Biomedical subjects
R Lederman
Publications and source records attributed to R Lederman.
Computerized evaluation of mammographic lesions: what diagnostic role does the shape of the individual microcalcifications play compared with the geometry of the cluster?
OBJECTIVE: The objective of this study was to compare the diagnostic role of features reflecting the geometry of clusters with features reflecting the shape of the individual microcalcification in a mammographic computer-aided diagnosis system. MATERIALS AND METHODS: Three hundred twenty-four cases of clustered microcalcifications with biopsy-proven results were digitized at 42-microm resolution and analyzed on a computerized system. The shape factor and number of neighbors were computed for each microcalcification, and the eccentricity of the cluster was computed as well. The shape factor is related to the individual microcalcification; the average number of neighbors and the cluster eccentricity reflect the cluster geometry. Stepwise discriminant analysis was used to evaluate the contribution of the extracted features in predicting malignancy. The performance of a classifier based on the features selected by stepwise discriminant analysis was evaluated by receiver operating characteristic (ROC) analysis. RESULTS: To obtain the best discrimination model, we used stepwise discriminant analysis to select the average number of neighbors and the shape of the individual microcalcification, but excluded cluster eccentricity. A classification scheme assigned the average number of neighbors a weighting factor, which was 1.49 times greater than that assigned to the shape factor of the individual microcalcification. A scheme based only on these two features yielded an ROC curve with an area under the curve (A(z)) of 0.87, indicating a positive predictive value of 61% for 98% sensitivity. CONCLUSION: Computerized analysis permitted calculations reflecting the shape of individual microcalcification and the geometry of clusters of microcalcifications. For the computerized classification scheme studied, the cluster geometry was more effective in differentiating benign from malignant clusters than was the shape of individual microcalcification.
Feasibility of implementing intervention methods in an adolescent worksite tobacco control study.
OBJECTIVE: To present feasibility data on SMART, the first teen worksite behavioural tobacco control intervention. DESIGN: This phase II study was designed to estimate the efficacy and feasibility of a small scale, randomised, controlled intervention. SETTING AND SUBJECTS: This study, addressing youths aged 15-18 years, was implemented in four intervention and five control grocery stores that had an average of 44 eligible teens. INTERVENTIONS: The tobacco use cessation and prevention interventions were based on social influences and peer leader models. Employee break rooms served as centres both for interactive activities including open houses, teen advisory boards, peer leader interviews, games and contests; and non-interactive interventions including bulletin boards and table tents with health messages and home mailings. MAIN PROCESS MEASURES: Project staff collected process data on the extent of implementation of intervention activities, participation rates in activities, and contacts with peer leaders. On the final survey, teens reported on awareness of, participation in, and motivation for participating in project activities. RESULTS: Indicators of feasibility were identified and discussed, including the number of activities implemented, teen participation, management support, cost, and barriers to and facilitators of implementation. During the 12 month intervention, a mean of 24.1 interactive activities and 55.3 non-interactive activities were implemented, and a mean 14.2% participation rate per activity per site was achieved. Eighty four per cent of teens reported being aware of SMART, and 39% reported participating in interactive and 67% in non-interactive activities. CONCLUSIONS: Teen smoking cessation rates in worksite programmes might be improved if they are conducted in companies where there is job stability and if teen programmes are part of worksite-wide tobacco control programmes that include both teens and adults.
Ultrasound-guided thrombin injection for the treatment of iatrogenic pseudoaneurysm of the femoral artery.
BACKGROUND: Pseudoaneurysm occurring after catheterization of the femoral artery is associated with significant morbidity. Percutaneous ultrasound-guided thrombin injection has recently emerged as a potential first-line therapy. OBJECTIVES: To evaluate the efficacy of this treatment in eight patients with iatrogenic femoral artery pseudoaneurysm. METHODS: After attempted treatment with external compression had failed, eight patients with iatrogenic femoral artery pseudoaneurysm were treated with thrombin injection. Treatment performed between 2 and 9 days following arterial puncture. The study group comprised seven males and one female ranging in age from 23 to 89 years (median 70). Seven had undergone cardiac catheterization with or without intervention, and five were receiving antiplatelet and/or anticoagulant drugs. Arterial pseudoaneurysm resulted from femoral vein catheterization in one patient. Using a sterile technique and real-time Doppler ultrasound guidance, a dilute solution of bovine thrombin (average dose 250 units, range 100-600), was slowly injected directly into the pseudoaneurysm until cessation of flow was seen. Patients were allowed to walk within 2 hours of the procedure and were followed up clinically and by color Doppler ultrasound during the admission. RESULTS: Cardiac catheterization had been inadvertently performed via the superficial or profunda femoris arteries in four of the eight patients. Thrombin injection was initially successful in all eight patients without complication. Thrombosis occurred immediately in every case. Early recanalization of pseudoaneurysm occurred in one patient despite repeat thrombin injection and attempted ultrasound-guided compression. He eventually required surgical repair. The final success rate was 87.5% (7/8). CONCLUSION: Faulty puncture technique is an important risk factor for the development of post-catheterization femoral artery pseudoaneurysm. Ultrasound-guided thrombin injection is a safe, rapid, well-tolerated, inexpensive and successful therapy. If initial external compression with a sandbag fails to result in thrombosis of the pseudoaneurysm then thrombin injection should be considered as first-line therapy. If unsuccessful, it does not preclude the use of alternative treatment modalities. Further study is necessary to assess the long-term effects of thrombin injection.
Improved mammographic interpretation of masses using computer-aided diagnosis.
The aim of this study was to evaluate the effectiveness of computerized image enhancement, to investigate criteria for discriminating benign from malignant mammographic findings by computer-aided diagnosis (CAD), and to test the role of quantitative analysis in improving the accuracy of interpretation of mass lesions. Forty sequential mammographically detected mass lesions referred for biopsy were digitized at high resolution for computerized evaluation. A prototype CAD system which included image enhancement algorithms was used for a better visualization of the lesions. Quantitative features which characterize the spiculation were automatically extracted by the CAD system for a user-defined region of interest (ROI). Reference ranges for malignant and benign cases were acquired from data generated by 214 known retrospective cases. The extracted parameters together with the reference ranges were presented to the radiologist for the analysis of 40 prospective cases. A pattern recognition scheme based on discriminant analysis was trained on the 214 retrospective cases, and applied to the prospective cases. Accuracy of interpretation with and without the CAD system, as well as the performance of the pattern recognition scheme, were analyzed using receiver operating characteristics (ROC) curves. A significant difference (p < 0.005) was found between features extracted by the CAD system for benign and malignant cases. Specificity of the CAD-assisted diagnosis improved significantly (p < 0.02) from 14 % for the conventional assessment to 50 %, and the positive predictive value increased from 0.47 to 0.62 (p < 0.04). The area under the ROC curve (A(z)) increased significantly (p < 0. 001) from 0.66 for the conventional assessment to 0.81 for the CAD-assisted analysis. The A(z) for the results of the pattern recognition scheme was higher (0.95). The results indicate that there is an improved accuracy of diagnosis with the use of the mammographic CAD system above that of the unassisted radiologist. Our findings suggest that objective quantitative features extracted from digitized mammographic findings may help in differentiating between benign and malignant masses, and can assist the radiologist in the interpretation of mass lesions.
Optimizing parameters for computer-aided diagnosis of microcalcifications at mammography.
RATIONALE AND OBJECTIVES: The purpose of this study was to optimize selection of the mammographic features most useful in discriminating benign from malignant clustered microcalcifications. MATERIALS AND METHODS: The computer-aided diagnosis (CAD) system automatically extracted from digitized mammograms 13 quantitative features characterizing microcalcification clusters. Archival cases (n = 134; patient age range, 31-77 years; mean age, 56.8 years) with known histopathologic results (79 malignant, 55 benign) were selected. Three radiologists at three facilities independently analyzed the microcalcifications by using the CAD system. Stepwise discriminant analysis selected the features best discriminating benign from malignant microcalcifications. A classification scheme was constructed on the basis of these optimized features, and its performance was evaluated by using receiver operating characteristic (ROC) analysis. RESULTS: Six of the 13 variables extracted by the CAD system were selected by stepwise determinant analysis for generating the classification scheme, which yielded an ROC curve with an area (Az) of 0.98, specificity of 83.64%, positive predictive value of 89.53%, and accuracy of 91.79% for 98% sensitivity. When patient age was an additional variable, the scheme's performance improved, but this was not statistically significant (Az = 0.98). The ROC curve of the classifier (without age as an additional variable) yielded a high Az of 0.96 for patients younger than 50 years and an even higher (P < .02) Az of 0.99 for those 50 years or older. CONCLUSION: Stepwise discriminant analysis optimized performance of a classification scheme for microcalcifications by selecting six optimized features. Scheme performance was significantly (P < .02) higher for women 50 years or older, but the addition of patient age as a variable did not produce a statistically significant increase in performance.
Quantitative characterization of mass lesions on digitized mammograms for computer-assisted diagnosis.
RATIONALE AND OBJECTIVES: To investigate features for discriminating benign from malignant mammographic findings by using computer-aided diagnosis (CAD) and to test the accuracy of CAD interpretations of mass lesions. METHODS: Fifty-five sequential, mammographically detected mass lesions, referred for biopsy, were digitized for computerized reevaluation with a CAD system. Quantitative features that characterize spiculation were automatically extracted by the CAD system. Data generated by 271 known retrospective cases were used to set reference values indicating the range for malignant and benign lesions. After conventional interpretation of the 55 prospective cases, they were evaluated a second time by the radiologist using the extracted features and the reference ranges. In addition, a pattern-recognition scheme based on the extracted features was used to classify the prospective cases. Accuracy of interpretation with and without the CAD system was evaluated using receiver operating characteristic (ROC) curve analysis. RESULTS: Sensitivity of the CAD diagnosis for the prospective cases improved from 92% to 100%. Specificity improved significantly from 26.7% to 66.7%. This was accompanied by a significant increase in the accuracy of diagnosis from 56.4% to 81.8% and in the positive predictive value from 51.1% to 71.4%. The Az for the CAD ROC curve significantly increased from 0.73 to 0.90. The performance of the classification scheme was slightly lower than that of the radiologists' interpretation with the CAD system. CONCLUSIONS: Use of the CAD system significantly improved the accuracy of diagnosis. The findings suggest that the classification scheme may improve the radiologist's ability to differentiate benign from malignant mass lesions in the interpretation of mammograms.
Results of employee involvement in planning and implementing the Treatwell 5-a-Day work-site study.
When work-site health promotion programs incorporate theories of community organization, it is likely that employee ownership and participation are enhanced. This article reports quantitative indicators of involvement of Employee Advisory Board (EAB) members in the Treatwell 5-a-Day work-site study and examines relationships between EAB member time spent on project activities and work-site size, with indicators of the extent of implementation and variables associated with behavior change and work-site support. The results reported here indicate that a greater number of EAB member hours spent on program activities was associated with a greater number of events implemented. Smaller work-site size was associated with greater employee awareness of the program and greater participation in project activities as reported on the employee survey. These results suggest that the number of hours employee representatives devote to project activities might be an important consideration in planning employee involvement in work-site health promotion programming.
The use of an interactive software program for quantitative characterization of microcalcifications on digitized film-screen mammograms.
RATIONALE AND OBJECTIVES: Mammography is relatively nonspecific for the early detection of breast cancer. This study evaluates the accuracy of mammographic interpretation using quantitative features characterizing microcalcifications, which are extracted by a computerized system. METHODS: A computer-aided diagnosis (CAD) system enabling digitization of film-screen mammograms and automatic feature extraction was developed. A classification scheme (discriminant analysis) based on these features was constructed and trained on 217 cases with known pathology. The diagnostic performance of the classification scheme was tested against the radiologist's conventional interpretation on 45 additional cases of microcalcifications, each analyzed independently by four radiologists. RESULTS: The sensitivity of the CAD system analysis (95.7%) was significantly better than that of conventional interpretation (84.8%). The positive predictive value of interpretation increased significantly, as did the area under the receiver operating characteristic curve. CONCLUSIONS: This classification scheme for microcalcifications, based on quantitative features characterizing the lesion, significantly improved the accuracy of mammographic interpretation.
Increasing fruit and vegetable consumption through worksites and families in the treatwell 5-a-day study.
OBJECTIVES: We report on the results of the Treatwell 5-a-Day study, a worksite intervention aimed at increasing consumption of fruits and vegetables. METHODS: Twenty-two worksites were randomly assigned to 3 groups: (1) a minimal intervention control group, (2) a worksite intervention, and (3) a worksite-plus-family intervention. The interventions used community-organizing strategies and were structured to target multiple levels of influence, following a socioecological model. Data were collected by self-administered employee surveys before and after the intervention; the response rate was 87% (n = 1359) at baseline and 76% (n = 1306) at follow-up. A process tracking system was used to document intervention delivery. RESULTS: After control for worksite, gender, education, occupation, race/ethnicity, and living situation, total fruit and vegetable intake increased by 19% in the worksite-plus-family group, 7% in the worksite intervention group and 0% in the control group (P = .05). These changes reflect a one half serving increase among workers in the worksite-plus-family group compared with the control group (P = .018). CONCLUSIONS: The worksite-plus-family intervention was more successful in increasing fruit and vegetable consumption than was the worksite intervention. Worksite interventions involving family members appear to be a promising strategy for influencing workers' dietary habits.
Analysis of clustered microcalcifications by using a single numeric classifier extracted from mammographic digital images.
RATIONALE AND OBJECTIVES: The authors prospectively tested the performance of a single numeric classifier constructed from a discriminative analysis classification system based on automatic computer-extracted quantitative features of clustered microcalcifications. MATERIALS AND METHODS: Mammographically detected clustered microcalcifications in patients who had been referred for biopsy were digitized at 600 dpi with an 8-bit gray scale. A software program was developed to extract features automatically from digitized images to describe the clustered microcalcifications quantitatively. The significance of these features was evaluated by using the Wilcoxon test, the Welch modified two-sample t test, and the two-sample Kolmogorov-Smirnov test. A discriminant analysis pattern recognition system was constructed to generate a single numeric classifier for each case, based on the extracted features. This system was trained on 137 archival known reference cases and its performance tested on 24 unknown prospective cases. The results were evaluated by using receiver operating characteristic analysis. RESULTS: Thirty-seven extracted parameters demonstrated a statistically significant difference between the values for the benign and for the malignant lesions. Seven independent factors were selected to construct the classifier and to evaluate the unknown prospective cases. The area under the receiver operating characteristic curve for the prospective cases was 0.88. CONCLUSION: A pattern recognition classifier based on quantitative features for clustered microcalcifications at screen-film mammography was found to perform satisfactorily. The software may be of value in the interpretation of mammographically detected microcalcifications.
Adaptation to pregnancy in three different ethnic groups: Latin-American, African-American, and Anglo-American.
Interview assessments on adaptation to pregnancy were made of Latin-American (N = 30), African-American (N = 34), and Anglo-American (N = 30) women in the latter half of their pregnancy. Most subjects were 18-27 years old, single, had 12 years or less education, and had a parity of 0 or 1. Psychosocial measures of adaptation to pregnancy included Acceptance of Pregnancy, Identification with Motherhood Role, Relationship with Mother and with Husband/Partner, and Preparation for Labour. Data were analyzed using chi-square for group differences. The results indicate that in all 3 groups pregnancy was unplanned but wanted. African Americans least often anticipated life changes as a result of pregnancy, cited fewest aspects of pregnancy that were gratifying to them, and least often chose to stay home with their infant. Most women in all ethnic groups reflected on their role as mother, but Latin Americans most often indicated that they wanted to be like their own mother and that they consulted with their mother about pregnancy and parenting. African Americans least often anticipated domestic help from their partner and most often expected help from other family members. Regarding intimate relationships with husband/partner, for all groups sexual intercourse decreased during pregnancy. Anglo-Americans reported the least number of problems/discomforts with intercourse, Latin Americans the most. Anglo-Americans most often found alternative methods of sexually satisfying their partner, African Americans least often. The results of this exploratory study have significance for differences in the delivery of health care to the 3 ethnic groups and warrant further research.
Induction procedures for psychogenic seizures: ethical and clinical considerations.
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Developing guidelines for local use: algorithms for cost-efficient outpatient management of cardiovascular disorders in a VA Medical Center.
Local use of practice guidelines requires paying close attention to the concerns of the patient within the framework of society, to the professional and educational needs of the provider, and to the realities of cost. One Veterans Affairs facility took the challenge of balancing these factors and developed their own algorithms for three cardiovascular disorders.
A critique of community-based secondary prevention with the pregnant adolescent.
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Effects of Maine's 1981 and Massachusetts' 1982 driving-under-the-influence legislation.
In 1981, Maine passed a drunk driving law with mandatory penalties and a new civil charge to increase the conviction rate. One year later, Massachusetts increased drunk driving penalties, particularly for repeat offenders and intoxicated drivers involved in fatal crashes. In Maine, single-vehicle nighttime fatal crashes declined 22 per cent the year before passage of the law, and 33 per cent the year after. Maine's rates returned to pre-law levels by the third post-law year. Prior to Massachusetts' new law, single-vehicle nighttime and overall fatal crashes there also declined 20% and 22%, whereas after this law fatal crash rates did not decline further compared with the pre-law year or other New England states. Pre- and post-law surveys indicate that both laws were followed by some increases in public perceptions that drunk drivers stopped by police would be arrested, convicted, and receive automatic penalties. But, few believed it was very likely that drunk drivers would be stopped. For only two of three years studied after Maine's law did more people there report decisions not to drive because they had drunk too much. In Massachusetts, reported driving after heavy drinking declined as much the year before as the three years after its law.
Tenoxicam in the treatment of extra-articular inflammatory processes.
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Development of a research group. A group dynamics view.
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