Preliminary reports in the emergency department: is a subspecialist radiologist more accurate than a radiology resident?

RATIONALE AND OBJECTIVES: To determine whether emergency department (ED) preliminary reports rendered by subspecialist attending radiologists who are reading outside their field of expertise are more accurate than reports rendered by radiology residents, and to compare error rates between radiologists and nonradiologists in the ED setting. MATERIALS AND METHODS: The study was performed at a large academic medical center with a busy ED. An electronic preliminary report generator was used in the ED to capture preliminary interpretations rendered in a clinical setting by radiology residents, junior attendings (within 2 years of taking their oral boards), senior attendings, and ED clinicians between August 1999 and November 2004. Each preliminary report was later reviewed by a final interpreting radiologist, and the preliminary interpretation was adjudicated for the presence of substantial discordances, defined as a difference in interpretation that might immediately impact the care of the patient. Of the 612,890 preliminary reports in the database, 65,780 (11%) met inclusion criteria for this study. A log-linear analysis was used to assess the effects of modality and type of author on preliminary report error rates. RESULTS: ED clinicians had significantly higher error rates when compared with any type of radiologist, regardless of modality. Within the radiologists, residents and junior attendings had lower error rates than did senior attendings, but the differences were not statistically significant. CONCLUSION: Subspecialized attending radiologists who interpret ED examinations outside their area of expertise have error rates similar to those of radiology residents. Nonradiologists have significantly higher error rates than radiologists and radiology residents when interpreting examinations in the ED.

Contrast dynamics during CT pulmonary angiogram: analysis of an inspiration associated artifact.

OBJECTIVE: Several artifacts have been observed during contrast-enhanced CT of the pulmonary arteries. We describe a physiological artifact caused by a transient interruption of the contrast column in the pulmonary arteries associated with inspiration immediately prior to imaging. This results from a variable inflow of unopacified blood from the inferior vena cava (IVC). MATERIALS AND METHODS: From 327 consecutive pulmonary CT-angiograms, all performed on a single detector scanner at 3 mm collimation (1.5 mm incremental reconstruction), 50 positive studies, 46 indeterminate studies, and 33 negative studies (129 exams) were retrospectively reviewed by a blinded observer to determine the frequency of the described contrast interruption, its severity (mild, moderate, or severe), and its possible contribution to misinterpretation of studies. The numerical change in Hounsfield units was assigned within the right ventricular chamber for each examination to correlate with the subjective evaluation of severity. Statistical significance was determined with P = 0.05%. RESULTS: The artifact was present in 48 (37.2%) of the 129 evaluated studies. It was greater in frequency (50.0%) with the negative studies. The presence was 25% with positive studies and 36.7% with indeterminate exams. The interruption was more often mild (<100 HU change) in severity (45.8%). Three (6.6%) definite false positives were detected where the misinterpretation was directly attributed to the artifact. Three (6.6%) other examinations called positive were also directly related to the interrupted contrast column. However, since no further pulmonary vascular evaluation was performed, these examinations can only be considered indeterminate. Two of the latter 3 studies demonstrated a severe (>150 HU change) and the other study demonstrated a moderate (100-150 HU) interruption of contrast opacification. CONCLUSIONS: During inspiration, there is a variable increase in unopacified venous blood from the IVC, briefly diluting the contrast column entering from the SVC. This interruption is common, though usually mild in severity. However, a short severe interruption of vascular opacification can lead to misinterpretation as a pulmonary embolus or contribute to an indeterminate examination.