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Small Pulmonary Artery Defects Are Not Reliable Indicators of Pulmonary Embolism.
Ann Am Thorac Soc. 2015 May 11;
Authors: Miller WT, Marinari LA, Barbosa E, Litt HI, Schmitt JE, Mahne A, Lee V, Akers SR
Abstract
OBJECTIVE: To evaluate the rate of agreement of pulmonary embolism in CT-pulmonary angiogram (CTPA) studies and to evaluate the rate of inaccurate interpretations in the community hospital setting.
METHODS: Using the keywords "pulmonary embolism/embolus/emboli," the radiology information system was searched for CTPA performed over a 3-year period at three US community hospitals. Studies containing probable or definite pulmonary emboli were reviewed independently by four subspecialty thoracic radiologists.
RESULTS: Agreement about the presence of PE progressively decreased with decreasing diameter of pulmonary vascular lesions (p<.0001). There was a sharp fall in observer agreement for PE of subsegmental lesions (p<.0001). The frequency of agreement decreased with decreasing quality of the imaging exam (p<.0001). Community radiologists were prone to false positive PE diagnosis of small and/or peripheral pulmonary arterial defects. The probability of a false positive diagnosis and indeterminate exams progressively increased with 1) more peripheral location of the lesion, 2) decreased size (short axis diameter) of the lesion and 3) with diminishing quality of the CT examination. 48/177 (27%) of subsegmental vascular defects identified by community radiologists were deemed indeterminate and 27/177 (15%) of subsegmental vascular defects were judged to be false positive for pulmonary embolism by the consensus diagnosis. 54/274 (20%) of vascular defects with short axis less than 6mm were indeterminate for pulmonary embolism and 37/274 (14%) of vascular defects with short axis less than 6mm were false positive for pulmonary embolism. 11/13 (85%) of vascular lesions identified as pulmonary emboli on the lowest quality CT examinations were false positive or indeterminate for pulmonary embolism. False positive examinations were most often due to respiratory motion artifact (19/38, 50%).
CONCLUSIONS: There is relatively poor interobserver agreement for subsegmental and/or small pulmonary artery defects, especially in CTPA degraded by technical artifacts. These factors can lead to an increased frequency of inaccurate interpretation or indeterminate diagnosis of small or peripheral defects. Caution is indicated in interpreting the significance of small vascular defects in CTPA.
PMID: 25961445 [PubMed - as supplied by publisher]