Radiology resident evaluation of head CT scan orders in the emergency department

Abstract

Background and purpose: Prior studies have revealed little difference in residents' abilities to interpret cranial CT scans. The purpose of this study was to assess the performance of radiology residents at different levels of training in the interpretation of emergency head CT images.

Methods: Radiology residents prospectively interpreted 1324 consecutive head CT scans ordered in the emergency department at the University of Arizona Health Science Center. The residents completed a preliminary interpretation form that included their interpretation and confidence in that interpretation. One of five neuroradiologists with a Certificate of Added Qualification subsequently interpreted the images and classified their assessment of the residents' interpretations as follows: "agree," "disagree-insignificant," or "disagree-significant." The data were analyzed by using analysis-of-variance or chi-squared methods.

Results: Overall, the agreement rate was 91%; the insignificant disagreement rate, 7%; and the significant disagreement rate, 2%. The level of training had a significant (P =.032) effect on the rate of agreement; upper-level residents had higher rates of agreement than those of more junior residents. There were 62 false-negative findings. The most commonly missed findings were fractures (n = 18) and chronic ischemic foci (n = 12). The most common false-positive interpretations involved 10 suspected intracranial hemorrhages and suspected fractures.

Conclusion: The level of resident training has a significant effect on the rate of disagreement between the preliminary interpretations of emergency cranial CT scans by residents and the final interpretations by neuroradiologists. Efforts to reduce residents' errors should focus on the identification of fractures and signs of chronic ischemic change.

Fig 1.

Axial CT scan (A) and MR image (B) show false-negative finding involving ischemic disease. A, Acute right occipital infarct is visible as both hypoattenuating gray matter and hypoattenuating white matter, with associated sulcal effacement (arrows). B, Proton density–weighted (2400/30 [TR/TE]) MR image confirms the findings (arrows).

Fig 2.

Axial CT image obtained in a patient with schizencephaly and callosal dysgenesis shows an error in synthesis that was considered significant. Note the communication of the right lateral ventricle with the subarachnoid space (arrows) and the characteristic configuration of the occipital horns.

Fig 3.

Contiguous 5-mm non–contrast-enhanced routine axial CT scans demonstrate a large mass (arrows) in the sella in a case of pituitary macroadenoma.

Fig 4.

Axial images show metastatic disease interpreted as infarction. A, CT image shows a right frontal lobe mass (arrows). B, On the CT section adjacent to A, vasogenic edema (arrows) is evident. C, Contrast-enhanced MR image more clearly shows the mass (arrows).