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PubMed2005

[Contributions of the epidemiological cancer registries to the evaluation of mammography screening in Germany].

INTRODUCTION: Before the country-wide introduction of mammography screening, testing of the organised screening took place in Weser-Ems, Bremen and Wiesbaden. Important quality assurance parameters (carcinomas detected during checkup intervals, tumour stage distribution, breast cancer incidence rate, breast cancer mortality rate) are to be evaluated via epidemiological cancer registries. For the model region Weser-Ems (MSWE) the record linkage with the epidemiological cancer registry Lower Saxony (EKN) was successfully accomplished. The technical realisation and first comparison analyses for the development of breast cancer incidence and of tumour size are reported. MATERIAL AND METHODS: The target population of the MSWE was 22,600 women aged 50-69 years. They were invited since May 2002 to mammography screening with a screening interval of two years. The record linkage of 12,913 women who participated until February 2004 in the MSWE, was realised by the use of the control number system of the epidemiological cancer registries. The observation time was between 6 and 25 month (median: 15 month). Reference population for comparison analyses were all women between 50 and 69 years of the remaining governmental district Weser-Ems (255,000 women). RESULTS: In the first record linkage 96 screening-cases (ICD-10 C50 + D05) could be identified. Additionally six interval cancers were determined (time between screening and diagnosis in months: median 5.5; mean 7.7). The breast cancer incidence increased in the MSWE area and in the control-area, the rise in the MSWE area being higher. The increase was especially observed with the small tumours. Women with breast cancer diagnosed by screening: 19.8% in-situ-cancer and 18.8% very small tumours < = 10 mm. In the control area Weser-Ems this rate with 5.6% in-situ-cancer and 14.5% very small tumours, was relatively high, indicating the spread of opportunistic mammographies in absence of organised screening. CONCLUSION: First effects of mammography screening can be evaluated early by comparison between screening data and the data of population-based cancer registries. Using the control number system of the epidemiological cancer registries and comparison by pseudonyms the evaluation of quality assurance parameters of the MSWE can be realised in compliance with the data security law. The feedback of cancers, detected during checkup intervals is not covered by the cancer registry law. For the implementation of the guidelines for early recognition cancer legal adjustments will be necessary. This concept can be easily adapted to other screening programme.

Age Factors↗
PubMed1997

[Morphology and contrast enhancement of ductal carcinoma in situ in dynamic 1.0 T MR mammography].

PURPOSE: The detectability with magnetic resonance mammography (MR-M) of non-invasive ductal carcinoma in situ (DCIS), its morphology, and patterns of contrast enhancement were studied. MATERIAL AND METHODS: A total of 849 MR-M examinations were performed in 741 patients using a dynamic, contrast-enhanced FLASH 3D sequence at 1.0 T. Surgical breast biopsies were obtained in 332 cases. Histological work-up confirmed 164 carcinomas, including 20 DCIS. RESULTS: Of 20 DCIS, 14 were correctly diagnosed by MR-M on the basis of focal increase of signal intensity. In two cases (10%), no increase of signal intensity was observed. In another three cases (15%), multifocal enhancement lead to a false-negative diagnosis. In one case (5%), DCIS was a random finding in a patient diagnosed and treated for adjacent phylloides tumour. The sensitivity of MR-M was 70%. 4 (20%) of the DCIS did not show microcalcifications at conventional mammography and were only detected at MR-M. The sensitivity of conventional mammography also amounted to 70%. However, the combination of both imaging methods increased sensitivity to 90%. CONCLUSION: Ductal carcinoma in situ is not reliably detectable by MR-mammography alone due to lack of a uniform pattern of enhancement.

Biopsy↗
PubMed1996

[Clinical relevance of mammography in men].

PURPOSE: During a period of four years 104 mammograms were performed in 89 men. Mastectomies were carried out on 23 men (group 1). 66 patients (group 2) were followed up clinically and in 15 patients serial mammograms were obtained. MATERIAL AND METHOD: In group 1 there were 5 patients with bilateral gynaecomastia, 9 with unilateral gynaecomastia and two with pseudogynaecomastia and there were 7 patients with malignancies. In group 2 there were 46 patients with bilateral gynaecomastia and 10 patients with unilateral gynaecomastia. Pseudogynaecomastia was found in 25 patients. There were 7 malignancies, of which 5 had been suspected clinically and one had been diagnosed as gynaecomastia by mammography. Two carcinomas in situ were missed clinically and also by mammography. CONCLUSION: When malignancy is not suspected on clinical grounds the first examination should be sonography, mammography being reserved for cases of doubt. Where, however, malignancy is suspected, and for follow-up, mammography retains its primary position.

Adolescent↗
PubMed1995

[Quality assurance by improved cooperation structures. The example of decentralized early detection mammography].

The German Mammography Study investigated into quality assurance measures for screening mammography, proceeding in a decentralised manner and focussing especially on structure, process and outcome of the study. The field phase lasted for three years, and during this period the technology of the equipment used in mammography improved, also to the indicators of process and of early outcome. The annual interval of examinations was well received. To include mammography into the German cancer screening programme is no easy matter: it requires a comprehensive cooperative quality assurance programme incorporating various institutions of medical care. Appropriate recommendations have been made to the Federal Committee of Physicians and Sickness Insurance Bodies.

Adult↗
PubMed1994

[Preoperative MR-mammography in diagnosed breast carcinoma. Useful information or useless extravagance?].

In a retrospective study the value of MR mammography in cases of radiological well-known carcinoma of the breast was evaluated preoperatively in 76 cases of histopathologically verified carcinoma one lesion was missed by MR imaging. Compared to the results of conventional X-ray mammography additional malignant lesions were detected in 5 patients ipsilaterally and in another 8 patients contralaterally by MR mammography only. In additional 4 cases MR mammography demonstrated suspicious lesions contralaterally, but histopathology revealed benign lesions. The therapeutic procedure was changed in 15 cases (18.5%) due to the findings of MR imaging: Ipsilateral mastectomy instead of tumorectomy (n = 5) or primary chemotherapy instead of operation (n = 1); contralateral additional tumorectomy (n = 3) or mastectomy (n = 2) by carcinoma and open biopsy (n = 4) by benign finding.

Adult↗
PubMed1991

[The value of mammography in patients up to the age of 35].

The use of mammography in young women is under debate. In this prospective study of 220 women aged up to 35 years, the indications for mammography were compared with the final diagnosis. In this way, an attempt was made to define the signs and symptoms that justify mammography in this age group. The results show that mammography is indicated only in the presence of palpable lumps. All other signs or symptoms should not be investigated by means of ionising radiation in this particular age bracket.

Adolescent↗
PubMed1994

[Magnetic resonance imaging of breast implants. Significance compared to mammography and ultrasonography].

Magnetic resonance imaging (MRI), mammography and ultrasonography were performed in 44 consecutive women (mean age 45 [29-70] years) with a total of 73 silicone breast implants. The implant had been inserted after mastectomy for cancer in 15 patients, for cosmetic breast augmentation in 29. MRI proved to be superior to the other two imaging modalities with respect to assessing implant content, capsule and surrounding tissues. In 39 patients MRI clearly demarcated the implant from the residual breast tissue. But in four patients the lateral MRI assessment was impaired by phase artefact and in one other by movement artefacts in a restless patient. Implant thickness was underestimated by mammography and ultrasonography compared with MRI. In nine cases mammography showed retromammary parenchyma, while MRI did so in 20. The posterior wall of the implant was visualized by mammography in only one patient, but in all of them by MRI. Ultrasonography failed in all patients to show the entire implant circumference. In three cases MRI was the only imaging method which revealed a defect in the implant capsule with extrusion of silicone.

Adult↗
PubMed1997

Interobserver variation in the interpretation of breast imaging. Comparison of mammography, ultrasonography, and both combined in the interpretation of palpable noncalcified breast masses.

PURPOSE: To analyze interobserver agreement in the interpretation of palpable noncalcified breast masses by means of mammography, ultrasonography, and a combination of both methods. MATERIAL AND METHODS: Mammograms and ultrasonograms of 100 benign breast masses and 100 malignant ones in 200 patients were retrospectively analyzed by 4 radiologists with experience in both imaging modalities. The images were analyzed independently and without knowledge of the final diagnosis. The analysis was performed in 3 sessions and used a 5-point rating scale for probability of malignancy. The interobserver variation was analyzed by means of observed agreement, kappa, and weighted kappa statistics based on the 5-point rating scale and a 3-level scale of the collapsed 5-point scale. The chi-square statistic was used for testing the equality of the kappa values. RESULTS: The overall kappa value on the 3-level scale was 0.48 (range 0.37-0.61) for ultrasonography, 0.58 (range 0.52-0.66) for mammography, and 0.71 (range 0.63-0.79) for the combined reading. The kappa values were statistically different for ultrasonography but did not differ significantly for the mammographic and combined readings. The combined reading showed higher kappa values than mammography alone, and the improvement was statistically significant for 3 of the 6 pairs of comparison. CONCLUSION: Radiologists differ substantially in their interpretations of mammograms and breast ultrasonograms. Agreement was highest in the combined reading, intermediate in mammography, and lowest in ultrasonography.

Breast Neoplasms↗
PubMed2005

A model for determining the effect of mammography service screening.

In an overview, Swedish mammography screening trials demonstrated a 29% reduction in breast cancer mortality in women aged 50-69 and no effect on total mortality. Three Danish regions introduced mammography screening in the 1990s. The authors developed a method to evaluate the effect of mammography service screening on breast cancer mortality and validated it applying it to total mortality, where no effect was expected. Study groups and historical and national control groups were analysed using Poisson regression. Total mortality in the screening regions and periods was close to that expected in the absence of screening. A small (3%) excess risk, also seen in a non-screening area, probably results from regional differences changing over time. The effect of this is inseparable from the screening effect. The design is adequate for analysing the effect of mammography service screening on breast cancer mortality.

Aged↗
PubMed2003

Getting no respect: barriers to mammography for a group of Swedish women.

Mammography screening is a highly sensitive and specific method to detect breast cancer at an early stage. If screening campaigns are to be cost effective, compliance is valuable. However, many women do not attend when called for mammography screening. Our aim in this study is to understand and explain why women become nonattenders. A sample of 16 nonattending women, aged between 43 and 73 years, participated in this qualitative study, by interviews or written comments. The core category discovered in the data was "getting no respect." The informants did not feel respected from either the society or the health care system. Below this core category, two categories were identified: the mammography examination and affecting circumstances. The performance and its effects comprised the content of the category of mammography examination. The category affecting circumstances included knowledge about risk factors, prevention, and practical or emotional arguments.

Adult↗
PubMed2001

Impact of a multimedia breast cancer education intervention on use of mammography by low-income Latinas.

BACKGROUND: This paper describes the results of a study of a multimedia breast cancer educational intervention for low-education, low-income Latinas. METHODS: Study participants were first exposed to an interactive, multimedia breast cancer educational intervention and then interviewed four months later to ascertain their mammography status. RESULTS: About 40% of the women who had either obtained or scheduled mammography since the intervention attributed their decision to the intervention. CONCLUSION: Women who had previously been screened and who understood that mammography was used as a breast cancer screening method were more likely to have scheduled or obtained mammography than other women.

Adult↗
PubMed1989

Dosimetric aspects of film/screen mammography: in-phantom dosimetry with thimble-type ionisation chambers.

The characteristics of 0.6 cm3 thimble-type Baldwin-Farmer (BF 2571) ionisation chambers for absorbed dose determinations in-phantom at mammography installations are investigated. The most important aspects for in-phantom dosimetry in mammography concern the conversion from air kerma to absorbed dose in mammary gland tissue, the energy dependence of the sensitivity of the ionisation chamber and the displacement correction factor for measurements in-phantom. Due to the considerable uncertainties in the elemental composition of the mammary glands the conversion from air kerma to absorbed dose in the mammary gland tissue has an uncertainty of the order of +/- 20%. The air kerma calibration factor of the BF-ionisation chamber is about 10% larger at mammography radiation qualities than at 300 kV x-rays or 137Cs gamma rays. For depths in excess of about 15 mm a displacement correction factor of 0.69 +/- 0.06 is derived for measurements with the BF 2571 chamber inside polymethylmethacrylate (PMMA) phantoms irradiated with 30 kV x-rays (first HVL:0.29 mm Al). The previously reported discrepancy between dose measurements with TLD and ionisation chambers at the entrance surface of a phantom for mammography radiation qualities is resolved and could be attributed to attenuation in the TLD encapsulation material.

Female↗
PubMed2003

An adaptive algorithm for the detection of microcalcifications in simulated low-dose mammography.

This paper uses the task of microcalcification detection as a benchmark problem to assess the potential for dose reduction in x-ray mammography. We present the results of a newly developed algorithm for detection of microcalcifications as a case study for a typical commercial film-screen system (Kodak Min-R 2000/2190). The first part of the paper deals with the simulation of dose reduction for film-screen mammography based on a physical model of the imaging process. Use of a more sensitive film-screen system is expected to result in additional smoothing of the image. We introduce two different models of that behaviour, called moderate and strong smoothing. We then present an adaptive, model-based microcalcification detection algorithm. Comparing detection results with ground-truth images obtained under the supervision of an expert radiologist allows us to establish the soundness of the detection algorithm. We measure the performance on the dose-reduced images in order to assess the loss of information due to dose reduction. It turns out that the smoothing behaviour has a strong influence on detection rates. For moderate smoothing. a dose reduction by 25% has no serious influence on the detection results. whereas a dose reduction by 50% already entails a marked deterioration of the performance. Strong smoothing generally leads to an unacceptable loss of image quality. The test results emphasize the impact of the more sensitive film-screen system and its characteristics on the problem of assessing the potential for dose reduction in film-screen mammography. The general approach presented in the paper can be adapted to fully digital mammography.

Algorithms↗
PubMed2004

Microcalcification detection using cone-beam CT mammography with a flat-panel imager.

The purpose of this study was to investigate microcalcification detectability using CT mammography with a flat-panel imager. To achieve this, a computer simulation was developed to model an amorphous-silicon, CsI based flat-panel imager system using a linear cascaded model. The breast was modelled as a hemi-ellipsoid shape with composition of 50% adipose and 50% glandular tissue. Microcalcifications were modelled as small spheres having a composition of calcium carbonate. The results show that with a mean glandular dose equivalent to that typically used in two-view screening mammography, CT mammography with a flat-panel detector is capable of providing images where most microcalcifications are detectable. A receiver operating characteristic (ROC) study was conducted by five physicist observers viewing simulated CT mammography reconstructions. The results suggest that the microcalcification with its diameter equal to or greater than 0.175 mm can be detected with an average area under the ROC curve (AUC) greater than 0.95 using 0.1 or 0.2 mm pixelized detectors. The results also indicate that the optimal pixel size of the detector is around 0.2 mm for microcalcification detection, based on the trade-off between detectability of microcalcifications and the time required for data acquisition and reconstruction.

Algorithms↗
PubMed2004

Effect of area x-ray beam equalization on image quality and dose in digital mammography.

In mammography, thick or dense breast regions persistently suffer from reduced contrast-to-noise ratio (CNR) because of degraded contrast from large scatter intensities and relatively high noise. Area x-ray beam equalization can improve image quality by increasing the x-ray exposure to under-penetrated regions without increasing the exposure to other breast regions. Optimal equalization parameters with respect to image quality and patient dose were determined through computer simulations and validated with experimental observations on a step phantom and an anthropomorphic breast phantom. Three parameters important in equalization digital mammography were considered: attenuator material (Z = 13-92), beam energy (22-34 kVp) and equalization level. A Mo/Mo digital mammography system was used for image acquisition. A prototype 16 x 16 piston driven equalization system was used for preparing patient-specific equalization masks. Simulation studies showed that a molybdenum attenuator and an equalization level of 20 were optimal for improving contrast, CNR and figure of merit (FOM = CNR2/dose). Experimental measurements using these parameters showed significant improvements in contrast, CNR and FOM. Moreover, equalized images of a breast phantom showed improved image quality. These results indicate that area beam equalization can improve image quality in digital mammography.

Artifacts↗
PubMed2005

Are phantoms useful for predicting the potential of dose reduction in full-field digital mammography?

A phantom study was performed in full-field digital mammography to investigate the opportunity and the magnitude of a possible dose reduction that would leave the image quality above the accepted thresholds associated with some classical phantoms. This preliminary work is intended to lay the groundwork for a future clinical study on the impact of dose reduction on clinical results. Three different mammography phantoms (ACR RMI 156, CIRS 11A and CDMAM 3.4) were imaged by a full-field digital mammography unit (GE Senographe 2000D) at different dose levels. Images were rated by three observers with softcopy reading and scoring methods specific to each phantom. Different types of data analysis were applied to the ACR (American College of Radiology) and the other two phantoms, respectively. With reference to the minimum acceptance score in screen/film accreditation programmes, the ACR phantom showed that about 45% dose reduction could be applied, while keeping the phantom scores above that threshold. A relative comparison was done for CIRS and CDMAM, for which no threshold is defined. CIRS scoring remained close to the reference level down to 40% dose reduction, the inter- and intra-observer variability being the main source of uncertainty. Contrast-detail curves provided by CDMAM overlapped down to 50% dose reduction, at least for object contrast values ranging between 30% and 3%. This multi-phantom study shows the potential of further reducing the dose in full-field digital mammography beyond the current values. A common dose reduction factor around 50% seems acceptable for all phantoms. However, caution is required before extrapolating the results for clinical use, given the limitations of these widely used phantoms, mainly related to their limited dynamic range and uniform background.

Equipment Failure Analysis↗
PubMed2006

The development of mammography.

This review traces the development of mammography physics over the last 50 years, concentrating mainly on technological changes and their inter-relations. It has been written for physicists with no specific mammography experience but a general interest in radiology, as much as for those with recent involvement in mammography. Topics covered include industrial film, xerography, intensifying screens, x-ray tube developments, image quality test objects, patient dose and performance checks. Some of these developments were necessary before population screening of healthy women could be considered, while others have resulted from increased opportunities for equipment manufactures which screening programmes created. The standpoint of this review is that of a physicist with long experience in a UK centre where mammography was performed on dedicated equipment well over 40 years ago and where screening has been performed continuously for 30 years.

Animals↗
PubMed2006

Dual-energy mammography: simulation studies.

This paper presents a mammography simulator and demonstrates its applicability in feasibility studies in dual-energy (DE) subtraction mammography. This mammography simulator is an evolution of a previously presented x-ray imaging simulation system, which has been extended with new functionalities that are specific for DE simulations. The new features include incident exposure and dose calculations, the implementation of a DE subtraction algorithm as well as amendments to the detector and source modelling. The system was then verified by simulating experiments and comparing their results against published data. The simulator was used to carry out a feasibility study of the applicability of DE techniques in mammography, and more precisely to examine whether this modality could result in better visualization and detection of microcalcifications. Investigations were carried out using a 3D breast software phantom of average thickness, monoenergetic and polyenergetic beam spectra and various detector configurations. Dual-shot techniques were simulated. Results showed the advantage of using monoenergetic in comparison with polyenergetic beams. Optimization studies with monochromatic sources were carried out to obtain the optimal low and high incident energies, based on the assessment of the figure of merit of the simulated microcalcifications in the subtracted images. The results of the simulation study with the optimal energies demonstrated that the use of the DE technique can improve visualization and increase detectability, allowing identification of microcalcifications of sizes as small as 200 microm. The quantitative results are also verified by means of a visual inspection of the synthetic images.

Algorithms↗