Biomedical subjects
Carl J D'Orsi
Publications and source records attributed to Carl J D'Orsi.
Detection of simulated lesions on data-compressed digital mammograms.
PURPOSE: To evaluate retrospectively the effect of a wavelet-based compression method on the detection of simulated masses of various sizes and clustered microcalcifications on data-compressed digital mammograms. MATERIALS AND METHODS: The images used in this study were acquired with institutional review board approval and patient informed consent, both of which allowed subsequent image data analysis. Patient identification was removed from images, and the study complied with requirements of the Health Insurance Portability and Accountability Act. Masses 3, 6, and 8 mm in diameter were analytically simulated and added to clinical mammographic backgrounds. In addition, microcalcifications were extracted from a clinical mammogram and hybridized with simulated microcalcifications for use in this study. Image compression conditions of 1:1, 15:1, and 30:1 were investigated. Observer responses were recorded with a six-point rating scale, and receiver operating characteristic (ROC) analysis was performed. In addition, two well-established numeric observer models were used to study the effect of image compression under the same compression conditions as were used with human observers. Analysis of variance was performed after observer adjustment to compare the mean values for area under the ROC curve (A(z)) across the three compression levels for the masses and microcalcification clusters. RESULTS: The results of the study indicated no significant differences in the A(z) values for masses with the compression conditions investigated. For images of microcalcifications, there were significant differences in A(z) values between compression ratios of 1:1 and 30:1 (P = .0005) and of 15:1 and 30:1 (P = .004); the difference between compression ratios of 1:1 and 15:1 was nonsignificant (P = .053). The observer models and human observers exhibited similar trends in detection of the masses investigated in this study. CONCLUSION: Detection of simulated masses was not affected by the compression method with the conditions used in this study, while the detection of microcalcifications was significantly reduced with a compression ratio of more than 15:1.
American College of Radiology Imaging Network digital mammographic imaging screening trial: objectives and methodology.
This study was approved by the Institutional Review Board (IRB) of the American College of Radiology Imaging Network (ACRIN) and each participating site and by the IRB and the Cancer Therapy Evaluation Program at the National Cancer Institute. The study was monitored by an independent Data Safety and Monitoring Board, which received interim analyses of data to ensure that the study would be terminated early if indicated by trends in the outcomes. The ACRIN, which is funded by the National Cancer Institute, conducted the Digital Mammographic Imaging Screening Trial (DMIST) primarily to compare the diagnostic accuracy of digital and screen-film mammography in asymptomatic women presenting for screening for breast cancer. Over the 25.5 months of enrollment, a total of 49 528 women were included at the 33 participating sites, which used five different types of digital mammography equipment. All participants underwent both screen-film and digital mammography. The digital and screen-film mammograms of each subject were independently interpreted by two radiologists. If findings of either examination were interpreted as abnormal, subsequent work-up occurred according to the recommendations of the interpreting radiologist. Breast cancer status was determined at biopsy or follow-up mammography 11-15 months after study entry. In addition to the measurement of diagnostic accuracy by using the interpretations of mammograms at the study sites, DMIST included evaluations of the relative cost-effectiveness and quality-of-life effects of digital versus screen-film mammography. Six separate reader studies using the de-identified archived DMIST mammograms will also assess the diagnostic accuracy of each of the individual digital mammography machines versus screen-film mammography machines, the effect of breast density on diagnostic accuracy of digital and screen-film mammography, and the effect of different rates of breast cancer on the diagnostic accuracy in a reader study.
Does litigation influence medical practice? The influence of community radiologists' medical malpractice perceptions and experience on screening mammography.
PURPOSE: To assess the relationship between radiologists' perception of and experience with medical malpractice and their patient-recall rates in actual community-based clinical settings. MATERIALS AND METHODS: All study activities were approved by the institutional review boards of the involved institutions, and patient and radiologist informed consent was obtained where necessary. This study was performed in three regions of the United States (Washington, Colorado, and New Hampshire). Radiologists who routinely interpret mammograms completed a mailed survey that included questions on demographic data, practice environment, and medical malpractice. Survey responses were linked to interpretive performance for all screening mammography examinations performed between January 1, 1996, and December 31, 2001. The odds of recall were modeled by using logistic regression analysis based on generalized estimating equations that adjust for study region. RESULTS: Of 181 eligible radiologists, 139 (76.8%) returned the survey with full consent. The analysis included 124 radiologists who had interpreted a total of 557 143 screening mammograms. Approximately half (64 of 122 [52.4%]) of the radiologists reported a prior malpractice claim, with 18 (14.8%) reporting mammography-related claims. The majority (n = 51 [81.0%]) of the 63 radiologists who responded to a question regarding the degree of stress caused by a medical malpractice claim described the experience as very or extremely stressful. More than three of every four radiologists (ie, 94 [76.4%] of 123) expressed concern about the impact medical malpractice has on mammography practice, with over half (72 [58.5%] of 123) indicating that their concern moderately to greatly increased the number of their recommendations for breast biopsies. Radiologists' estimates of their future malpractice risk were substantially higher than the actual historical risk. Almost one of every three radiologists (43 of 122 [35.3%]) had considered withdrawing from mammogram interpretation because of malpractice concerns. No significant association was found between recall rates and radiologists' experiences or perceptions of medical malpractice. CONCLUSION: U.S. radiologists are extremely concerned about medical malpractice and report that this concern affects their recall rates and biopsy recommendations. However, medical malpractice experience and concerns were not associated with recall or false-positive rates. Heightened concern of almost all radiologists may be a key reason that recall rates are higher in the United States than in other countries, but this hypothesis requires further study.
Community-based mammography practice: services, charges, and interpretation methods.
OBJECTIVE: The purpose of our study was to accurately describe facility characteristics among community-based screening and diagnostic mammography practices in the United States. MATERIALS AND METHODS: A survey was developed and applied to community-based facilities providing screening mammography in three geographically distinct locations in the states of Washington, Colorado, and New Hampshire. The facility survey was conducted between December 2001 and September 2002. Characteristics surveyed included facility type, services offered, charges for screening and diagnostic mammography, information systems, and interpretation methods, including the frequency of double interpretation. RESULTS: Among 45 responding facilities, services offered included screening mammography at all facilities, diagnostic mammography at 34 facilities (76%), breast sonography at 30 (67%), breast MRI at seven (16%), and nuclear medicine breast scanning at seven (16%). Most facilities surveyed were radiology practices in nonhospital settings. Eight facilities (18%) reported performing clinical breast examinations routinely along with screening mammography. Only five screening sites (11%) used computer-aided detection (CAD) and only two (5%) used digital mammography. Nearly two thirds of facilities interpreted screening mammography examinations on-site, whereas 91% of facilities interpreted diagnostic examinations on-site. Only three facilities (7%) interpreted screening examinations on line as they were performed. Approximately half of facilities reported using some type of double interpretation, although the methods of double interpretation and the fraction of cases double-interpreted varied widely across facilities. On average, approximately 15% of screening examinations and 10% of diagnostic examinations were reported as being double-interpreted. CONCLUSION: Comparison of this survey's results with those collected a decade earlier indicates dramatic changes in the practice of mammography, including a clear distinction between screening and diagnostic mammography, batch interpretation of screening mammograms, and improved quality assurance and medical audit tools. Diffusion of new technologies such as CAD and digital mammography was not widespread. The methods of double-interpretation and the fraction of cases double-interpreted varied widely across study sites.
The association between obesity and screening mammography accuracy.
BACKGROUND: Obesity is increasing among American women, especially as they age. The influence of obesity on the accuracy of screening mammography has not been studied extensively. METHODS: We analyzed 100 622 screening mammography examinations performed on members of a nonprofit health plan. The relationship between body mass index (weight in kilograms divided by the square of height in meters) and measures of screening accuracy was assessed. Body mass index was categorized as underweight or normal weight (<25), overweight (25-29), obesity class I (30-34), and obesity classes II to III (> or =35). RESULTS: Compared with underweight or normal weight women, overweight and obese women were more likely to be recalled for additional tests after adjusting for important covariates, including age and breast density (overweight odds ratio [OR], 1.17; 95% confidence interval [CI], 1.11-1.23); obesity class I OR, 1.27; 95% CI, 1.19-1.35; obesity classes II-III OR, 1.31; 95% CI, 1.22-1.41). As body mass index increased, women were more likely to have lower specificity (overweight OR, 0.86; 95% CI, 0.81-0.90; obesity class I OR, 0.79; 95% CI, 0.74-0.84; and obesity classes II-III OR, 0.77; 95% CI, 0.71-0.82). No statistically significant differences were noted in sensitivity. Adjusted receiver operating characteristic analysis showed statistically significant improvement in the area under the curve (AUC) for underweight or normal weight women (AUC = 0.941) vs overweight women (AUC = 0.916, P =.02) and underweight or normal weight women vs obesity classes II and III women (AUC = 0.904, P =.02). CONCLUSIONS: Obese women had more than a 20% increased risk of having false-positive mammography results compared with underweight and normal weight women, although sensitivity was unchanged. Achieving a normal weight may improve screening mammography performance.
A perceptual evaluation of JPEG 2000 image compression for digital mammography: contrast-detail characteristics.
In this investigation the effect of JPEG 2000 compression on the contrast-detail (CD) characteristics of digital mammography images was studied using an alternative forced choice (AFC) technique. Images of a contrast-detail phantom, acquired using a clinical full-field digital mammography system, were compressed using a commercially available software product (JPEG 2000). Data compression was achieved at ratios of 1:1, 10:1, 20:1, and 30:1 and the images were reviewed by seven observers on a high-resolution display. Psychophysical detection characteristics were first computed by fitting perception data using a maximum-likelihood technique from which CD curves were derived at 50%, 62.5%, and 75% threshold levels. Statistical analysis indicated no significant difference in the perception of mean disk thickness up to 20:1 compression except for disk diameter of 1 mm. All other compression combinations exhibited significant degradation in CD characteristics.
Mammography: will adequate manpower exist?
Data exist that clearly demonstrate the dominant role of screening mammography in breast cancer mortality reduction with an ever-increasing population of women who are eligible to receive the benefits of screening. The critical question now concerns the current and future availability of those who perform and interpret these life-saving examinations.
Digital mammography.
Despite its technical advantages, early clinical trials comparing digital mammography with film mammography for screening have been somewhat disappointing. Digital mammography,however, is in its infancy and can be expected to improve more rapidly than film mammography. Some areas of improvement being observed now include the development of new detector technologies; more powerful and better-designed interpretation workstations; and novel advanced applications, such as tomosynthesis and contrast-enhanced mammography, which are not possible with standard film mammography.
International variation in screening mammography interpretations in community-based programs.
BACKGROUND: Variations in mammography interpretations may have important clinical and economic implications. To evaluate international variability in mammography interpretation, we analyzed published reports from community-based screening programs from around the world. METHODS: A total of 32 publications were identified in MEDLINE that fit the study inclusion criteria. Data abstracted from the publications included features of the population screened, examination technique, and clinical outcomes, including the percentage of mammograms judged to be abnormal, positive predictive value of an abnormal mammogram (PPV(A)), positive predictive value of a biopsy performed (PPV(B)), and percentages of breast cancer patients with ductal carcinoma in situ (DCIS) and minimal disease (DCIS and/or tumor size < or =10 mm). North American screening programs were compared with those from other countries using meta-regression analysis. All statistical tests were two-sided. RESULTS: Wide ranges were noted for the percentage of mammograms judged to be abnormal (1.2%-15.0%), for PPV(A) (3.4%-48.7%), for PPV(B) (5.0%-85.2%), for percentage diagnosed with DCIS (4.3%-68.1%), and for percentage diagnosed with minimal disease (14.0%-80.6%). The percentage of mammograms judged to be abnormal were 2-4 percentage points higher in North American screening programs than they were in programs from other countries, after adjusting for covariates such as percentage of women who were less than 50 years of age and calendar year in which the mammogram was performed. The percentage of mammograms judged to be abnormal had a negative association with PPV(A) and PPV(B) (both P<.001) and a positive association with the frequency of DCIS cases diagnosed (P =.008) and the number of DCIS cases diagnosed per 1000 screens (P =.024); no consistent relationship was observed with the proportion of breast cancer diagnoses reported as having minimal disease or the number of minimal disease cases diagnosed per 1000 screens. CONCLUSION: North American screening programs appear to interpret a higher percentage of mammograms as abnormal than programs from other countries without evident benefit in the yield of cancers detected per 1000 screens, although an increase in DCIS detection was noted.
Does training in the Breast Imaging Reporting and Data System (BI-RADS) improve biopsy recommendations or feature analysis agreement with experienced breast imagers at mammography?
PURPOSE: To determine whether training in the Breast Imaging Reporting and Data System (BI-RADS) improves observer performance and agreement with the consensus of experienced breast imagers with regard to mammographic feature analysis and final assessment. MATERIALS AND METHODS: A test set of mammograms was developed, with 54 proven lesions consisting of 28 masses (nine [32%] malignancies) and 26 microcalcifications (10 [38%] malignancies). Three experienced breast imagers reviewed cases independently and by means of consensus. Twenty-three practicing mammogram-interpreting physicians reviewed mammograms before and after a day's lectures on BI-RADS. Observer performance before and after training was measured by means of agreement (kappa) with consensus description and assessments, rate of biopsy of malignant and benign lesions, and areas under receiver operating characteristic (ROC) curves. Performance was also measured for 11 participants 2-3 months after training. RESULTS: Improved agreement with consensus feature analysis was found for mass margins and/or asymmetries, with a pretraining generalized kappa value of 0.36 and a posttraining generalized kappa value of 0.41. Similar improvement was seen for description of calcification morphology (pretraining kappa value of 0.36 improving to 0.44 after training). No improvement was seen in describing calcification distribution. Final assessments were more consistent after training, with a pretraining kappa value of 0.31, as compared with 0.45 after training. The mean biopsy rate for malignant lesions improved from 73% (range, 53%-89%) before training to 88% (range, 74%-100%) after training, with minimal increase in mean biopsy rate of benign lesions (43% [range, 26%-60%] before to 51% [range, 31%-63%] after training), and no net change in area under the ROC curve, as compared with histopathologic findings. For the subset of participants with delayed follow-up, no significant decline in posttraining results was seen. CONCLUSION: BI-RADS training resulted in improved agreement with the consensus of experienced breast imagers for feature analysis and final assessment. It is important that trainees showed improved rates of recommending biopsy for malignant lesions. This effect was maintained over 2-3 months.
Flat-panel digital mammography system: contrast-detail comparison between screen-film radiographs and hard-copy images.
PURPOSE: To compare the contrast-detail (CD) characteristics of screen-film (SF) and postprocessed digital images by using a phantom-based method. MATERIALS AND METHODS: Images of a CD phantom with polymerized methyl methacrylate were acquired with SF and full-field digital mammography systems at matched exposure conditions. A four-alternative forced-choice experiment was conducted with seven observers participating in the study. Each observer was required to identify randomly located disks in phantom images from which detection curves were computed. The CD diagrams for the SF and digital systems were estimated from the detection curves and compared at 50% and 62.5% threshold levels. Furthermore, a theoretic model was used to estimate the CD performance of the SF and digital systems. RESULTS: Analysis of covariance for mixed models was used with the natural logarithm of disk thickness as the dependent variable, the natural logarithm of disk diameter as the covariate, and the observer as a random factor. The results of statistical analysis indicated significant differences between the CD characteristics of SF and digital mammographic images at both 50% (P <.001) and 62.5% (P <.001) detection thresholds. CONCLUSION: The authors conclude that digital CD curves, on average, exhibit threshold contrast characteristics that are lower (better) than those of SF mammography.
Clinical comparison of full-field digital mammography and screen-film mammography for detection of breast cancer.
OBJECTIVE: The purpose of this work is to compare full-field digital mammography and screen-film mammography for the detection of breast cancer in a screening population. SUBJECTS AND METHODS: Full-field digital mammography was performed in addition to screen-film mammography in 6736 examinations of women 40 years old and older presenting for screening mammography at either of two institutions. Two views of each breast were acquired with each technique. The digital and screen-film mammograms were each interpreted independently. In addition to a clinical assessment, each finding was assigned a probability of malignancy for use in receiver operating characteristic analysis. In cases in which the digital and screen-film interpretations differed, a side-by-side analysis was performed to determine the reasons for the discrepancy. With few exceptions, findings detected on either technique were evaluated with additional imaging and, if warranted, biopsy. RESULTS: Additional evaluation was recommended on at least one technique in 1467 cases. These additional evaluations led to 181 biopsies and the detection of 42 cancers. Nine cancers were detected only on digital mammography, 15 were detected only on screen-film mammography, and 18 were detected on both. The difference in cancer detection is not statistically significant (p > 0.1). Digital mammography resulted in fewer recalls than did screenfilm mammography (799 vs 1007, p < 0.001). The difference between the receiver operating characteristic curve area for digital (0.74) and screen-film (0.80) mammography was not significant (p > 0.1). Reasons for discrepant interpretations of cancer were approximately equally distributed among those relating to lesion conspicuity, lesion appearance, and interpretation. CONCLUSION: No significant difference in cancer detection was observed between digital mammography and screen-film mammography. Digital mammography resulted in fewer recalls than did screen-film mammography.
Digital mammography.
Digital mammography, using novel detector technology, has been shown to be at least as sensitive as screen-film mammography for detecting early breast cancer. However, there are barriers to overcome, particularly in soft-copy display, workstation design, and equipment cost. These problems are actively being addressed and are solvable, eventually allowing digital mammography to assume a "prime time" role.
Radiologist uncertainty and the interpretation of screening.
OBJECTIVE: To determine radiologists' reactions to uncertainty when interpreting mammography and the extent to which radiologist uncertainty explains variability in interpretive performance. METHODS: The authors used a mailed survey to assess demographic and clinical characteristics of radiologists and reactions to uncertainty associated with practice. Responses were linked to radiologists' actual interpretive performance data obtained from 3 regionally located mammography registries. RESULTS: More than 180 radiologists were eligible to participate, and 139 consented for a response rate of 76.8%. Radiologist gender, more years interpreting, and higher volume were associated with lower uncertainty scores. Positive predictive value, recall rates, and specificity were more affected by reactions to uncertainty than sensitivity or negative predictive value; however, none of these relationships was statistically significant. CONCLUSION: Certain practice factors, such as gender and years of interpretive experience, affect uncertainty scores. Radiologists' reactions to uncertainty do not appear to affect interpretive performance.
Mammographers' perception of women's breast cancer risk.
OBJECTIVE: To understand mammographers' perception of individual women's breast cancer risk. MATERIALS AND METHODS: Radiologists interpreting screening mammography examinations completed a mailed survey consisting of questions pertaining to demographic and clinical practice characteristics, as well as 2 vignettes describing different risk profiles of women. Respondents were asked to estimate the probability of a breast cancer diagnosis in the next 5 years for each vignette. Vignette responses were plotted against mean recall rates in actual clinical practice. RESULTS: The survey was returned by 77% of eligible radiologists. Ninety-three percent of radiologists overestimated risk in the vignette involving a 70-year-old woman; 96% overestimated risk in the vignette involving a 41-year-old woman. Radiologists who more accurately estimated breast cancer risk were younger, worked full-time, were affiliated with an academic medical center, had fellowship training, had fewer than 10 years experience interpreting mammograms, and worked more than 40% of the time in breast imaging. However, only age was statistically significant. No association was found between radiologists' risk estimate and their recall rate. CONCLUSION: U.S. radiologists have a heightened perception of breast cancer risk.