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Title: The effect of a priori information on the cognitive processes and search patterns of radiologists when searching for lung nodules and the consequences for malpractice litigation.
Keywords: Perception;Eye-tracking;Malpractice;Expert witness;Chest
Publisher: University of Sydney;Faculty of Health Sciences
Description: Aims: The effect of target prevalence on the performance of radiologists is well described, but the effect of target prevalence expectation has not been fully explored. This thesis aims to: 1) Demonstrate the effect of a priori information on performance. 2) Identify whether a priori information modifies the visual search patterns of radiologists. 3) Establish whether any such effects influence the opinion of expert witnesses in medical malpractice litigation. Methods: All studies received institutional ethics approval. There were three studies. Study 1: A dataset of adult chest images was utilised consisting of 57 cases, of which 10 contained a single lung nodule. These were shown to 33 board certified radiologists. Before viewing, the radiologists were divided into three groups and were allocated to two of three conditions. Each condition offered different clinical information (previous cancer, no history, visa applicant). They were instructed to search for evidence of malignancy based on the differing clinical information. The radiologists were unaware of disease prevalence. They were also unaware that the same dataset was used for each of the three conditions. Each reader was asked to locate any nodule and to provide a confidence rating using a scale of 1-5. Location sensitivity, specificity and JAFROC figure of merit were used to compare radiologist’s performance between conditions. Study 2: The same methodology as described in study 1 was utilised. In this experiment, the visual search patterns of 17 board certified radiologists were undertaken. Search time, dwell time and time to first fixation metrics were analysed. Study3: Twelve board certified radiologists were asked to interpret 40 adult chest images (50%) abnormal twice with each reading separated by a two week washout period. Generic clinical information (defendant’s read: cough 3+ weeks) was proffered for the initial viewing and very specific location based clinical information for the final read (expert witness read). Location sensitivity, case sensitivity and specificity were used to compare radiologist performance between conditions. Results Study 1: A significant reduction in specificity was shown for the cancer compared with the visa condition (W = -41 P = 0.02). No other significant findings were demonstrated for this or the other condition comparisons. No significant difference in the performance of each group of radiologists was noted when viewing images under the same conditions. Study 2: For all images there was a significantly longer search time at high prevalence expectation compared to low prevalence expectation (W = 75.19, P = < 0.0001). Mann – Whitney analysis of the abnormal images demonstrated that the dwell time on correctly identified lesions was significantly shorter at low prevalence expectation compared to both unknown (U=364.5, P=0.02) and high prevalence expectation (U= 397.0, P=0.0002). Study 3: Our final results demonstrated that there was a significant difference in location based sensitivity (W = -45 P = 0.02) between the two conditions with nodule detection increasing under the second condition. Specificity increased outside the lobe of interest (W = 727 P=< 0.0001) and decreased within the lobe of interest (W = -237 P= 0.03) significantly in the “expert witness” read. Case based sensitivity and case based specificity were unaffected. Conclusions: There is a reduction in specificity with high compared with low prevalence expectation. An increase in false positive decisions can have important clinical consequences leading to unnecessary interventions. The results and their implications emphasise the caution that should be placed on providing accurate referral criteria. Search and dwell times were all affected by changing a priori information where such information fosters an expectation of abnormality. This final study showed evidence that increased clinical information affects the performance of radiologists. This effect may bias expert witnesses in radiological malpractice litigation.;Access is restricted to staff and students of the University of Sydney . UniKey credentials are required. Non university access may be obtained by visiting the University of Sydney Library.
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Type Of Material: OTHER
Appears in Collections:Postgraduate Theses

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