Purpose: To measure diagnostic accuracy of fracture detection, visual accommodation, reading time, and subjective ratings of fatigue and visual strain before and after a day of clinical reading. Methods:Forty attending radiologists and radiology residents viewed 60 de-identified HIPAA compliant bone examinations, half with fractures, once before any clinical reading (Early) and once after a day of clinical reading (Late). Reading time was recorded. Visual accommodation (ability to maintain focus) was measured before and after each reading session. Subjective ratings of symptoms of fatigue and oculomotor strain were collected. The study was approved by local IRBs.Results: Diagnostic accuracy was reduced significantly after a day of clinical reading, with average receiver operating characteristic (ROC) area under the curve (AUC) of 0.885 for Early reading and 0.852 for Late reading (p < 0.05). After a day of image interpretation, visual accommodation was no more variable, though error in visual accommodation was greater (p < 0.01) and subjective ratings of fatigue were higher. Conclusions:After a day of clinical reading, radiologists have reduced ability to focus, increased symptoms of fatigue and oculomotor strain, and reduced ability to detect fractures. Radiologists need to be aware of the effects of fatigue on diagnostic accuracy and take steps to mitigate these effects.

There are several different statistical methods for analysing multireader ROC studies, with the Dorfman-Berbaum-Metz (DBM) method being the most frequently used. Another method is the corrected F method proposed by Obuchowski and Rockette (OR). The DBM and OR procedures at first appear quite different: DBM is a three-way ANOVA analysis of pseudovalues while OR is a two-way ANOVA analysis of accuracy estimates with correlated errors. We show that the original DBM and OR F statistics for testing the null hypothesis of equal treatments have the same form and will typically have similar values; however, differences in the denominator degrees of freedom will result in differences in p-values even when the F statistics are identical. We show how the methods can be generalized to include variations in the accuracy measure, covariance method, and degrees of freedom. Identical results are obtained when the methods agree with respect to all three of these procedure parameters; hence for a particular choice of procedure parameters the choice of method appears to depend mainly on software preference and availability. The methods are compared using data from a factorial study with two modalities, five readers, and 114 patients.

Purpose A previous study demonstrated decreased diagnostic accuracy for finding fractures and decreased ability to focus on skeletal radiographs after a long working day. Skeletal radiographic examinations commonly have images that are displayed statically. This study investigated whether diagnostic accuracy for detecting pulmonary nodules in computed tomography (CT) of the chest displayed dynamically would be similarly affected by fatigue. Methods Twenty-two radiologists and 22 residents were given two tests searching CT chest sequences for a solitary pulmonary nodule before and after a day of clinical reading. To measure search time, ten lung CT sequences, each containing 20 consecutive sections and a single nodule, were inspected using free search and navigation. To measure diagnostic accuracy, one hundred CT sequences, each with 20 sections and half with nodules, were displayed at preset scrolling speed and duration. Accuracy was measured using ROC analysis. Visual strain was measured via dark vergence, an indicator of the ability to keep the eyes focused on the display. Results Diagnostic accuracy was reduced after a day of clinical reading (p = 0.0246), but search time was not affected (p > 0.05). After a day of reading, dark vergence was significantly larger and more variable (p = 0.0098), reflecting higher levels of visual strain and subjective ratings of fatigue were also higher. Conclusions After their usual workday, radiologists experience increased fatigue and decreased diagnostic accuracy for detecting pulmonary nodules on CT. Effects of fatigue may be mitigated by active interaction with the display.

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