Mammography in the 1990s: the United States and Canada

Quality assurance in Mammography: An overview

Since 1989, hundreds of thousands of lives have been saved worldwide by the widespread use of screening mammography alongside new developments in breast cancer treatment [1]. The ability of screening mammography to detect cancer early, when treatment is most effective, is optimized when it is performed in the highest quality manner and accessed by all eligible candidates. Currently, worldwide, there are over 14 guidance documents for mammographic quality [2]. Some countries, such as the United Kingdom (UK), monitor quality through a national screening program. In the United States (US), where 39 million mammograms are performed annually [3], there is not a national screening program, but the federal government mandates minimum quality standards for the performance of mammography. Among a consortium of European countries, the European Reference Organisation for Quality Assured Breast Screening and Diagnostic Services (EUREF) promotes voluntary adherence to European mammography quality standards. Setting quality standards at national or international levels ensures the uniformity of practice and identifies substandard practices in need of improvement, ultimately maximizing the benefit of screening mammography.

Breast cancer screening: an evidence-based update

Routine screening mammography is recommended by most groups issuing breast cancer screening guidelines, especially for women 50 years of age and older. However, both the potential benefits and risks of screening should be discussed with individual patients to allow for shared decision making regarding their participation in screening, age of commencement and conclusion, and interval of mammography screening.

Fracture risk assessment after BMD examination: whose job is it, anyway?

Fracture risk assessments on bone mineral density reports guide family physicians' treatment decisions but are subject to inaccuracy. Qualitative analysis of interviews with 22 family physicians illustrates their pervasive questioning of reported assessment accuracy and independent assumption of responsibility for assessment. Assumption of responsibility is common despite duplicating specialists' work.

INTRODUCTION

Fracture risk is the basis for recommendations of treatment for osteoporosis, but assessments on bone mineral density (BMD) reports are subject to known inaccuracies. This creates a complex situation for referring physicians, who must rely on assessments to inform treatment decisions. This study was designed to broadly understand physicians' current experiences with and preferences for BMD reporting; the present analysis focuses on their interpretation and use of the fracture risk assessments on reports, specifically

METHODS

A qualitative, thematic analysis of one-on-one interviews with 22 family physicians in Ontario, Canada was performed.

RESULTS

The first major theme identified in interview data reflects questioning by family physicians of reported fracture risk assessments' accuracy. Several major subthemes related to this included questioning of: 1) accuracy in raw bone mineral density measures (e.g., g/cm(2)); 2) accurate inclusion of modifying risk factors; and 3) the fracture risk assessment methodology employed. A second major theme identified was family physicians' independent assumption of responsibility for risk assessment and its interpretation. Many participants reported that they computed risk assessments in their practice to ensure accuracy, even when provided with assessments on reports.

CONCLUSIONS

Results indicate family physicians question accuracy of risk assessments on BMD reports and often assume responsibility both for revising and relating assessments to treatment recommendations. This assumption of responsibility is common despite the fact that it may duplicate the efforts of reading physicians. Better capture of risk information on BMD referrals, quality control standards for images and standardization of risk reporting may help attenuate some inefficiency.

Clinical image evaluation of film mammograms in Korea: comparison with the ACR standard

Objective

The goal of this study is to compare the overall quality of film mammograms taken according to the Korean standards with the American College of Radiology (ACR) standard for clinical image evaluation and to identify means of improving mammography quality in Korea.

Materials and Methods

Four hundred and sixty eight sets of film mammograms were evaluated with respect to the Korean and ACR standards for clinical image evaluation. The pass and failure rates of mammograms were compared by medical facility types. Average scores in each category of the two standards were evaluated. Receiver operating characteristic curve analysis was used to identify an optimal Korean standard pass mark by taking the ACR standard as the reference standard.

Results

93.6% (438/468) of mammograms passed the Korean standard, whereas only 80.1% (375/468) passed the ACR standard (p < 0.001). Non-radiologic private clinics had the lowest pass rate (88.1%: Korean standard, 71.8%: ACR standard) and the lowest total score (76.0) by the Korean standard. Average scores of positioning were lowest (19.3/29 by the Korean standard and 3.7/5 by the ACR standard). A cutoff score of 77.0 for the Korean standard was found to correspond to a pass level when the ACR standard was applied.

Conclusion

We suggest that tighter regulations, such as, raising the Korean pass mark, subtracting more for severe deficiencies, or considering a very low scores in even a single category as failure, are needed to improve the quality of mammography in Korea.

Effects of quality assurance regulatory enforcement on performance of mammography systems: evidence from large-scale surveys in Taiwan

OBJECTIVE

The Standards for Medical Exposure Quality Assurance in mammography systems were enacted on July 1, 2008, in Taiwan. This study aimed to evaluate the trends in performance of mammography units before and after the regulation started on the basis of annual on-site surveys from 2008 to 2010.

MATERIALS AND METHODS

On-site measurements were conducted on 215, 205, and 209 mammography units in 2008, 2009, and 2010, respectively, which accounted for more than 95% of all units in Taiwan. Phantom image quality, average glandular dose (AGD), and half-value layer were evaluated on all systems. Processor conditions, compression conditions, radiation output, and computed radiography exposure indicators were assessed on units participating in mammography screening in 2008 and on all units in the later years. Evaluations of maximum compression force and automatic exposure control reproducibility were added into the protocol from 2009 onward.

RESULTS

Mean phantom scores were improved significantly from 2008 to 2009 (11.63 ± 1.30 vs 12.31 ± 0.94, p < 0.05) and remained stable for 2010 (12.35 ± 0.87). Mean AGDs were 1.48 ± 0.47, 1.38 ± 0.41, and 1.37 ± 0.42 mGy over the 3 years, with a significant reduction from 2008 to 2009 (p < 0.05). For film-screen mammography systems, variations of sensitometric curves were greatly reduced in 2009 and 2010 when compared with 2008. Passing rates were increased after the regulation took effect in almost all aspects.

CONCLUSION

Results from large-scale on-site surveys showed an overall improvement in performance after quality assurance in mammography was enforced in Taiwan.

Reconstruction of absorbed doses to fibroglandular tissue of the breast of women undergoing mammography (1960 to the present)

The assessment of potential benefits versus harms from mammographic examinations as described in the controversial breast cancer screening recommendations of the U.S. Preventive Task Force included limited consideration of absorbed dose to the fibroglandular tissue of the breast (glandular tissue dose), the tissue at risk for breast cancer. Epidemiological studies on cancer risks associated with diagnostic radiological examinations often lack accurate information on glandular tissue dose, and there is a clear need for better estimates of these doses. Our objective was to develop a quantitative summary of glandular tissue doses from mammography by considering sources of variation over time in key parameters, including imaging protocols, X-ray target materials, voltage, filtration, incident air kerma, compressed breast thickness, and breast composition. We estimated the minimum, maximum and mean values for glandular tissue dose for populations of exposed women within 5-year periods from 1960 to the present, with the minimum to maximum range likely including 90% to 95% of the entirety of the dose range from mammography in North America and Europe. Glandular tissue dose from a single view in mammography is presently about 2 mGy, about one-sixth the dose in the 1960s. The ratio of our estimates of maximum to minimum glandular tissue doses for average-size breasts was about 100 in the 1960s compared to a ratio of about 5 in recent years. Findings from our analysis provide quantitative information on glandular tissue doses from mammographic examinations that can be used in epidemiological studies of breast cancer.

Pediatric digital radiography summit overview: state of confusion

On Feb. 4, 2010, the Alliance for Radiation Safety in Pediatric Radiology held a Pediatric Digital Radiography Summit. The goal was for radiologists, radiologic technologists, medical physicists, and vendor representatives, including engineers, medical physicists and education specialists, to discuss the challenges to achieving the ALARA (as low as reasonably achievable) principle in pediatric digital radiography and to lay the groundwork for overcoming these obstacles. This article focuses on the state of confusion that exists for radiologists and radiologic technologists who use digital radiography equipment. Radiologists might have a difficult time accepting lower dose (noisy images), and radiologic technologists might respond by increasing patient exposures, which results in excessive patient doses. For reporting exposures, vendors have a history of using proprietary terms that confuse users. In addition, technical parameters cannot be easily exported for quality assurance, and there is no national standard for digital radiography. Presentations in this minisymposium focus on suggestions for the cooperative development of new technical standards, education and training to improve the quality of digital radiography in pediatric patients and promote radiation protection for children.

Managing radiation use in medical imaging: a multifaceted challenge

This special report aims to inform the medical community about the many challenges involved in managing radiation exposure in a way that maximizes the benefit-risk ratio. The report discusses the state of current knowledge and key questions in regard to sources of medical imaging radiation exposure, radiation risk estimation, dose reduction strategies, and regulatory options.

Factors affecting decreasing radiation dose for mammography in North Carolina after 2002: an analysis of Food and Drug Administration annual surveys

RATIONALE AND OBJECTIVES

We sought to determine which factors affected the decrease in average glandular dose recorded at the annual U.S. Food and Drug Administration Mammography Quality Standards Act inspections of mammography equipment in North Carolina from 2002 through 2005.

MATERIALS AND METHODS

Average glandular dose, half-value layer, kVp, equipment age, processing speed, and system speed for every mammography unit in the state were collected by Food and Drug Administration-trained state inspectors. A mixed-effect model was used to evaluate the changes of glandular dose over time and to identify the factors associated with these changes.

RESULTS

There was a statistically significant decrease in average glandular dose in North Carolina since 2002. Factors that were statistically significantly associated with this effect were changes in kVp, equipment age, processing speed, and system speed.

CONCLUSION

Average glandular dose for mammography has decreased in North Carolina after 2002. This change is probably at least partially due to the cumulative effect of direct intervention by mammography consultants and statewide educational seminars on mammography quality control.

United States radiological health activities: inspection results of mammography facilities

Purpose:

The Mammography Quality Standards Act (MQSA) was enacted in 1992 to set national standards for high-quality mammography, including standards for mammographic X-ray equipment, patient dose, clinical image quality, and related technical parameters. The MQSA also requires minimum qualifications for radiologic technologists, interpreting physicians and medical physicists, mandates acceptable practices for quality-control, quality-assurance, and requires processes to audit medical outcomes. This paper presents the findings of MQSA inspections of facilities, which characterize significant factors affecting mammography quality in the United States.

Materials and Methods:

Trained inspectors collected data regarding X-ray technical factors, made exposure measurements for the determination of mean glandular dose (MGD), evaluated image quality, and inspected the quality of the film-processing environment. The average annual facility and total U.S. screening exam workloads were computed using workload data reported by facilities.

Results:

Mammography facilities have made technical improvements as evidenced by a narrower distribution of doses, higher phantom-film background optical densities associated with higher phantom image-quality scores, and better film processing. It is estimated that approximately 36 million screening mammography exams were conducted in 2006, a rate that is almost triple the exam volume estimated for 1997. Digital mammography (DM) is now in use at approximately 14% (1,191 of 8,834) of MQSA-certified mammography facilities. The results indicate that DM can offer lower dose to the patient while providing comparable or better image quality.

Digital mammography: effects of reduced radiation dose on diagnostic performance

PURPOSE

To experimentally determine the relationship between radiation dose and observer accuracy in the detection and discrimination of simulated lesions for digital mammography.

MATERIALS AND METHODS

This HIPAA-compliant study received institutional review board approval; the informed consent requirement was waived. Three hundred normal craniocaudal images were selected from an existing database of digital mammograms. Simulated mammographic lesions that mimicked benign and malignant masses and clusters of microcalcifications (3.3-7.4 cm in diameter) were then superimposed on images. Images were rendered without and with added radiographic noise to simulate effects of reducing the radiation dose to one half and one quarter of the clinical dose. Images were read by five experienced breast imaging radiologists. Results were analyzed to determine effects of reduced dose on overall interpretation accuracy, detection of microcalcifications and masses, discrimination between benign and malignant masses, and interpretation time.

RESULTS

Overall accuracy decreased from 0.83 with full dose to 0.78 and 0.62 with half and quarter doses, respectively. The decrease associated with transition from full dose to quarter dose was significant (P < .01), primarily because of an effect on detection of microcalcifications (P < .01) and discrimination of masses (P < .05). The level of dose reduction did not significantly affect detection of malignant masses (P > .5). However, reduced dose resulted in an increased mean interpretation time per image by 28% (P < .0001).

CONCLUSION

These findings suggest that dose reduction in digital mammography has a measurable but modest effect on diagnostic accuracy. The small magnitude of the effect in response to the drastic reduction of dose suggests potential for modest dose reductions in digital mammography.

Evaluation of dual-energy subtraction of digital mammography images under conditions found in a commercial unit

Radiological contrast-to-noise ratio (CNR) is evaluated in subtracted images of microcalcifications in breast tissue. CNR is calculated for dual-kVp subtraction combining beams available in a Senographe 2000D, assuming single breast compression. Spectra were obtained from Boone et al (1997 Med. Phys. 24 1863-73), and the study was limited to lowest 25 kV Mo/Mo and highest 40 kV Rh/Rh beams, for 2.58 x 10(-4) C kg(-1) (1R) total exposure. For a standard case combining 25 kVp Mo/Mo and 40 kVp Rh/Rh beams, predicted maximum CNR for 300 microm calcification in 5 cm thick, 50% glandular, breast is about 1.2, below Rose's criterion for visualization. Total mean glandular doses are about 2.5 cGy for a standard case. The effect that input factors might have on predictions has been evaluated. Choice between alternative spectra can affect CNR by 50%. Assumed calcification composition leads to differences of 67% in calculated CNR, and assumed breast tissue composition can alter CNR by 45%; these results are weakly dependent on calcification or breast thickness, or on the assumed fraction of glandular tissue. CNR values are related to detected spectra effective energy. Calculations predict that above 37 kVp Mo/Mo beams are more energetic than Rh/Rh at the same kVp, due to beam hardening.

Global quality control perspective for the physical and technical aspects of screen-film mammography--image quality and radiation dose

The systematic monitoring of image quality and radiation dose is an ultimate solution to ensuring the continuously high quality of mammography examination. At present several protocols exist around the world, and different test objects are used for quality control (QC) of the physical and technical aspects of screen-film mammography. This situation may lead to differences in radiation image quality and dose reported. This article reviews the global QC perspective for the physical and technical aspects of screen-film mammography with regard to image quality and radiation dose. It points out issues that must be resolved in terms of radiation dose and that also affect the comparison.

The ACR’s Mammography Accreditation Program: Ten Years of Experience Since MQSA

The ACR's Mammography Accreditation Program has been helping facilities improve the quality of mammography through peer review and professional feedback since 1987. Initially conceived as a voluntary program, accreditation became mandatory when the Mammography Quality Standards Act (MQSA) of 1992 required all U.S. mammography facilities to become accredited and certified by October 1, 1994. Currently, the ACR is the largest of four accrediting bodies approved by the U.S. Food and Drug Administration, accrediting 12,729 units at 8325 facilities by October 1, 2004. Between 1987 and 1991, 70% of the mammography units applying for accreditation with the ACR passed on their first attempts. In 2003, 88.3% of the units passed on their first attempts, indicating a marked improvement in the quality of mammography in the United States since MQSA went into effect 10 years ago.

Evaluation of equipment performance, patient dose, imaging quality, and diagnostic coincidence in five Mexico City mammography services

BACKGROUND

Regulations concerning the use of x-rays in medical diagnoses were published in Mexico in 1997. In this work, we evaluate technical aspects of mammography services in the Mexico City area and radiation dose and coincidence between the radiological interpretation by the institution radiologist and by a panel of experts.

METHODS

Following methodology proposed by the American College of Radiology and the European Community among others, we have evaluated the performance of six mammography systems in Mexico City public and private services. The studied services carry out approximately one half of the mammography studies in the capital's metropolitan area.

RESULTS

The systems comply with 53-82% of a total of 31 applied quality control tests and measurements, which include the mammography unit, x-ray generation, collimation, automatic exposure control, compression devices, grid and image receptor, film processing, darkroom, viewboxes, dose, film rejection, and image quality. The elements that most frequently fail are film processing, darkroom, and light boxes; average ACR phantom score is 11.2 (9.5, 12.0); mean average glandular dose measured with the phantom is 1.00 (0.71-1.15) mGy, and measured in patients is 1.75 (0.3, 4.9) mGy; coincidence between radiologic reports (BI-RADS) by the institution radiologist and a panel of experts is obtained in 35% of studied cases.

CONCLUSIONS

Statistical analysis of results indicated that the level of equipment performance is correlated with image quality, image quality estimated by the panel of radiologists is correlated with phantom score, and coincidence in clinical mammography reports is not correlated with equipment performance and appears to depend on the radiologist's experience.

Adverse effects of screening mammography

The main risks and other adverse consequences from screening mammography include discomfort from breast compression, patient recall for additional imaging, and false positive biopsies. Although these risks affect a larger number of women than those who benefit from screening, the risks are less consequential than the life-sparing benefits from early detection. Radiation risk, even for multiple screenings, is negligible at current mammography doses. Anxiety before screening or resulting from supplementary imaging work-up, short-term follow-up, cyst aspiration, and biopsy has not dampened the enthusiasm of most women for the value of early detection.

Nationwide Evaluation of X-ray Trends Survey of Abdomen and Lumbosacral Spine Radiography

Results of the 1995 Nationwide Evaluation of X-ray Trends (NEXT) survey of facilities that perform diagnostic radiographic examinations of the abdomen and lumbosacral spine were compared with those of previous NEXT surveys conducted in 1987 and 1989. A clinically validated radiographic phantom was used in the 1995 survey to capture data about radiation exposure and image quality. Additional data were obtained regarding clinical techniques, facility workloads, x-ray beam quality, film processing quality, and darkroom fog. Mean skin-entrance air kerma for the abdomen examination dropped from 3.2 mGy (in 1987) to 2.8 mGy at hospitals and from 3.4 mGy (in 1989) to 3.0 mGy at nonhospital facilities. Mean skin-entrance air kerma also decreased for the lumbosacral spine examination from 3.7 mGy (in 1987) to 3.3 mGy at hospitals and from 3.8 mGy (in 1989) to 3.2 mGy at nonhospital facilities. The quality of film processing improved, although 58 (18.3%) of 317 surveyed facilities did not meet the Mammography Quality Standards Act standard for film processing quality, compared with 185 (5.9%) of 3,120 mammography facilities inspected in 1995. Finally, 181 (58.0%) of 312 surveyed facilities had darkroom fog levels greater than the Mammography Quality Standards Act standard, compared with 1,426 (16.6%) of 8,605 mammography facilities inspected in 1995.

Factors affecting increasing radiation dose for mammography in North Carolina from 1997 through 2001: an analysis of Food and Drug Administration annual surveys

RATIONALE AND OBJECTIVES

To determine which factors affected the increase in average glandular dose recorded at the annual US Food and Drug Administration Mammography Quality Standards Act inspections of mammography equipment in North Carolina from 1997 to 2001.

MATERIALS AND METHODS

Average glandular dose, HVL, kVp, ambient light, luminance, equipment age, processing speed, and system speed for every mammography unit at all facilities in the state were collected by state inspectors. A mixed-effect model was used to assess the average changes of glandular dose over time and to identify the factors associated with these changes.

RESULTS

There was a statistically significant increase in the average glandular dose in North Carolina in 1999, 2000, and 2001 when compared with the baseline year of 1997. Factors that were statistically significantly linked to this effect were changes in kVp, processing speed, and system speed.

CONCLUSION

Average glandular dose for mammography has recently increased in North Carolina. This change is likely caused by changes in screen-film products and processing techniques.

Breast tomography with synchrotron radiation: preliminary results

A system for in vivo breast imaging with monochromatic x-rays has been designed and built at the synchrotron radiation facility Elettra in Trieste (Italy) and will be operational in 2004. The system design involves the possibility of performing both planar mammography and breast tomography. In the present work, the first results obtained with a test set-up for breast tomography are shown and discussed. Tomographic images of in vitro breasts were acquired using monochromatic x-ray beams in the energy range 20-28 keV and a linear array silicon pixel detector. Tomograms were reconstructed using standard filtered backprojection algorithms; the effect of different filters was evaluated. The attenuation coefficients of fibroglandular and adipose tissue were measured, and a quantitative comparison of images acquired at different energies was performed by calculating the differential signal-to-noise ratio of fibroglandular details in adipose tissue. All images required a dose comparable to the dose delivered in clinical, conventional mammography and showed a high resolution of the breast structures without the overlapping effects that limit the visibility of the structures in 2D mammography. A quantitative evaluation of the images proves that the image quality at a given dose increases in the considered energy range and for the considered breast sizes.

Does hormone replacement therapy increase the frequency of breast atypical hyperplasia in postmenopausal women? Results from the Bouches du Rhone district screening campaign

It is thought that the risk of atypical hyperplasia (AH) increases with age, particularly among postmenopausal women. Three hypotheses were investigated to try to explain this phenomena: use of hormone replacement therapy (HRT), increased breast cancer screening and improvements in radiological quality. Data were collected from the Bouches du Rhône breast cancer screening programme database and from the pathological registry of all women operated on for breast diseases in the district. The AH incidence rate was studied using a Poisson regression analysis. The change in the profile of breast diseases was explored through studying changes in the proportion of AH among benign lesions and malignant diseases. The AH incidence rate significantly increased over time (13.6% per year). The proportion of AH among the benign diseases increased with time and was significantly higher for HRT users (Odds Ratio (OR)=2.05; 95% Confidence Interval (CI): 1.43-2.93). While AH decreased with age among HRT non-users, it increased among users as a proportion of both benign and malignant lesions. The AH incidence rate significantly increased among pre- and postmenopausal women. Our study suggests that this increase is partly explained by the incidental discovery of these lesions by mammography and partly by a real increase of the disease among HRT users.

Comparison between high-resolution helical CT and pathology in breast examination

PURPOSE

To determine whether high-resolution helical CT can show the architectural features of breast carcinomas of non-limited extent (non-BCLE) and to establish the CT characteristic morphology of non-BCLE.

MATERIAL AND METHODS

We prospectively studied high-resolution helical CT of 136 invasive breast carcinomas before breast-conserving surgery. Non-BCLE were defined as ductal carcinomas in situ and invasive carcinomas beyond 1 cm from the edge of the dominant mass. Non-BCLE were defined as positive if enhanced beyond 1 cm from the edge of the focal enhancement on CT. After surgical resection, specimens were sliced in serial sections at 5-mm intervals, and the gross morphology and histology were correlated with the appearance of the preoperative CT lesion images.

RESULTS

Non-BCLE were present in 47 invasive carcinomas. The sensitivity and specificity of non-BCLE evaluation by high-resolution helical CT were 70% and 89%, respectively. The morphology of non-BCLE on CT agreed with histologic findings. The morphological pattern on CT significantly correlated with intraductal tumor density adjacent to invasive tumor.

CONCLUSION

Comparison of high-resolution helical CT with histologic data suggests that demonstration of a non-BCLE morphology can make the CT breast carcinoma local staging more accurate.

Breast US: assessment of technical quality and image interpretation

PURPOSE

To determine whether ultrasonography (US) of the breast performed at a wide range of clinical practices conforms to the American College of Radiology (ACR) standards for quality and to assess the interpretations of breast sonograms.

MATERIALS AND METHODS

Static images from 152 breast US examinations performed at 86 institutions were evaluated for compliance with ACR guidelines for breast US hardware, technical factors, imaging protocol, and image annotation. Official interpretations submitted by the referring facilities were compared with static images submitted by the facility. Discrepancies were confirmed by two dedicated breast radiologists after repeat imaging, short-interval follow-up imaging, or biopsy.

RESULTS

A total of 60.5% of cases did not comply with at least one ACR guideline on breast US and included 9.2% of cases with inadequate equipment, 14.7% of cases with inappropriate focal zone placement, at least 14% of cases with static images in only one imaging plane, and 25% of cases with incomplete patient identifiers. Clinically relevant interpretation errors and interpretation discrepancies were confirmed in 23 (15.1%) of 152 cases.

CONCLUSION

The majority of breast US examinations did not comply with at least some of the standards for quality set forth by the ACR. Attention to these basic standards could substantially improve image quality.

A survey of clinical factors and patient dose in mammography

A survey was conducted to estimate the mean glandular dose (MGD) for women undergoing mammography and to report the distribution of doses, compressed breast thickness, glandular tissue content, and mammographic technique factors used. From 24,471 mammograms, of 6,006 women, clinical data were collected. The survey data included mammograms from seven modern units using a molybdenum (Mo) anode and either Mo or rhodium (Rh) filter. Exposure factors for each mammogram were recorded automatically onto a floppy disk on each unit. All mammography units were calibrated individually using breast tissue equivalent attenuation slabs of varying glandular content, so the breast glandular content could be estimated on the basis of exposure factors and compressed breast thickness. The MGD was estimated for each mammogram based on the normalized glandular dose and calculated entrance exposure in air. The survey found a median MGD of 2.6 mGy. The median breast glandular tissue content was 28% and the median compressed breast thickness was 5.1 cm. Also, patient attenuation data were converted to equivalent BR-12 and acrylic thickness to help determine appropriate phantom thicknesses required for mammography unit automatic exposure control performance assessment.

Three-dimensional helical CT of the breast: accuracy for measuring extent of breast cancer candidates for breast conserving surgery

OBJECTIVE

To evaluate the accuracy of three-dimensional (3D) helical computed tomography (CT) for assessing the extent of breast cancer of candidates for breast conserving surgery.

METHODS

Results of helical CT were studied in 144 lesions of 144 patients with breast cancer before breast-conserving surgery. A lesion was defined as positive if focal enhancement was detected by CT within 100 s after contrast material administration. After resection, tumors were histopathologically mapped and correlated with the extent of 3D images.

RESULTS

Helical CT enabled detection of 143 tumors but not of one ductal carcinoma in situ (DCIS). The median deviation of the tumor extension revealed by 3D helical CT images from pathological assessment was 7.7 mm (range 0-60 mm). The extent of tumors was significantly correlated with CT measurements (r = 0.714, p < 0.0001). By multivariate analysis, the presence of invasive tumors with intraductal extensions beyond the edge of the invasive tumor and histologic type (DCIS) were significant risk factors for deviation of the tumor extension revealed by 3D helical CT images from pathological assessment.

CONCLUSION

Three dimensional helical CT of the breast is an accurate preoperative imaging modality for assessing the extent of breast cancer candidates for breast conserving surgery.

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.

Breast imaging: from 1965 to the present

The current state of the art for breast imaging is reviewed in comparison with the methods of practice commonly in use 25-35 years ago to demonstrate the most important advances that have taken place in imaging techniques, operational considerations, interpretive approaches, and interventional procedures. Since 1965, breast imaging has progressed from the simple assessment of breast disease in a selected small number of symptomatic women to the comprehensive evaluation of both breast health and disease in a substantial percentage of all women aged 40 years and older. In the process, breast imaging has become an established radiologic subspecialty that accounts for at least 10% of all examinations performed by radiologists. Indeed, mammography now is the most common imaging examination that directly results in the reduction of mortality from disease.

Breast cancer: genetic predisposition and exposure to radiation

The identification of breast cancer susceptibility genes, such as BRCA1, BRCA2, ATM, and p53, has been accompanied by the examination of the effects of radiation in combination with genetic mutations at these loci. Women at high risk for developing breast cancer may respond differently than the general population to low- and high-dose radiation exposures associated with screening and treatment. Epidemiologic studies are being performed to investigate the effects of radiation on subsequent breast cancer development in genetically predisposed individuals. Mouse strains with specific genetic modifications are being created to study the consequence of both inherited mutations and radiation on mammary gland carcinogenesis. Finally, studies investigating DNA damage-response pathways after radiation exposure are being performed. Recent work on the effects of several known or suspected breast cancer susceptibility genes, alone or in combination with radiation, is presented here, and directions for future research are considered.

Breast cancer screening, diagnosis, and treatment

The incidence of breast cancer in US women remains disturbingly high, and unfortunately primary care physicians still frequently encounter patients in whom the disease is suspected or, even worse, confirmed. Fortunately, however, the body of knowledge surrounding the disease has grown dramatically during the past decade, and major advances have been made in the understanding of breast cancer risk, prevention, diagnosis, and treatment. Controversies persist, particularly those concerning the screening of younger women, but consensus now exists regarding many clinical issues relevant to primary care practice. Although multidisciplinary subspecialty expertise must be made available to all women with known or suspected breast cancer, the primary care physician has an important role to play when dealing with patients with this condition. The following article focuses on what primary care practitioners need to know to expertly contribute to the diagnosis, counseling, and initial treatment of women with this disease.