergo the same imaging exam (mammography), to selection of a screening modality or modalities based an individual-risk or other classification.

Screen-detected breast lesions with malignant needle core biopsy diagnoses and no malignancy identified in subsequent surgical excision specimens (potential false-positive diagnosis)

Although breast needle core biopsy (NCB) is now a standard diagnostic procedure in the triple assessment of screen-detected breast lesions, data on the false-positive diagnoses of malignancy (malignant NCB 'B5' with normal/benign surgery) are lacking. In this study, we have studied a large series of NCBs (101,440) to assess the causes and pitfalls resulting in false-positive NCB diagnoses and to evaluate their impact on patients' management in the screening service. Our results showed that of 40,395 malignant NCBs reported during the period of this study, 174 NCBs are considered as false-positives (0.43%; (95% confidence interval [CI]=0.37-0.49%)). However, on review, 165 cases (95%) were found to be the result of true removal of the whole lesion in the core with subsequent negative excision biopsy samples (true-positive NCBs). This may reflect sampling of small screen detected lesions and the use of larger core biopsies at assessment. The remaining 9 cases were considered as true false-positive cores, giving a false-positive rate of 0.02% (95% CI=0.01-0.04%). Analysis of these 9 cases showed that 8 cases, originally diagnosed as DCIS, were classified as borderline lesions or lesions of uncertain malignant potential after surgical excision. The classification and management of such borderline lesions remains controversial and diagnostic surgical excision is usually the optimum management. One case was the result of pathological misinterpretation of fat necrosis as invasive carcinoma. This was the only case that resulted in a significant over-management of the patient. In conclusion, our results showed that the true false-positive rate of NCB is extremely rare. Significant over-management of screen-detected breast lesions as a result of false-positive NCB may be considered almost nil.

[Mammographic evaluation of dense breasts: techniques and limits]

Breast density is a radiological concept based on the proportion of radiopaque glandular tissue relative to radiolucent fatty tissue. Mammographic evaluation of dense breasts is more difficult, related to technical difficulties, with decreased rates for detection and characterization of breast lesions, resulting in reduced sensitivity with increased number of interval cancers at routine follow-up when compared to radiolucent breasts. We will review the definition of dense breasts and their frequency, especially their relationship with the age of patients. We will discuss the current technical problems and the impact of breast density on the efficacy of conventional mammography. We will discuss the value of digital mammography, the role of computer assisted diagnosis (CAD) systems and tomosynthesis in the evaluation of dense breasts.

[Current situation and future perspectives of digital mammography]

Digital mammography has extensively replaced conventional film screen mammography and is now the standard in combination with soft copy reading in clinical as well as screening mammography. Large international multicenter studies demonstrate an equivalent or superior detection rate of breast cancers by digital in comparison to conventional mammography especially in dense breasts, premenopausal and perimenopausal women and women less than 50 years old. Computer-aided detection (CAD) is important for the experienced investigator (increased specificity). Digital mammography also offers further options, such as tomosynthesis, digital contrast-enhanced mammography and the combination of digital mammography and ultrasound. The future in breast diagnosis will be the fusion of images from different digital systems.

Breast tomosynthesis and digital mammography: a comparison of breast cancer visibility and BIRADS classification in a population of cancers with subtle mammographic findings

The main purpose was to compare breast cancer visibility in one-view breast tomosynthesis (BT) to cancer visibility in one- or two-view digital mammography (DM). Thirty-six patients were selected on the basis of subtle signs of breast cancer on DM. One-view BT was performed with the same compression angle as the DM image in which the finding was least/not visible. On BT, 25 projections images were acquired over an angular range of 50 degrees, with double the dose of one-view DM. Two expert breast imagers classified one- and two-view DM, and BT findings for cancer visibility and BIRADS cancer probability in a non-blinded consensus study. Forty breast cancers were found in 37 breasts. The cancers were rated more visible on BT compared to one-view and two-view DM in 22 and 11 cases, respectively, (p < 0.01 for both comparisons). Comparing one-view DM to one-view BT, 21 patients were upgraded on BIRADS classification (p < 0.01). Comparing two-view DM to one-view BT, 12 patients were upgraded on BIRADS classification (p < 0.01). The results indicate that the cancer visibility on BT is superior to DM, which suggests that BT may have a higher sensitivity for breast cancer detection.

Cost-effective screening for breast cancer worldwide: current state and future directions

Affordability of healthcare is highly limited by its skyrocketing cost. Access to screening and diagnostic medical equipment and medicine in developing countries is inadequate for the majority of the population. There is a tremendous worldwide need to detect breast cancer at its earliest stage. These needs must be balanced by the ability of countries to provide breast cancer screening technology to their populations. We reviewed the diagnostic accuracy, procedure cost and cost-effectiveness of currently available technique for breast screening and diagnosis including clinical breast examination, mammography, ultrasound, magnetic resonance imaging, biopsy and a new modality for cancer diagnostics termed elasticity imaging that has emerged in the last decade. Clinical results demonstrate that elasticity imaging even in its simplest and least sophisticated versions, like tactile imaging, has significant diagnostic potential comparable and exceeding that of conventional imaging techniques. In view of many countries with limited resources, effective yet less expensive modes of screening must be considered worldwide. The tactile imaging is one method that has the potential to provide cost-effective breast cancer screening and diagnostics.

Utilization and cost of diagnostic imaging and biopsies following positive screening mammography in the southern breast cancer screening region of the Netherlands, 2000-2005

We prospectively assessed trends in utilization and costs of diagnostic services of screen-positive women in a biennial breast cancer screening program for women aged 50-75 years. All 2,062 women with suspicious findings at screening mammography in the southern region of the Netherlands between 1 January 2000 and 1 July 2005 (158,997 screens) were included. Data were collected on any diagnostic examinations, interventional procedures, and surgical consultations with two-year follow-up. We used national reimbursement rates to estimate imaging costs and percutaneous biopsy costs. Cost prices, charged by hospitals, were used to estimate open surgical biopsy costs and surgical consultation costs. The largest increase in utilization of diagnostic procedures per 100 referrals was observed for axillary ultrasound (from 3.9 in 2000 to 33.5 in 2005) and for stereotactic core biopsy (from 2.1 in 2000 to 26.8 in 2005). Per 100 referrals, the open surgical biopsy rate decreased from 34.7 (2000) to 4.6 (2005) and the number of outpatient surgical consultations fluctuated between 269.8 (2000) and 309.7 (2004). Mean costs for the diagnosis of one cancer were Euro1,501 and ranged from Euro1,223 (2002) to Euro1,647 (2003). Surgical biopsies comprised 54.1% of total diagnostic costs for women screened in 2000, but decreased to 9.9% for women screened in 2005. Imaging costs increased from 23.7 to 43.8%, percutaneous biopsy costs from 9.9 to 27.2%, and consultation costs from 12.3 to 19.1%. We conclude that diagnostic costs per screen-detected cancer remained fairly stable through the years, although huge changes in the use of different diagnostic procedures were observed.