Evaluation of Head CT Exams - Resident & Attending Diagnoses Elizabeth Krupinski, PhD William Berger, MD William Erly, MD University of Arizona

Rationale w Many medical centers offer 24-hour CT interpretation for the ED On-call system Teleradiology w Radiology residents often provide preliminary interpretations

Rationale w Previous reports indicate overall resident miss rates are low (< 2%) w No one has looked at differences between upper & lower level residents w Assessing the types of errors made by residents may help focus educational efforts

Methods w 1324 consecutive CT head exams ordered by ED w Initially interpreted by 1 of 18 radiology residents Interpretation Confidence rating on 6-point scale w 1 of 5 CAQ neuroradiologists interpreted exams same day or next morning Determined correlation of diagnoses

Correlation of Interpretations w Agree w Disagree - Insignificant No potential for adverse patient outcome Failure to identify ischemic white matter degeneration There was no error in synthesis

Correlation of Interpretations w Disagree - Significant Potential for adverse patient outcome Mistaking cytoxic edema of metestatic disease for ischemic change Gross error in synthesis without adverse outcome potential Mistaking dysgenesis of the corpus callosum for chronic hydrocephalus

Diagnostic Correlation

Disagreement Cases X 2 = 44.46, df = 2, p =

Year of Residency X 2 = 13.80, df = 6, p = 0.032

Resident Confidence X 2 = 37.55, df = 4, p =

Year of Residency F = 92.01, p =

Confidence & Cases X 2 = 74.56, df = 2, p =

Disagree - Insignificant w 42 False Negatives Chronic ischemic foci Fractures Atrophy w 17 False Positives Intracranial hemorrhage Fractures

Disagree - Significant w 14 False Negative Fractures Acute right occipital infarct Temporal lobe contusion Chronic cortical infarct Clius mass Small thalamic hemorrhage

Disagree - Significant w 3 Misinterpretation Metastatic disease as ischemic focus Tumor as infarct Chiari II malformation with callosal dysgenesis as hygroma-hydrocephalus-mass effect w 2 False Positive Cerebellar Hemorrhage Cerebral contusion

Conclusions w Resident error is low (< 2%) w Rate of potential change in patient outcome due to resident misinterpretation is low (0.05%) w Year of residency affects performance & confidence

Conclusions w When resident confidence is low, immediate consultation with neuroradiologist is advisable w Efforts to reduce resident errors should focus on ensuring that all bone window images are reviewed and on the signs of cytoxic versus vasogenic edema