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.
Historically, radiology research has been dominated by chest and breast screening. Few studies have examined complex
interpretative tasks such as the reading of multidimensional brain CT or MRI scans. Additionally, no studies at the time
of writing have explored the interpretation of stroke images; from novices through to experienced practitioners using eye
movement analysis. Finally, there appears a lack of evidence on the clinical effects of radiology reports and their
influence on image appraisal and clinical diagnosis. A computer-based, eye-tracking study was designed to assess
diagnostic accuracy and interpretation in stroke CT and MR imagery. Eight predetermined clinical cases, five images per
case, were presented to participants (novices, trainee, and radiologists; n=8). The presence or absence of abnormalities
was rated on a five-point Likert scale and their locations reported. Half cases of the cases were accompanied by clinical
information; half were not, to assess the impact of information on observer performance. Results highlight differences in
visual search patterns amongst novice, trainee and expert observers; the most marked differences occurred between
novice readers and experts. Experts spent more time in challenging areas of interest (AOI) than novices and trainee, and
were more confident unless a lesion was large and obvious. The time to first AOI fixation differed by size, shape and
clarity of lesion. 'Time to lesion' dropped significantly when recognition appeared to occur between slices. The
influence of clinical information was minimal.
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