Influence of using recommended radiological criteria on MDCT-angiography diagnosis of single isolated subsegmental pulmonary embolism

Objectives We assessed the rate of false-positive diagnoses of MDCT-pulmonary angiography (MDCT-A) in patients with single isolated subsegmental pulmonary embolism (SISSPE). Methods All patients who underwent MDCT-A between 2006 and 2017 for ruling out acute pulmonary embolism (PE) and received an initial diagnosis of SISSPE were included. The MDCT-A of these patients were reviewed retrospectively by four experienced thoracic radiologists, who applied radiological criteria recommended by the American College of Chest Physicians Antithrombotic Guidelines (ACCP 2016) for the diagnosis of SISSPE. Data extracted from medical records were history of venous thromboembolism (VTE), alternative diagnoses, other diagnostic studies for VTE, anticoagulation, bleeding complications, and VTE over the following 3 months. Results Of 3839 patients undergoing MDCT-A, PE was found in 1021 (26.6%) and SISSPE in 59 (1.5% overall and 5.8% of all patients with PE). An alternative diagnosis to PE was made on the basis of CT in 33 (55.9%) patients. Forty-one (69.5%) patients received anticoagulants, and major life-threatening bleeding complications occurred in 2, with one death. Recurrent PE was not documented in any patient with SISSPE. In the retrospective assessment of the 59 cases of SISSPE, 21 were negative for PE, with a false-positive rate of 35.6% (21/59); so the percentage of SISSPE cases after the revision was 3.7% of all patients with PE; 11 of these 21 patients received anticoagulation. Conclusions Radiologists should be aware of the high rate of false-positives when making the diagnosis of SISSPE on MDCT-A without using strict diagnostic criteria. Misdiagnosis exposes patients to unnecessary anticoagulation. Key Points • Radiologist should be aware of the high rate of false-positive diagnoses of single isolated subsegmental pulmonary embolism (SISSPE) in MDCT-pulmonary angiography (MDCT-A) performed for ruling out pulmonary embolism. • Misdiagnosis of SISSPE in MDCT-A can be reduced by using strict diagnostic radiological criteria recommended by the American College of Chest Physicians Antithrombotic Guidelines. • Unnecessary anticoagulation therapy with potential severe bleeding complications may result from misdiagnosis of SISSPE.