Hazel J. Scott

The assessment of stroke multidimensional CT and MR imaging using eye movement analysis: does modality preference enhance observer performance?

Although CT and MR imaging is now commonplace in the radiology department, few studies have examined complex interpretative tasks such as the reading of multidimensional brain CT or MRI scans from the observer performance perspective, especially with reference to Stroke. Modality performance studies have demonstrated a similar sensitivity of less than 50% for both conventional modalities, with neither modality proving superior to the other in Stroke observer performance tasks (Mohr, 1995; Lansberg, 2000; Wintermark, 2007). Visual search studies have not extensively explored stroke imaging and an in-depth, comparative eye-movement study between CT and MRI has not yet been conducted. A computer-based, eye-tracking study was designed to assess diagnostic accuracy and interpretation in stroke CT and MR imagery. Forty eight predetermined clinical cases, with five images per case, were presented to participants (novices, trainees and radiologists; n=28). The presence or absence of abnormalities was rated on a four-point Likert scale and their locations reported. Results highlight differences in visual search patterns amongst novice, trainee and expert observers; the most marked differences occurred between novice readers and experts. In terms of modality differences; novice and expert readers spent longer appraising CT images than MR, compared with trainees, who spent longer appraising MR than CT images. Image analysis trends did not appear to differ between modalities, but time spent within clinical images, accuracy and relative confidence performing the task did differ between CT and MR reader groups. To-date few studies have explored observer performance in neuroradiology and the present study examines multi-slice image appraisal by comparing matched pairs of CT and MRI Stroke cases.

Generic Infrastructure for Medical Informatics (GIMI): The Development of a Mammographic Training System

In the UK, a large-scale collaborative research project (GIMI: Generic Infrastructures for Medical Informatics) is underway which is concerned with the development of a secure IT infrastructure to support very widespread medical research across the country. One aspect of this project is to develop a training tool for potential use by mammographers in the UK Breast Screening Programme. A working prototype system has been developed which is currently being tested by clinical colleagues so as to enable it to be further developed prior to any wider deployment. This is currently based on knowing an individuals strengths and weaknesses in mammographic interpretation. The background to the project is given and then the ongoing research is detailed together with future plans for the proposed system.

Breast Screening: visual search as an aid for digital mammographic interpretation training

Digital mammography is gradually being introduced across all breast screening centres in the UK during 2010. This provides increased training opportunities using lower resolution, lower cost and more widely available devices, in addition to the clinical digital mammography workstations. This study examined how experienced breast screening personnel performed when they examined sets of difficult DICOM two-view screening cases in three conditions: on GE digital mammography workstations, on a standard LCD monitor (using a DICOM viewer) and an iPhone (running Osirix software). In each condition they either viewed the full images unaided or were permitted to use the post-processing manipulations of pan, zoom and window level/width adjustments. For each case they had to report the feature type, rate their confidence on the presence of abnormality, classify the case and specify case density. Their visual search behaviour was recorded throughout using a head mounted eye tracker. Additionally aspects of their real life screening performance and performance on a national self assessment scheme were examined. Data indicate that screening experience plays a major role in doing well on the self assessment scheme. Task performance was best on the clinical workstation. However, the data also suggest that a DICOM viewer that runs on a PC or laptop with a standard LCD display allows viewing digital images in full resolution support impressive cancer detection performance. The iPhone is not ideal for examining full images due to the amount of scrolling and zooming required. Overall, the results indicate that low cost devices could be used to provide additional tailored training as long as device resolution and HCI aspects are carefully considered.

Mammographic interpretation training: how useful is handheld technology?

In the UK a national self-assessment scheme (PERFORMS) for mammographers is undertaken as part of the National Health Search Breast Screening Programme. Where appropriate, further training is suggested to improve performance. Ideally, such training would be on-demand; that is whenever and wherever an individual decides to undertake it. To use a portable device for such a purpose would be attractive on many levels. However, it is not known whether handheld technology can be used effectively for viewing mammographic images. Previous studies indicate the potential for viewing medical images with fairly low spatial resolution (e.g. CT, MRI) on PDAs. In this study, we set out to investigate factors that might affect the feasibility of using PDAs as a training technology for examining large, high resolution mammographic images. Two studies are reported: 20 mammographers examined a series of mammograms presented on a PDA, specifying the location of any abnormality. Secondly, a group of technologists examined a series of mammograms presented at different sizes and resolutions to mimic presentation on a PDA and their eye movements were recorded. The results indicate the potential for using PDAs to show such large, high resolution images if suitable Human-computer Interaction (HCI) techniques are employed.

Breast screening technologists: Does real-life case volume affect performance?

In the UK fewer radiologists are now specialising in breast cancer screening. Consequently, a number of technologists have been specially trained to read mammograms so as to double-read with existing radiologists. Each year the majority of these film-readers examine a set of difficult cases as a means of self-assessing their skills. We investigated whether the technologists performed as well as breast-screening radiologists on this difficult test set. We also investigated technologists’ performance over a number of years to compare the performance of those technologists who have read a greater number of breast screening films and those who have had less experience. Finally, we investigated real-life experience and performance on the scheme by comparing; volume of cases read, experience, and technologists’ performance over time versus radiologists’ performance. Data for approximately 250 breast screening Radiologists and 80 specially trained technologists over three years for six sets of 60 difficult recent screening cases were examined. Overall, those technologists who have not read the same volume of cases as radiologists did not perform as well on this particular task. Although when the group was fractionated by volume of cases read in real-life and the number of years reading cases, then the technologists performed at a level similar to the radiologists.

Computer-Based Learning to Improve Breast Cancer Detection Skills

In breast cancer screening it is important both to improve and maintain cancer detection skills at their highest levels. The introduction of digital imaging enables computer-based learning to be undertaken outside breast screening centres using a range of different devices. The potential for providing computer-based interpretation training using low-cost devices is detailed. The results demonstrated that naive observers can be trained to recognise certain key breast cancer appearances using a low cost display monitor along with a range of HCI techniques.

Breast ultrasound training scheme

Ultrasonography is a common follow-up procedure in breast screening to help elucidate the nature of potential abnormalities. Due to the inherent properties of the imaging modality, these images are of fairly low resolution, as compared with mammography, and therefore pose a different interpretation problem for the radiologist or imaging specialist. We describe the steps involved in the development of a PC-based training scheme for improving the interpretation of ultrasound images. Using the existing current literature, ultrasound image features were identified. The key features and the reported difficulty that individuals had in identifying these were then logged. The construction of an image database was then undertaken with the aim of amassing both static images and video clips of imagery that posed particular interpretative challenges. Various optional interfaces that allow participants to make and record decisions are currently being assessed. Once complete, the system will be fully trialled and then will be made available freely available to UK screening personnel.

European breast screening performance: does case volume matter?

U.K. breast screening radiologists typically read over 5,000 screening cases per annum, whereas in Europe this figure may be lower as in some countries national breast screening programs are in development. The PERFORMS scheme in the UK permits radiologists annual self-assessment of their film-reader skills. As part of a Bavarian breast-screening training scheme a number of German radiologists have now also read the current PERFORMS case set. We investigated whether real-life case volume affects reading performance by the comparison of matched groups reading these screening cases. For each case, individuals identified which key mammographic features were present, whether the case was abnormal and should be recalled or not. For this analysis the participants were matched on volume of cases read and years of experience. Assessment of case volume was elicited by questionnaire data. The radiologists were compared on several key performance measures; cancers detected, correct recall and correct return to screen, signal detection performance statistics and real-life screening practice. It was found that whilst the performance of the Bavarian radiologists on the current test sets was extremely good, on average they performed less well than their UK counterparts. Reasons for this are considered.