Has the mammography quality standards act affected the mammography quality in North Carolina?

OBJECTIVE: The United States Food and Drug Administration implemented federal regulations governing mammography under the Mammography Quality Standards Act (MQSA) of 1992. During 1995, its first year in implementation, we examined the impact of the MQSA on the quality of mammography in North Carolina. MATERIALS AND METHODS: All mammography facilities were inspected during 1993-1994, and again in 1995. Both inspections evaluated mean glandular radiation dose, phantom image evaluation, darkroom fog, and developer temperature. Two mammography health specialists employed by the North Carolina Division of Radiation Protection performed all inspections and collected and codified data. RESULTS: The percentage of facilities that met quality standards increased from the first inspection to the second inspection. Phantom scores passing rate was 31.6% versus 78.2%; darkroom fog passing rate was 74.3% versus 88.5%; and temperature difference passing rate was 62.4% versus 86.9%. CONCLUSION: In 1995, the first year that the MQSA was in effect, there was a significant improvement in the quality of mammography in North Carolina. This improvement probably resulted from facilities' compliance with federal regulations.     

Characterization of microcalcification: can digital monitor zooming replace magnification mammography in full-field digital mammography?

The aim of this study was to compare the diagnostic accuracy and image quality of microcalcifications in zoomed digital contact mammography with digital magnification mammography. Three radiologists with different levels of experience in mammography reviewed 120 microcalcification clusters in 111 patients with a full-field digital mammography system relying on digital magnification mammogram (MAG) images and zoomed images from contact mammography (ZOOM) using commercially available zooming systems on monitors. Each radiologist estimated the probability of malignancy and rated the image quality and confidence rate. Performance was evaluated by sensitivity, specificity, positive predictive value, negative predictive value, and receiver operating characteristic (ROC) analysis. All three radiologists rated MAG images higher than ZOOM images for sensitivity with statistical significance (average value, 92% vs. 87%, P < 0.05) and performance by ROC analysis improved with MAG imaging. The confidence rate for diagnosis decision and the assessment of lesion characteristics were also better in MAG images than in ZOOM images with statistical significance (P < 0.0001). Digital magnification mammography can enhance diagnostic performance when characterizing microcalcifications. Images zoomed from digital contact mammography cannot serve as an alternative to direct magnification digital mammography. This work was supported by the Korea Research Foundation Grant funded by the Korean Government (MOEHRD) (KRF-2007-313-E00363).     

Why do women refrain from mammography screening?

IntroductionBreast cancer is the leading cause of death for middle-aged women in Sweden. Approximately 600,000 women are surveyed annually within the national screening program. However, 20% of Swedish women do not participate in mammography screening. Participation in mammography screening is a complex phenomenon that has many dimensions. The aim of this study was to explore the reasons why women refrain from mammography screening from the perspective of non-attending women.MethodA qualitative approach was chosen, and 10 women were interviewed. The interviews were analysed using qualitative content analysis.ResultsTwo categories were identified: individual needs and absence of active promotion. “Non-personalized system” was the main theme that emerged from the analysis.ConclusionThe mammography screening does not adapt to the needs of each individual. This may be the reason why some women refrain from mammography screening.     

Can positron emission mammography help to identify clinically significant breast cancer in women with suspicious calcifications on mammography?

Objective

To evaluate the diagnostic accuracy of positron emission mammography (PEM) for identifying malignant lesions in patients with suspicious microcalcifications detected on mammography.

Methods

A prospective, single-centre study that evaluated 40 patients with suspicious calcifications at mammography and indication for percutaneous or surgical biopsy, with mean age of 56.4 years (range: 28-81 years). Patients who agreed to participate in the study underwent PEM with 18F-fluorodeoxyglucose before the final histological evaluation. PEM findings were compared with mammography and histological findings.

Results

Most calcifications (n?=?34; 85.0 %) were classified as BIRADS 4. On histology, there were 25 (62.5 %) benign and 15 (37.5 %) malignant lesions, including 11 (27.5 %) ductal carcinoma in situ (DCIS) and 4 (10 %) invasive carcinomas. On subjective analysis, PEM was positive in 15 cases (37.5 %) and most of these cases (n?=?14; 93.3 %) were confirmed as malignant on histology. There was one false-positive result, which corresponded to a fibroadenoma, and one false negative, which corresponded to an intermediate-grade DCIS. PEM had a sensitivity of 93.3 %, specificity of 96.0 % and accuracy of 95 %.

Conclusion

PEM was able to identify all invasive carcinomas and high-grade DCIS (nuclear grade 3) in the presented sample, suggesting that this method may be useful for further evaluation of patients with suspected microcalcifications.

Key Points

? Many patients with suspicious microcalcifications at mammography have benign results at biopsy. ? PEM may help to identify invasive carcinomas and high-grade DCIS. ? Management of patients with suspicious calcifications can be improved.

     

Does digital mammography in a decentralized breast cancer screening program lead to screening performance parameters comparable with film-screen mammography?

Objective:

To evaluate if the screening performance parameters of digital mammography (DM) in a decentralized screening organization were comparable with film-screen mammography (FSM).

Methods:

A nationwide screening program was launched in 2001, and since 2005 screening with DM has been allowed. Firstly, the parameters of the three regional screening units (RSUs) that first switched to DM (11,355 women) were compared with the FSM period of the same three RSUs (23,325 women). Secondly, they were compared with the results of the whole central breast unit (CBU).

Results:

The recall rate (RR) of the DM group in the initial round was 2.64% [2.40% for FSM (p?=?0.43)] and in the subsequent round 1.20% [1.58% for FSM (p?=?0.03)]. The cancer detection rate (CDR) was 0.59% for DM and 0.64% for FSM (p?=?0.56). The percentage of ductal carcinoma in situ was 0.07% for DM and 0.16% for FSM (p?=?0.02). The positive predictive value was high in the subsequent rounds (DM 48.00%, FSM 45.93%) and lower in the initial round (DM 24.05%, FSM 24.86%). Compared with the results of the whole CBU, DM showed no significant difference.

Conclusion:

DM can be introduced in a decentralized screening organization with a high CDR without increasing the RR.     

Can mechanical imaging increase the specificity of mammography screening?

Objectives

This study aimed to investigate the effects of adding adjunct mechanical imaging to mammography breast screening. We hypothesized that mechanical imaging could detect increased local pressure caused by both malignant and benign breast lesions and that a pressure threshold for malignancy could be established. The impact of this on breast screening was investigated with regard to reductions in recall and biopsy rates.

Methods

155 women recalled from breast screening were included in the study, which was approved by the regional ethical review board (dnr 2013/620). Mechanical imaging readings were acquired of the symptomatic breast. The relative mean pressure on the suspicious area (RMPA) was defined and a threshold for malignancy was established.

Results

Biopsy-proven invasive cancers had a median RMPA of 3.0 (interquartile range (IQR)?=?3.7), significantly different from biopsy-proven benign at 1.3 (IQR?=?1.0) and non-biopsied cases at 1.0 (IQR?=?1.3) (P?<?0.001). The lowest RMPA for invasive cancer was 1.4, with 23 biopsy-proven benign and 33 non-biopsied cases being below this limit. Had these women not been recalled, recall rates would have been reduced by 36% and biopsy rates by 32%.

Conclusions

If implemented in a screening situation, this may substantially lower the number of false positives.

Key Points

? Mechanical imaging is used as an adjunct to mammography in breast screening. ? A threshold pressure can be established for malignant breast cancer. ? Recalls and biopsies can be substantially reduced.

     

Breast compression in mammography: how much is enough?

The amount of breast compression that is applied during mammography potentially influences image quality and the discomfort experienced. The aim of this study was to determine the relationship between applied compression force, breast thickness, reported discomfort and image quality. Participants were women attending routine breast screening by mammography at BreastScreen New South Wales Central and Eastern Sydney. During the mammographic procedure, an 'extra' craniocaudal (CC) film was taken at a reduced level of compression ranging from 10 to 30 Newtons. Breast thickness measurements were recorded for both the normal and the extra CC film. Details of discomfort experienced, cup size, menstrual status, existing breast pain and breast problems were also recorded. Radiologists were asked to compare the image quality of the normal and manipulated film. The results indicated that 24% of women did not experience a difference in thickness when the compression was reduced. This is an important new finding because the aim of breast compression is to reduce breast thickness. If breast thickness is not reduced when compression force is applied then discomfort is increased with no benefit in image quality. This has implications for mammographic practice when determining how much breast compression is sufficient. Radiologists found a decrease in contrast resolution within the fatty area of the breast between the normal and the extra CC film, confirming a decrease in image quality due to insufficient applied compression force.     

Zooming method (× 2.0) of digital mammography vs digital magnification view (× 1.8) in full-field digital mammography for the diagnosis of microcalcifications

The purpose of this study was to determine whether the interpretation of microcalcifications assessed on images zoomed (× 2.0) from digital mammograms is at least equivalent to that from digital magnification mammography (× 1.8) with respect to diagnostic accuracy and image quality. Three radiologists with different levels of experience in mammography reviewed each full-field digital mammography reader set for 185 patients with pathologically proven microcalcification clusters, which consisted of digital magnification mammograms (MAGs) with a magnification factor of 1.8 and images zoomed from mammograms (ZOOM) with a zoom factor of 2.0. Each radiologist rated their suspicion of breast cancer in microcalcific lesions using a six-point scale and the image quality and their confidence in the decisions using a five-point scale. Results were analysed according to display methods using areas under the receiver operating characteristic curves (A_z value) for ZOOM and MAGs to interpret microcalcifications, and the Wilcoxon matched pairs signed rank test for image quality and confidence levels. There was no statistically significant difference in the level of suspicion of breast cancer between the ZOOM and MAG groups (A_z = 0.8680 for ZOOM; A_z = 0.8682 for MAG; p = 0.9897). However, MAG images were significantly better than ZOOM images in terms of visual imaging quality (p < 0.001), and the confidence level with MAG was better than with ZOOM (p < 0.001). In conclusion, the performance of radiologists in the diagnosis of microcalcifications using ZOOM was similar to that using MAGs, although image quality and confidence levels were better using MAGs.Magnification mammography produces better spatial resolution and signal-to-noise ratio than does contact mammography. It is well established as a valuable adjunct to contact mammography, especially for the diagnosis of microcalcifications, despite the additional radiation exposure and increased radiation dose because of the shorter distance between the breast and X-ray source during examination [1–4].However, with respect to full-field digital mammography (FFDM), a few studies using zoomed images from contact mammograms have recently been reported and, as a result, a debate has arisen over whether a digital zooming system of FFDM can replace the magnification view of digital mammography [5–7]. Whereas Fischer et al [5] reported that zoomed images of a digital contact mammogram were equivalent to direct magnification of FFDM for the interpretation of microcalcifications, our previous report suggested that magnification mammography yielded better sensitivity and receiver operating characteristic (ROC) analysis than did zoomed images [7]. However, that study compared images zoomed by a factor of 1.3 with images magnified by a factor of 1.8. Therefore, we wondered whether using a zooming factor comparable to a magnification factor of 1.8 would yield the same results.The purpose of this study was to determine whether the diagnostic accuracy and image quality of microcalcification assessments using images twice zoomed from contact mammograms were equivalent to those obtained using digital magnification mammography by a magnification factor of 1.8.     

Artifacts in contrast-enhanced mammography: are there differences between vendors?

PurposeContrast-Enhanced Mammography (CEM) produces a dual-energy subtracted (DES) image that demonstrates iodine uptake (neovascularity) in breast tissue. We aim to review a range of artifacts on DES images produced using equipment from two different vendors and compare their incidence and subjective severity.MethodsWe retrospectively reviewed CEM studies performed between September 2013 and March 2017 using GE Senographe Essential (n = 100) and Hologic Selenia Dimensions (n = 100) equipment. Artifacts were categorized and graded in severity by a subspecialist breast radiologist and one of two medical imaging technologists in consensus. The incidence of artifacts between vendors was compared by calculating the relative risk, and the severity gradings were compared using a Wilcoxon rank-sum test.ResultsElephant rind, corrugations and the black line on chest wall artifact were seen exclusively in Hologic images.Artifacts such as cloudy fat, negative rim around lesion and white line on pectoral muscle were seen in significantly more Hologic images (p < 0.05) whilst halo, ripple, skin line enhancement, black line on pectoral muscle, bright pectorals, chest wall high-lighting and air gap were seen in significantly more GE images (p < 0.05).The severity gradings for cloudy fat had a significantly higher mean rank in Hologic images (p < 0.001) whilst halo and ripple artifacts had a significantly higher mean rank in GE images (p < 0.001 and p = 0.028 respectively).ConclusionThe type, incidence and subjective severity of CEM-specific artifacts differ between vendors. Further research is needed, but differences in algorithms used to produce the DE image are postulated to be a significant contributor.     

Communicating results of diagnostic mammography: what do patients think?

RATIONALE AND OBJECTIVES: The purpose of this study was to investigate women's preferences for who (radiologist or referring physician) should communicate the results of diagnostic mammography. MATERIALS AND METHODS: Data from 153 women presenting to two sites for diagnostic mammography between February and June 1995 were collected with a 24-item, self-administered, closed-ended survey. For both normal and abnormal hypothetical results, contingency tables with chi2 tests and multiple logistic regression were used to determine the association, if any, between women's characteristics and their preferences. RESULTS: Women undergoing diagnostic mammography preferred that their radiologists disclose their normal (90%) and abnormal (88%) mammogram results to them immediately after their examination, rather than have their referring physicians disclose results at a later time. In the case of normal findings, women whose regular physicians were specialists were less likely to want to hear first from their radiologists (odds ratio [OR] = 0.06; 95% confidence interval [CI] = 0.01, 0.77; P = .03), but women who were nervous about learning their results were more likely to want to hear first from their radiologists (OR = 4.5; 95% CI = 1.2, 17.3; P = .03). CONCLUSION: Radiologists may want to consider assessing women's preferences for who communicates their mammogram results, as most women in this study preferred to hear these results from their radiologists rather than waiting to hear from their referring physicians.     

Pressure and breast thickness in mammography—an exploratory calibration study

Objective

To perform a calibration study to provide data to help improve consistency in the pressure that is applied during mammography.

Methods

Automatic readouts of breast thickness accuracy vary between mammography machines; therefore, one machine was selected for calibration. 250 randomly selected patients were invited to participate; 235 agreed, and 940 compression data sets were recorded (breast thickness, breast density and pressure). Pressure (measured in decanewtons) was increased from 5 daN through 1-daN intervals until the practitioner felt that the pressure was appropriate for imaging; at each pressure increment, breast thickness was recorded.

Results

Graphs were generated and equations derived; second-order polynomial trend lines were applied using the method of least squares. No difference existed between breast densities, but a difference did exist between “small” (15×29 cm) and “medium/large” (18×24/24×30 cm) paddles. Accordingly, data were combined. Graphs show changes in thickness from 5-daN pressure for craniocaudal and mediolateral oblique views for the small and medium/large paddles combined. Graphs were colour coded into three segments indicating high, intermediate and low gradients [≤−2 (light grey); −1.99 to −1 (mid-grey); and ≥−0.99 (dark grey)]. We propose that 13 daN could be an appropriate termination pressure on this mammography machine.

Conclusion

Using patient compression data we have calibrated a mammography machine to determine its breast compression characteristics. This calibration data could be used to guide practice to minimise pressure variations between practitioners, thereby improving patient experience and reducing potential variation in image quality.

Advances in knowledge

For the first time, pressure–thickness graphs are now available to help guide mammographers in the application of pressure.In 2008, within the UK, breast cancer was the second most diagnosed cancer in females. Internationally, it accounted for nearly 11% of female cancer deaths [1]. For breast cancer detection, mammography plays an important role in screening symptomatic populations and rigorous quality assurance procedures are applied accordingly [2,3]. There is a particular emphasis on equipment performance [4] and image reader ability to identify abnormalities [5]. By contrast, surprisingly little quality assurance emphasis is placed on the clinical image acquisition phase—especially the optimisation of pressure to reduce breast thickness.Pressure is considered necessary to reduce breast thickness and for many years this reduction has been associated with image quality enhancement and radiation dose limitation [6]. Within the UK, there is no specific protocol for thickness reduction, but it is generally accepted that pressure should be applied slowly and gently to ensure that the breast is held firmly in place and the skin is taut to touch or that blanching occurs [3,7,8]. The National Health Service Breast Screening Programme (NHSBSP) suggests that pressure should not exceed 20 daN. Limited literature exists about the application of pressure. However, Sullivan et al [9] demonstrated a relationship between pressure and thickness, and a maximum value of 16 daN was suggested. By contrast, Chida et al [10] used a standard compression force of 12 daN; if patients experienced pain a reduced force of 9 daN was suggested. Documented variation of opinion therefore exists.Practitioner subjectivity associated with pressure application has been a concern for many years [11], and in 2004 Poulos and McLean [12] predicted that lack of attention to this could lead to large variations. In 2011, Mercer et al [13] concluded, from a cross-sectional clinical study of 500 females and 14 practitioners (radiographers and assistant practitioners), that large variations existed, and 3 categories of “compressor” were identified by their mean compression values: low—7.4 daN [standard deviation (SD) 1.5]; medium—8.8 daN (SD 1.5); and high—11.1 daN (SD 2.1). Importantly, Mercer et al concluded that the variation is highly dependent upon the practitioner. The study by Mercer et al raises concerns about the consistency of care, radiation dose and image quality, and suggests that more objective criteria for the application of pressure in mammography are required.On reviewing the literature it is clear that little is published on the optimisation of pressure in mammography; for instance, almost no empirical data are available to describe how the in vivo female breast behaves when pressure is applied to it. This may partly explain why the NHSBSP guidance is lacking in detail and also why this aspect of practice is not adequately quality assured.In this exploratory study we present a method and data to describe the relationship between pressure and female breast thickness. Because mammography machine and paddle combinations have readout thickness inaccuracies [14,15], we have verified the relationship only for one machine by using a sample from its “typical” clinical population. It is worth remembering that Hauge et al [14] used a deformable breast phantom to determine how readout thickness varied from actual thickness; the experiment was conducted under clinically realistic conditions, which incurred bend and distortion across the paddle surface. These are not accounted for in standard medical physics quality control tests. With this in mind, it might be that, for the same pressure, thickness values will be different between mammography machines and different paddles. Similarly, there may be patient differences too, particularly between screening and symptomatic caseloads. Calibrating a mammography unit based on its local caseload would therefore seem an important first step.Our study follows a similar design to work conducted by Hoflehner et al [16] and Poulos and McLean [12]. For one mammography machine, we outline a method to determine breast compression characteristics which include typical end points for pressure cessation and critical stages within the compression cycle. We conclude by proposing that our approach could be used to establish local pressure standards on which practice might be based and assessed.     

Can contrast enhanced mammography solve the problem of dense breast lesions?

Objective

To assess the diagnostic accuracy of dual-energy contrast-enhanced digital mammography (CEDM) as an adjunct to mammography (MX) vs. MX alone and vs. mammography plus ultrasound (US) in dense breasts.

Materials and methods

60 women with suspected findings on MX and/or US underwent CEDM. A pair of low- and high-energy images was acquired using a modified full-field digital mammography system. Exposures were taken in MLO at 2 min and in CC at 4 min after the injection of 1.5 ml/kg of an iodinated contrast agent. Sensitivity, specificity, and area under the ROC curve were estimated.

Results

The results from pathology identified 16 benign and 44 malignant cases. Areas under the ROC curves were significantly superior for MX + CEDM than it was for MX alone using BI-RADS. Sensitivity was higher for MX + CEDM than it was for MX (97.7% vs. 93.2%) with no loss in specificity. The lesion size was closer to the histological size for CEDM. All 12 histologically proven multifocal lesions were correctly detected by MX + CEDM vs. 6 and 8 lesions by MX and US respectively.

Conclusion

Initial clinical results show that CEDM has better diagnostic accuracy than mammography alone and mammography + ultrasound especially in dense breasts.     

Can the size of microcalcifications predict malignancy of clusters at mammography?

RATIONALE AND OBJECTIVES: The purpose of this study was to determine whether the size of mammographically detected microcalcifications is predictive of malignancy. MATERIALS AND METHODS: Two hundred sixty mammograms showing clustered microcalcifications with proven diagnoses (160 malignant, 100 benign) were respectively reviewed by experienced mammographers. Lesions that were obviously benign in appearance were excluded from the study. A computer-aided diagnosis system digitized the lesions at 600 dpi, and the microcalcifications on the digital image were interactively defined by mammographers. Subsequently, three quantitative features that reflected the size of the microcalcifications-length, area, and brightness-were automatically extracted by the system. For each feature, the standard average of values obtained for individual calcifications within the cluster and the average with emphasis on extreme values (E) obtained in a single cluster were analyzed and matched with pathologic results. RESULTS: In the malignant group of cases, the mean values of the standard average length and area were significantly higher (P < .0001) than the mean values in the benign group. Distribution analysis demonstrated that an average length of more than 0.41 mm was associated with malignant lesions 77% of the time, while an average length of less than 0.41 mm was associated with benign lesions 71% of the time. The mean of the average length (E) and area (E) of microcalcifications within the cluster demonstrated an even higher discriminative power when compared with the standard average length and area. The average brightness, on the other hand, showed only a low discriminative power. CONCLUSION: Digital computerized analysis of mammographically detected calcifications demonstrated that the average length and area of the calcifications in benign clusters were significantly smaller than those in malignant clusters.