Issues to consider before implementing digital breast tomosynthesis into a breast imaging practice.

OBJECTIVE. The purpose of this article is to discuss issues surrounding the implementation of digital breast tomosynthesis (DBT) into a clinical breast imaging practice and assist radiologists, technologists, and administrators who are considering the addition of this new technology to their practices. CONCLUSION. When appropriate attention is given to image acquisition, interpretation, storage, technologist and radiologist training, patient selection, billing, radiation dose, and marketing, implementation of DBT into a breast imaging practice can be successful.

Implications of CISNET modeling on number needed to screen and mortality reduction with digital mammography in women 40-49 years old.

OBJECTIVE: In this article, we evaluate the implications of recent Cancer Intervention and Surveillance Modeling Network (CISNET) modeling of benefits and harms of screening to women 40-49 years old using annual digital mammography. CONCLUSION: We show that adding annual digital mammography of women 40-49 years old to biennial screening of women 50-74 years old increases lives saved by 27% and life-years gained by 47%. Annual digital mammography in women 40-49 years old saves 42% more lives and life-years than biennial digital mammography. The number needed to screen to save one life (NNS) with annual digital mammography in women 40-49 years old is 588.

The "laboratory" effect: comparing radiologists' performance and variability during prospective clinical and laboratory mammography interpretations.

PURPOSE: To compare radiologists' performance during interpretation of screening mammograms in the clinic with their performance when reading the same mammograms in a retrospective laboratory study. MATERIALS AND METHODS: This study was conducted under an institutional review board-approved, HIPAA-compliant protocol; the need for informed consent was waived. Nine experienced radiologists rated an enriched set of mammograms that they had personally read in the clinic (the "reader-specific" set) mixed with an enriched "common" set of mammograms that none of the participants had previously read in the clinic by using a screening Breast Imaging Reporting and Data System (BI-RADS) rating scale. The original clinical recommendations to recall the women for a diagnostic work-up, for both reader-specific and common sets, were compared with their recommendations during the retrospective experiment. The results are presented in terms of reader-specific and group-averaged sensitivity and specificity levels and the dispersion (spread) of reader-specific performance estimates. RESULTS: On average, the radiologists' performance was significantly better in the clinic than in the laboratory (P = .035). Interreader dispersion of the computed performance levels was significantly lower during the clinical interpretations (P < .01). CONCLUSION: Retrospective laboratory experiments may not represent either expected performance levels or interreader variability during clinical interpretations of the same set of mammograms in the clinical environment well.

Binary and multi-category ratings in a laboratory observer performance study: a comparison.

The authors investigated radiologists, performances during retrospective interpretation of screening mammograms when using a binary decision whether to recall a woman for additional procedures or not and compared it with their receiver operating characteristic (ROC) type performance curves using a semi-continuous rating scale. Under an Institutional Review Board approved protocol nine experienced radiologists independently rated an enriched set of 155 examinations that they had not personally read in the clinic, mixed with other enriched sets of examinations that they had individually read in the clinic, using both a screening BI-RADS rating scale (recall/not recall) and a semi-continuous ROC type rating scale (0 to 100). The vertical distance, namely the difference in sensitivity levels at the same specificity levels, between the empirical ROC curve and the binary operating point were computed for each reader. The vertical distance averaged over all readers was used to assess the proximity of the performance levels under the binary and ROC-type rating scale. There does not appear to be any systematic tendency of the readers towards a better performance when using either of the two rating approaches, namely four readers performed better using the semi-continuous rating scale, four readers performed better with the binary scale, and one reader had the point exactly on the empirical ROC curve. Only one of the nine readers had a binary "operating point" that was statistically distant from the same reader's empirical ROC curve. Reader-specific differences ranged from -0.046 to 0.128 with an average width of the corresponding 95% confidence intervals of 0.2 and p-values ranging for individual readers from 0.050 to 0.966. On average, radiologists performed similarly when using the two rating scales in that the average distance between the run in individual reader's binary operating point and their ROC curve was close to zero. The 95% confidence interval for the fixed-reader average (0.016) was (-0.0206, 0.0631) (two-sided p-value 0.35). In conclusion the authors found that in retrospective observer performance studies the use of a binary response or a semi-continuous rating scale led to consistent results in terms of performance as measured by sensitivity-specificity operating points.

Effect of Arrival of Prior Mammograms on Recall Negation for Screening Mammograms Performed With Digital Breast Tomosynthesis in a Clinical Setting.

PURPOSE: This retrospective study evaluates the effect of comparison with prior mammograms on recall negation for screening mammography performed with digital breast tomosynthesis (DBT) in a clinical setting and compares it with that performed without DBT. METHODS: This is an Institutional Review Board-approved, HIPAA-compliant retrospective review of the electronic medical record for all nonbaseline screening mammograms performed in clinical practice over 13 months. For each mammogram, we recorded if DBT were used, the BI-RADS assigned at initial interpretation, and whether prior mammograms were available at initial interpretation. If prior mammograms arrived later for comparison, the final BI-RADS assigned after comparison was recorded. A mammogram assigned a BI-RADS 0 at initial interpretation and assigned a BI-RADS 1 or BI-RADS 2 after prior mammograms arrived for comparison was labeled as a recall that was negated by the arrival of prior mammograms. The number of recalls negated for mammograms that used DBT was compared with that for mammograms that did not use DBT. RESULTS: Arrival of prior mammograms for comparison negated the need for recall for mammograms performed with DBT by 67.67% and negated the need for recall for mammograms performed without DBT by 55.80%. After adjusting for age, density, and time between mammograms, the percentage of recalls negated by comparison with prior mammograms was not significantly different for mammograms performed with DBT than it was for those performed without DBT. CONCLUSION: Comparison with prior mammograms remains important for the minimization of recall rates during the use of DBT for screening mammography in the clinical setting.

A method to improve visual similarity of breast masses for an interactive computer-aided diagnosis environment.

The purpose of this study was to develop and test a method for selecting "visually similar" regions of interest depicting breast masses from a reference library to be used in an interactive computer-aided diagnosis (CAD) environment. A reference library including 1000 malignant mass regions and 2000 benign and CAD-generated false-positive regions was established. When a suspicious mass region is identified, the scheme segments the region and searches for similar regions from the reference library using a multifeature based k-nearest neighbor (KNN) algorithm. To improve selection of reference images, we added an interactive step. All actual masses in the reference library were subjectively rated on a scale from 1 to 9 as to their "visual margins speculations". When an observer identifies a suspected mass region during a case interpretation he/she first rates the margins and the computerized search is then limited only to regions rated as having similar levels of spiculation (within +/-1 scale difference). In an observer preference study including 85 test regions, two sets of the six "similar" reference regions selected by the KNN with and without the interactive step were displayed side by side with each test region. Four radiologists and five nonclinician observers selected the more appropriate ("similar") reference set in a two alternative forced choice preference experiment. All four radiologists and five nonclinician observers preferred the sets of regions selected by the interactive method with an average frequency of 76.8% and 74.6%, respectively. The overall preference for the interactive method was highly significant (p < 0.001). The study demonstrated that a simple interactive approach that includes subjectively perceived ratings of one feature alone namely, a rating of margin "spiculation," could substantially improve the selection of "visually similar" reference images.

Compliance With Screening Mammography Guidelines After a False-Positive Mammogram.

PURPOSE: To assess whether women with a false-positive mammogram who do return for screening are less likely to be compliant with screening mammography guidelines than are women with a negative mammogram. METHODS: This institutional review board-approved, HIPAA-compliant retrospective cohort study includes women >40 years old who received 9,385 consecutive, nonbaseline screening mammograms between December 1, 2012 and December 31, 2013. Using linear regression, we evaluated differences in time between mammograms by prior recall status, after adjusting for location of current mammogram (outpatient office versus mobile unit) and age. Using Fisher's exact test, we evaluated the association between compliance with screening guidelines and the recall status on prior mammogram, and compared by location the proportions of noncompliant women who were recalled from prior mammogram. RESULTS: Time between mammograms does not differ based on prior recall status (P = .83). There is no association between compliance with screening mammography guidelines and recall status on prior mammogram (ACR guidelines P = .398, United States Preventive Services Task Force guidelines P = .416). Noncompliant women recalled on prior mammogram are more likely to undergo mammography at the outpatient office rather than the mobile unit (ACR guidelines P = .0004, United States Preventive Services Task Force guidelines P = .0032). CONCLUSIONS: A prior false-positive mammogram is not a significant deterrent to compliance with screening guidelines in those women who return for screening.

Digital Breast Tomosynthesis Utilization in the United States: A Survey of Physician Members of the Society of Breast Imaging.

PURPOSE: To assess utilization of digital breast tomosynthesis (DBT) and examine criteria for offering DBT to patients. METHODS: We created an online survey for physician members of the Society of Breast Imaging to assess their use of DBT. The questions covered availability of DBT at the participant's practice, whether DBT was used for clinical care or research, clinical decision rules guiding patient selection for DBT, costs associated with DBT, plans to obtain DBT, and breast imaging practice characteristics. Fisher's exact tests and logistic regression were used to compare DBT users and nonusers. RESULTS: In all, 670 members responded (response rate = 37%). Of these, 200 (30.0%) respondents reported using DBT, with 89% of these using DBT clinically. Participants were more likely to report DBT use if they worked at an academic practice (odds ratio [OR], 2.07; 95% confidence interval [CI], 1.41 to 3.03; P < .001), a practice with more than 3 breast imagers (OR, 2.36; 95% CI, 1.62 to 3.43; P < .001), or a practice with 7 or more mammography units (OR, 3.05; 95% CI, 2.11 to 4.39; P < .001). Criteria used to select patients to undergo DBT varied, with 107 (68.2%) using exam type (screening versus diagnostic), 25 (15.9%) using mammographic density, and 25 (15.9%) using breast cancer risk. Fees for DBT ranged from $25 to $250. In addition, 62.3% of nonusers planned to obtain DBT. CONCLUSION: DBT is becoming more common but remains a limited resource. Clinical guidelines would assist practices in deciding whether to adopt DBT and in standardizing which patients should receive DBT.

Direct Interactive Public Education by Breast Radiologists About Screening Mammography: Impact on Anxiety and Empowerment.

PURPOSE: Anxiety has been called a "harm" of screening mammography. The authors provided direct, interactive education to lay audiences and measured these sessions' impact on anxiety and any increased understanding of breast cancer screening. METHODS: Academic breast radiologist provided seven 1-hour sessions of structured lectures and question-and-answer periods. Lay language and radiologic images were used to discuss disease background, screening guidelines, and areas of debate. One hundred seventeen participants (mean age, 45 ± 15 years) completed voluntary, anonymous, institutional review board-approved pre and postsession questionnaires relaying their attitudes regarding screening and the impact of the sessions. Results are summarized descriptively. RESULTS: Mean reported anxiety regarding screening (on a scale ranging from 1-5; 1 = no anxiety) was 2.5 ± 1.3. Anxiety was attributed to unknown results (56.4%), anticipation of pain (21.8%), known risk factors (14.5%), general uncertainty (12.7%), waiting for results (9.1%), possibility of more procedures (3.6%), and personal breast cancer history (3.6%). Ninety-seven percent reported that immediate results would lower anxiety (78% of those women indicated a 75%-100% decrease in anxiety); 93% reported that radiologist consultation with images would lower anxiety (75.6% indicated a 75%-100% decrease in anxiety). After the lecture, women reported (on a scale ranging from 1-5) increased understanding of the topic (4.7 ± 0.6), encouragement to screen (4.6 ± 0.7), and reduced anxiety (4.0 ± 1.1). Ninety-seven percent to 100% provided correct responses to these questions: rationale for screening in the absence of family history, recall does not equate to cancer diagnosis, benefit of prior films, and continued importance of physical examination. CONCLUSION: Attendees of radiologist-provided direct public lectures reported decreased anxiety and improved knowledge regarding screening mammography. The resultant reduced anxiety ("harm") and educational empowerment help enable informed decision making and may promote screening attendance.

Direct Interactive Public Education by Breast Radiologists About Screening Mammography: Impact on Anxiety and Empowerment.

PURPOSE: Anxiety has been called a "harm" of screening mammography. The authors provided direct, interactive education to lay audiences and measured these sessions' impact on anxiety and any increased understanding of breast cancer screening. METHODS: Academic breast radiologist provided seven 1-hour sessions of structured lectures and question-and-answer periods. Lay language and radiologic images were used to discuss disease background, screening guidelines, and areas of debate. One hundred seventeen participants (mean age, 45 ± 15 years) completed voluntary, anonymous, institutional review board-approved pre and postsession questionnaires relaying their attitudes regarding screening and the impact of the sessions. Results are summarized descriptively. RESULTS: Mean reported anxiety regarding screening (on a scale ranging from 1-5; 1 = no anxiety) was 2.5 ± 1.3. Anxiety was attributed to unknown results (56.4%), anticipation of pain (21.8%), known risk factors (14.5%), general uncertainty (12.7%), waiting for results (9.1%), possibility of more procedures (3.6%), and personal breast cancer history (3.6%). Ninety-seven percent reported that immediate results would lower anxiety (78% of those women indicated a 75%-100% decrease in anxiety); 93% reported that radiologist consultation with images would lower anxiety (75.6% indicated a 75%-100% decrease in anxiety). After the lecture, women reported (on a scale ranging from 1-5) increased understanding of the topic (4.7 ± 0.6), encouragement to screen (4.6 ± 0.7), and reduced anxiety (4.0 ± 1.1). Ninety-seven percent to 100% provided correct responses to these questions: rationale for screening in the absence of family history, recall does not equate to cancer diagnosis, benefit of prior films, and continued importance of physical examination. CONCLUSION: Attendees of radiologist-provided direct public lectures reported decreased anxiety and improved knowledge regarding screening mammography. The resultant reduced anxiety ("harm") and educational empowerment help enable informed decision making and may promote screening attendance.

"Memory effect" in observer performance studies of mammograms.

RATIONALE AND OBJECTIVE: To evaluate breast radiologists' recognition of mammograms showing cancers that they correctly detected or "missed" during clinical interpretations. MATERIALS AND METHODS: Two similar experiments were conducted. In the first, 33 bilateral screening mammograms were reviewed by four breast imagers. These included five cancers that each radiologist had detected, two cancers that each radiologist had "missed," and five mammograms recalled by other radiologists that were not cancer. Radiologists were asked if they had interpreted the mammogram in clinic and if the mammogram was suspicious for cancer. In the second experiment, four different breast imagers reviewed 48 mammograms that included five cancers that each radiologist had detected, two cancers that each radiologist had "missed," and five mammograms that were recalled by each radiologist but were not cancer. Using chi-square analysis, the performance of the radiologists on screening mammograms they had read in clinic was compared with their performance on mammograms read in clinic by other radiologists. RESULTS: Seven of eight radiologists did not remember interpreting any of the mammograms in clinic. One radiologist correctly remembered interpreting one mammogram in clinic, but interpreted it incorrectly. Average performance showed no significant difference (P = .60) between mammograms they had interpreted in clinic and those interpreted by others. CONCLUSION: Radiologists do not remember most mammograms showing cancer that they have interpreted, either correctly or incorrectly, after they are mixed with mammograms showing cancer that were interpreted by other radiologists. Screening mammograms can be used in observer performance studies in which the interpreting radiologist participates as an observer.

A method to test the reproducibility and to improve performance of computer-aided detection schemes for digitized mammograms.

The purpose of this study is to develop a new method for assessment of the reproducibility of computer-aided detection (CAD) schemes for digitized mammograms and to evaluate the possibility of using the implemented approach for improving CAD performance. Two thousand digitized mammograms (representing 500 cases) with 300 depicted verified masses were selected in the study. Series of images were generated for each digitized image by resampling after a series of slight image rotations. A CAD scheme developed in our laboratory was applied to all images to detect suspicious mass regions. We evaluated the reproducibility of the scheme using the detection sensitivity and false-positive rates for the original and resampled images. We also explored the possibility of improving CAD performance using three methods of combining results from the original and resampled images, including simple grouping, averaging output scores, and averaging output scores after grouping. The CAD scheme generated a detection score (from 0 to 1) for each identified suspicious region. A region with a detection score >0.5 was considered as positive. The CAD scheme detected 238 masses (79.3% case-based sensitivity) and identified 1093 false-positive regions (average 0.55 per image) in the original image dataset. In eleven repeated tests using original and ten sets of rotated and resampled images, the scheme detected a maximum of 271 masses and identified as many as 2359 false-positive regions. Two hundred and eighteen masses (80.4%) and 618 false-positive regions (26.2%) were detected in all 11 sets of images. Combining detection results improved reproducibility and the overall CAD performance. In the range of an average false-positive detection rate between 0.5 and 1 per image, the sensitivity of the scheme could be increased approximately 5% after averaging the scores of the regions detected in at least four images. At low false-positive rate (e.g., < or =average 0.3 per image), the grouping method alone could increase CAD sensitivity by 7%. The study demonstrated that reproducibility of a CAD scheme can be tested using a set of slightly rotated and resampled images. Because the reproducibility of true-positive detections is generally higher than that of false-positive detections, combining detection results generated from subsets of rotated and resampled images could improve both reproducibility and overall performance of CAD schemes.

Integrated density of a lesion: a quantitative, mammographically derived, invariable measure.

A method for quantitatively estimating lesion "size" from mammographic images was developed and evaluated. The main idea behind the measure, termed "integrated density" (ID), is that the total x-ray attenuation attributable to an object is theoretically invariant with respect to the projected view and object deformation. Because it is possible to estimate x-ray attenuation of a lesion from relative film densities, after appropriate corrections for background, the invariant property of the measure is expected to result in an objective method for evaluating the "sizes" of breast lesions. ID was calculated as the integral of the estimated image density attributable to a lesion, relative to surrounding background, over the area of the lesion and after corrections for the nonlinearity of the film characteristic curve. This effectively provides a measure proportional to lesion volume. We computed ID and more traditional measures of size (such as "mass diameter" and "effective size") for 100 pairs of ipsilateral mammographic views, each containing a lesion that was relatively visible in both views. The correlation between values calculated for each measure from corresponding pairs of ipsilateral views were computed and compared. All three size-related measures (mass diameter, effective size, and ID) exhibited reasonable linear relationship between paired views (r2>0.7, P<0.001). Specifically, the ID measures for the 100 masses were found to be highly correlated (r2=0.9, P<0.001) between ipsilateral views of the same mass. The correlation increased substantially (r2=0.95), when a measure with linear dimensions of length was defined as the cube root of ID. There is a high degree of correlation between ID-based measures obtained from different views of the same mass. ID-based measures showed a higher degree of invariance than mass diameter or effective size.

Computerized assessment of tissue composition on digitized mammograms.

RATIONALE AND OBJECTIVES: The authors developed a computerized method for the quantitative assessment of breast tissue composition on digitized mammograms. MATERIALS AND METHODS: Three radiologists were asked to review 200 digitized mammograms and independently provide a Breast Imaging Reporting and Data System-like rating for breast tissue composition on a scale of 0 to 4. These values were incorporated into a "consensus" rating that was used as a reference point in the development and evaluation of a computerized method. After tissue segmentation that excluded nontissue areas, a set of quantitative features was computed. A computerized summary index that attempts to reproduce the radiologists' ratings was developed. Correlation coefficients (Pearson r) were used to compare the computerized index with the consensus ratings. RESULTS: Some individual features computed for the relatively dense breast areas showed good correlation (r > 0.8) with the radiologists' subjective ratings. The summary index of tissue composition demonstrated a significant correlation (r = 0.87), as well. CONCLUSION: Computerized methods that show good correlation with radiologists' ratings of breast tissue composition can be developed.

Digital breast tomosynthesis utilization in the United States: a survey of physician members of the Society of Breast Imaging.

PURPOSE: To assess utilization of digital breast tomosynthesis (DBT) and examine criteria for offering DBT to patients. METHODS: We created an online survey for physician members of the Society of Breast Imaging to assess their use of DBT. The questions covered availability of DBT at the participant's practice, whether DBT was used for clinical care or research, clinical decision rules guiding patient selection for DBT, costs associated with DBT, plans to obtain DBT, and breast imaging practice characteristics. Fisher's exact tests and logistic regression were used to compare DBT users and nonusers. RESULTS: In all, 670 members responded (response rate = 37%). Of these, 200 (30.0%) respondents reported using DBT, with 89% of these using DBT clinically. Participants were more likely to report DBT use if they worked at an academic practice (odds ratio [OR], 2.07; 95% confidence interval [CI], 1.41 to 3.03; P < .001), a practice with more than 3 breast imagers (OR, 2.36; 95% CI, 1.62 to 3.43; P < .001), or a practice with 7 or more mammography units (OR, 3.05; 95% CI, 2.11 to 4.39; P < .001). Criteria used to select patients to undergo DBT varied, with 107 (68.2%) using exam type (screening versus diagnostic), 25 (15.9%) using mammographic density, and 25 (15.9%) using breast cancer risk. Fees for DBT ranged from $25 to $250. In addition, 62.3% of nonusers planned to obtain DBT. CONCLUSION: DBT is becoming more common but remains a limited resource. Clinical guidelines would assist practices in deciding whether to adopt DBT and in standardizing which patients should receive DBT.

Agreement of the order of overall performance levels under different reading paradigms.

RATIONALE AND OBJECTIVES: To investigate consistency of the orders of performance levels when interpreting mammograms under three different reading paradigms. MATERIALS AND METHODS: We performed a retrospective observer study in which nine experienced radiologists rated an enriched set of mammography examinations that they personally had read in the clinic ("individualized") mixed with a set that none of them had read in the clinic ("common set"). Examinations were interpreted under three different reading paradigms: binary using screening Breast Imaging Reporting and Data System (BI-RADS), receiver-operating characteristic (ROC), and free-response ROC (FROC). The performance in discriminating between cancer and noncancer findings under each of the paradigms was summarized using Youden's index/2+0.5 (Binary), nonparameteric area under the ROC curve (AUC), and an overall FROC index (JAFROC-2). Pearson correlation coefficients were then computed to assess consistency in the ordering of observers' performance levels. Statistical significance of the computed correlation coefficients was assessed using bootstrap confidence intervals obtained by resampling sets of examination-specific observations. RESULTS: All but one of the computed pair-wise correlation coefficients were larger than 0.66 and were significantly different from zero. The correlation between the overall performance measures under the Binary and ROC paradigms was the lowest (0.43) and was not significantly different from zero (95% confidence interval -0.078 to 0.733). CONCLUSION: The use of different evaluation paradigms in the laboratory tends to lead to consistent ordering of the overall performance levels of observers. However, one should recognize that conceptually similar performance indexes resulting from different paradigms often measure different performance characteristics and thus disagreements are not only possible but frequently quite natural.

Is maximum positive predictive value a good indicator of an optimal screening mammography practice?

OBJECTIVE: Positive predictive value (PPV1) has been used as one important indicator of the quality of screening mammography programs. We show how the relationship between sensitivity and recall rate may affect the operating point at which optimal (maximum) PPV1 occurs. CONCLUSION: Optimal (maximum) PPV1 can occur at any sensitivity level and should not be used as the sole indicator for practice optimization because it does not take into account the number of cancers that would be missed at that sensitivity.

Trends in recall, biopsy, and positive biopsy rates for screening mammography in an academic practice.

PURPOSE: To retrospectively evaluate whether recall, biopsy, and positive biopsy rates for a group of radiologists who met requirements of Mammography Quality Standards Act of 1992 (MQSA) demonstrated any change over time during a 27-month period (nine consecutive calendar quarters). MATERIALS AND METHODS: Institutional review board approved study protocol, and informed consent was waived. All screening mammograms that had been interpreted by MQSA-qualified radiologists between January 1, 2001, and March 31, 2003, were reviewed. Group recall rates, biopsy rates, and detected cancer rates for nine calendar quarters were computed and attributed to performance date of original screening mammogram. Type of biopsy performed was classified as follows: stereotactic vacuum-assisted biopsy, ultrasonography (US)-guided core biopsy, US-guided fine-needle aspiration biopsy, surgical excision, and multiple biopsies. chi(2) Test for trend (two sided) and linear regression were used to assess trends over time for recall and biopsy rates, biopsy rates according to type of biopsy performed, and percentage of biopsy results positive for cancer. RESULTS: Group recall rate did not show a statistically significant trend during period studied (P = .59). Biopsy rates increased significantly from 13.02 to 20.12 per 1000 screening examinations (P < .001). A corresponding substantial decrease was seen in percentage of biopsies in which malignancy was found, although this trend was not statistically significant (P = .24). A significant increase (from 4.72 to 9.88 per 1000 screening examinations) was found in rate of stereotactic vacuum-assisted 11-gauge core biopsies performed (P < .001). CONCLUSION: Observed increase in biopsy rates reinforces the need to carefully select patients for biopsy to achieve efficient, efficacious, and cost-effective programs for early detection of breast cancers.

Mammography with computer-aided detection: reproducibility assessment initial experience.

PURPOSE: To examine the performance and reproducibility of a commercially available computer-aided detection (CAD) system with a set of mammograms obtained in 100 patients who had undergone biopsy after positive findings at mammography. MATERIALS AND METHODS: One hundred positive mammographic examinations (four views each), depicting 96 masses and 50 microcalcification clusters, were scanned and analyzed three times by the CAD system. Reproducibility of detection sensitivity and the individual CAD-generated cues in the three images were examined. Both abnormality- and region-based detection sensitivities were compared. RESULTS: Forty-eight (96.0%) of 50 microcalcification clusters were marked on all three images in the abnormality-based analysis. Of the remaining two clusters, one was marked in two images and one was marked in only one. The abnormality-based sensitivity for mass detection ranged from 66.7% (64 of 96) to 70.8% (68 of 96). The system generated identical patterns (including images with and those without cues) for all three images in 53.3% (213 of 400) of images. For true-positive cluster regions, 88.9% (80 of 90) were marked at the same location in all images. For true-positive mass regions, 69.5% (82 of 118) were marked at the same locations in all images. In false-positive detections, only 44.0% (81 of 184) of false-positive mass regions and 31.9% (38 of 119) of false-positive cluster regions were marked at the same locations on all three images. CONCLUSION: Reproducibility of marked regions generated by the CAD system is improved from that reported previously, largely as a result of the substantial reduction in the false-positive detection rates. Reproducibility of true-positive identification of masses remains an important issue that may have methodologic and clinical practice implications.

Computer-aided detection performance in mammographic examination of masses: assessment.

PURPOSE: To compare performance of two computer-aided detection (CAD) systems and an in-house scheme applied to five groups of sequentially acquired screening mammograms. MATERIALS AND METHODS: Two hundred nineteen film-based mammographic examinations, classified into five groups, were included in this study. Group 1 included 58 examinations in which verified malignant masses were detected during screening; group 2, 39 in which all available latest examinations were performed prior to diagnosis of these malignant masses (subset of 39 women from group 1); group 3, 22 in which findings were interpreted as negative but were verified as cancer within 1 year from the negative interpretation (missed cancers); group 4, 50 in which findings were negative and patients were not recalled for additional procedures; and group 5, 50 in which patients were recalled for additional procedures and findings were negative for cancer. In all examinations, images were processed with two Food and Drug Administration-approved commercially available CAD systems and an in-house scheme. Performance levels in terms of true-positive detection rates and number of false-positive identifications per image and per examination were compared. RESULTS: Mass detection rates in positive examinations (group 1) were 67%-72%. Detection rates among three systems were not significantly different (P > .05). In 50 negative screening examinations (group 4), false-positive rates ranged from 1.08 to 1.68 per four-view examination. Performance level differences among systems were significant for false-positive rates (P = .008). Performance of all systems was at levels lower than publicly suggested in some retrospective studies. False-positive CAD cueing rates were significantly higher for negative examinations in which patients were recalled (group 5) than they were for those in which patients were not recalled (group 4) (P < or = .002). CONCLUSION: Performance of CAD systems for mass detection at mammography varies significantly, depending on examination and system used. Actual performance of all systems in clinical environment can be improved.