Rationale and Objectives
To evaluate the interpretation of computed tomographic pulmonary angiograms performed outside of regular reporting hours, comparing the initial interpretation by the radiology resident to the attending radiologist.
Materials and Methods
Records for 840 consecutive computed tomographic pulmonary angiograms (CTPA) performed outside of regular reporting hours at two tertiary referral centers from January 1, 2004–December 31, 2005 were reviewed. The preliminary interpretation by the on-call radiology resident was compared to the subsequent final report issued by a subspecialty trained chest radiologist. Studies were stratified as positive, negative, or equivocal for pulmonary embolus. Cases with discordant interpretations or negative CTPA were reviewed to determine impact on clinical outcome. Patients were followed up to 12 months after CTPA to document any subsequent thromboembolic event.
Results
Sixteen percent (131/840) of CTPAs were reported positive by the staff radiologist. There was agreement in 90% (752/840) of studies ( P = .76, 95% confidence interval, 0.71–0.81) with 86% (114/133) agreement for studies interpreted as positive by residents, 95% (582/612) for studies interpreted as negative by residents, and 63% (60/95) for studies interpreted as equivocal by residents. Studies of optimal quality had higher interobserver agreement than studies of suboptimal quality ( P < .0001). In-patient studies were more likely to be positive than emergency room patients (20% vs. 13%) ( P = .004). No adverse clinical outcomes were attributed to discordant interpretations.
Conclusions
Radiology residents provide a high level interpretation of on-call CTPA studies, achieving good concordance with the attending radiologists’ assessment.
Acute pulmonary embolism (PE) is estimated to cause 50,000 to 100,000 deaths annually in the United States ( ). It is a potentially treatable condition; therefore, an accurate and early diagnosis is essential. Computed tomographic pulmonary angiography (CTPA) is an important diagnostic tool used to evaluate patients presenting with symptoms suggestive of PE. Given the potential seriousness of a positive diagnosis, these examinations are triaged as high priority scans, and during regular working hours, a staff radiologist will communicate a report to the patient’s physician expeditiously to facilitate appropriate management.
At many academic institutions, CTPA examinations that are performed out of regular clinical hours (“on call”) are initially read by radiology residents, who provide a preliminary interpretation. A staff radiologist subsequently reviews the study. Several studies have demonstrated good concordance between resident and attending interpretations of on-call studies in general ( ), but there have been a limited number of studies examining resident interpretation of CTPA ( ). These studies are limited by a small number of patients and have few resident observers. Moreover, the impact of the initial radiology report on clinical decision-making and patient outcome has not been assessed in these studies. Ginsberg et al. ( ) performed a larger retrospective study with 658 CTPA examinations in which they compared the performance of on-call radiology fellows with that of staff radiologists and reported a good correlation between the two groups. These results cannot easily be extrapolated to most academic institutions in which radiology residents, not fellows, are the primary interpreters of these studies after hours.
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Materials and methods
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CT Technique
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Residency Structure and Precall Preparation
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Interpretation
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Data Collection and Analysis
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Table 1
Data Recorded for Each CT Pulmonary Angiogram
Age Sex Date study completed Hospital site (A, B) Patient location (inpatient, emergency department) Time study completed Time resident report entered Rank of resident Resident interpretation Staff interpretation Type of scanner (4-, 8-, 64-row detector)
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Results
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Agreement
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Table 2
Summary of Interpretations of 840 CT Pulmonary Angiograms by Radiology Residents and Attending Staff
Resident Interpretation Attending Interpretation Negative (%) Equivocal (%) Positive (%) Negative (%) 582 (69) 19 (2.3) 11 (1.3) Equivocal (%) 29 (3.5) 60 (7) 6 (0.7) Positive (%) 13 (1.5) 6 (0.7) 114 (13.6) Total (%) 624 (74) 85 (10) 131 (15.6)
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Discordant Results
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Clinical Outcome for Discordant Cases
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Table 3
Clinical Outcome in Discordant Interpretations
Type of Discordant Interpretation (Resident/Staff) No. of Patients Anticoagulated/No. of Discordant CT Pulmonary Angiograms Comments Negative/positive 11/11 No complications from delay in AC Positive/negative 2/13 2 short-term AC, discontinued with no complications Negative/equivocal 5/19 2 short-term AC, discontinued with no complications 1 long-term AC as patient clinically high risk for embolism, no complications 2 lifelong AC Positive/equivocal 3/6 1 short-term AC, discontinued with no complications 1 long-term AC as repeat CT 1 day later was positive, no complications 1 lifelong AC Equivocal/positive 6/6 No complications from delay in AC Equivocal/negative 7/29 5 short-term AC, discontinued with no complications 2 lifelong AC
AC, anticoagulation therapy.
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Clinical Significance of a Negative CTPA Study
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Follow-up Studies
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Agreement by Quality
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Table 4
Factors Limiting the Interpretation of CT Pulmonary Angiograms in 112 Patients
Number of Scans Factor ⁎ N = 112 (%) Poor contrast opacification 54 (48) Respiratory motion 50 (45) Streak artifact 2 (2) Cardiac pulsation artifact 1 (1) Patient motion 1 (1) Atelectasis 1 (1) Not specified 3 (3)
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Agreement by Year of Residency
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Agreement by Type of Scanner
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Likelihood of a Positive Study Based on Patent Location
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Discussion
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