Breast imaging: mammography and ultrasonography.

Mammography is the primary imaging for breast cancer screening and diagnosis. Recent improvements in mammography are related to programs established by professional societies and government agencies to bring standardization and quality assurance in the technical improvements that have extended its contributions to breast imaging. This article addresses the current roles and limitations of mammography and ultrasonography in the detection and diagnosis of breast cancer.

Stereotactic core-needle breast biopsy: a multi-institutional prospective trial.

PURPOSE: To assess the accuracy of stereotactic core-needle biopsy (CNB) of nonpalpable breast lesions within the context of clinically important parameters of anticipated tissue-sampling error and concordance with mammographic findings. MATERIALS AND METHODS: CNB was performed in 1,003 patients, with results validated at surgery or clinical and mammographic follow-up. Mammographic findings were scored according to the American College of Radiology Breast Imaging Reporting and Data System with a similar correlative scale for histopathologic samples obtained at either CNB or surgery. Agreement of CNB findings with surgical findings or evidence of no change during clinical and mammographic follow-up (median, 24 months) for benign lesions was used to determine results. Three forms of diagnostic discrimination measures (strict, working [strict conditioned by tissue sampling error], applied [working conditioned by concordance of imaging and CNB findings) were used to evaluate the correlation of CNB, surgical, and follow-up results. RESULTS: Strict, working, and applied sensitivities were 91% +/- 1.9; 92% +/- 1.8, and 98% +/- 0.9, respectively; strict, working, and applied specificities were 100%, 98% +/- 0.8, and 73% +/- 0.9; strict, working, and applied accuracies were 97%, 96%, and 79%. CONCLUSION: Percutaneous stereotactic CNB is an accurate method to establish a histopathologic diagnosis of nonpalpable breast lesions. Accuracy increases when additional surgery is performed for lesions with anticipated sampling error or when CNB findings are discordant with mammographic findings. An understanding of the interrelationship among these parameters is necessary to properly assess results.

Imaging of breast masses.

The American College of Radiology Breast Imaging and Reporting Data System (ACR BI-RADS) defines a mass as a space-occupying lesion seen in at least two projections. This article focuses on the management of breast masses with mammography and ultrasonography. Recommended work-up pathways are modified for nonpalpable masses, palpable masses in women over the age of 30, and palpable masses in women under the age of 30. The suggested protocols are based on scientific peer-reviewed literature whenever possible, but when evidence based studies are not available, the author relies on expert opinion.

Reasons for failure of a mammography unit at clinical image review in the American College of Radiology Mammography Accreditation Program.

PURPOSE: To identify the most common deficiencies in the quality of mammograms submitted for clinical image evaluation (evaluation of image from actual patient referred for mammography). MATERIALS AND METHODS: In 1997, the American College of Radiology Mammography Accreditation Program reviewed clinical images for 2,341 mammography units. For each mammography unit, the facility submitted bilateral mediolateral oblique and craniocaudal mammograms obtained in a woman with fatty breasts and a woman with dense breasts. Images were reviewed independently by two experienced radiologists. Reviewers listed the general categories and specific deficiencies that led to a decision to fail the unit that produced the clinical images. RESULTS: Of the 2,341 mammography units, 1,034 (44%) failed the clinical image evaluation process. Of 6,128 categories cited by reviewers as deficient, 1,250 (20%) involved problems in positioning; 944 (15%), exposure; 887 (14%), compression; 806 (13%), sharpness; 785 (13%), contrast; 703 (11%), labeling; 465 (8%), artifacts; and 288 (5%), noise. A significantly higher proportion of failures was attributed to positioning deficiencies for fatty breasts than for dense breasts (P =.028). Higher proportions of failures in dense breasts were related to compression (P <.001) and exposure (P <.001) deficiencies. CONCLUSION: Common problems in clinical image quality have been identified. This information should be useful for educators and facilities striving to improve the quality of mammography.

Benign versus malignant solid breast masses: US differentiation.

PURPOSE: To investigate the general applicability and interobserver variability of ultrasonographic (US) features in differentiating benign from malignant solid breast masses. MATERIALS AND METHODS: One hundred sixty-two consecutive solid masses with a tissue diagnosis were reviewed. Three radiologists reviewed the masses without knowledge of clinical history or histologic examination results. RESULTS: US features that most reliably characterize masses as benign were a round or oval shape (67 of 71 [94%] were benign), circumscribed margins (95 of 104 [91%] were benign), and a width-to-anteroposterior (AP) dimension ratio greater than 1.4 (82 of 92 [89%] were benign). Features that characterize masses as malignant included irregular shape (19 of 31 [61%] were malignant), microlobulated (four of six [67%] were malignant) or spiculated (two of three [67%] were malignant) margins, and width-to-AP dimension ratio of 1.4 or less (28 of 70 [40%] were malignant). If the three most reliable criteria had been strictly applied by each radiologist, the overall cancer biopsy yield would have increased (from 23% to 39%) by 16%. When US images and mammograms were available, the increase in biopsy yield contributed by US was not statistically significant (2%, P = .73). However, in independent reviews, one to three reviewers interpreted four carcinomas as benign at US. CONCLUSION: The data confirm that certain US features can help differentiate benign from malignant masses. However, practice and interpreter variability should be further explored before these criteria are generally applied to defer biopsy of solid masses.

Effects of estrogen and estrogen-progestin on mammographic parenchymal density. Postmenopausal Estrogen/Progestin Interventions (PEPI) Investigators.

BACKGROUND: In longitudinal studies, greater mammographic density is associated with an increased risk for breast cancer. OBJECTIVE: To assess differences between placebo, estrogen, and three estrogen-progestin regimens on change in mammographic density. DESIGN: Subset analysis of a 3-year, multicenter, double-blind, randomized, placebo-controlled trial. SETTING: Seven ambulatory study centers. PARTICIPANTS: 307 of the 875 women in the Postmenopausal Estrogen/Progestin Interventions Trial. Participants had a baseline mammogram and at least one follow-up mammogram available, adhered to treatment, had not taken estrogen for at least 5 years before baseline, and did not have breast implants. INTERVENTION: Treatments were placebo, conjugated equine estrogens (CEE), CEE plus cyclic medroxyprogesterone acetate (MPA), CEE plus daily MPA, and CEE plus cyclic micronized progesterone (MP). MEASUREMENTS: Change in radiographic density (according to American College of Radiology Breast Imaging Reporting and Data System grades) on mammography. RESULTS: Almost all increases in mammographic density occurred within the first year. At 12 months, the percentage of women with density grade increases was 0% (95% CI, 0.0% to 4.6%) in the placebo group, 3.5% (CI, 1.0% to 12.0%) in the CEE group, 23.5% (CI, 11.9% to 35.1%) in the CEE plus cyclic MPA group, 19.4% (CI, 9.9% to 28.9%) in the CEE plus daily MPA group, and 16.4% (CI, 6.6% to 26.2%) in the CEE plus cyclic MP group. At 12 months, the odds of an increase in mammographic density were 13.1 (95% CI, 2.4 to 73.3) with CEE plus cyclic MPA, 9.0 (CI, 1.6 to 50.1) with CEE plus daily MPA, and 7.2 (CI, 1.3 to 40.0) with CEE plus cyclic micronized progesterone compared with CEE alone. CONCLUSIONS: Further study of the magnitude and meaning of increased mammographic density due to use of estrogen and estrogen-progestins is warranted because mammographic density may be a marker for risk for breast cancer.

Establishing minimum performance standards, calibration intervals, and optimal exposure values for a whole breast digital mammography unit.

Methods are developed to establish minimum performance standards, calibration intervals, and criteria for exposure control for a whole breast digital mammography system. A prototype phantom was designed, and an automatic method programmed, to analyze CNR, resolution, and dynamic range between CCD components in the image receptor and over time. The phantom was imaged over a 5 month period and the results are analyzed to predict future performance. White field recalibration was analyzed by subtracting white fields obtained at different intervals. Exposure effects were compared by imaging the prototype phantom at different kVp, filtration (Mo vs Rh) and mAs. Calcification detection tests showed that phantom images, obtained at 28 kVp with a Mo/Mo anode/filter and low mAs technique, often could not depict Al2O3 specks 0.24 mm in diameter, while a 28 kVp Mo/Rh, higher mAs technique usually could. Stability of the system tested suggests that monthly phantom imaging may suffice. Differences in CCD performance are greater (12%) than differences in a single CCD over time (6%). White field recalibration is needed weekly because of pixel variations in sensitivity which occur if longer intervals between recalibration occur. When mean glandular dose is matched, Rh filtration gives better phantom performance at 28 kVp than Mo filtration at 26 kVp and is recommended for clinical exposures. An aluminum step wedge shows markedly increased dynamic range when exit exposure is increased by using a higher energy spectrum beam. Phantoms for digital mammography units should cover the entire image receptor, should test intersections between components of the receptor, and should be automatically analyzed.

Breast sonography.

Ultrasonography (US) is well established as the most useful adjunctive breast imaging modality. While the traditional role of ultrasonography has been to differentiate between cystic and solid breast masses, recent advances in ultrasound technology and interpretation have the potential to expand greatly the role of this modality in the evaluation of breast disease. This paper reviews the current status of sonography as used in clinical practice and examines recent progress in equipment, technique, and interpretation of breast ultrasonography.

Multifeature analysis of Gd-enhanced MR images of breast lesions.

The objective of this study was to determine whether linear discriminant analysis of different independent features of MR images of breast lesions can increase the sensitivity and specificity of this technique. For MR images of 23 benign and 20 malignant breast lesions, three independent classes of features, including characteristics of Gd-DTPA-uptake curve, boundary, and texture were evaluated. The three classes included five, four and eight features each, respectively. Discriminant analysis was applied both within and across the three classes, to find the best combination of features yielding the highest classification accuracy. The highest specificity and sensitivity of the different classes considered independently were as follows: Gd-uptake curves, 83% and 70%; boundary features, 86% and 70%; and texture, 70% and 75%, respectively. A combination of one feature each from the first two classes and age yielded a specificity of 79% and sensitivity of 90%, whereas highest figures of 93% and 95%, respectively, were obtained when a total of 10 features were combined across different classes. Statistical analysis of different independent classes of features in MR images of breast lesions can improve the classification accuracy of this technique significantly.

Breast calcification and mass detection with mammographic anode-filter combinations of molybdenum, tungsten, and rhodium.

PURPOSE: To determine whether contrast loss on mammograms obtained with tungsten (W)-molybdenum (Mo), rhodium (Rh)-Rh, and W-Rh anode-filter units affects calcification and mass detection relative to that on mammograms obtained with Mo-Mo anode-filter units. MATERIALS AND METHODS: Three unfixed cadaveric breasts of 4.0-, 5.5-, or 7.0-cm thickness were imaged with three mammographic units with Mo-Mo, W-Mo, Rh-Rh, and W-Rh anode-filter combinations. Calcification clusters (<300 microm in diameter) and masses (0.5-1.2 cm) placed on the cadaveric breasts simulated abnormal mammograms. Thirty-five images without and 57 images with added calcifications and masses were acquired with a 180-speed screen-film system and interpreted by four mammographic specialists. With a 150-speed screen-film system, 10 normal images and 30 abnormal images with added calcifications were obtained with Mo-Mo and Rh-Rh equipment and read by three of the four radiologists. RESULTS: For the 180-speed system, there were statistically significant differences (P < .05) in detection of calcifications on Mo-Mo images compared with W-Mo, Rh-Rh, and W-Rh images. These differences disappeared with the 150-speed system. For mass detection with the 180-speed system, W-Rh was significantly better than Mo-Mo (P = .02). CONCLUSION: Dose savings and increased penetration with Rh-Rh and W-Rh anode-filter combinations may decrease calcification detection if fast screen-film systems are used, but mass detection may be improved.

Determinants of quality in mammography.

Mammography is a technically difficult examination, and experienced professionals with excellent dedicated mammographic equipment and processing conditions are essential to the delivery of quality examinations. However, the determinants of quality in mammography encompass more than just the technical components. The whole process, beginning with the scheduling of the examination and ending with the analysis of effectiveness of interpretations by a medical audit, ultimately determines the quality of the examination.

Effects of ambient light and view box luminance on the detection of calcifications in mammography.

OBJECTIVE: Viewing conditions can affect diagnostic performance differently depending on background optical densities. We quantified detection accuracy when viewing calcifications in glandular tissue under recommended viewing conditions versus accuracy with lower view box luminance and higher ambient lighting. MATERIALS AND METHODS: A phantom with adipose, 50% adipose and 50% glandular, and glandular-simulating material was imaged, and images were interpreted by five medical imaging physicists using two lighting conditions: the recommended one, high view box luminance (4365 nits) with low ambient light (25 lx), and a suboptimal one, low view box luminance (1763 nits) with moderate ambient lighting (290 lx). Then, a dense (Breast Imaging Reporting and Data System breast composition pattern type 4) unfixed cadaveric breast with numerous native calcifications was imaged 28 times. Nineteen of the films had added clusters of simulated calcifications. Three radiology fellows, each with 11 months of training in mammography, identified the added calcification clusters in the images under the two lighting conditions. Changes in phantom analysis and accuracy of the clinical diagnosis were compared for each lighting condition. RESULTS: On mammograms of the phantom, both speck and fibril identification were degraded by an average of 1.4 objects for the adipose-simulating section (with its darker optical density). For medium optical densities, found in the section with the simulation of 50% glandular and 50% adipose tissue, suboptimal lighting conditions had little or no effect on speck and fibril identification. For sections of the phantom that simulated glandular tissue, an average of 0.6 specks or fibers were not seen when lighting was suboptimal. With the dense cadaveric breast, the fraction of added calcification clusters detected by the three observers improved by an average of 17% when low luminance viewers and high ambient light were replaced with recommended viewing conditions; individual scores of the observers improved significantly: p values ranged from .02 to .05. CONCLUSION: Luminance of the view box and ambient lighting significantly affect detection of calcifications in dense breasts when images are interpreted by radiologists with about 1 year of training in mammography. Detection of calcifications in phantoms is primarily degraded for adipose tissue with its darker optical density. However, when lighting conditions are suboptimal, some observers also have trouble detecting calcifications in glandular tissue with its low optical density.

Status of mammography education and knowledge of radiology residents.

PURPOSE: To evaluate breast imaging training and knowledge of radiology residents over a 3-year period. MATERIALS AND METHODS: From 1992 through 1994, the American College of Radiology (ACR) sponsored a 1-day comprehensive breast imaging seminar, which was attended by 2,249 radiology residents at the 6-week radiologic-pathology course of the Armed Forces Institute of Pathology. At each course, the residents were asked to complete a demographics survey and identical pre- and post-tests to assess knowledge before and after the seminar. RESULTS: The majority of residents who attended the Armed Forces Institute of Pathology course were in their 2nd or 3rd year of radiology training, and 75% (1,682 of 2,249 residents) responded that they had training in breast imaging before the ACR seminar. There was an increase in the median residency training time devoted to mammography from 4-6 weeks in 1992 to 8-11 weeks in 1994. There was no statistically significant change in the pretest scores over the 3 years, with persistent weaknesses in knowledge about quality control and mammographic technique. There was improvement in short-term knowledge after the ACR seminar. CONCLUSION: Despite increased time spent in breast imaging training in radiology residency programs from 1992 through 1994, there was no statistically significant improvement in the baseline knowledge of residents who attended this course. This 1-day course improved short-term knowledge of breast imaging.

An update on core needle biopsy for radiologically detected breast lesions.

BACKGROUND: Traditionally, radiologically detected lesions of the breast have been evaluated by open surgical biopsy with wire localization. Recently, core needle biopsy has been introduced as an alternative to open surgical biopsy. The authors evaluated their own results with long term follow-up after core needle biopsy and reviewed the experience of other physicians with this new technique. METHODS: Four hundred thirty-one core needle biopsies performed at UCLA were analyzed. The outcome of these cases was determined by either surgery or long term follow-up. Statistical analysis was performed to determine the accuracy of the method. RESULTS: Definitive outcome was obtained in 96% of the core needle biopsy cases, with a median follow-up time of 18 months (range, 6-38 months). The authors achieved a sensitivity of 99% and a specificity of 100%. The false-negative rate was 1.7%. There were no complications in this series. CONCLUSIONS: Core needle biopsy is a highly accurate and safe method for the diagnosis of radiologically detected lesions of the breast.

Mobile mammography: results of a national survey.

PURPOSE: to learn about mobile mammography in the United States. MATERIALS AND METHODS: A survey of 82 questions was designed, pilot tested, and sent to mobile mammography facilities. The questions addressed many aspects of mobile programs, including administrative, financial, equipment, personnel, film processing, quality assurance, and communication of results. RESULTS: Of the 367 facilities that were mailed surveys, 159 facilities completed the survey, and 30 (19%) of those had discontinued their mobile programs. Seventy-six of 158 (48%) mobile facilities had performed mobile mammography for 1-5 years, and 69 of 158 (44%) had performed mobile mammography for more than 5 years. Seventy-two of 156 (46%) facilities were hospital-owned, and 25 of 156 (16%) were radiologist-owned. One hundred seven of 159 (67%) mobile facilities performed screening only. One hundred fourteen of 152 (75%) facilities charged +80.00 or less for screening. Mobile facilities averaged 20 examinations per day and served diverse populations. Sixty-seven of 159 (42%) facilities accepted self-referred women. Thirty-one percent of the facilities performed on-board processing. Only 71 of 149 (47%) facilities were financially profitable or breaking even, but 112 of 154 (73%) facilities would undertake a mobile project again. CONCLUSION: Mobile programs provide an opportunity to increase access to screening mammography, but they face many obstacles.

The regulation of mammography.

There has been a long history of public and professional concern about the safety and quality of mammography. Whereas concerns about radiation dose levels dominated the 1970s, the type of equipment used in mammography was the focus of the 1980s. In the early 1990s, there was a lack of confidence in the overall quality of mammography. These problems have stood in the way of the widespread utilization of mammography to reduce mortality from breast cancer. The Mammography Accreditation Program of the American College of Radiology, state regulations, and the Mammography Quality Standards Act of 1992 came about to ensure a minimum level of quality that would encourage women to participate in breast cancer screening programs. Designing regulations that ensure quality mammography for women, without burdening mammography facilities with unnecessary costs and depletion of their resources, is one of the most difficult challenges facing the U.S. Food and Drug Administration.

Mammographically guided fine-needle aspiration cytology of the breast: reducing the rate of insufficient specimens.

OBJECTIVE: The purpose of our study was to reduce the rate of insufficient specimens from fine-needle aspiration cytology (FNAC) of impalpable mammographically detected breast lesions. SUBJECTS AND METHODS: Our previous rate of insufficient specimens for FNAC was 27%. We implemented the following strategies to reduce this rate and improve accuracy: retraining of radiologists in FNAC procedures, more vigorous sampling, on-site evaluation of specimens by cytopathologist or cytotechnologist, exclusive use of stereotaxic guidance, stereotaxic equipment calibration program, and verification of initial needle placement. RESULTS: Of 77 patients with impalpable abnormalities who underwent FNAC with the new protocol, six (8%) had insufficient specimens for cytologic diagnosis: Four were incorrectly judged to contain sufficient material at the time of FNAC, one refused to complete the FNAC, and one had a vasovagal reaction. Of the six cases with insufficient specimens, four were benign at biopsy, one was malignant, and one was determined to be benign on the basis of mammographic stability. CONCLUSION: Modification of techniques and implementation of a quality assurance program can significantly improve the insufficient specimen rate for FNAC. Correlation of mammographic and cytologic findings also improves the management of these cases.