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Biomedical subjects

D D Dorfman

Publications and source records attributed to D D Dorfman.

At least 19 recordsLinked to original sources
PubMed1998

Role of faulty visual search in the satisfaction of search effect in chest radiography.

RATIONALE AND OBJECTIVES: The authors tested the hypothesis that satisfaction of search effect, which is associated with the failure to detect native chest abnormalities in the presence of simulated nodules, is caused by reduced gaze on the native abnormalities. MATERIALS AND METHODS: Gaze dwell time of 20 radiologists was recorded for the region around abnormalities on images. Ten radiographs were reviewed, nine of which contained native abnormalities. Each image was seen with and without a simulated nodule. RESULTS: The decrease in the rate of true-positive findings in the detection of native abnormalities on images that contained simulated nodules confirmed the occurrence of a satisfaction of search effect. Gaze times on native abnormalities (up to the time of report of the abnormalities) were the same for images with nodules in which native abnormalities were missed (gaze time, 9.4 seconds) as they were for images without nodules in which native abnormalities were detected (gaze time, 9.5 seconds). Gaze time on missed native abnormalities was not affected by the presence (7.80 seconds) or absence (7.45 seconds) of nodules. CONCLUSION: Reduction in gaze dwell time on the missed abnormalities is not the cause of satisfaction of search errors in chest radiographs.

False Positive Reactions↗
PubMed1998

Monte Carlo validation of a multireader method for receiver operating characteristic discrete rating data: factorial experimental design.

RATIONALE AND OBJECTIVES: The authors conducted a series of null-case Monte Carlo simulations to evaluate the Dorfman-Berbaum-Metz (DBM) method for comparing modalities with multireader receiver operating characteristic (ROC) discrete rating data. MATERIALS AND METHODS: Monte Carlo simulations were performed by using discrete ratings on fully crossed factorial designs with two modalities and three, five, and 10 hypothetical readers. The null hypothesis was true for all simulations. The population ROC areas, latent variable structures, case sample sizes, and normal/abnormal case sample ratios used in another study were used in these simulations. RESULTS: For equal allocation ratios and small (Az = 0.702) and moderate (Az = 0.855) ROC areas, the empirical type I error rate closely matched the nominal alpha level. For very large ROC areas (Az = 0.961), however, the empirical type I error rate was somewhat smaller than the nominal alpha level. This conservatism increased with decreasing case sample size and asymmetric normal/abnormal case allocation ratio. The empirical type I error rate was sometimes slightly larger than the nominal alpha level with many cases and few readers, where there was large residual, relatively small treatment-by-case interaction and relatively large treatment-by-reader interaction. CONCLUSION: The results suggest that the DBM method provides trustworthy alpha levels with discrete ratings when the ROC area is not too large and case and reader sample sizes are not too small. In other situations, the test tends to be somewhat conservative or slightly liberal.

Diagnostic Imaging↗
PubMed1997

Proper receiver operating characteristic analysis: the bigamma model.

RATIONALE AND OBJECTIVES: The standard binormal model is the most commonly used model for fitting receiver operating characteristic rating data; however, it sometimes produces inappropriate fits that cross the chance line with degenerate data sets. The authors proposed and evaluated a proper constant-shape bigamma model to handle binormal degeneracy. METHODS: Monte Carlo samples were generated from both a standard binormal population model and a proper constant-shape bigamma model in a series of Monte Carlo studies. RESULTS: The results confirm that the standard binormal model is robust in large samples with no degenerate data sets and that the standard binormal model is not robust in small samples because of degenerate data sets. CONCLUSION: A proper constant-shape bigamma model seems to solve the problem of degeneracy without inappropriate chance line crossings. The bigamma fitting model outperformed the standard binormal fitting model in small samples and gave similar results in large samples.

Decision Making↗
PubMed1996

Cause of satisfaction of search effects in contrast studies of the abdomen.

RATIONALE AND OBJECTIVES: Extraintestinal abnormalities visible without contrast material on abdominal radiographs are reported less frequently when contrast examinations are performed. Gaze dwell time was used to determine whether this difference is due to failure by observers to scan plain-film regions of contrast studies or discounting of plain-film abnormalities that were actually scanned. METHODS: Patients were included whose contrast studies had elicited the largest reductions in positive responses compared with their plain-film studies in a previous detection experiment. Gaze of 10 radiologists was studied. RESULTS: Significantly less time was spent gazing at non-contrast regions of contrast examinations than at the corresponding regions of radiographs. Errors with radiographs were based primarily on failures of recognition and decision making, whereas errors with contrast studies were based primarily on faulty scanning. CONCLUSION: Satisfaction of search errors on contrast examinations are caused by reduction in scanning of noncontrast regions.

Contrast Media↗
PubMed1995

Degeneracy and discrete receiver operating characteristic rating data.

RATIONALE AND OBJECTIVES: Observer performance studies sometimes use too few cases for estimating diagnostic accuracy from binormal receiver operating characteristic (ROC) curves. One important problem is degenerate data sets. We compared a new algorithm, RSCORE4, with the exact-solution approach to degeneracy in ROCFIT and with the Wilcoxon statistic. METHODS: Degenerate ROC solutions result from empty cells in the data matrix. We addressed this problem by adding a small constant to empty cells in a maximum-likelihood program, RSCORE4. When this method failed, the program branched to a pattern-search algorithm. We tested the program in a series of Monte Carlo studies. RESULTS: RSCORE4 converged to nondegenerate solutions in every case and gave results closer to population values than ROCFIT or Wilcoxon. ROCFIT converged to exact-fit degenerate solutions, those with zero or infinite parameter values, in more than 40% of the samples. The Wilcoxon statistic was biased. CONCLUSION: RSCORE4 seems to outperform other currently recommended methods for dealing with degeneracy.

Algorithms↗
PubMed1994

Influence of clinical history on perception of abnormalities in pediatric radiographs.

RATIONALE AND OBJECTIVES: We tested whether having clinical information would improve perception or simply decision making. METHODS: Sixty-four pediatric chest and abdominal radiographs, half of which had abnormalities, were presented to nine radiologists under one of two conditions. In one condition, history consistent with abnormalities actually present for positive cases was provided for positive and matched negative cases before inspection. In a second condition, this information was provided only after inspection was completed and the radiograph was no longer available. Because detailed visual memory is short-lived, the image information was no longer available when the history was provided after inspection. A control condition measured detection without history. RESULTS: Detection was significantly better with history provided before inspection. Detection did not differ for history provided after inspection and inspection without history. CONCLUSION: The only difference between conditions with history was in whether history influenced perception; history affected decision making in both conditions. Clinical history affected perception in interpreting radiographs, not simply decision making.

Adolescent↗
PubMed1994

Satisfaction of search in the detection of plain-film abnormalities in abdominal contrast studies.

RATIONALE AND OBJECTIVES: Satisfaction of search (SOS) occurs when a lesion is "missed" after detecting another lesion in the same radiograph. The authors investigated the SOS effect in abdominal contrast studies. METHODS: The authors measured detection of 23 plain film abnormalities in 43 patients who had plain film and contrast examinations. Each plain-film and contrast study was examined independently by 10 radiologists in two sessions, with receiver operating characteristic (ROC) curve areas estimated with the computer program RSCORE-J (University of Iowa, Iowa City, IA) for each condition. RESULTS: Observers more often missed plain film abnormalities present on contrast studies but also made fewer false-positive (FP) responses. There was no change in ROC area, but decision criteria grew more conservative. CONCLUSIONS: The reduction of detecting plain-film abnormalities in contrast examinations differs from the SOS effect of other imaging studies. The reduction in true-positive (TP) and false-positive (FP) rates suggests that a different cause may underlie these misses.

Contrast Media↗
PubMed1993

The influence of clinical history on visual search with single and multiple abnormalities.

RATIONALE AND OBJECTIVES: Facilitation of detection by clinical history generally has been found with a single abnormality per image but not with multiple abnormalities. Multiple abnormalities per image can occasion a "satisfaction-of-search" effect in which detection of one lesion is reduced in the presence of other distant lesions. Our experiment studied the combined effect of multiple abnormalities and clinical history on accuracy. METHODS: Detection of native lesions was measured 1) with histories suggestive of the native abnormality; 2) with these histories and added simulated pulmonary nodules; and 3) with the same added nodules and histories suggestive of metastatic disease. These conditions also were compared with those of a previous experiment that were similar but included no history. RESULTS: Detection was substantially improved for appropriately prompted abnormalities even in the presence of a pulmonary nodule. In fact, satisfaction of search was not found in the presence of an appropriate history. Detection of unprompted abnormalities was unchanged when prompts indicated other abnormalities actually present. Prompted abnormalities were detected earlier in search. CONCLUSIONS: History appears to direct perceptual resources to the prompted abnormalities, thereby alleviating satisfaction of search. The presence of nodules yielded a small but consistent reduction in total search time for searches involving false responses, suggesting that satisfaction of search may depend more on reduction in search time than had been indicated by previous research.

Diagnostic Errors↗
PubMed1991

Time course of satisfaction of search.

"Satisfaction of search" (SOS) refers to the effect in which a second lesion remains undetected after detection of another lesion on the same radiograph. The objective of this study was to clarify our understanding of SOS by relating it to total time of inspection and time intervals before, between, and after discovery of lesions. Detection accuracy of native lesions in chest radiographs, before and after the addition of a simulated nodular lesion, was measured for ten observers. Analysis of data from this and a previous experiment showed that average perceptual accuracy of individual receiver operating characteristic curves was significantly reduced with the addition of the nodules. Plots and analyses of search time revealed that, on average, during a typical 46-second inspection of a case, simulated nodules were found at 18 seconds, native abnormalities at 25 seconds, and false positives occurred at 33 seconds. Time needed to find nodules did not depend on whether native lesions were present; time to find native lesions did not change with addition of nodules; and total search time was the same for images with one, two, or no lesions. The detection results show that the SOS effect was obtained, but that interrupting search in order to measure it also diminishes accuracy. Analysis of the time course data relates SOS to perceptual capture and strategic halting of search.

Diagnostic Errors↗
PubMed1990

Satisfaction of search in diagnostic radiology.

A subset of underreading errors (false-negative responses) in radiology has been attributed to "satisfaction of search," which occurs when lesions remain undetected after detection of an initial lesion. This phenomenon has not been studied in the experimental laboratory. A primary goal of this study was to develop a procedure or paradigm to study satisfaction of search. The authors measured detection accuracy for native lesions in images before and after the addition of a simulated nodular lesion. Simulated and native lesions were not spatially superimposed and the native abnormalities were physically identical with and without the nodules. Only responses related to the native lesion were analyzed. Accuracy parameters of receiver operating characteristic (ROC) curves were estimated by the method of maximum likelihood and jackknife. The average perceptual accuracy of the individual ROC curves as measured by Az and de' was significantly reduced with addition of the nodules (t = 2.364, p = 0.025, t = 2.648, p = 0.017, respectively). Az and de' parameters of the pooled ROC curve showed a similar effect (t = 1.573, p = 0.080; t = 1.934, p = 0.047, respectively). The results indicated a substantial satisfaction-of-search effect, with diminished accuracy in perception of native lesions.

Adolescent↗
PubMed1988

Influence of clinical history upon detection of nodules and other lesions.

The authors reexamined a suspected difference in the effects of clinical information upon detection of nodules vs. more diverse lesions by directly incorporating classification specificity into detection ROC analysis. Categorical prompts, correct for specific abnormalities, led to detection superior to unprompted reading when non-nodule trials (various lesion types) were analyzed. Trials that contained pulmonary nodules, or contained no lesions but had been preceded by "possible tuberculosis" or "rule out metastatic disease" prompts, failed to demonstrate the diagnostic prompt superiority. Perceptual responses may differ when nodules are compared with more complex lesions.

Diagnostic Errors↗
PubMed1986

Tentative diagnoses facilitate the detection of diverse lesions in chest radiographs.

The influence of clinical history upon detection has been frequently studied. In a unique investigation, detection of diverse abnormalities commonly encountered in practice was tested, and the influence of clinical history was conceptualized as suggesting a tentative diagnosis. Categorical prompts that were correct for specific abnormalities resulted in detection superior to that with unprompted reading. Prompts that were plausible but incorrect for abnormal and normal cases led to very few false-positive responses, and subsequent reports of specific abnormalities were as accurate as in unprompted reading. It is concluded that appropriate clinical history results in improved perceptual performance rather than simply improved decision-making.

Adult↗