Histologic work-up of non-palpable breast lesions classified as probably benign at initial mammography and/or ultrasound (BI-RADS category 3).

PURPOSE: To determine the accuracy of a probably benign assessment of non-palpable breast lesions (BI-RADS category 3) at mammography and/or ultrasound with immediate histological work-up. MATERIALS AND METHODS: Stereotactic or ultrasound guided core needle breast biopsy (NBB) was performed to evaluate 288 lesions, which were prospectively assessed as BI-RADS category 3. Imaging findings included 195 masses, 73 calcification cases, 16 focal asymmetries, and four architectural distortion cases. After NBB, patients underwent either open surgical biopsy (OSB) (n=204) or mammographic follow-up (n=84) for at least 24 months. Histological results of NBB were compared with those of OSB. RESULTS: Three of the 288 lesions (1.0%) proved to be malignant at histological work-up, two of them were ductal carcinoma in situ (DCIS) and one of them was an invasive carcinoma. NBB revealed invasive carcinoma in 1/288 (0.35%) and atypical ductal hyperplasia (ADH) in 13/288 (4.5%) lesions. OSB revealed DCIS in 2/204 (1%) and invasive carcinoma in 1/204 (0.5%) lesions. The two DCIS were underestimated as ADH by NBB. The remaining 285 (99%) lesions proved to be benign at OSB or remained stable during follow-up. CONCLUSION: Confirmed by tissue diagnosis, the low likelihood of malignancy of prospectively assessed probably benign lesions is below the 2% threshold established for BI-RADS category 3. Imaging follow-up is a safe and effective alternative to immediate histological work-up for such lesions.

Movement of a biopsy-site marker clip after completion of stereotactic directional vacuum-assisted breast biopsy: case report.

A 51-year-old woman underwent stereotactic core biopsy of suspicious microcalcifications in the upper outer left breast with subsequent metallic clip deployment. Postprocedure mammograms demonstrated accurate placement of the clip. However, mammography 10 months later revealed movement of the clip 4 cm medially in the breast.

Mammographic screening: international perspective.

The twentieth century saw the introduction of mammography as a diagnostic tool and its refinement as a screening method. It appears guaranteed that women who are well informed will seek mammography screening with high expectations of technical quality and accurate interpretation. More refined knowledge of breast anatomy and pathology will assist radiologists to interpret with high specificity. We will learn how to recognized more accurately normal structures and doubtful findings. We will gain experience in interpretation through faithful review of interval cancers and subtle screen-detected cancers, and will use educational tools that have the potential to improve the efficiency of education by directing attention to specific deficiencies. Mammographic screening has been advanced through the efforts of dedicated teams of physicians, scientists, and other professionals throughout the world. The international communication of ideas and discoveries will continue to challenge the boundaries of what can be accomplished in early detection as well as noninvasive therapy, and this body of knowledge will continue to be enriched by these diverse contributions.

International investigation of breast MRI: results of a multicentre study (11 sites) concerning diagnostic parameters for contrast-enhanced MRI based on 519 histopathologically correlated lesions.

A multicentre study was undertaken to provide fundamentals for improved standardization and optimized interpretation guidelines of dynamic contrast-enhanced MRI. Only patients scheduled for biopsy of a clinical or imaging abnormality were included. They underwent standardized dynamic MRI on Siemens 1.0 (163 valid lesions > or = 5 mm) or 1.5 T (395 valid lesions > or = 5 mm) using 3D fast low-angle shot (FLASH; 87 s) before and five times after standardized bolus of 0.2 mmol Gd-DTPA/kg. One-Tesla and 1.5 T data were analysed separately using a discriminant analysis. Only histologically correlated lesions entered the statistical evaluation. Histopathology and imaging were correlated in retrospect and in open. The best results were achieved by combining up to five wash-in or wash-out parameters. Different weighting of false-negative vs false-positive calls allowed formulation of a statistically based interpretation scheme yielding optimized rules for the highest possible sensitivity (specificity 30%), for moderate (50%) or high (64-71%) specificity. The sensitivities obtained at the above specificity levels were better at 1.0 T (98, 97, or 96%) than at 1.5 T (96, 93, 86%). Using a widely available standardized MR technique definition of statistically founded interpretation rules is possible. Choice of an optimum interpretation rule may vary with the clinical question. Prospective testing remains necessary. Differences of 1.0 and 1.5 T are not statistically significant but may be due to pulse sequences.

Mammographic characteristics of 115 missed cancers later detected with screening mammography and the potential utility of computer-aided detection.

PURPOSE: To retrospectively determine the mammographic characteristics of cancers missed at screening mammography and assess the ability of computer-aided detection (CAD) to mark the missed cancers. MATERIALS AND METHODS: A multicenter retrospective study accrued 1,083 consecutive cases of breast cancer detected at screening mammography. Prior mammograms were available in 427 cases. Of these, 286 had lesions visible in retrospect. The 286 cases underwent blinded review by panels of radiologists; a majority recommended recall for 112 cases. Two experienced radiologists compared prior mammograms in 110 of these cases with the subsequent screening mammograms (when cancer was detected), noting mammographic characteristics of breast density, lesion type, size, morphology, and subjective reasons for possible miss. The prior mammograms were then analyzed with a CAD program. RESULTS: There were 110 patients with 115 cancers. On the prior mammograms with missed cancers, 35 (30%) of the 115 lesions were calcifications, with 17 of 35 (49%) clustered or pleomorphic. Eighty of the 115 (70%) were mass lesions, with 32 of 80 (40%) spiculated or irregular. For calcifications and masses, the most frequently suggested reasons for possible miss were dense breasts (12 of 35; 34%) and distracting lesions (35 of 80; 44%), respectively. CAD marked 30 (86%) of 35 missed calcifications and 58 (73%) of 80 missed masses. CONCLUSION: Detection errors affected cases with calcifications and masses. CAD marked most (77%; 88 of 115) cancers missed at screening mammography that radiologists retrospectively judged to merit recall.

Medical audit of diagnostic mammography examinations: comparison with screening outcomes obtained concurrently.

OBJECTIVE: We performed a medical audit of our diagnostic mammography practice and compared clinical outcomes with those of screening mammography examinations performed concurrently. MATERIALS AND METHODS: We analyzed 46,857 consecutive mammography examinations (10,007 diagnostic, 36,850 screening) from 1997 to 2000, including data on demographics, image interpretation, and biopsy (including size, nodal status, and cancer stage). RESULTS: The mean age at diagnostic mammography was 55.8 years (mean age at screening mammogram, 59.1 years; p < 0.0001). Among patients who underwent diagnostic examinations, 14.7% had a strong or very strong family history of breast cancer (screening, 11.6%; p < 0.0001). Examination findings were interpreted as abnormal in 14.4% (screening, 5.2%; p < 0.0001). Biopsy was performed in 11.9% (screening, 1.4%; p < 0.0001). Forty-six percent of the biopsies were positive for malignancy (screening, 38%; p < 0.0001). The cancer detection rate was 55 per 1000 (screening, 5/1000; p < 0.0001). Of cancers found, 74.4% were stage 0 or I (screening, 89.3%; p < 0.0001), average size was 18.0 mm (screening, 12.9 mm; p < 0.0001), and axillary nodes were positive for malignancy in 19.9% of invasive cancers (screening, 6.3; p < 0.0001). Differences between diagnostic and screening outcomes were attributable predominantly to the subgroup of diagnostic examinations performed for evaluation of palpable masses. CONCLUSION: Medical auditing of diagnostic mammography examinations yields substantially different results compared with those of screening examinations, including different patient demographics; higher number of positive biopsies; higher cancer detection rates; and larger, more advanced-stage cancers. Diagnostic and screening data should be segregated during auditing, or if this is not possible, analysis of combined results should be based on known differences between diagnostic and screening outcomes.

Successful methods to reduce false-positive mammography interpretations.

Several approaches to mammographic interpretation and breast imaging management have been developed that substantially reduce the frequency of false-positive cases, involving both recall examinations and biopsies, without meaningfully reducing the detection of nonpalpable favorable-prognosis cancers. By applying these approaches successfully, on a nationwide scale, radiologists should be able to demonstrate convincingly that the benefits of mammography far outweigh the risks of false-positive interpretations. The challenge we face is to learn to use the approaches effectively, thereby achieving widespread use.

Multiple bilateral masses detected on screening mammography: assessment of need for recall imaging.

OBJECTIVE: When multiple bilateral partially circumscribed masses having a similar appearance are detected on screening mammography, some radiologists recommend recall examination to identify imaging features suggestive of malignancy that are not evident on standard screening views. This study assesses the need for such recall imaging. SUBJECTS AND METHODS: Cases of multiple masses were identified by reviewing the mammographic reports of 84,615 consecutive screening examinations. Each case of multiple masses was prospectively interpreted as benign, with recommendations for follow-up mammography in 1 year and for aspiration of any palpable masses if clinically indicated. Subsequently diagnosed cancers were identified through data linkage with our regional tumor registry and through our institution's computer-based outcomes tracking system. RESULTS: Among 84,615 consecutive screening examinations, we identified 1440 (1.7%) cases of multiple masses. Among the multiple-masses cohort, two interval cancers were found. Both were early-stage (T1bN0M0; T1cN0M0) and low-grade (histologic grade 1) cancers. The interval cancer rate among the multiple-masses cohort was 0.14%, which is somewhat lower than the age-matched United States incident cancer rate of 0.24%. CONCLUSION: The frequency of cancer development and the stage at cancer diagnosis among nonrecalled cases of multiple masses are similar to those observed in the general screening mammography population. Therefore, recall imaging for women with multiple masses does not appear to be justified.

Dynamic high-spatial-resolution MR imaging of suspicious breast lesions: diagnostic criteria and interobserver variability.

OBJECTIVE: Our study was undertaken to develop diagnostic rules and to assess the reproducibility of dynamic and morphologic parameters for the characterization of suspicious breast lesions using dynamic high-spatial-resolution MR imaging. MATERIALS AND METHODS: Fifty-seven patients with suspicious mammographic or palpable findings underwent preoperative contrast-enhanced MR imaging of the breast using a three-time-point method of acquisition. Each lesion was prospectively analyzed by two independent radiologists for morphologic and visual dynamic enhancement characteristics. A classification and regression tree was used to examine the optimal order, cutoff points, and combination of imaging parameters to build a diagnostic rule separating benign from malignant lesions using histopathology findings as the standard of reference. Kappa statistics were used to determine observer variability. RESULTS: Among 23 benign and 34 malignant lesions (12 invasive, three ductal carcinoma in situ, and 19 mixed cancer), margin morphology (p = 0.001) and enhancement pattern (p = 0.001) were the most significant MR imaging findings for lesion characterization. Focal mass lesions were classified as malignant when spiculated margins or both the washout enhancement pattern and "nonsmooth" margins were present. Interobserver agreement was almost perfect for washout pattern and substantial for margin assessment. In the limited population tested retrospectively, the diagnostic rule yielded a sensitivity and positive predictive value of 97% each and a specificity and negative predictive value of 96% each. CONCLUSION: The washout enhancement pattern combined with lesion margin assessment on dynamic contrast-enhanced high-resolution MR imaging of the breast allows reproducible lesion characterization and may be a highly specific diagnostic tool.

Potential contribution of computer-aided detection to the sensitivity of screening mammography.

PURPOSE: To determine the false-negative rate in screening mammography, the capability of computer-aided detection (CAD) to identify these missed lesions, and whether or not CAD increases the radiologists' recall rate. MATERIALS AND METHODS: All available screening mammograms that led to the detection of biopsy-proved cancer (n = 1,083) and the most recent corresponding prior mammograms (n = 427) were collected from 13 facilities. Panels of radiologists evaluated the retrospectively visible prior mammograms by means of blinded review. All mammograms were analyzed by a CAD system that marks features associated with cancer. The recall rates of 14 radiologists were prospectively measured before and after installation of the CAD system. RESULTS: At retrospective review, 67% (286 of 427) of screening mammography-detected breast cancers were visible on the prior mammograms. At independent, blinded review by panels of radiologists, 27% (115 of 427) were interpreted as warranting recall on the basis of a statistical evaluation index; and the CAD system correctly marked 77% (89 of 115) of these cases. The original attending radiologists' sensitivity was 79% (427 of [427 + 115]). There was no statistically significant increase in the radiologists' recall rate when comparing the values before (8.3%) with those after (7.6%) installation of the CAD system. CONCLUSION: The original attending radiologists had a false-negative rate of 21% (115 of [427 + 115]). CAD prompting could have potentially helped reduce this false-negative rate by 77% (89 of 115) without an increase in the recall rate.

Standardized abnormal interpretation and cancer detection ratios to assess reading volume and reader performance in a breast screening program.

PURPOSE: To determine the relationship between annual screening volume and radiologist performance in the Screening Mammography Program of British Columbia, Canada. MATERIALS AND METHODS: Standardized abnormal interpretation ratios and standardized cancer detection ratios were constructed for 35 readers with at least 3 years of experience with the Screening Mammography Program of British Columbia. The ratios were used to compare individual reader performance with the mean program performance after adjustment for the age and screening history (first versus subsequent screening examinations) of the women who underwent screening. RESULTS: The mean standardized abnormal interpretation ratio was better for readers of 2,000-2,999 (n = 8) and 3,000-3,999 (n = 9) screening mammograms per year than for those of less than 2,000 (n = 9) and 4, 000-5,199 (n = 9) screening mammograms per year. Differences in the mean standardized abnormal interpretation ratios were significant (P <.05) between the readers of less than 2,000 and of 2,000-2,999 screening mammograms per year, between readers of less than 2,000 and of 3,000-3,999 screening mammograms per year and between readers of 3,000-3,999 and of 4,000-5,199 screening mammograms per year. The mean standardized cancer detection ratio improved gradually with increasing annual volume, but the differences between groups were not statistically significant. Five of the eight readers of 2,000-2, 999 mammograms were reading 2,475 or more screening mammograms per year. CONCLUSION: Standardized abnormal interpretation ratios and standardized cancer detection ratios provide a method of comparing two important performance measures in a screening program. A minimum of 2,500 interpretations per year is associated with lower abnormal interpretation rates and average or better cancer detection rates.

Effect of obesity on screening mammography: outcomes analysis of 88,346 consecutive examinations.

OBJECTIVE: We determined differences in the rates of recall, biopsy, and cancer detection for screening mammography as a function of adiposity. MATERIALS AND METHODS: Eighty-eight thousand three hundred forty-six consecutive screening mammography examinations were performed from April 1985 to August 1997. Patient weights were normalized to ideal weight correcting for height and were subdivided into adiposity cohorts including underweight by greater than 10%; ideal weight +/- 10%; overweight by 11-24%; overweight by 25-39%; and overweight by greater than 40%. The rates of recall, biopsy, cancer detection, and cancer stage were calculated and were analyzed using the chi-square test for trend. Cancer size was analyzed using linear regression analysis. RESULTS: Reliable (p < 0.05) and meaningful differences were seen between cohorts of increasing adiposity for rates of recall, biopsy, and cancer detection. An increase in recall rate occurred with progressively increasing adiposity (3.88%, 4.89%, 5.11%, 5.47%, 5.55% [p < 0.0001]). The rate of biopsy also increased with increasing adiposity (0.98%, 1.31%, 1.35%, 1.59%, 1.65% [p < 0.0002]), as did the rate of screening-detected cancer (number of cases of cancer per 1000 women screened) (3.74, 4.29, 5.34, 4.70, 6.04 [p < 0.015]). Finally, increased adiposity also correlated with increased median cancer size (p < 0.02) and with more advanced stage at diagnosis (p = 0.046). CONCLUSION: Increasing adiposity correlates with progressive increases in the rates of recall, biopsy, and cancer detection for women undergoing screening mammography. Increasing adiposity also correlates with increased cancer size and stage, providing further support for obesity as a risk factor for breast cancer.

Efficacy of step-oblique mammography for confirmation and localization of densities seen on only one standard mammographic view.

OBJECTIVE: Step-oblique mammography is a technique used to determine with confidence whether a mammographic finding visible on multiple images on only one projection (but not elucidated using standard additional mammographic projections such as the roll view) represents a summation artifact or a true mass, and to precisely localize the true mass for further evaluation (if applicable). This paper describes the step-oblique technique and evaluates its efficacy. MATERIALS AND METHODS: Between January 1, 1993 and December 31, 1998, 69 consecutive women underwent step-oblique mammography for the evaluation of densities seen on multiple images in only one standard projection. Additional images were obtained at 15 degrees stepped increments in obliquity. If a one-projection-only finding was not seen on step-oblique images, the density was judged to represent a summation artifact, completing the examination. If a density was visualized and could be triangulated concordantly on step-oblique images ranging from the craniocaudal to the 90 degrees lateral projection, then it was judged to represent a real lesion. Such a lesion was further characterized (mass, neodensity, architectural distortion, focal asymmetric density) and was localized precisely in three dimensions, permitting imaging-guided tissue diagnosis, if appropriate. For all study patients, we also recorded BI-RADS (American College of Radiology Breast Imaging and Data Reporting System) assessment categories; pathology results for biopsied lesions; and mammographic follow-up, clinical follow-up, and linkage to regional tumor registry for nonbiopsied lesions for which at least 2 years had elapsed since step-oblique mammography. RESULTS: Step-oblique mammography differentiated 50 real lesions from 19 summation artifacts. All 50 real lesions, although initially visible on only one standard projection, were successfully localized in three dimensions. Subsequent management resulted in the prompt detection and diagnosis of seven breast cancers and 21 benign lesions. None of the remaining findings managed by follow-up rather than biopsy have subsequently been found to be malignant. CONCLUSION: Step-oblique mammography is an effective means of evaluating the mammographic finding visible on multiple images on only one standard projection.

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.

Outcome analysis for women undergoing annual versus biennial screening mammography: a review of 24,211 examinations.

OBJECTIVE: Our goal was to determine differences in outcome measures between women undergoing annual versus biennial screening mammography. MATERIALS AND METHODS: A retrospective review of prospectively collected data on 24,211 consecutive screening mammography examinations was performed in women aged 40-79 years, all of whom had undergone previous normal screening mammography. Annual screening and biennial screening were defined as examinations performed 10-14 months and 22-26 months, respectively, after previous normal screening mammography. The rates of recall, biopsy, cancer detection, and interval cancer for annual and biennial screening cohorts were calculated, as were tumor size, lymph node status, and stage of invasive cancer. Interval cancer cases were identified by linkage with a regional tumor registry. RESULTS: Of the 4306 biennially screened women, 160 were recalled (3.7%), 45 were biopsied (1.0%), and cancer was detected in 19 (0.44%). Of the 19,905 annually screened women, 518 were recalled (2.6%), 150 were biopsied (0.75%), and cancer was detected in 71 (0.36%). Of the 3278 registry-linked biennially screened women, five had interval cancer (0.15%); of the 15,031 registry-linked annually screened women, 10 had interval cancer (0.07%). For biennial screening-detected cancer and interval invasive cancer combined, the median tumor size was 15 mm, 24% had lymph node metastasis, and 29% were stage 2 or higher. For annual screening-detected cancer, these measures were 11 mm, 14% positive nodes, and 17% stage 2+ cancer, respectively. CONCLUSION: Annual screening mammography results in lower recall rates than does biennial screening (p < .0001). Moreover, annual screening results in the detection of smaller tumors that have a more favorable prognosis (p = .04).

Variability and accuracy in mammographic interpretation using the American College of Radiology Breast Imaging Reporting and Data System.

BACKGROUND: Several studies, which were limited by their small sample size and selection of difficult cases for review, have reported substantial variability among radiologists in interpretation of mammographic examinations. We have determined, in the largest study to date, intraobserver and interobserver agreement in interpreting screening mammography and accuracy of mammography by use of the American College of Radiology Breast Imaging Reporting and Data System (BI-RADS). METHODS: The mammographic examinations were randomly selected on the basis of original mammographic interpretation and cancer outcome from 71,713 screening examinations performed by the Mobile Mammography Screening Program of the University of California, San Francisco, during the period from April 1985 through February 1995. The final sample included 786 abnormal examinations with no cancer detected, 267 abnormal examinations with cancer detected, and 1563 normal examinations. Films were read separately by two radiologists according to BI-RADS. Cancer status was determined by contacting women's physicians and by linkage to the regional Surveillance, Epidemiology, and End Results Program. RESULTS: There was moderate agreement between radiologists in reporting the presence of a finding when cancer was present (kappa = 0.54) and substantial agreement when cancer was not present (kappa = 0.62). Agreement was moderate in assigning one of the five assessment categories but was statistically significantly lower when cancer was present relative to when cancer was not present (kappa = 0.46 versus 0.56; two-sided P = .02). Agreement for reporting the presence of a finding and mammographic assessment was two-fold more likely for examinations with less dense breasts. Agreement was higher on repeat readings by the same radiologists than between radiologists. The sensitivity of mammography was lower with BI-RADS than with the original system for mammographic interpretation, but the positive predictive value of mammography was higher. CONCLUSION: Considerable variability in interpretation of mammographic examinations exists; this variability and the accuracy of mammography are neither improved nor diminished with use of BI-RADS.