Mount Sinai Beth Israel, New York, NY
Copyright 2016, American College of Chest Physicians. All Rights Reserved.
SESSION TITLE: Pulmonary Vascular Disease - PE/DVT
SESSION TYPE: Original Investigation Poster
PRESENTED ON: Wednesday, October 26, 2016 at 01:30 PM - 02:30 PM
PURPOSE: Chest CT Angiography (CTA) is a sensitive and specific test for diagnosing acute Pulmonary Embolism (PE); however, literature suggests it is associated with a significant false positive rate when a solitary PE is diagnosed in the segmental and sub-segmental branches. The aim of this study was to determine the false positive chest CTA rate and to evaluate the clinical characteristics of these patients and the radiological quality of these scans. We hypothesized that false positive scans would be more commonly diagnosed by a Chest Radiologist (CR) as compared to a general radiologist (GR) or radiology trainee (RT) and that providing all relevant clinical information might increase diagnostic accuracy.
METHODS: We generated a randomized list of one hundred previously interpreted Chest CTA performed at large urban academic medical center that included a proportional number of scans positive for multi-vessel PE, negative for PE, and positive for sole segmental and subsegmental PE. Scans were obtained from a retrospective database of consecutive patients who underwent CTA with PE protocol in the emergency department. The CR, GR, and RT's separately read each scan blinded to the original interpretation. They commented on the presence of a PE, it’s location, and image quality. The scans were subsequently interpreted a second time by the same radiologists but with clinical information available including vital signs, a independently calculated Wells Scores, and if available a D-Dimer. The CR's interpretation was defined as the gold standard for all analysis. Statistical analysis was performed using R-Studio.
RESULTS: When the original CTA was re-read, the discordance (DR) and false positive rate (FPR) for PE determined by the CR was 16.1% and 34%, respectively. Subsequently, the GR and two RT's demonstrated a FPR of 10%, 13%, and 6%, respectively when compared to the gold standard. The discordance rate between the original CTA and re-read CTA occurred most frequently when the PE was solitary (81.2%) or located in the segmental (31.3%), and subsegmental (61.5%) branch. The discordance rate did not change when radiologists were given clinical information. The DR between the CR and the GR was 5%. Of the false positive CTA (n=16), the CR rated 87.5% of them as suboptimal in quality and 31.2% as non-diagnostic. Forty three percent had unlikely pretest probability for PE. The CR rated 45% of all exams read as suboptimal in quality and 16% non-diagnostic.
CONCLUSIONS: There was a high discordance and false positive rate of Chest CTA diagnosed after a chest radiologist reviewed previous chest CTA. A significant number of false positive scans occurred in suboptimal scans that had sole segmental and subsegmental PE and where the pre-test probability was low.
CLINICAL IMPLICATIONS: In view of potential bleeding complications and costs associated with anti-coagulation for the treatment of pulmonary embolism, we recommend that Chest CTA be interpreted by a radiologist with advanced training. When a positive Chest CTA is suboptimal and the patient's pre-test probability is low, there should be significant concern for a false positive interpretation. Providing information on the patient's pre-test probability to the CR may not increase overall diagnostic accuracy.
DISCLOSURE: The following authors have nothing to disclose: Jason Filopei, Stacey Verzosa, Jaime Deseda, Rydhwana Hossain, Jody Shen, Michael Obedian, Morris Hayim, Aloke Chakravarti, Dairon Garcia, David Steiger
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